xref: /openbmc/linux/mm/page_alloc.c (revision bcda5fd3)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/mm/page_alloc.c
4  *
5  *  Manages the free list, the system allocates free pages here.
6  *  Note that kmalloc() lives in slab.c
7  *
8  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
9  *  Swap reorganised 29.12.95, Stephen Tweedie
10  *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
11  *  Reshaped it to be a zoned allocator, Ingo Molnar, Red Hat, 1999
12  *  Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999
13  *  Zone balancing, Kanoj Sarcar, SGI, Jan 2000
14  *  Per cpu hot/cold page lists, bulk allocation, Martin J. Bligh, Sept 2002
15  *          (lots of bits borrowed from Ingo Molnar & Andrew Morton)
16  */
17 
18 #include <linux/stddef.h>
19 #include <linux/mm.h>
20 #include <linux/highmem.h>
21 #include <linux/swap.h>
22 #include <linux/interrupt.h>
23 #include <linux/pagemap.h>
24 #include <linux/jiffies.h>
25 #include <linux/memblock.h>
26 #include <linux/compiler.h>
27 #include <linux/kernel.h>
28 #include <linux/kasan.h>
29 #include <linux/module.h>
30 #include <linux/suspend.h>
31 #include <linux/pagevec.h>
32 #include <linux/blkdev.h>
33 #include <linux/slab.h>
34 #include <linux/ratelimit.h>
35 #include <linux/oom.h>
36 #include <linux/topology.h>
37 #include <linux/sysctl.h>
38 #include <linux/cpu.h>
39 #include <linux/cpuset.h>
40 #include <linux/memory_hotplug.h>
41 #include <linux/nodemask.h>
42 #include <linux/vmalloc.h>
43 #include <linux/vmstat.h>
44 #include <linux/mempolicy.h>
45 #include <linux/memremap.h>
46 #include <linux/stop_machine.h>
47 #include <linux/random.h>
48 #include <linux/sort.h>
49 #include <linux/pfn.h>
50 #include <linux/backing-dev.h>
51 #include <linux/fault-inject.h>
52 #include <linux/page-isolation.h>
53 #include <linux/debugobjects.h>
54 #include <linux/kmemleak.h>
55 #include <linux/compaction.h>
56 #include <trace/events/kmem.h>
57 #include <trace/events/oom.h>
58 #include <linux/prefetch.h>
59 #include <linux/mm_inline.h>
60 #include <linux/mmu_notifier.h>
61 #include <linux/migrate.h>
62 #include <linux/hugetlb.h>
63 #include <linux/sched/rt.h>
64 #include <linux/sched/mm.h>
65 #include <linux/page_owner.h>
66 #include <linux/kthread.h>
67 #include <linux/memcontrol.h>
68 #include <linux/ftrace.h>
69 #include <linux/lockdep.h>
70 #include <linux/nmi.h>
71 #include <linux/psi.h>
72 #include <linux/padata.h>
73 #include <linux/khugepaged.h>
74 #include <linux/buffer_head.h>
75 #include <asm/sections.h>
76 #include <asm/tlbflush.h>
77 #include <asm/div64.h>
78 #include "internal.h"
79 #include "shuffle.h"
80 #include "page_reporting.h"
81 
82 /* Free Page Internal flags: for internal, non-pcp variants of free_pages(). */
83 typedef int __bitwise fpi_t;
84 
85 /* No special request */
86 #define FPI_NONE		((__force fpi_t)0)
87 
88 /*
89  * Skip free page reporting notification for the (possibly merged) page.
90  * This does not hinder free page reporting from grabbing the page,
91  * reporting it and marking it "reported" -  it only skips notifying
92  * the free page reporting infrastructure about a newly freed page. For
93  * example, used when temporarily pulling a page from a freelist and
94  * putting it back unmodified.
95  */
96 #define FPI_SKIP_REPORT_NOTIFY	((__force fpi_t)BIT(0))
97 
98 /*
99  * Place the (possibly merged) page to the tail of the freelist. Will ignore
100  * page shuffling (relevant code - e.g., memory onlining - is expected to
101  * shuffle the whole zone).
102  *
103  * Note: No code should rely on this flag for correctness - it's purely
104  *       to allow for optimizations when handing back either fresh pages
105  *       (memory onlining) or untouched pages (page isolation, free page
106  *       reporting).
107  */
108 #define FPI_TO_TAIL		((__force fpi_t)BIT(1))
109 
110 /*
111  * Don't poison memory with KASAN (only for the tag-based modes).
112  * During boot, all non-reserved memblock memory is exposed to page_alloc.
113  * Poisoning all that memory lengthens boot time, especially on systems with
114  * large amount of RAM. This flag is used to skip that poisoning.
115  * This is only done for the tag-based KASAN modes, as those are able to
116  * detect memory corruptions with the memory tags assigned by default.
117  * All memory allocated normally after boot gets poisoned as usual.
118  */
119 #define FPI_SKIP_KASAN_POISON	((__force fpi_t)BIT(2))
120 
121 /* prevent >1 _updater_ of zone percpu pageset ->high and ->batch fields */
122 static DEFINE_MUTEX(pcp_batch_high_lock);
123 #define MIN_PERCPU_PAGELIST_HIGH_FRACTION (8)
124 
125 struct pagesets {
126 	local_lock_t lock;
127 };
128 static DEFINE_PER_CPU(struct pagesets, pagesets) = {
129 	.lock = INIT_LOCAL_LOCK(lock),
130 };
131 
132 #ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID
133 DEFINE_PER_CPU(int, numa_node);
134 EXPORT_PER_CPU_SYMBOL(numa_node);
135 #endif
136 
137 DEFINE_STATIC_KEY_TRUE(vm_numa_stat_key);
138 
139 #ifdef CONFIG_HAVE_MEMORYLESS_NODES
140 /*
141  * N.B., Do NOT reference the '_numa_mem_' per cpu variable directly.
142  * It will not be defined when CONFIG_HAVE_MEMORYLESS_NODES is not defined.
143  * Use the accessor functions set_numa_mem(), numa_mem_id() and cpu_to_mem()
144  * defined in <linux/topology.h>.
145  */
146 DEFINE_PER_CPU(int, _numa_mem_);		/* Kernel "local memory" node */
147 EXPORT_PER_CPU_SYMBOL(_numa_mem_);
148 #endif
149 
150 /* work_structs for global per-cpu drains */
151 struct pcpu_drain {
152 	struct zone *zone;
153 	struct work_struct work;
154 };
155 static DEFINE_MUTEX(pcpu_drain_mutex);
156 static DEFINE_PER_CPU(struct pcpu_drain, pcpu_drain);
157 
158 #ifdef CONFIG_GCC_PLUGIN_LATENT_ENTROPY
159 volatile unsigned long latent_entropy __latent_entropy;
160 EXPORT_SYMBOL(latent_entropy);
161 #endif
162 
163 /*
164  * Array of node states.
165  */
166 nodemask_t node_states[NR_NODE_STATES] __read_mostly = {
167 	[N_POSSIBLE] = NODE_MASK_ALL,
168 	[N_ONLINE] = { { [0] = 1UL } },
169 #ifndef CONFIG_NUMA
170 	[N_NORMAL_MEMORY] = { { [0] = 1UL } },
171 #ifdef CONFIG_HIGHMEM
172 	[N_HIGH_MEMORY] = { { [0] = 1UL } },
173 #endif
174 	[N_MEMORY] = { { [0] = 1UL } },
175 	[N_CPU] = { { [0] = 1UL } },
176 #endif	/* NUMA */
177 };
178 EXPORT_SYMBOL(node_states);
179 
180 atomic_long_t _totalram_pages __read_mostly;
181 EXPORT_SYMBOL(_totalram_pages);
182 unsigned long totalreserve_pages __read_mostly;
183 unsigned long totalcma_pages __read_mostly;
184 
185 int percpu_pagelist_high_fraction;
186 gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
187 DEFINE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, init_on_alloc);
188 EXPORT_SYMBOL(init_on_alloc);
189 
190 DEFINE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_FREE_DEFAULT_ON, init_on_free);
191 EXPORT_SYMBOL(init_on_free);
192 
193 static bool _init_on_alloc_enabled_early __read_mostly
194 				= IS_ENABLED(CONFIG_INIT_ON_ALLOC_DEFAULT_ON);
195 static int __init early_init_on_alloc(char *buf)
196 {
197 
198 	return kstrtobool(buf, &_init_on_alloc_enabled_early);
199 }
200 early_param("init_on_alloc", early_init_on_alloc);
201 
202 static bool _init_on_free_enabled_early __read_mostly
203 				= IS_ENABLED(CONFIG_INIT_ON_FREE_DEFAULT_ON);
204 static int __init early_init_on_free(char *buf)
205 {
206 	return kstrtobool(buf, &_init_on_free_enabled_early);
207 }
208 early_param("init_on_free", early_init_on_free);
209 
210 /*
211  * A cached value of the page's pageblock's migratetype, used when the page is
212  * put on a pcplist. Used to avoid the pageblock migratetype lookup when
213  * freeing from pcplists in most cases, at the cost of possibly becoming stale.
214  * Also the migratetype set in the page does not necessarily match the pcplist
215  * index, e.g. page might have MIGRATE_CMA set but be on a pcplist with any
216  * other index - this ensures that it will be put on the correct CMA freelist.
217  */
218 static inline int get_pcppage_migratetype(struct page *page)
219 {
220 	return page->index;
221 }
222 
223 static inline void set_pcppage_migratetype(struct page *page, int migratetype)
224 {
225 	page->index = migratetype;
226 }
227 
228 #ifdef CONFIG_PM_SLEEP
229 /*
230  * The following functions are used by the suspend/hibernate code to temporarily
231  * change gfp_allowed_mask in order to avoid using I/O during memory allocations
232  * while devices are suspended.  To avoid races with the suspend/hibernate code,
233  * they should always be called with system_transition_mutex held
234  * (gfp_allowed_mask also should only be modified with system_transition_mutex
235  * held, unless the suspend/hibernate code is guaranteed not to run in parallel
236  * with that modification).
237  */
238 
239 static gfp_t saved_gfp_mask;
240 
241 void pm_restore_gfp_mask(void)
242 {
243 	WARN_ON(!mutex_is_locked(&system_transition_mutex));
244 	if (saved_gfp_mask) {
245 		gfp_allowed_mask = saved_gfp_mask;
246 		saved_gfp_mask = 0;
247 	}
248 }
249 
250 void pm_restrict_gfp_mask(void)
251 {
252 	WARN_ON(!mutex_is_locked(&system_transition_mutex));
253 	WARN_ON(saved_gfp_mask);
254 	saved_gfp_mask = gfp_allowed_mask;
255 	gfp_allowed_mask &= ~(__GFP_IO | __GFP_FS);
256 }
257 
258 bool pm_suspended_storage(void)
259 {
260 	if ((gfp_allowed_mask & (__GFP_IO | __GFP_FS)) == (__GFP_IO | __GFP_FS))
261 		return false;
262 	return true;
263 }
264 #endif /* CONFIG_PM_SLEEP */
265 
266 #ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
267 unsigned int pageblock_order __read_mostly;
268 #endif
269 
270 static void __free_pages_ok(struct page *page, unsigned int order,
271 			    fpi_t fpi_flags);
272 
273 /*
274  * results with 256, 32 in the lowmem_reserve sysctl:
275  *	1G machine -> (16M dma, 800M-16M normal, 1G-800M high)
276  *	1G machine -> (16M dma, 784M normal, 224M high)
277  *	NORMAL allocation will leave 784M/256 of ram reserved in the ZONE_DMA
278  *	HIGHMEM allocation will leave 224M/32 of ram reserved in ZONE_NORMAL
279  *	HIGHMEM allocation will leave (224M+784M)/256 of ram reserved in ZONE_DMA
280  *
281  * TBD: should special case ZONE_DMA32 machines here - in those we normally
282  * don't need any ZONE_NORMAL reservation
283  */
284 int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES] = {
285 #ifdef CONFIG_ZONE_DMA
286 	[ZONE_DMA] = 256,
287 #endif
288 #ifdef CONFIG_ZONE_DMA32
289 	[ZONE_DMA32] = 256,
290 #endif
291 	[ZONE_NORMAL] = 32,
292 #ifdef CONFIG_HIGHMEM
293 	[ZONE_HIGHMEM] = 0,
294 #endif
295 	[ZONE_MOVABLE] = 0,
296 };
297 
298 static char * const zone_names[MAX_NR_ZONES] = {
299 #ifdef CONFIG_ZONE_DMA
300 	 "DMA",
301 #endif
302 #ifdef CONFIG_ZONE_DMA32
303 	 "DMA32",
304 #endif
305 	 "Normal",
306 #ifdef CONFIG_HIGHMEM
307 	 "HighMem",
308 #endif
309 	 "Movable",
310 #ifdef CONFIG_ZONE_DEVICE
311 	 "Device",
312 #endif
313 };
314 
315 const char * const migratetype_names[MIGRATE_TYPES] = {
316 	"Unmovable",
317 	"Movable",
318 	"Reclaimable",
319 	"HighAtomic",
320 #ifdef CONFIG_CMA
321 	"CMA",
322 #endif
323 #ifdef CONFIG_MEMORY_ISOLATION
324 	"Isolate",
325 #endif
326 };
327 
328 compound_page_dtor * const compound_page_dtors[NR_COMPOUND_DTORS] = {
329 	[NULL_COMPOUND_DTOR] = NULL,
330 	[COMPOUND_PAGE_DTOR] = free_compound_page,
331 #ifdef CONFIG_HUGETLB_PAGE
332 	[HUGETLB_PAGE_DTOR] = free_huge_page,
333 #endif
334 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
335 	[TRANSHUGE_PAGE_DTOR] = free_transhuge_page,
336 #endif
337 };
338 
339 int min_free_kbytes = 1024;
340 int user_min_free_kbytes = -1;
341 int watermark_boost_factor __read_mostly = 15000;
342 int watermark_scale_factor = 10;
343 
344 static unsigned long nr_kernel_pages __initdata;
345 static unsigned long nr_all_pages __initdata;
346 static unsigned long dma_reserve __initdata;
347 
348 static unsigned long arch_zone_lowest_possible_pfn[MAX_NR_ZONES] __initdata;
349 static unsigned long arch_zone_highest_possible_pfn[MAX_NR_ZONES] __initdata;
350 static unsigned long required_kernelcore __initdata;
351 static unsigned long required_kernelcore_percent __initdata;
352 static unsigned long required_movablecore __initdata;
353 static unsigned long required_movablecore_percent __initdata;
354 static unsigned long zone_movable_pfn[MAX_NUMNODES] __initdata;
355 static bool mirrored_kernelcore __meminitdata;
356 
357 /* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
358 int movable_zone;
359 EXPORT_SYMBOL(movable_zone);
360 
361 #if MAX_NUMNODES > 1
362 unsigned int nr_node_ids __read_mostly = MAX_NUMNODES;
363 unsigned int nr_online_nodes __read_mostly = 1;
364 EXPORT_SYMBOL(nr_node_ids);
365 EXPORT_SYMBOL(nr_online_nodes);
366 #endif
367 
368 int page_group_by_mobility_disabled __read_mostly;
369 
370 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
371 /*
372  * During boot we initialize deferred pages on-demand, as needed, but once
373  * page_alloc_init_late() has finished, the deferred pages are all initialized,
374  * and we can permanently disable that path.
375  */
376 static DEFINE_STATIC_KEY_TRUE(deferred_pages);
377 
378 /*
379  * Calling kasan_poison_pages() only after deferred memory initialization
380  * has completed. Poisoning pages during deferred memory init will greatly
381  * lengthen the process and cause problem in large memory systems as the
382  * deferred pages initialization is done with interrupt disabled.
383  *
384  * Assuming that there will be no reference to those newly initialized
385  * pages before they are ever allocated, this should have no effect on
386  * KASAN memory tracking as the poison will be properly inserted at page
387  * allocation time. The only corner case is when pages are allocated by
388  * on-demand allocation and then freed again before the deferred pages
389  * initialization is done, but this is not likely to happen.
390  */
391 static inline bool should_skip_kasan_poison(struct page *page, fpi_t fpi_flags)
392 {
393 	return static_branch_unlikely(&deferred_pages) ||
394 	       (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
395 		(fpi_flags & FPI_SKIP_KASAN_POISON)) ||
396 	       PageSkipKASanPoison(page);
397 }
398 
399 /* Returns true if the struct page for the pfn is uninitialised */
400 static inline bool __meminit early_page_uninitialised(unsigned long pfn)
401 {
402 	int nid = early_pfn_to_nid(pfn);
403 
404 	if (node_online(nid) && pfn >= NODE_DATA(nid)->first_deferred_pfn)
405 		return true;
406 
407 	return false;
408 }
409 
410 /*
411  * Returns true when the remaining initialisation should be deferred until
412  * later in the boot cycle when it can be parallelised.
413  */
414 static bool __meminit
415 defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
416 {
417 	static unsigned long prev_end_pfn, nr_initialised;
418 
419 	/*
420 	 * prev_end_pfn static that contains the end of previous zone
421 	 * No need to protect because called very early in boot before smp_init.
422 	 */
423 	if (prev_end_pfn != end_pfn) {
424 		prev_end_pfn = end_pfn;
425 		nr_initialised = 0;
426 	}
427 
428 	/* Always populate low zones for address-constrained allocations */
429 	if (end_pfn < pgdat_end_pfn(NODE_DATA(nid)))
430 		return false;
431 
432 	if (NODE_DATA(nid)->first_deferred_pfn != ULONG_MAX)
433 		return true;
434 	/*
435 	 * We start only with one section of pages, more pages are added as
436 	 * needed until the rest of deferred pages are initialized.
437 	 */
438 	nr_initialised++;
439 	if ((nr_initialised > PAGES_PER_SECTION) &&
440 	    (pfn & (PAGES_PER_SECTION - 1)) == 0) {
441 		NODE_DATA(nid)->first_deferred_pfn = pfn;
442 		return true;
443 	}
444 	return false;
445 }
446 #else
447 static inline bool should_skip_kasan_poison(struct page *page, fpi_t fpi_flags)
448 {
449 	return (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
450 		(fpi_flags & FPI_SKIP_KASAN_POISON)) ||
451 	       PageSkipKASanPoison(page);
452 }
453 
454 static inline bool early_page_uninitialised(unsigned long pfn)
455 {
456 	return false;
457 }
458 
459 static inline bool defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
460 {
461 	return false;
462 }
463 #endif
464 
465 /* Return a pointer to the bitmap storing bits affecting a block of pages */
466 static inline unsigned long *get_pageblock_bitmap(const struct page *page,
467 							unsigned long pfn)
468 {
469 #ifdef CONFIG_SPARSEMEM
470 	return section_to_usemap(__pfn_to_section(pfn));
471 #else
472 	return page_zone(page)->pageblock_flags;
473 #endif /* CONFIG_SPARSEMEM */
474 }
475 
476 static inline int pfn_to_bitidx(const struct page *page, unsigned long pfn)
477 {
478 #ifdef CONFIG_SPARSEMEM
479 	pfn &= (PAGES_PER_SECTION-1);
480 #else
481 	pfn = pfn - round_down(page_zone(page)->zone_start_pfn, pageblock_nr_pages);
482 #endif /* CONFIG_SPARSEMEM */
483 	return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
484 }
485 
486 static __always_inline
487 unsigned long __get_pfnblock_flags_mask(const struct page *page,
488 					unsigned long pfn,
489 					unsigned long mask)
490 {
491 	unsigned long *bitmap;
492 	unsigned long bitidx, word_bitidx;
493 	unsigned long word;
494 
495 	bitmap = get_pageblock_bitmap(page, pfn);
496 	bitidx = pfn_to_bitidx(page, pfn);
497 	word_bitidx = bitidx / BITS_PER_LONG;
498 	bitidx &= (BITS_PER_LONG-1);
499 
500 	word = bitmap[word_bitidx];
501 	return (word >> bitidx) & mask;
502 }
503 
504 /**
505  * get_pfnblock_flags_mask - Return the requested group of flags for the pageblock_nr_pages block of pages
506  * @page: The page within the block of interest
507  * @pfn: The target page frame number
508  * @mask: mask of bits that the caller is interested in
509  *
510  * Return: pageblock_bits flags
511  */
512 unsigned long get_pfnblock_flags_mask(const struct page *page,
513 					unsigned long pfn, unsigned long mask)
514 {
515 	return __get_pfnblock_flags_mask(page, pfn, mask);
516 }
517 
518 static __always_inline int get_pfnblock_migratetype(const struct page *page,
519 					unsigned long pfn)
520 {
521 	return __get_pfnblock_flags_mask(page, pfn, MIGRATETYPE_MASK);
522 }
523 
524 /**
525  * set_pfnblock_flags_mask - Set the requested group of flags for a pageblock_nr_pages block of pages
526  * @page: The page within the block of interest
527  * @flags: The flags to set
528  * @pfn: The target page frame number
529  * @mask: mask of bits that the caller is interested in
530  */
531 void set_pfnblock_flags_mask(struct page *page, unsigned long flags,
532 					unsigned long pfn,
533 					unsigned long mask)
534 {
535 	unsigned long *bitmap;
536 	unsigned long bitidx, word_bitidx;
537 	unsigned long old_word, word;
538 
539 	BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4);
540 	BUILD_BUG_ON(MIGRATE_TYPES > (1 << PB_migratetype_bits));
541 
542 	bitmap = get_pageblock_bitmap(page, pfn);
543 	bitidx = pfn_to_bitidx(page, pfn);
544 	word_bitidx = bitidx / BITS_PER_LONG;
545 	bitidx &= (BITS_PER_LONG-1);
546 
547 	VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page);
548 
549 	mask <<= bitidx;
550 	flags <<= bitidx;
551 
552 	word = READ_ONCE(bitmap[word_bitidx]);
553 	for (;;) {
554 		old_word = cmpxchg(&bitmap[word_bitidx], word, (word & ~mask) | flags);
555 		if (word == old_word)
556 			break;
557 		word = old_word;
558 	}
559 }
560 
561 void set_pageblock_migratetype(struct page *page, int migratetype)
562 {
563 	if (unlikely(page_group_by_mobility_disabled &&
564 		     migratetype < MIGRATE_PCPTYPES))
565 		migratetype = MIGRATE_UNMOVABLE;
566 
567 	set_pfnblock_flags_mask(page, (unsigned long)migratetype,
568 				page_to_pfn(page), MIGRATETYPE_MASK);
569 }
570 
571 #ifdef CONFIG_DEBUG_VM
572 static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
573 {
574 	int ret = 0;
575 	unsigned seq;
576 	unsigned long pfn = page_to_pfn(page);
577 	unsigned long sp, start_pfn;
578 
579 	do {
580 		seq = zone_span_seqbegin(zone);
581 		start_pfn = zone->zone_start_pfn;
582 		sp = zone->spanned_pages;
583 		if (!zone_spans_pfn(zone, pfn))
584 			ret = 1;
585 	} while (zone_span_seqretry(zone, seq));
586 
587 	if (ret)
588 		pr_err("page 0x%lx outside node %d zone %s [ 0x%lx - 0x%lx ]\n",
589 			pfn, zone_to_nid(zone), zone->name,
590 			start_pfn, start_pfn + sp);
591 
592 	return ret;
593 }
594 
595 static int page_is_consistent(struct zone *zone, struct page *page)
596 {
597 	if (zone != page_zone(page))
598 		return 0;
599 
600 	return 1;
601 }
602 /*
603  * Temporary debugging check for pages not lying within a given zone.
604  */
605 static int __maybe_unused bad_range(struct zone *zone, struct page *page)
606 {
607 	if (page_outside_zone_boundaries(zone, page))
608 		return 1;
609 	if (!page_is_consistent(zone, page))
610 		return 1;
611 
612 	return 0;
613 }
614 #else
615 static inline int __maybe_unused bad_range(struct zone *zone, struct page *page)
616 {
617 	return 0;
618 }
619 #endif
620 
621 static void bad_page(struct page *page, const char *reason)
622 {
623 	static unsigned long resume;
624 	static unsigned long nr_shown;
625 	static unsigned long nr_unshown;
626 
627 	/*
628 	 * Allow a burst of 60 reports, then keep quiet for that minute;
629 	 * or allow a steady drip of one report per second.
630 	 */
631 	if (nr_shown == 60) {
632 		if (time_before(jiffies, resume)) {
633 			nr_unshown++;
634 			goto out;
635 		}
636 		if (nr_unshown) {
637 			pr_alert(
638 			      "BUG: Bad page state: %lu messages suppressed\n",
639 				nr_unshown);
640 			nr_unshown = 0;
641 		}
642 		nr_shown = 0;
643 	}
644 	if (nr_shown++ == 0)
645 		resume = jiffies + 60 * HZ;
646 
647 	pr_alert("BUG: Bad page state in process %s  pfn:%05lx\n",
648 		current->comm, page_to_pfn(page));
649 	dump_page(page, reason);
650 
651 	print_modules();
652 	dump_stack();
653 out:
654 	/* Leave bad fields for debug, except PageBuddy could make trouble */
655 	page_mapcount_reset(page); /* remove PageBuddy */
656 	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
657 }
658 
659 static inline unsigned int order_to_pindex(int migratetype, int order)
660 {
661 	int base = order;
662 
663 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
664 	if (order > PAGE_ALLOC_COSTLY_ORDER) {
665 		VM_BUG_ON(order != pageblock_order);
666 		base = PAGE_ALLOC_COSTLY_ORDER + 1;
667 	}
668 #else
669 	VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER);
670 #endif
671 
672 	return (MIGRATE_PCPTYPES * base) + migratetype;
673 }
674 
675 static inline int pindex_to_order(unsigned int pindex)
676 {
677 	int order = pindex / MIGRATE_PCPTYPES;
678 
679 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
680 	if (order > PAGE_ALLOC_COSTLY_ORDER) {
681 		order = pageblock_order;
682 		VM_BUG_ON(order != pageblock_order);
683 	}
684 #else
685 	VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER);
686 #endif
687 
688 	return order;
689 }
690 
691 static inline bool pcp_allowed_order(unsigned int order)
692 {
693 	if (order <= PAGE_ALLOC_COSTLY_ORDER)
694 		return true;
695 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
696 	if (order == pageblock_order)
697 		return true;
698 #endif
699 	return false;
700 }
701 
702 static inline void free_the_page(struct page *page, unsigned int order)
703 {
704 	if (pcp_allowed_order(order))		/* Via pcp? */
705 		free_unref_page(page, order);
706 	else
707 		__free_pages_ok(page, order, FPI_NONE);
708 }
709 
710 /*
711  * Higher-order pages are called "compound pages".  They are structured thusly:
712  *
713  * The first PAGE_SIZE page is called the "head page" and have PG_head set.
714  *
715  * The remaining PAGE_SIZE pages are called "tail pages". PageTail() is encoded
716  * in bit 0 of page->compound_head. The rest of bits is pointer to head page.
717  *
718  * The first tail page's ->compound_dtor holds the offset in array of compound
719  * page destructors. See compound_page_dtors.
720  *
721  * The first tail page's ->compound_order holds the order of allocation.
722  * This usage means that zero-order pages may not be compound.
723  */
724 
725 void free_compound_page(struct page *page)
726 {
727 	mem_cgroup_uncharge(page);
728 	free_the_page(page, compound_order(page));
729 }
730 
731 void prep_compound_page(struct page *page, unsigned int order)
732 {
733 	int i;
734 	int nr_pages = 1 << order;
735 
736 	__SetPageHead(page);
737 	for (i = 1; i < nr_pages; i++) {
738 		struct page *p = page + i;
739 		p->mapping = TAIL_MAPPING;
740 		set_compound_head(p, page);
741 	}
742 
743 	set_compound_page_dtor(page, COMPOUND_PAGE_DTOR);
744 	set_compound_order(page, order);
745 	atomic_set(compound_mapcount_ptr(page), -1);
746 	if (hpage_pincount_available(page))
747 		atomic_set(compound_pincount_ptr(page), 0);
748 }
749 
750 #ifdef CONFIG_DEBUG_PAGEALLOC
751 unsigned int _debug_guardpage_minorder;
752 
753 bool _debug_pagealloc_enabled_early __read_mostly
754 			= IS_ENABLED(CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT);
755 EXPORT_SYMBOL(_debug_pagealloc_enabled_early);
756 DEFINE_STATIC_KEY_FALSE(_debug_pagealloc_enabled);
757 EXPORT_SYMBOL(_debug_pagealloc_enabled);
758 
759 DEFINE_STATIC_KEY_FALSE(_debug_guardpage_enabled);
760 
761 static int __init early_debug_pagealloc(char *buf)
762 {
763 	return kstrtobool(buf, &_debug_pagealloc_enabled_early);
764 }
765 early_param("debug_pagealloc", early_debug_pagealloc);
766 
767 static int __init debug_guardpage_minorder_setup(char *buf)
768 {
769 	unsigned long res;
770 
771 	if (kstrtoul(buf, 10, &res) < 0 ||  res > MAX_ORDER / 2) {
772 		pr_err("Bad debug_guardpage_minorder value\n");
773 		return 0;
774 	}
775 	_debug_guardpage_minorder = res;
776 	pr_info("Setting debug_guardpage_minorder to %lu\n", res);
777 	return 0;
778 }
779 early_param("debug_guardpage_minorder", debug_guardpage_minorder_setup);
780 
781 static inline bool set_page_guard(struct zone *zone, struct page *page,
782 				unsigned int order, int migratetype)
783 {
784 	if (!debug_guardpage_enabled())
785 		return false;
786 
787 	if (order >= debug_guardpage_minorder())
788 		return false;
789 
790 	__SetPageGuard(page);
791 	INIT_LIST_HEAD(&page->lru);
792 	set_page_private(page, order);
793 	/* Guard pages are not available for any usage */
794 	__mod_zone_freepage_state(zone, -(1 << order), migratetype);
795 
796 	return true;
797 }
798 
799 static inline void clear_page_guard(struct zone *zone, struct page *page,
800 				unsigned int order, int migratetype)
801 {
802 	if (!debug_guardpage_enabled())
803 		return;
804 
805 	__ClearPageGuard(page);
806 
807 	set_page_private(page, 0);
808 	if (!is_migrate_isolate(migratetype))
809 		__mod_zone_freepage_state(zone, (1 << order), migratetype);
810 }
811 #else
812 static inline bool set_page_guard(struct zone *zone, struct page *page,
813 			unsigned int order, int migratetype) { return false; }
814 static inline void clear_page_guard(struct zone *zone, struct page *page,
815 				unsigned int order, int migratetype) {}
816 #endif
817 
818 /*
819  * Enable static keys related to various memory debugging and hardening options.
820  * Some override others, and depend on early params that are evaluated in the
821  * order of appearance. So we need to first gather the full picture of what was
822  * enabled, and then make decisions.
823  */
824 void init_mem_debugging_and_hardening(void)
825 {
826 	bool page_poisoning_requested = false;
827 
828 #ifdef CONFIG_PAGE_POISONING
829 	/*
830 	 * Page poisoning is debug page alloc for some arches. If
831 	 * either of those options are enabled, enable poisoning.
832 	 */
833 	if (page_poisoning_enabled() ||
834 	     (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) &&
835 	      debug_pagealloc_enabled())) {
836 		static_branch_enable(&_page_poisoning_enabled);
837 		page_poisoning_requested = true;
838 	}
839 #endif
840 
841 	if ((_init_on_alloc_enabled_early || _init_on_free_enabled_early) &&
842 	    page_poisoning_requested) {
843 		pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, "
844 			"will take precedence over init_on_alloc and init_on_free\n");
845 		_init_on_alloc_enabled_early = false;
846 		_init_on_free_enabled_early = false;
847 	}
848 
849 	if (_init_on_alloc_enabled_early)
850 		static_branch_enable(&init_on_alloc);
851 	else
852 		static_branch_disable(&init_on_alloc);
853 
854 	if (_init_on_free_enabled_early)
855 		static_branch_enable(&init_on_free);
856 	else
857 		static_branch_disable(&init_on_free);
858 
859 #ifdef CONFIG_DEBUG_PAGEALLOC
860 	if (!debug_pagealloc_enabled())
861 		return;
862 
863 	static_branch_enable(&_debug_pagealloc_enabled);
864 
865 	if (!debug_guardpage_minorder())
866 		return;
867 
868 	static_branch_enable(&_debug_guardpage_enabled);
869 #endif
870 }
871 
872 static inline void set_buddy_order(struct page *page, unsigned int order)
873 {
874 	set_page_private(page, order);
875 	__SetPageBuddy(page);
876 }
877 
878 /*
879  * This function checks whether a page is free && is the buddy
880  * we can coalesce a page and its buddy if
881  * (a) the buddy is not in a hole (check before calling!) &&
882  * (b) the buddy is in the buddy system &&
883  * (c) a page and its buddy have the same order &&
884  * (d) a page and its buddy are in the same zone.
885  *
886  * For recording whether a page is in the buddy system, we set PageBuddy.
887  * Setting, clearing, and testing PageBuddy is serialized by zone->lock.
888  *
889  * For recording page's order, we use page_private(page).
890  */
891 static inline bool page_is_buddy(struct page *page, struct page *buddy,
892 							unsigned int order)
893 {
894 	if (!page_is_guard(buddy) && !PageBuddy(buddy))
895 		return false;
896 
897 	if (buddy_order(buddy) != order)
898 		return false;
899 
900 	/*
901 	 * zone check is done late to avoid uselessly calculating
902 	 * zone/node ids for pages that could never merge.
903 	 */
904 	if (page_zone_id(page) != page_zone_id(buddy))
905 		return false;
906 
907 	VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
908 
909 	return true;
910 }
911 
912 #ifdef CONFIG_COMPACTION
913 static inline struct capture_control *task_capc(struct zone *zone)
914 {
915 	struct capture_control *capc = current->capture_control;
916 
917 	return unlikely(capc) &&
918 		!(current->flags & PF_KTHREAD) &&
919 		!capc->page &&
920 		capc->cc->zone == zone ? capc : NULL;
921 }
922 
923 static inline bool
924 compaction_capture(struct capture_control *capc, struct page *page,
925 		   int order, int migratetype)
926 {
927 	if (!capc || order != capc->cc->order)
928 		return false;
929 
930 	/* Do not accidentally pollute CMA or isolated regions*/
931 	if (is_migrate_cma(migratetype) ||
932 	    is_migrate_isolate(migratetype))
933 		return false;
934 
935 	/*
936 	 * Do not let lower order allocations pollute a movable pageblock.
937 	 * This might let an unmovable request use a reclaimable pageblock
938 	 * and vice-versa but no more than normal fallback logic which can
939 	 * have trouble finding a high-order free page.
940 	 */
941 	if (order < pageblock_order && migratetype == MIGRATE_MOVABLE)
942 		return false;
943 
944 	capc->page = page;
945 	return true;
946 }
947 
948 #else
949 static inline struct capture_control *task_capc(struct zone *zone)
950 {
951 	return NULL;
952 }
953 
954 static inline bool
955 compaction_capture(struct capture_control *capc, struct page *page,
956 		   int order, int migratetype)
957 {
958 	return false;
959 }
960 #endif /* CONFIG_COMPACTION */
961 
962 /* Used for pages not on another list */
963 static inline void add_to_free_list(struct page *page, struct zone *zone,
964 				    unsigned int order, int migratetype)
965 {
966 	struct free_area *area = &zone->free_area[order];
967 
968 	list_add(&page->lru, &area->free_list[migratetype]);
969 	area->nr_free++;
970 }
971 
972 /* Used for pages not on another list */
973 static inline void add_to_free_list_tail(struct page *page, struct zone *zone,
974 					 unsigned int order, int migratetype)
975 {
976 	struct free_area *area = &zone->free_area[order];
977 
978 	list_add_tail(&page->lru, &area->free_list[migratetype]);
979 	area->nr_free++;
980 }
981 
982 /*
983  * Used for pages which are on another list. Move the pages to the tail
984  * of the list - so the moved pages won't immediately be considered for
985  * allocation again (e.g., optimization for memory onlining).
986  */
987 static inline void move_to_free_list(struct page *page, struct zone *zone,
988 				     unsigned int order, int migratetype)
989 {
990 	struct free_area *area = &zone->free_area[order];
991 
992 	list_move_tail(&page->lru, &area->free_list[migratetype]);
993 }
994 
995 static inline void del_page_from_free_list(struct page *page, struct zone *zone,
996 					   unsigned int order)
997 {
998 	/* clear reported state and update reported page count */
999 	if (page_reported(page))
1000 		__ClearPageReported(page);
1001 
1002 	list_del(&page->lru);
1003 	__ClearPageBuddy(page);
1004 	set_page_private(page, 0);
1005 	zone->free_area[order].nr_free--;
1006 }
1007 
1008 /*
1009  * If this is not the largest possible page, check if the buddy
1010  * of the next-highest order is free. If it is, it's possible
1011  * that pages are being freed that will coalesce soon. In case,
1012  * that is happening, add the free page to the tail of the list
1013  * so it's less likely to be used soon and more likely to be merged
1014  * as a higher order page
1015  */
1016 static inline bool
1017 buddy_merge_likely(unsigned long pfn, unsigned long buddy_pfn,
1018 		   struct page *page, unsigned int order)
1019 {
1020 	struct page *higher_page, *higher_buddy;
1021 	unsigned long combined_pfn;
1022 
1023 	if (order >= MAX_ORDER - 2)
1024 		return false;
1025 
1026 	combined_pfn = buddy_pfn & pfn;
1027 	higher_page = page + (combined_pfn - pfn);
1028 	buddy_pfn = __find_buddy_pfn(combined_pfn, order + 1);
1029 	higher_buddy = higher_page + (buddy_pfn - combined_pfn);
1030 
1031 	return page_is_buddy(higher_page, higher_buddy, order + 1);
1032 }
1033 
1034 /*
1035  * Freeing function for a buddy system allocator.
1036  *
1037  * The concept of a buddy system is to maintain direct-mapped table
1038  * (containing bit values) for memory blocks of various "orders".
1039  * The bottom level table contains the map for the smallest allocatable
1040  * units of memory (here, pages), and each level above it describes
1041  * pairs of units from the levels below, hence, "buddies".
1042  * At a high level, all that happens here is marking the table entry
1043  * at the bottom level available, and propagating the changes upward
1044  * as necessary, plus some accounting needed to play nicely with other
1045  * parts of the VM system.
1046  * At each level, we keep a list of pages, which are heads of continuous
1047  * free pages of length of (1 << order) and marked with PageBuddy.
1048  * Page's order is recorded in page_private(page) field.
1049  * So when we are allocating or freeing one, we can derive the state of the
1050  * other.  That is, if we allocate a small block, and both were
1051  * free, the remainder of the region must be split into blocks.
1052  * If a block is freed, and its buddy is also free, then this
1053  * triggers coalescing into a block of larger size.
1054  *
1055  * -- nyc
1056  */
1057 
1058 static inline void __free_one_page(struct page *page,
1059 		unsigned long pfn,
1060 		struct zone *zone, unsigned int order,
1061 		int migratetype, fpi_t fpi_flags)
1062 {
1063 	struct capture_control *capc = task_capc(zone);
1064 	unsigned long buddy_pfn;
1065 	unsigned long combined_pfn;
1066 	unsigned int max_order;
1067 	struct page *buddy;
1068 	bool to_tail;
1069 
1070 	max_order = min_t(unsigned int, MAX_ORDER - 1, pageblock_order);
1071 
1072 	VM_BUG_ON(!zone_is_initialized(zone));
1073 	VM_BUG_ON_PAGE(page->flags & PAGE_FLAGS_CHECK_AT_PREP, page);
1074 
1075 	VM_BUG_ON(migratetype == -1);
1076 	if (likely(!is_migrate_isolate(migratetype)))
1077 		__mod_zone_freepage_state(zone, 1 << order, migratetype);
1078 
1079 	VM_BUG_ON_PAGE(pfn & ((1 << order) - 1), page);
1080 	VM_BUG_ON_PAGE(bad_range(zone, page), page);
1081 
1082 continue_merging:
1083 	while (order < max_order) {
1084 		if (compaction_capture(capc, page, order, migratetype)) {
1085 			__mod_zone_freepage_state(zone, -(1 << order),
1086 								migratetype);
1087 			return;
1088 		}
1089 		buddy_pfn = __find_buddy_pfn(pfn, order);
1090 		buddy = page + (buddy_pfn - pfn);
1091 
1092 		if (!page_is_buddy(page, buddy, order))
1093 			goto done_merging;
1094 		/*
1095 		 * Our buddy is free or it is CONFIG_DEBUG_PAGEALLOC guard page,
1096 		 * merge with it and move up one order.
1097 		 */
1098 		if (page_is_guard(buddy))
1099 			clear_page_guard(zone, buddy, order, migratetype);
1100 		else
1101 			del_page_from_free_list(buddy, zone, order);
1102 		combined_pfn = buddy_pfn & pfn;
1103 		page = page + (combined_pfn - pfn);
1104 		pfn = combined_pfn;
1105 		order++;
1106 	}
1107 	if (order < MAX_ORDER - 1) {
1108 		/* If we are here, it means order is >= pageblock_order.
1109 		 * We want to prevent merge between freepages on isolate
1110 		 * pageblock and normal pageblock. Without this, pageblock
1111 		 * isolation could cause incorrect freepage or CMA accounting.
1112 		 *
1113 		 * We don't want to hit this code for the more frequent
1114 		 * low-order merging.
1115 		 */
1116 		if (unlikely(has_isolate_pageblock(zone))) {
1117 			int buddy_mt;
1118 
1119 			buddy_pfn = __find_buddy_pfn(pfn, order);
1120 			buddy = page + (buddy_pfn - pfn);
1121 			buddy_mt = get_pageblock_migratetype(buddy);
1122 
1123 			if (migratetype != buddy_mt
1124 					&& (is_migrate_isolate(migratetype) ||
1125 						is_migrate_isolate(buddy_mt)))
1126 				goto done_merging;
1127 		}
1128 		max_order = order + 1;
1129 		goto continue_merging;
1130 	}
1131 
1132 done_merging:
1133 	set_buddy_order(page, order);
1134 
1135 	if (fpi_flags & FPI_TO_TAIL)
1136 		to_tail = true;
1137 	else if (is_shuffle_order(order))
1138 		to_tail = shuffle_pick_tail();
1139 	else
1140 		to_tail = buddy_merge_likely(pfn, buddy_pfn, page, order);
1141 
1142 	if (to_tail)
1143 		add_to_free_list_tail(page, zone, order, migratetype);
1144 	else
1145 		add_to_free_list(page, zone, order, migratetype);
1146 
1147 	/* Notify page reporting subsystem of freed page */
1148 	if (!(fpi_flags & FPI_SKIP_REPORT_NOTIFY))
1149 		page_reporting_notify_free(order);
1150 }
1151 
1152 /*
1153  * A bad page could be due to a number of fields. Instead of multiple branches,
1154  * try and check multiple fields with one check. The caller must do a detailed
1155  * check if necessary.
1156  */
1157 static inline bool page_expected_state(struct page *page,
1158 					unsigned long check_flags)
1159 {
1160 	if (unlikely(atomic_read(&page->_mapcount) != -1))
1161 		return false;
1162 
1163 	if (unlikely((unsigned long)page->mapping |
1164 			page_ref_count(page) |
1165 #ifdef CONFIG_MEMCG
1166 			page->memcg_data |
1167 #endif
1168 			(page->flags & check_flags)))
1169 		return false;
1170 
1171 	return true;
1172 }
1173 
1174 static const char *page_bad_reason(struct page *page, unsigned long flags)
1175 {
1176 	const char *bad_reason = NULL;
1177 
1178 	if (unlikely(atomic_read(&page->_mapcount) != -1))
1179 		bad_reason = "nonzero mapcount";
1180 	if (unlikely(page->mapping != NULL))
1181 		bad_reason = "non-NULL mapping";
1182 	if (unlikely(page_ref_count(page) != 0))
1183 		bad_reason = "nonzero _refcount";
1184 	if (unlikely(page->flags & flags)) {
1185 		if (flags == PAGE_FLAGS_CHECK_AT_PREP)
1186 			bad_reason = "PAGE_FLAGS_CHECK_AT_PREP flag(s) set";
1187 		else
1188 			bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set";
1189 	}
1190 #ifdef CONFIG_MEMCG
1191 	if (unlikely(page->memcg_data))
1192 		bad_reason = "page still charged to cgroup";
1193 #endif
1194 	return bad_reason;
1195 }
1196 
1197 static void check_free_page_bad(struct page *page)
1198 {
1199 	bad_page(page,
1200 		 page_bad_reason(page, PAGE_FLAGS_CHECK_AT_FREE));
1201 }
1202 
1203 static inline int check_free_page(struct page *page)
1204 {
1205 	if (likely(page_expected_state(page, PAGE_FLAGS_CHECK_AT_FREE)))
1206 		return 0;
1207 
1208 	/* Something has gone sideways, find it */
1209 	check_free_page_bad(page);
1210 	return 1;
1211 }
1212 
1213 static int free_tail_pages_check(struct page *head_page, struct page *page)
1214 {
1215 	int ret = 1;
1216 
1217 	/*
1218 	 * We rely page->lru.next never has bit 0 set, unless the page
1219 	 * is PageTail(). Let's make sure that's true even for poisoned ->lru.
1220 	 */
1221 	BUILD_BUG_ON((unsigned long)LIST_POISON1 & 1);
1222 
1223 	if (!IS_ENABLED(CONFIG_DEBUG_VM)) {
1224 		ret = 0;
1225 		goto out;
1226 	}
1227 	switch (page - head_page) {
1228 	case 1:
1229 		/* the first tail page: ->mapping may be compound_mapcount() */
1230 		if (unlikely(compound_mapcount(page))) {
1231 			bad_page(page, "nonzero compound_mapcount");
1232 			goto out;
1233 		}
1234 		break;
1235 	case 2:
1236 		/*
1237 		 * the second tail page: ->mapping is
1238 		 * deferred_list.next -- ignore value.
1239 		 */
1240 		break;
1241 	default:
1242 		if (page->mapping != TAIL_MAPPING) {
1243 			bad_page(page, "corrupted mapping in tail page");
1244 			goto out;
1245 		}
1246 		break;
1247 	}
1248 	if (unlikely(!PageTail(page))) {
1249 		bad_page(page, "PageTail not set");
1250 		goto out;
1251 	}
1252 	if (unlikely(compound_head(page) != head_page)) {
1253 		bad_page(page, "compound_head not consistent");
1254 		goto out;
1255 	}
1256 	ret = 0;
1257 out:
1258 	page->mapping = NULL;
1259 	clear_compound_head(page);
1260 	return ret;
1261 }
1262 
1263 static void kernel_init_free_pages(struct page *page, int numpages, bool zero_tags)
1264 {
1265 	int i;
1266 
1267 	if (zero_tags) {
1268 		for (i = 0; i < numpages; i++)
1269 			tag_clear_highpage(page + i);
1270 		return;
1271 	}
1272 
1273 	/* s390's use of memset() could override KASAN redzones. */
1274 	kasan_disable_current();
1275 	for (i = 0; i < numpages; i++) {
1276 		u8 tag = page_kasan_tag(page + i);
1277 		page_kasan_tag_reset(page + i);
1278 		clear_highpage(page + i);
1279 		page_kasan_tag_set(page + i, tag);
1280 	}
1281 	kasan_enable_current();
1282 }
1283 
1284 static __always_inline bool free_pages_prepare(struct page *page,
1285 			unsigned int order, bool check_free, fpi_t fpi_flags)
1286 {
1287 	int bad = 0;
1288 	bool skip_kasan_poison = should_skip_kasan_poison(page, fpi_flags);
1289 
1290 	VM_BUG_ON_PAGE(PageTail(page), page);
1291 
1292 	trace_mm_page_free(page, order);
1293 
1294 	if (unlikely(PageHWPoison(page)) && !order) {
1295 		/*
1296 		 * Do not let hwpoison pages hit pcplists/buddy
1297 		 * Untie memcg state and reset page's owner
1298 		 */
1299 		if (memcg_kmem_enabled() && PageMemcgKmem(page))
1300 			__memcg_kmem_uncharge_page(page, order);
1301 		reset_page_owner(page, order);
1302 		return false;
1303 	}
1304 
1305 	/*
1306 	 * Check tail pages before head page information is cleared to
1307 	 * avoid checking PageCompound for order-0 pages.
1308 	 */
1309 	if (unlikely(order)) {
1310 		bool compound = PageCompound(page);
1311 		int i;
1312 
1313 		VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
1314 
1315 		if (compound)
1316 			ClearPageDoubleMap(page);
1317 		for (i = 1; i < (1 << order); i++) {
1318 			if (compound)
1319 				bad += free_tail_pages_check(page, page + i);
1320 			if (unlikely(check_free_page(page + i))) {
1321 				bad++;
1322 				continue;
1323 			}
1324 			(page + i)->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
1325 		}
1326 	}
1327 	if (PageMappingFlags(page))
1328 		page->mapping = NULL;
1329 	if (memcg_kmem_enabled() && PageMemcgKmem(page))
1330 		__memcg_kmem_uncharge_page(page, order);
1331 	if (check_free)
1332 		bad += check_free_page(page);
1333 	if (bad)
1334 		return false;
1335 
1336 	page_cpupid_reset_last(page);
1337 	page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
1338 	reset_page_owner(page, order);
1339 
1340 	if (!PageHighMem(page)) {
1341 		debug_check_no_locks_freed(page_address(page),
1342 					   PAGE_SIZE << order);
1343 		debug_check_no_obj_freed(page_address(page),
1344 					   PAGE_SIZE << order);
1345 	}
1346 
1347 	kernel_poison_pages(page, 1 << order);
1348 
1349 	/*
1350 	 * As memory initialization might be integrated into KASAN,
1351 	 * kasan_free_pages and kernel_init_free_pages must be
1352 	 * kept together to avoid discrepancies in behavior.
1353 	 *
1354 	 * With hardware tag-based KASAN, memory tags must be set before the
1355 	 * page becomes unavailable via debug_pagealloc or arch_free_page.
1356 	 */
1357 	if (kasan_has_integrated_init()) {
1358 		if (!skip_kasan_poison)
1359 			kasan_free_pages(page, order);
1360 	} else {
1361 		bool init = want_init_on_free();
1362 
1363 		if (init)
1364 			kernel_init_free_pages(page, 1 << order, false);
1365 		if (!skip_kasan_poison)
1366 			kasan_poison_pages(page, order, init);
1367 	}
1368 
1369 	/*
1370 	 * arch_free_page() can make the page's contents inaccessible.  s390
1371 	 * does this.  So nothing which can access the page's contents should
1372 	 * happen after this.
1373 	 */
1374 	arch_free_page(page, order);
1375 
1376 	debug_pagealloc_unmap_pages(page, 1 << order);
1377 
1378 	return true;
1379 }
1380 
1381 #ifdef CONFIG_DEBUG_VM
1382 /*
1383  * With DEBUG_VM enabled, order-0 pages are checked immediately when being freed
1384  * to pcp lists. With debug_pagealloc also enabled, they are also rechecked when
1385  * moved from pcp lists to free lists.
1386  */
1387 static bool free_pcp_prepare(struct page *page, unsigned int order)
1388 {
1389 	return free_pages_prepare(page, order, true, FPI_NONE);
1390 }
1391 
1392 static bool bulkfree_pcp_prepare(struct page *page)
1393 {
1394 	if (debug_pagealloc_enabled_static())
1395 		return check_free_page(page);
1396 	else
1397 		return false;
1398 }
1399 #else
1400 /*
1401  * With DEBUG_VM disabled, order-0 pages being freed are checked only when
1402  * moving from pcp lists to free list in order to reduce overhead. With
1403  * debug_pagealloc enabled, they are checked also immediately when being freed
1404  * to the pcp lists.
1405  */
1406 static bool free_pcp_prepare(struct page *page, unsigned int order)
1407 {
1408 	if (debug_pagealloc_enabled_static())
1409 		return free_pages_prepare(page, order, true, FPI_NONE);
1410 	else
1411 		return free_pages_prepare(page, order, false, FPI_NONE);
1412 }
1413 
1414 static bool bulkfree_pcp_prepare(struct page *page)
1415 {
1416 	return check_free_page(page);
1417 }
1418 #endif /* CONFIG_DEBUG_VM */
1419 
1420 static inline void prefetch_buddy(struct page *page)
1421 {
1422 	unsigned long pfn = page_to_pfn(page);
1423 	unsigned long buddy_pfn = __find_buddy_pfn(pfn, 0);
1424 	struct page *buddy = page + (buddy_pfn - pfn);
1425 
1426 	prefetch(buddy);
1427 }
1428 
1429 /*
1430  * Frees a number of pages from the PCP lists
1431  * Assumes all pages on list are in same zone, and of same order.
1432  * count is the number of pages to free.
1433  *
1434  * If the zone was previously in an "all pages pinned" state then look to
1435  * see if this freeing clears that state.
1436  *
1437  * And clear the zone's pages_scanned counter, to hold off the "all pages are
1438  * pinned" detection logic.
1439  */
1440 static void free_pcppages_bulk(struct zone *zone, int count,
1441 					struct per_cpu_pages *pcp)
1442 {
1443 	int pindex = 0;
1444 	int batch_free = 0;
1445 	int nr_freed = 0;
1446 	unsigned int order;
1447 	int prefetch_nr = READ_ONCE(pcp->batch);
1448 	bool isolated_pageblocks;
1449 	struct page *page, *tmp;
1450 	LIST_HEAD(head);
1451 
1452 	/*
1453 	 * Ensure proper count is passed which otherwise would stuck in the
1454 	 * below while (list_empty(list)) loop.
1455 	 */
1456 	count = min(pcp->count, count);
1457 	while (count > 0) {
1458 		struct list_head *list;
1459 
1460 		/*
1461 		 * Remove pages from lists in a round-robin fashion. A
1462 		 * batch_free count is maintained that is incremented when an
1463 		 * empty list is encountered.  This is so more pages are freed
1464 		 * off fuller lists instead of spinning excessively around empty
1465 		 * lists
1466 		 */
1467 		do {
1468 			batch_free++;
1469 			if (++pindex == NR_PCP_LISTS)
1470 				pindex = 0;
1471 			list = &pcp->lists[pindex];
1472 		} while (list_empty(list));
1473 
1474 		/* This is the only non-empty list. Free them all. */
1475 		if (batch_free == NR_PCP_LISTS)
1476 			batch_free = count;
1477 
1478 		order = pindex_to_order(pindex);
1479 		BUILD_BUG_ON(MAX_ORDER >= (1<<NR_PCP_ORDER_WIDTH));
1480 		do {
1481 			page = list_last_entry(list, struct page, lru);
1482 			/* must delete to avoid corrupting pcp list */
1483 			list_del(&page->lru);
1484 			nr_freed += 1 << order;
1485 			count -= 1 << order;
1486 
1487 			if (bulkfree_pcp_prepare(page))
1488 				continue;
1489 
1490 			/* Encode order with the migratetype */
1491 			page->index <<= NR_PCP_ORDER_WIDTH;
1492 			page->index |= order;
1493 
1494 			list_add_tail(&page->lru, &head);
1495 
1496 			/*
1497 			 * We are going to put the page back to the global
1498 			 * pool, prefetch its buddy to speed up later access
1499 			 * under zone->lock. It is believed the overhead of
1500 			 * an additional test and calculating buddy_pfn here
1501 			 * can be offset by reduced memory latency later. To
1502 			 * avoid excessive prefetching due to large count, only
1503 			 * prefetch buddy for the first pcp->batch nr of pages.
1504 			 */
1505 			if (prefetch_nr) {
1506 				prefetch_buddy(page);
1507 				prefetch_nr--;
1508 			}
1509 		} while (count > 0 && --batch_free && !list_empty(list));
1510 	}
1511 	pcp->count -= nr_freed;
1512 
1513 	/*
1514 	 * local_lock_irq held so equivalent to spin_lock_irqsave for
1515 	 * both PREEMPT_RT and non-PREEMPT_RT configurations.
1516 	 */
1517 	spin_lock(&zone->lock);
1518 	isolated_pageblocks = has_isolate_pageblock(zone);
1519 
1520 	/*
1521 	 * Use safe version since after __free_one_page(),
1522 	 * page->lru.next will not point to original list.
1523 	 */
1524 	list_for_each_entry_safe(page, tmp, &head, lru) {
1525 		int mt = get_pcppage_migratetype(page);
1526 
1527 		/* mt has been encoded with the order (see above) */
1528 		order = mt & NR_PCP_ORDER_MASK;
1529 		mt >>= NR_PCP_ORDER_WIDTH;
1530 
1531 		/* MIGRATE_ISOLATE page should not go to pcplists */
1532 		VM_BUG_ON_PAGE(is_migrate_isolate(mt), page);
1533 		/* Pageblock could have been isolated meanwhile */
1534 		if (unlikely(isolated_pageblocks))
1535 			mt = get_pageblock_migratetype(page);
1536 
1537 		__free_one_page(page, page_to_pfn(page), zone, order, mt, FPI_NONE);
1538 		trace_mm_page_pcpu_drain(page, order, mt);
1539 	}
1540 	spin_unlock(&zone->lock);
1541 }
1542 
1543 static void free_one_page(struct zone *zone,
1544 				struct page *page, unsigned long pfn,
1545 				unsigned int order,
1546 				int migratetype, fpi_t fpi_flags)
1547 {
1548 	unsigned long flags;
1549 
1550 	spin_lock_irqsave(&zone->lock, flags);
1551 	if (unlikely(has_isolate_pageblock(zone) ||
1552 		is_migrate_isolate(migratetype))) {
1553 		migratetype = get_pfnblock_migratetype(page, pfn);
1554 	}
1555 	__free_one_page(page, pfn, zone, order, migratetype, fpi_flags);
1556 	spin_unlock_irqrestore(&zone->lock, flags);
1557 }
1558 
1559 static void __meminit __init_single_page(struct page *page, unsigned long pfn,
1560 				unsigned long zone, int nid)
1561 {
1562 	mm_zero_struct_page(page);
1563 	set_page_links(page, zone, nid, pfn);
1564 	init_page_count(page);
1565 	page_mapcount_reset(page);
1566 	page_cpupid_reset_last(page);
1567 	page_kasan_tag_reset(page);
1568 
1569 	INIT_LIST_HEAD(&page->lru);
1570 #ifdef WANT_PAGE_VIRTUAL
1571 	/* The shift won't overflow because ZONE_NORMAL is below 4G. */
1572 	if (!is_highmem_idx(zone))
1573 		set_page_address(page, __va(pfn << PAGE_SHIFT));
1574 #endif
1575 }
1576 
1577 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
1578 static void __meminit init_reserved_page(unsigned long pfn)
1579 {
1580 	pg_data_t *pgdat;
1581 	int nid, zid;
1582 
1583 	if (!early_page_uninitialised(pfn))
1584 		return;
1585 
1586 	nid = early_pfn_to_nid(pfn);
1587 	pgdat = NODE_DATA(nid);
1588 
1589 	for (zid = 0; zid < MAX_NR_ZONES; zid++) {
1590 		struct zone *zone = &pgdat->node_zones[zid];
1591 
1592 		if (pfn >= zone->zone_start_pfn && pfn < zone_end_pfn(zone))
1593 			break;
1594 	}
1595 	__init_single_page(pfn_to_page(pfn), pfn, zid, nid);
1596 }
1597 #else
1598 static inline void init_reserved_page(unsigned long pfn)
1599 {
1600 }
1601 #endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
1602 
1603 /*
1604  * Initialised pages do not have PageReserved set. This function is
1605  * called for each range allocated by the bootmem allocator and
1606  * marks the pages PageReserved. The remaining valid pages are later
1607  * sent to the buddy page allocator.
1608  */
1609 void __meminit reserve_bootmem_region(phys_addr_t start, phys_addr_t end)
1610 {
1611 	unsigned long start_pfn = PFN_DOWN(start);
1612 	unsigned long end_pfn = PFN_UP(end);
1613 
1614 	for (; start_pfn < end_pfn; start_pfn++) {
1615 		if (pfn_valid(start_pfn)) {
1616 			struct page *page = pfn_to_page(start_pfn);
1617 
1618 			init_reserved_page(start_pfn);
1619 
1620 			/* Avoid false-positive PageTail() */
1621 			INIT_LIST_HEAD(&page->lru);
1622 
1623 			/*
1624 			 * no need for atomic set_bit because the struct
1625 			 * page is not visible yet so nobody should
1626 			 * access it yet.
1627 			 */
1628 			__SetPageReserved(page);
1629 		}
1630 	}
1631 }
1632 
1633 static void __free_pages_ok(struct page *page, unsigned int order,
1634 			    fpi_t fpi_flags)
1635 {
1636 	unsigned long flags;
1637 	int migratetype;
1638 	unsigned long pfn = page_to_pfn(page);
1639 	struct zone *zone = page_zone(page);
1640 
1641 	if (!free_pages_prepare(page, order, true, fpi_flags))
1642 		return;
1643 
1644 	migratetype = get_pfnblock_migratetype(page, pfn);
1645 
1646 	spin_lock_irqsave(&zone->lock, flags);
1647 	if (unlikely(has_isolate_pageblock(zone) ||
1648 		is_migrate_isolate(migratetype))) {
1649 		migratetype = get_pfnblock_migratetype(page, pfn);
1650 	}
1651 	__free_one_page(page, pfn, zone, order, migratetype, fpi_flags);
1652 	spin_unlock_irqrestore(&zone->lock, flags);
1653 
1654 	__count_vm_events(PGFREE, 1 << order);
1655 }
1656 
1657 void __free_pages_core(struct page *page, unsigned int order)
1658 {
1659 	unsigned int nr_pages = 1 << order;
1660 	struct page *p = page;
1661 	unsigned int loop;
1662 
1663 	/*
1664 	 * When initializing the memmap, __init_single_page() sets the refcount
1665 	 * of all pages to 1 ("allocated"/"not free"). We have to set the
1666 	 * refcount of all involved pages to 0.
1667 	 */
1668 	prefetchw(p);
1669 	for (loop = 0; loop < (nr_pages - 1); loop++, p++) {
1670 		prefetchw(p + 1);
1671 		__ClearPageReserved(p);
1672 		set_page_count(p, 0);
1673 	}
1674 	__ClearPageReserved(p);
1675 	set_page_count(p, 0);
1676 
1677 	atomic_long_add(nr_pages, &page_zone(page)->managed_pages);
1678 
1679 	/*
1680 	 * Bypass PCP and place fresh pages right to the tail, primarily
1681 	 * relevant for memory onlining.
1682 	 */
1683 	__free_pages_ok(page, order, FPI_TO_TAIL | FPI_SKIP_KASAN_POISON);
1684 }
1685 
1686 #ifdef CONFIG_NUMA
1687 
1688 /*
1689  * During memory init memblocks map pfns to nids. The search is expensive and
1690  * this caches recent lookups. The implementation of __early_pfn_to_nid
1691  * treats start/end as pfns.
1692  */
1693 struct mminit_pfnnid_cache {
1694 	unsigned long last_start;
1695 	unsigned long last_end;
1696 	int last_nid;
1697 };
1698 
1699 static struct mminit_pfnnid_cache early_pfnnid_cache __meminitdata;
1700 
1701 /*
1702  * Required by SPARSEMEM. Given a PFN, return what node the PFN is on.
1703  */
1704 static int __meminit __early_pfn_to_nid(unsigned long pfn,
1705 					struct mminit_pfnnid_cache *state)
1706 {
1707 	unsigned long start_pfn, end_pfn;
1708 	int nid;
1709 
1710 	if (state->last_start <= pfn && pfn < state->last_end)
1711 		return state->last_nid;
1712 
1713 	nid = memblock_search_pfn_nid(pfn, &start_pfn, &end_pfn);
1714 	if (nid != NUMA_NO_NODE) {
1715 		state->last_start = start_pfn;
1716 		state->last_end = end_pfn;
1717 		state->last_nid = nid;
1718 	}
1719 
1720 	return nid;
1721 }
1722 
1723 int __meminit early_pfn_to_nid(unsigned long pfn)
1724 {
1725 	static DEFINE_SPINLOCK(early_pfn_lock);
1726 	int nid;
1727 
1728 	spin_lock(&early_pfn_lock);
1729 	nid = __early_pfn_to_nid(pfn, &early_pfnnid_cache);
1730 	if (nid < 0)
1731 		nid = first_online_node;
1732 	spin_unlock(&early_pfn_lock);
1733 
1734 	return nid;
1735 }
1736 #endif /* CONFIG_NUMA */
1737 
1738 void __init memblock_free_pages(struct page *page, unsigned long pfn,
1739 							unsigned int order)
1740 {
1741 	if (early_page_uninitialised(pfn))
1742 		return;
1743 	__free_pages_core(page, order);
1744 }
1745 
1746 /*
1747  * Check that the whole (or subset of) a pageblock given by the interval of
1748  * [start_pfn, end_pfn) is valid and within the same zone, before scanning it
1749  * with the migration of free compaction scanner.
1750  *
1751  * Return struct page pointer of start_pfn, or NULL if checks were not passed.
1752  *
1753  * It's possible on some configurations to have a setup like node0 node1 node0
1754  * i.e. it's possible that all pages within a zones range of pages do not
1755  * belong to a single zone. We assume that a border between node0 and node1
1756  * can occur within a single pageblock, but not a node0 node1 node0
1757  * interleaving within a single pageblock. It is therefore sufficient to check
1758  * the first and last page of a pageblock and avoid checking each individual
1759  * page in a pageblock.
1760  */
1761 struct page *__pageblock_pfn_to_page(unsigned long start_pfn,
1762 				     unsigned long end_pfn, struct zone *zone)
1763 {
1764 	struct page *start_page;
1765 	struct page *end_page;
1766 
1767 	/* end_pfn is one past the range we are checking */
1768 	end_pfn--;
1769 
1770 	if (!pfn_valid(start_pfn) || !pfn_valid(end_pfn))
1771 		return NULL;
1772 
1773 	start_page = pfn_to_online_page(start_pfn);
1774 	if (!start_page)
1775 		return NULL;
1776 
1777 	if (page_zone(start_page) != zone)
1778 		return NULL;
1779 
1780 	end_page = pfn_to_page(end_pfn);
1781 
1782 	/* This gives a shorter code than deriving page_zone(end_page) */
1783 	if (page_zone_id(start_page) != page_zone_id(end_page))
1784 		return NULL;
1785 
1786 	return start_page;
1787 }
1788 
1789 void set_zone_contiguous(struct zone *zone)
1790 {
1791 	unsigned long block_start_pfn = zone->zone_start_pfn;
1792 	unsigned long block_end_pfn;
1793 
1794 	block_end_pfn = ALIGN(block_start_pfn + 1, pageblock_nr_pages);
1795 	for (; block_start_pfn < zone_end_pfn(zone);
1796 			block_start_pfn = block_end_pfn,
1797 			 block_end_pfn += pageblock_nr_pages) {
1798 
1799 		block_end_pfn = min(block_end_pfn, zone_end_pfn(zone));
1800 
1801 		if (!__pageblock_pfn_to_page(block_start_pfn,
1802 					     block_end_pfn, zone))
1803 			return;
1804 		cond_resched();
1805 	}
1806 
1807 	/* We confirm that there is no hole */
1808 	zone->contiguous = true;
1809 }
1810 
1811 void clear_zone_contiguous(struct zone *zone)
1812 {
1813 	zone->contiguous = false;
1814 }
1815 
1816 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
1817 static void __init deferred_free_range(unsigned long pfn,
1818 				       unsigned long nr_pages)
1819 {
1820 	struct page *page;
1821 	unsigned long i;
1822 
1823 	if (!nr_pages)
1824 		return;
1825 
1826 	page = pfn_to_page(pfn);
1827 
1828 	/* Free a large naturally-aligned chunk if possible */
1829 	if (nr_pages == pageblock_nr_pages &&
1830 	    (pfn & (pageblock_nr_pages - 1)) == 0) {
1831 		set_pageblock_migratetype(page, MIGRATE_MOVABLE);
1832 		__free_pages_core(page, pageblock_order);
1833 		return;
1834 	}
1835 
1836 	for (i = 0; i < nr_pages; i++, page++, pfn++) {
1837 		if ((pfn & (pageblock_nr_pages - 1)) == 0)
1838 			set_pageblock_migratetype(page, MIGRATE_MOVABLE);
1839 		__free_pages_core(page, 0);
1840 	}
1841 }
1842 
1843 /* Completion tracking for deferred_init_memmap() threads */
1844 static atomic_t pgdat_init_n_undone __initdata;
1845 static __initdata DECLARE_COMPLETION(pgdat_init_all_done_comp);
1846 
1847 static inline void __init pgdat_init_report_one_done(void)
1848 {
1849 	if (atomic_dec_and_test(&pgdat_init_n_undone))
1850 		complete(&pgdat_init_all_done_comp);
1851 }
1852 
1853 /*
1854  * Returns true if page needs to be initialized or freed to buddy allocator.
1855  *
1856  * First we check if pfn is valid on architectures where it is possible to have
1857  * holes within pageblock_nr_pages. On systems where it is not possible, this
1858  * function is optimized out.
1859  *
1860  * Then, we check if a current large page is valid by only checking the validity
1861  * of the head pfn.
1862  */
1863 static inline bool __init deferred_pfn_valid(unsigned long pfn)
1864 {
1865 	if (!(pfn & (pageblock_nr_pages - 1)) && !pfn_valid(pfn))
1866 		return false;
1867 	return true;
1868 }
1869 
1870 /*
1871  * Free pages to buddy allocator. Try to free aligned pages in
1872  * pageblock_nr_pages sizes.
1873  */
1874 static void __init deferred_free_pages(unsigned long pfn,
1875 				       unsigned long end_pfn)
1876 {
1877 	unsigned long nr_pgmask = pageblock_nr_pages - 1;
1878 	unsigned long nr_free = 0;
1879 
1880 	for (; pfn < end_pfn; pfn++) {
1881 		if (!deferred_pfn_valid(pfn)) {
1882 			deferred_free_range(pfn - nr_free, nr_free);
1883 			nr_free = 0;
1884 		} else if (!(pfn & nr_pgmask)) {
1885 			deferred_free_range(pfn - nr_free, nr_free);
1886 			nr_free = 1;
1887 		} else {
1888 			nr_free++;
1889 		}
1890 	}
1891 	/* Free the last block of pages to allocator */
1892 	deferred_free_range(pfn - nr_free, nr_free);
1893 }
1894 
1895 /*
1896  * Initialize struct pages.  We minimize pfn page lookups and scheduler checks
1897  * by performing it only once every pageblock_nr_pages.
1898  * Return number of pages initialized.
1899  */
1900 static unsigned long  __init deferred_init_pages(struct zone *zone,
1901 						 unsigned long pfn,
1902 						 unsigned long end_pfn)
1903 {
1904 	unsigned long nr_pgmask = pageblock_nr_pages - 1;
1905 	int nid = zone_to_nid(zone);
1906 	unsigned long nr_pages = 0;
1907 	int zid = zone_idx(zone);
1908 	struct page *page = NULL;
1909 
1910 	for (; pfn < end_pfn; pfn++) {
1911 		if (!deferred_pfn_valid(pfn)) {
1912 			page = NULL;
1913 			continue;
1914 		} else if (!page || !(pfn & nr_pgmask)) {
1915 			page = pfn_to_page(pfn);
1916 		} else {
1917 			page++;
1918 		}
1919 		__init_single_page(page, pfn, zid, nid);
1920 		nr_pages++;
1921 	}
1922 	return (nr_pages);
1923 }
1924 
1925 /*
1926  * This function is meant to pre-load the iterator for the zone init.
1927  * Specifically it walks through the ranges until we are caught up to the
1928  * first_init_pfn value and exits there. If we never encounter the value we
1929  * return false indicating there are no valid ranges left.
1930  */
1931 static bool __init
1932 deferred_init_mem_pfn_range_in_zone(u64 *i, struct zone *zone,
1933 				    unsigned long *spfn, unsigned long *epfn,
1934 				    unsigned long first_init_pfn)
1935 {
1936 	u64 j;
1937 
1938 	/*
1939 	 * Start out by walking through the ranges in this zone that have
1940 	 * already been initialized. We don't need to do anything with them
1941 	 * so we just need to flush them out of the system.
1942 	 */
1943 	for_each_free_mem_pfn_range_in_zone(j, zone, spfn, epfn) {
1944 		if (*epfn <= first_init_pfn)
1945 			continue;
1946 		if (*spfn < first_init_pfn)
1947 			*spfn = first_init_pfn;
1948 		*i = j;
1949 		return true;
1950 	}
1951 
1952 	return false;
1953 }
1954 
1955 /*
1956  * Initialize and free pages. We do it in two loops: first we initialize
1957  * struct page, then free to buddy allocator, because while we are
1958  * freeing pages we can access pages that are ahead (computing buddy
1959  * page in __free_one_page()).
1960  *
1961  * In order to try and keep some memory in the cache we have the loop
1962  * broken along max page order boundaries. This way we will not cause
1963  * any issues with the buddy page computation.
1964  */
1965 static unsigned long __init
1966 deferred_init_maxorder(u64 *i, struct zone *zone, unsigned long *start_pfn,
1967 		       unsigned long *end_pfn)
1968 {
1969 	unsigned long mo_pfn = ALIGN(*start_pfn + 1, MAX_ORDER_NR_PAGES);
1970 	unsigned long spfn = *start_pfn, epfn = *end_pfn;
1971 	unsigned long nr_pages = 0;
1972 	u64 j = *i;
1973 
1974 	/* First we loop through and initialize the page values */
1975 	for_each_free_mem_pfn_range_in_zone_from(j, zone, start_pfn, end_pfn) {
1976 		unsigned long t;
1977 
1978 		if (mo_pfn <= *start_pfn)
1979 			break;
1980 
1981 		t = min(mo_pfn, *end_pfn);
1982 		nr_pages += deferred_init_pages(zone, *start_pfn, t);
1983 
1984 		if (mo_pfn < *end_pfn) {
1985 			*start_pfn = mo_pfn;
1986 			break;
1987 		}
1988 	}
1989 
1990 	/* Reset values and now loop through freeing pages as needed */
1991 	swap(j, *i);
1992 
1993 	for_each_free_mem_pfn_range_in_zone_from(j, zone, &spfn, &epfn) {
1994 		unsigned long t;
1995 
1996 		if (mo_pfn <= spfn)
1997 			break;
1998 
1999 		t = min(mo_pfn, epfn);
2000 		deferred_free_pages(spfn, t);
2001 
2002 		if (mo_pfn <= epfn)
2003 			break;
2004 	}
2005 
2006 	return nr_pages;
2007 }
2008 
2009 static void __init
2010 deferred_init_memmap_chunk(unsigned long start_pfn, unsigned long end_pfn,
2011 			   void *arg)
2012 {
2013 	unsigned long spfn, epfn;
2014 	struct zone *zone = arg;
2015 	u64 i;
2016 
2017 	deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn, start_pfn);
2018 
2019 	/*
2020 	 * Initialize and free pages in MAX_ORDER sized increments so that we
2021 	 * can avoid introducing any issues with the buddy allocator.
2022 	 */
2023 	while (spfn < end_pfn) {
2024 		deferred_init_maxorder(&i, zone, &spfn, &epfn);
2025 		cond_resched();
2026 	}
2027 }
2028 
2029 /* An arch may override for more concurrency. */
2030 __weak int __init
2031 deferred_page_init_max_threads(const struct cpumask *node_cpumask)
2032 {
2033 	return 1;
2034 }
2035 
2036 /* Initialise remaining memory on a node */
2037 static int __init deferred_init_memmap(void *data)
2038 {
2039 	pg_data_t *pgdat = data;
2040 	const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
2041 	unsigned long spfn = 0, epfn = 0;
2042 	unsigned long first_init_pfn, flags;
2043 	unsigned long start = jiffies;
2044 	struct zone *zone;
2045 	int zid, max_threads;
2046 	u64 i;
2047 
2048 	/* Bind memory initialisation thread to a local node if possible */
2049 	if (!cpumask_empty(cpumask))
2050 		set_cpus_allowed_ptr(current, cpumask);
2051 
2052 	pgdat_resize_lock(pgdat, &flags);
2053 	first_init_pfn = pgdat->first_deferred_pfn;
2054 	if (first_init_pfn == ULONG_MAX) {
2055 		pgdat_resize_unlock(pgdat, &flags);
2056 		pgdat_init_report_one_done();
2057 		return 0;
2058 	}
2059 
2060 	/* Sanity check boundaries */
2061 	BUG_ON(pgdat->first_deferred_pfn < pgdat->node_start_pfn);
2062 	BUG_ON(pgdat->first_deferred_pfn > pgdat_end_pfn(pgdat));
2063 	pgdat->first_deferred_pfn = ULONG_MAX;
2064 
2065 	/*
2066 	 * Once we unlock here, the zone cannot be grown anymore, thus if an
2067 	 * interrupt thread must allocate this early in boot, zone must be
2068 	 * pre-grown prior to start of deferred page initialization.
2069 	 */
2070 	pgdat_resize_unlock(pgdat, &flags);
2071 
2072 	/* Only the highest zone is deferred so find it */
2073 	for (zid = 0; zid < MAX_NR_ZONES; zid++) {
2074 		zone = pgdat->node_zones + zid;
2075 		if (first_init_pfn < zone_end_pfn(zone))
2076 			break;
2077 	}
2078 
2079 	/* If the zone is empty somebody else may have cleared out the zone */
2080 	if (!deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn,
2081 						 first_init_pfn))
2082 		goto zone_empty;
2083 
2084 	max_threads = deferred_page_init_max_threads(cpumask);
2085 
2086 	while (spfn < epfn) {
2087 		unsigned long epfn_align = ALIGN(epfn, PAGES_PER_SECTION);
2088 		struct padata_mt_job job = {
2089 			.thread_fn   = deferred_init_memmap_chunk,
2090 			.fn_arg      = zone,
2091 			.start       = spfn,
2092 			.size        = epfn_align - spfn,
2093 			.align       = PAGES_PER_SECTION,
2094 			.min_chunk   = PAGES_PER_SECTION,
2095 			.max_threads = max_threads,
2096 		};
2097 
2098 		padata_do_multithreaded(&job);
2099 		deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn,
2100 						    epfn_align);
2101 	}
2102 zone_empty:
2103 	/* Sanity check that the next zone really is unpopulated */
2104 	WARN_ON(++zid < MAX_NR_ZONES && populated_zone(++zone));
2105 
2106 	pr_info("node %d deferred pages initialised in %ums\n",
2107 		pgdat->node_id, jiffies_to_msecs(jiffies - start));
2108 
2109 	pgdat_init_report_one_done();
2110 	return 0;
2111 }
2112 
2113 /*
2114  * If this zone has deferred pages, try to grow it by initializing enough
2115  * deferred pages to satisfy the allocation specified by order, rounded up to
2116  * the nearest PAGES_PER_SECTION boundary.  So we're adding memory in increments
2117  * of SECTION_SIZE bytes by initializing struct pages in increments of
2118  * PAGES_PER_SECTION * sizeof(struct page) bytes.
2119  *
2120  * Return true when zone was grown, otherwise return false. We return true even
2121  * when we grow less than requested, to let the caller decide if there are
2122  * enough pages to satisfy the allocation.
2123  *
2124  * Note: We use noinline because this function is needed only during boot, and
2125  * it is called from a __ref function _deferred_grow_zone. This way we are
2126  * making sure that it is not inlined into permanent text section.
2127  */
2128 static noinline bool __init
2129 deferred_grow_zone(struct zone *zone, unsigned int order)
2130 {
2131 	unsigned long nr_pages_needed = ALIGN(1 << order, PAGES_PER_SECTION);
2132 	pg_data_t *pgdat = zone->zone_pgdat;
2133 	unsigned long first_deferred_pfn = pgdat->first_deferred_pfn;
2134 	unsigned long spfn, epfn, flags;
2135 	unsigned long nr_pages = 0;
2136 	u64 i;
2137 
2138 	/* Only the last zone may have deferred pages */
2139 	if (zone_end_pfn(zone) != pgdat_end_pfn(pgdat))
2140 		return false;
2141 
2142 	pgdat_resize_lock(pgdat, &flags);
2143 
2144 	/*
2145 	 * If someone grew this zone while we were waiting for spinlock, return
2146 	 * true, as there might be enough pages already.
2147 	 */
2148 	if (first_deferred_pfn != pgdat->first_deferred_pfn) {
2149 		pgdat_resize_unlock(pgdat, &flags);
2150 		return true;
2151 	}
2152 
2153 	/* If the zone is empty somebody else may have cleared out the zone */
2154 	if (!deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn,
2155 						 first_deferred_pfn)) {
2156 		pgdat->first_deferred_pfn = ULONG_MAX;
2157 		pgdat_resize_unlock(pgdat, &flags);
2158 		/* Retry only once. */
2159 		return first_deferred_pfn != ULONG_MAX;
2160 	}
2161 
2162 	/*
2163 	 * Initialize and free pages in MAX_ORDER sized increments so
2164 	 * that we can avoid introducing any issues with the buddy
2165 	 * allocator.
2166 	 */
2167 	while (spfn < epfn) {
2168 		/* update our first deferred PFN for this section */
2169 		first_deferred_pfn = spfn;
2170 
2171 		nr_pages += deferred_init_maxorder(&i, zone, &spfn, &epfn);
2172 		touch_nmi_watchdog();
2173 
2174 		/* We should only stop along section boundaries */
2175 		if ((first_deferred_pfn ^ spfn) < PAGES_PER_SECTION)
2176 			continue;
2177 
2178 		/* If our quota has been met we can stop here */
2179 		if (nr_pages >= nr_pages_needed)
2180 			break;
2181 	}
2182 
2183 	pgdat->first_deferred_pfn = spfn;
2184 	pgdat_resize_unlock(pgdat, &flags);
2185 
2186 	return nr_pages > 0;
2187 }
2188 
2189 /*
2190  * deferred_grow_zone() is __init, but it is called from
2191  * get_page_from_freelist() during early boot until deferred_pages permanently
2192  * disables this call. This is why we have refdata wrapper to avoid warning,
2193  * and to ensure that the function body gets unloaded.
2194  */
2195 static bool __ref
2196 _deferred_grow_zone(struct zone *zone, unsigned int order)
2197 {
2198 	return deferred_grow_zone(zone, order);
2199 }
2200 
2201 #endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
2202 
2203 void __init page_alloc_init_late(void)
2204 {
2205 	struct zone *zone;
2206 	int nid;
2207 
2208 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
2209 
2210 	/* There will be num_node_state(N_MEMORY) threads */
2211 	atomic_set(&pgdat_init_n_undone, num_node_state(N_MEMORY));
2212 	for_each_node_state(nid, N_MEMORY) {
2213 		kthread_run(deferred_init_memmap, NODE_DATA(nid), "pgdatinit%d", nid);
2214 	}
2215 
2216 	/* Block until all are initialised */
2217 	wait_for_completion(&pgdat_init_all_done_comp);
2218 
2219 	/*
2220 	 * We initialized the rest of the deferred pages.  Permanently disable
2221 	 * on-demand struct page initialization.
2222 	 */
2223 	static_branch_disable(&deferred_pages);
2224 
2225 	/* Reinit limits that are based on free pages after the kernel is up */
2226 	files_maxfiles_init();
2227 #endif
2228 
2229 	buffer_init();
2230 
2231 	/* Discard memblock private memory */
2232 	memblock_discard();
2233 
2234 	for_each_node_state(nid, N_MEMORY)
2235 		shuffle_free_memory(NODE_DATA(nid));
2236 
2237 	for_each_populated_zone(zone)
2238 		set_zone_contiguous(zone);
2239 }
2240 
2241 #ifdef CONFIG_CMA
2242 /* Free whole pageblock and set its migration type to MIGRATE_CMA. */
2243 void __init init_cma_reserved_pageblock(struct page *page)
2244 {
2245 	unsigned i = pageblock_nr_pages;
2246 	struct page *p = page;
2247 
2248 	do {
2249 		__ClearPageReserved(p);
2250 		set_page_count(p, 0);
2251 	} while (++p, --i);
2252 
2253 	set_pageblock_migratetype(page, MIGRATE_CMA);
2254 
2255 	if (pageblock_order >= MAX_ORDER) {
2256 		i = pageblock_nr_pages;
2257 		p = page;
2258 		do {
2259 			set_page_refcounted(p);
2260 			__free_pages(p, MAX_ORDER - 1);
2261 			p += MAX_ORDER_NR_PAGES;
2262 		} while (i -= MAX_ORDER_NR_PAGES);
2263 	} else {
2264 		set_page_refcounted(page);
2265 		__free_pages(page, pageblock_order);
2266 	}
2267 
2268 	adjust_managed_page_count(page, pageblock_nr_pages);
2269 	page_zone(page)->cma_pages += pageblock_nr_pages;
2270 }
2271 #endif
2272 
2273 /*
2274  * The order of subdivision here is critical for the IO subsystem.
2275  * Please do not alter this order without good reasons and regression
2276  * testing. Specifically, as large blocks of memory are subdivided,
2277  * the order in which smaller blocks are delivered depends on the order
2278  * they're subdivided in this function. This is the primary factor
2279  * influencing the order in which pages are delivered to the IO
2280  * subsystem according to empirical testing, and this is also justified
2281  * by considering the behavior of a buddy system containing a single
2282  * large block of memory acted on by a series of small allocations.
2283  * This behavior is a critical factor in sglist merging's success.
2284  *
2285  * -- nyc
2286  */
2287 static inline void expand(struct zone *zone, struct page *page,
2288 	int low, int high, int migratetype)
2289 {
2290 	unsigned long size = 1 << high;
2291 
2292 	while (high > low) {
2293 		high--;
2294 		size >>= 1;
2295 		VM_BUG_ON_PAGE(bad_range(zone, &page[size]), &page[size]);
2296 
2297 		/*
2298 		 * Mark as guard pages (or page), that will allow to
2299 		 * merge back to allocator when buddy will be freed.
2300 		 * Corresponding page table entries will not be touched,
2301 		 * pages will stay not present in virtual address space
2302 		 */
2303 		if (set_page_guard(zone, &page[size], high, migratetype))
2304 			continue;
2305 
2306 		add_to_free_list(&page[size], zone, high, migratetype);
2307 		set_buddy_order(&page[size], high);
2308 	}
2309 }
2310 
2311 static void check_new_page_bad(struct page *page)
2312 {
2313 	if (unlikely(page->flags & __PG_HWPOISON)) {
2314 		/* Don't complain about hwpoisoned pages */
2315 		page_mapcount_reset(page); /* remove PageBuddy */
2316 		return;
2317 	}
2318 
2319 	bad_page(page,
2320 		 page_bad_reason(page, PAGE_FLAGS_CHECK_AT_PREP));
2321 }
2322 
2323 /*
2324  * This page is about to be returned from the page allocator
2325  */
2326 static inline int check_new_page(struct page *page)
2327 {
2328 	if (likely(page_expected_state(page,
2329 				PAGE_FLAGS_CHECK_AT_PREP|__PG_HWPOISON)))
2330 		return 0;
2331 
2332 	check_new_page_bad(page);
2333 	return 1;
2334 }
2335 
2336 #ifdef CONFIG_DEBUG_VM
2337 /*
2338  * With DEBUG_VM enabled, order-0 pages are checked for expected state when
2339  * being allocated from pcp lists. With debug_pagealloc also enabled, they are
2340  * also checked when pcp lists are refilled from the free lists.
2341  */
2342 static inline bool check_pcp_refill(struct page *page)
2343 {
2344 	if (debug_pagealloc_enabled_static())
2345 		return check_new_page(page);
2346 	else
2347 		return false;
2348 }
2349 
2350 static inline bool check_new_pcp(struct page *page)
2351 {
2352 	return check_new_page(page);
2353 }
2354 #else
2355 /*
2356  * With DEBUG_VM disabled, free order-0 pages are checked for expected state
2357  * when pcp lists are being refilled from the free lists. With debug_pagealloc
2358  * enabled, they are also checked when being allocated from the pcp lists.
2359  */
2360 static inline bool check_pcp_refill(struct page *page)
2361 {
2362 	return check_new_page(page);
2363 }
2364 static inline bool check_new_pcp(struct page *page)
2365 {
2366 	if (debug_pagealloc_enabled_static())
2367 		return check_new_page(page);
2368 	else
2369 		return false;
2370 }
2371 #endif /* CONFIG_DEBUG_VM */
2372 
2373 static bool check_new_pages(struct page *page, unsigned int order)
2374 {
2375 	int i;
2376 	for (i = 0; i < (1 << order); i++) {
2377 		struct page *p = page + i;
2378 
2379 		if (unlikely(check_new_page(p)))
2380 			return true;
2381 	}
2382 
2383 	return false;
2384 }
2385 
2386 inline void post_alloc_hook(struct page *page, unsigned int order,
2387 				gfp_t gfp_flags)
2388 {
2389 	set_page_private(page, 0);
2390 	set_page_refcounted(page);
2391 
2392 	arch_alloc_page(page, order);
2393 	debug_pagealloc_map_pages(page, 1 << order);
2394 
2395 	/*
2396 	 * Page unpoisoning must happen before memory initialization.
2397 	 * Otherwise, the poison pattern will be overwritten for __GFP_ZERO
2398 	 * allocations and the page unpoisoning code will complain.
2399 	 */
2400 	kernel_unpoison_pages(page, 1 << order);
2401 
2402 	/*
2403 	 * As memory initialization might be integrated into KASAN,
2404 	 * kasan_alloc_pages and kernel_init_free_pages must be
2405 	 * kept together to avoid discrepancies in behavior.
2406 	 */
2407 	if (kasan_has_integrated_init()) {
2408 		kasan_alloc_pages(page, order, gfp_flags);
2409 	} else {
2410 		bool init = !want_init_on_free() && want_init_on_alloc(gfp_flags);
2411 
2412 		kasan_unpoison_pages(page, order, init);
2413 		if (init)
2414 			kernel_init_free_pages(page, 1 << order,
2415 					       gfp_flags & __GFP_ZEROTAGS);
2416 	}
2417 
2418 	set_page_owner(page, order, gfp_flags);
2419 }
2420 
2421 static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags,
2422 							unsigned int alloc_flags)
2423 {
2424 	post_alloc_hook(page, order, gfp_flags);
2425 
2426 	if (order && (gfp_flags & __GFP_COMP))
2427 		prep_compound_page(page, order);
2428 
2429 	/*
2430 	 * page is set pfmemalloc when ALLOC_NO_WATERMARKS was necessary to
2431 	 * allocate the page. The expectation is that the caller is taking
2432 	 * steps that will free more memory. The caller should avoid the page
2433 	 * being used for !PFMEMALLOC purposes.
2434 	 */
2435 	if (alloc_flags & ALLOC_NO_WATERMARKS)
2436 		set_page_pfmemalloc(page);
2437 	else
2438 		clear_page_pfmemalloc(page);
2439 }
2440 
2441 /*
2442  * Go through the free lists for the given migratetype and remove
2443  * the smallest available page from the freelists
2444  */
2445 static __always_inline
2446 struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
2447 						int migratetype)
2448 {
2449 	unsigned int current_order;
2450 	struct free_area *area;
2451 	struct page *page;
2452 
2453 	/* Find a page of the appropriate size in the preferred list */
2454 	for (current_order = order; current_order < MAX_ORDER; ++current_order) {
2455 		area = &(zone->free_area[current_order]);
2456 		page = get_page_from_free_area(area, migratetype);
2457 		if (!page)
2458 			continue;
2459 		del_page_from_free_list(page, zone, current_order);
2460 		expand(zone, page, order, current_order, migratetype);
2461 		set_pcppage_migratetype(page, migratetype);
2462 		return page;
2463 	}
2464 
2465 	return NULL;
2466 }
2467 
2468 
2469 /*
2470  * This array describes the order lists are fallen back to when
2471  * the free lists for the desirable migrate type are depleted
2472  */
2473 static int fallbacks[MIGRATE_TYPES][3] = {
2474 	[MIGRATE_UNMOVABLE]   = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE,   MIGRATE_TYPES },
2475 	[MIGRATE_MOVABLE]     = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_TYPES },
2476 	[MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE,   MIGRATE_MOVABLE,   MIGRATE_TYPES },
2477 #ifdef CONFIG_CMA
2478 	[MIGRATE_CMA]         = { MIGRATE_TYPES }, /* Never used */
2479 #endif
2480 #ifdef CONFIG_MEMORY_ISOLATION
2481 	[MIGRATE_ISOLATE]     = { MIGRATE_TYPES }, /* Never used */
2482 #endif
2483 };
2484 
2485 #ifdef CONFIG_CMA
2486 static __always_inline struct page *__rmqueue_cma_fallback(struct zone *zone,
2487 					unsigned int order)
2488 {
2489 	return __rmqueue_smallest(zone, order, MIGRATE_CMA);
2490 }
2491 #else
2492 static inline struct page *__rmqueue_cma_fallback(struct zone *zone,
2493 					unsigned int order) { return NULL; }
2494 #endif
2495 
2496 /*
2497  * Move the free pages in a range to the freelist tail of the requested type.
2498  * Note that start_page and end_pages are not aligned on a pageblock
2499  * boundary. If alignment is required, use move_freepages_block()
2500  */
2501 static int move_freepages(struct zone *zone,
2502 			  unsigned long start_pfn, unsigned long end_pfn,
2503 			  int migratetype, int *num_movable)
2504 {
2505 	struct page *page;
2506 	unsigned long pfn;
2507 	unsigned int order;
2508 	int pages_moved = 0;
2509 
2510 	for (pfn = start_pfn; pfn <= end_pfn;) {
2511 		page = pfn_to_page(pfn);
2512 		if (!PageBuddy(page)) {
2513 			/*
2514 			 * We assume that pages that could be isolated for
2515 			 * migration are movable. But we don't actually try
2516 			 * isolating, as that would be expensive.
2517 			 */
2518 			if (num_movable &&
2519 					(PageLRU(page) || __PageMovable(page)))
2520 				(*num_movable)++;
2521 			pfn++;
2522 			continue;
2523 		}
2524 
2525 		/* Make sure we are not inadvertently changing nodes */
2526 		VM_BUG_ON_PAGE(page_to_nid(page) != zone_to_nid(zone), page);
2527 		VM_BUG_ON_PAGE(page_zone(page) != zone, page);
2528 
2529 		order = buddy_order(page);
2530 		move_to_free_list(page, zone, order, migratetype);
2531 		pfn += 1 << order;
2532 		pages_moved += 1 << order;
2533 	}
2534 
2535 	return pages_moved;
2536 }
2537 
2538 int move_freepages_block(struct zone *zone, struct page *page,
2539 				int migratetype, int *num_movable)
2540 {
2541 	unsigned long start_pfn, end_pfn, pfn;
2542 
2543 	if (num_movable)
2544 		*num_movable = 0;
2545 
2546 	pfn = page_to_pfn(page);
2547 	start_pfn = pfn & ~(pageblock_nr_pages - 1);
2548 	end_pfn = start_pfn + pageblock_nr_pages - 1;
2549 
2550 	/* Do not cross zone boundaries */
2551 	if (!zone_spans_pfn(zone, start_pfn))
2552 		start_pfn = pfn;
2553 	if (!zone_spans_pfn(zone, end_pfn))
2554 		return 0;
2555 
2556 	return move_freepages(zone, start_pfn, end_pfn, migratetype,
2557 								num_movable);
2558 }
2559 
2560 static void change_pageblock_range(struct page *pageblock_page,
2561 					int start_order, int migratetype)
2562 {
2563 	int nr_pageblocks = 1 << (start_order - pageblock_order);
2564 
2565 	while (nr_pageblocks--) {
2566 		set_pageblock_migratetype(pageblock_page, migratetype);
2567 		pageblock_page += pageblock_nr_pages;
2568 	}
2569 }
2570 
2571 /*
2572  * When we are falling back to another migratetype during allocation, try to
2573  * steal extra free pages from the same pageblocks to satisfy further
2574  * allocations, instead of polluting multiple pageblocks.
2575  *
2576  * If we are stealing a relatively large buddy page, it is likely there will
2577  * be more free pages in the pageblock, so try to steal them all. For
2578  * reclaimable and unmovable allocations, we steal regardless of page size,
2579  * as fragmentation caused by those allocations polluting movable pageblocks
2580  * is worse than movable allocations stealing from unmovable and reclaimable
2581  * pageblocks.
2582  */
2583 static bool can_steal_fallback(unsigned int order, int start_mt)
2584 {
2585 	/*
2586 	 * Leaving this order check is intended, although there is
2587 	 * relaxed order check in next check. The reason is that
2588 	 * we can actually steal whole pageblock if this condition met,
2589 	 * but, below check doesn't guarantee it and that is just heuristic
2590 	 * so could be changed anytime.
2591 	 */
2592 	if (order >= pageblock_order)
2593 		return true;
2594 
2595 	if (order >= pageblock_order / 2 ||
2596 		start_mt == MIGRATE_RECLAIMABLE ||
2597 		start_mt == MIGRATE_UNMOVABLE ||
2598 		page_group_by_mobility_disabled)
2599 		return true;
2600 
2601 	return false;
2602 }
2603 
2604 static inline bool boost_watermark(struct zone *zone)
2605 {
2606 	unsigned long max_boost;
2607 
2608 	if (!watermark_boost_factor)
2609 		return false;
2610 	/*
2611 	 * Don't bother in zones that are unlikely to produce results.
2612 	 * On small machines, including kdump capture kernels running
2613 	 * in a small area, boosting the watermark can cause an out of
2614 	 * memory situation immediately.
2615 	 */
2616 	if ((pageblock_nr_pages * 4) > zone_managed_pages(zone))
2617 		return false;
2618 
2619 	max_boost = mult_frac(zone->_watermark[WMARK_HIGH],
2620 			watermark_boost_factor, 10000);
2621 
2622 	/*
2623 	 * high watermark may be uninitialised if fragmentation occurs
2624 	 * very early in boot so do not boost. We do not fall
2625 	 * through and boost by pageblock_nr_pages as failing
2626 	 * allocations that early means that reclaim is not going
2627 	 * to help and it may even be impossible to reclaim the
2628 	 * boosted watermark resulting in a hang.
2629 	 */
2630 	if (!max_boost)
2631 		return false;
2632 
2633 	max_boost = max(pageblock_nr_pages, max_boost);
2634 
2635 	zone->watermark_boost = min(zone->watermark_boost + pageblock_nr_pages,
2636 		max_boost);
2637 
2638 	return true;
2639 }
2640 
2641 /*
2642  * This function implements actual steal behaviour. If order is large enough,
2643  * we can steal whole pageblock. If not, we first move freepages in this
2644  * pageblock to our migratetype and determine how many already-allocated pages
2645  * are there in the pageblock with a compatible migratetype. If at least half
2646  * of pages are free or compatible, we can change migratetype of the pageblock
2647  * itself, so pages freed in the future will be put on the correct free list.
2648  */
2649 static void steal_suitable_fallback(struct zone *zone, struct page *page,
2650 		unsigned int alloc_flags, int start_type, bool whole_block)
2651 {
2652 	unsigned int current_order = buddy_order(page);
2653 	int free_pages, movable_pages, alike_pages;
2654 	int old_block_type;
2655 
2656 	old_block_type = get_pageblock_migratetype(page);
2657 
2658 	/*
2659 	 * This can happen due to races and we want to prevent broken
2660 	 * highatomic accounting.
2661 	 */
2662 	if (is_migrate_highatomic(old_block_type))
2663 		goto single_page;
2664 
2665 	/* Take ownership for orders >= pageblock_order */
2666 	if (current_order >= pageblock_order) {
2667 		change_pageblock_range(page, current_order, start_type);
2668 		goto single_page;
2669 	}
2670 
2671 	/*
2672 	 * Boost watermarks to increase reclaim pressure to reduce the
2673 	 * likelihood of future fallbacks. Wake kswapd now as the node
2674 	 * may be balanced overall and kswapd will not wake naturally.
2675 	 */
2676 	if (boost_watermark(zone) && (alloc_flags & ALLOC_KSWAPD))
2677 		set_bit(ZONE_BOOSTED_WATERMARK, &zone->flags);
2678 
2679 	/* We are not allowed to try stealing from the whole block */
2680 	if (!whole_block)
2681 		goto single_page;
2682 
2683 	free_pages = move_freepages_block(zone, page, start_type,
2684 						&movable_pages);
2685 	/*
2686 	 * Determine how many pages are compatible with our allocation.
2687 	 * For movable allocation, it's the number of movable pages which
2688 	 * we just obtained. For other types it's a bit more tricky.
2689 	 */
2690 	if (start_type == MIGRATE_MOVABLE) {
2691 		alike_pages = movable_pages;
2692 	} else {
2693 		/*
2694 		 * If we are falling back a RECLAIMABLE or UNMOVABLE allocation
2695 		 * to MOVABLE pageblock, consider all non-movable pages as
2696 		 * compatible. If it's UNMOVABLE falling back to RECLAIMABLE or
2697 		 * vice versa, be conservative since we can't distinguish the
2698 		 * exact migratetype of non-movable pages.
2699 		 */
2700 		if (old_block_type == MIGRATE_MOVABLE)
2701 			alike_pages = pageblock_nr_pages
2702 						- (free_pages + movable_pages);
2703 		else
2704 			alike_pages = 0;
2705 	}
2706 
2707 	/* moving whole block can fail due to zone boundary conditions */
2708 	if (!free_pages)
2709 		goto single_page;
2710 
2711 	/*
2712 	 * If a sufficient number of pages in the block are either free or of
2713 	 * comparable migratability as our allocation, claim the whole block.
2714 	 */
2715 	if (free_pages + alike_pages >= (1 << (pageblock_order-1)) ||
2716 			page_group_by_mobility_disabled)
2717 		set_pageblock_migratetype(page, start_type);
2718 
2719 	return;
2720 
2721 single_page:
2722 	move_to_free_list(page, zone, current_order, start_type);
2723 }
2724 
2725 /*
2726  * Check whether there is a suitable fallback freepage with requested order.
2727  * If only_stealable is true, this function returns fallback_mt only if
2728  * we can steal other freepages all together. This would help to reduce
2729  * fragmentation due to mixed migratetype pages in one pageblock.
2730  */
2731 int find_suitable_fallback(struct free_area *area, unsigned int order,
2732 			int migratetype, bool only_stealable, bool *can_steal)
2733 {
2734 	int i;
2735 	int fallback_mt;
2736 
2737 	if (area->nr_free == 0)
2738 		return -1;
2739 
2740 	*can_steal = false;
2741 	for (i = 0;; i++) {
2742 		fallback_mt = fallbacks[migratetype][i];
2743 		if (fallback_mt == MIGRATE_TYPES)
2744 			break;
2745 
2746 		if (free_area_empty(area, fallback_mt))
2747 			continue;
2748 
2749 		if (can_steal_fallback(order, migratetype))
2750 			*can_steal = true;
2751 
2752 		if (!only_stealable)
2753 			return fallback_mt;
2754 
2755 		if (*can_steal)
2756 			return fallback_mt;
2757 	}
2758 
2759 	return -1;
2760 }
2761 
2762 /*
2763  * Reserve a pageblock for exclusive use of high-order atomic allocations if
2764  * there are no empty page blocks that contain a page with a suitable order
2765  */
2766 static void reserve_highatomic_pageblock(struct page *page, struct zone *zone,
2767 				unsigned int alloc_order)
2768 {
2769 	int mt;
2770 	unsigned long max_managed, flags;
2771 
2772 	/*
2773 	 * Limit the number reserved to 1 pageblock or roughly 1% of a zone.
2774 	 * Check is race-prone but harmless.
2775 	 */
2776 	max_managed = (zone_managed_pages(zone) / 100) + pageblock_nr_pages;
2777 	if (zone->nr_reserved_highatomic >= max_managed)
2778 		return;
2779 
2780 	spin_lock_irqsave(&zone->lock, flags);
2781 
2782 	/* Recheck the nr_reserved_highatomic limit under the lock */
2783 	if (zone->nr_reserved_highatomic >= max_managed)
2784 		goto out_unlock;
2785 
2786 	/* Yoink! */
2787 	mt = get_pageblock_migratetype(page);
2788 	if (!is_migrate_highatomic(mt) && !is_migrate_isolate(mt)
2789 	    && !is_migrate_cma(mt)) {
2790 		zone->nr_reserved_highatomic += pageblock_nr_pages;
2791 		set_pageblock_migratetype(page, MIGRATE_HIGHATOMIC);
2792 		move_freepages_block(zone, page, MIGRATE_HIGHATOMIC, NULL);
2793 	}
2794 
2795 out_unlock:
2796 	spin_unlock_irqrestore(&zone->lock, flags);
2797 }
2798 
2799 /*
2800  * Used when an allocation is about to fail under memory pressure. This
2801  * potentially hurts the reliability of high-order allocations when under
2802  * intense memory pressure but failed atomic allocations should be easier
2803  * to recover from than an OOM.
2804  *
2805  * If @force is true, try to unreserve a pageblock even though highatomic
2806  * pageblock is exhausted.
2807  */
2808 static bool unreserve_highatomic_pageblock(const struct alloc_context *ac,
2809 						bool force)
2810 {
2811 	struct zonelist *zonelist = ac->zonelist;
2812 	unsigned long flags;
2813 	struct zoneref *z;
2814 	struct zone *zone;
2815 	struct page *page;
2816 	int order;
2817 	bool ret;
2818 
2819 	for_each_zone_zonelist_nodemask(zone, z, zonelist, ac->highest_zoneidx,
2820 								ac->nodemask) {
2821 		/*
2822 		 * Preserve at least one pageblock unless memory pressure
2823 		 * is really high.
2824 		 */
2825 		if (!force && zone->nr_reserved_highatomic <=
2826 					pageblock_nr_pages)
2827 			continue;
2828 
2829 		spin_lock_irqsave(&zone->lock, flags);
2830 		for (order = 0; order < MAX_ORDER; order++) {
2831 			struct free_area *area = &(zone->free_area[order]);
2832 
2833 			page = get_page_from_free_area(area, MIGRATE_HIGHATOMIC);
2834 			if (!page)
2835 				continue;
2836 
2837 			/*
2838 			 * In page freeing path, migratetype change is racy so
2839 			 * we can counter several free pages in a pageblock
2840 			 * in this loop although we changed the pageblock type
2841 			 * from highatomic to ac->migratetype. So we should
2842 			 * adjust the count once.
2843 			 */
2844 			if (is_migrate_highatomic_page(page)) {
2845 				/*
2846 				 * It should never happen but changes to
2847 				 * locking could inadvertently allow a per-cpu
2848 				 * drain to add pages to MIGRATE_HIGHATOMIC
2849 				 * while unreserving so be safe and watch for
2850 				 * underflows.
2851 				 */
2852 				zone->nr_reserved_highatomic -= min(
2853 						pageblock_nr_pages,
2854 						zone->nr_reserved_highatomic);
2855 			}
2856 
2857 			/*
2858 			 * Convert to ac->migratetype and avoid the normal
2859 			 * pageblock stealing heuristics. Minimally, the caller
2860 			 * is doing the work and needs the pages. More
2861 			 * importantly, if the block was always converted to
2862 			 * MIGRATE_UNMOVABLE or another type then the number
2863 			 * of pageblocks that cannot be completely freed
2864 			 * may increase.
2865 			 */
2866 			set_pageblock_migratetype(page, ac->migratetype);
2867 			ret = move_freepages_block(zone, page, ac->migratetype,
2868 									NULL);
2869 			if (ret) {
2870 				spin_unlock_irqrestore(&zone->lock, flags);
2871 				return ret;
2872 			}
2873 		}
2874 		spin_unlock_irqrestore(&zone->lock, flags);
2875 	}
2876 
2877 	return false;
2878 }
2879 
2880 /*
2881  * Try finding a free buddy page on the fallback list and put it on the free
2882  * list of requested migratetype, possibly along with other pages from the same
2883  * block, depending on fragmentation avoidance heuristics. Returns true if
2884  * fallback was found so that __rmqueue_smallest() can grab it.
2885  *
2886  * The use of signed ints for order and current_order is a deliberate
2887  * deviation from the rest of this file, to make the for loop
2888  * condition simpler.
2889  */
2890 static __always_inline bool
2891 __rmqueue_fallback(struct zone *zone, int order, int start_migratetype,
2892 						unsigned int alloc_flags)
2893 {
2894 	struct free_area *area;
2895 	int current_order;
2896 	int min_order = order;
2897 	struct page *page;
2898 	int fallback_mt;
2899 	bool can_steal;
2900 
2901 	/*
2902 	 * Do not steal pages from freelists belonging to other pageblocks
2903 	 * i.e. orders < pageblock_order. If there are no local zones free,
2904 	 * the zonelists will be reiterated without ALLOC_NOFRAGMENT.
2905 	 */
2906 	if (alloc_flags & ALLOC_NOFRAGMENT)
2907 		min_order = pageblock_order;
2908 
2909 	/*
2910 	 * Find the largest available free page in the other list. This roughly
2911 	 * approximates finding the pageblock with the most free pages, which
2912 	 * would be too costly to do exactly.
2913 	 */
2914 	for (current_order = MAX_ORDER - 1; current_order >= min_order;
2915 				--current_order) {
2916 		area = &(zone->free_area[current_order]);
2917 		fallback_mt = find_suitable_fallback(area, current_order,
2918 				start_migratetype, false, &can_steal);
2919 		if (fallback_mt == -1)
2920 			continue;
2921 
2922 		/*
2923 		 * We cannot steal all free pages from the pageblock and the
2924 		 * requested migratetype is movable. In that case it's better to
2925 		 * steal and split the smallest available page instead of the
2926 		 * largest available page, because even if the next movable
2927 		 * allocation falls back into a different pageblock than this
2928 		 * one, it won't cause permanent fragmentation.
2929 		 */
2930 		if (!can_steal && start_migratetype == MIGRATE_MOVABLE
2931 					&& current_order > order)
2932 			goto find_smallest;
2933 
2934 		goto do_steal;
2935 	}
2936 
2937 	return false;
2938 
2939 find_smallest:
2940 	for (current_order = order; current_order < MAX_ORDER;
2941 							current_order++) {
2942 		area = &(zone->free_area[current_order]);
2943 		fallback_mt = find_suitable_fallback(area, current_order,
2944 				start_migratetype, false, &can_steal);
2945 		if (fallback_mt != -1)
2946 			break;
2947 	}
2948 
2949 	/*
2950 	 * This should not happen - we already found a suitable fallback
2951 	 * when looking for the largest page.
2952 	 */
2953 	VM_BUG_ON(current_order == MAX_ORDER);
2954 
2955 do_steal:
2956 	page = get_page_from_free_area(area, fallback_mt);
2957 
2958 	steal_suitable_fallback(zone, page, alloc_flags, start_migratetype,
2959 								can_steal);
2960 
2961 	trace_mm_page_alloc_extfrag(page, order, current_order,
2962 		start_migratetype, fallback_mt);
2963 
2964 	return true;
2965 
2966 }
2967 
2968 /*
2969  * Do the hard work of removing an element from the buddy allocator.
2970  * Call me with the zone->lock already held.
2971  */
2972 static __always_inline struct page *
2973 __rmqueue(struct zone *zone, unsigned int order, int migratetype,
2974 						unsigned int alloc_flags)
2975 {
2976 	struct page *page;
2977 
2978 	if (IS_ENABLED(CONFIG_CMA)) {
2979 		/*
2980 		 * Balance movable allocations between regular and CMA areas by
2981 		 * allocating from CMA when over half of the zone's free memory
2982 		 * is in the CMA area.
2983 		 */
2984 		if (alloc_flags & ALLOC_CMA &&
2985 		    zone_page_state(zone, NR_FREE_CMA_PAGES) >
2986 		    zone_page_state(zone, NR_FREE_PAGES) / 2) {
2987 			page = __rmqueue_cma_fallback(zone, order);
2988 			if (page)
2989 				goto out;
2990 		}
2991 	}
2992 retry:
2993 	page = __rmqueue_smallest(zone, order, migratetype);
2994 	if (unlikely(!page)) {
2995 		if (alloc_flags & ALLOC_CMA)
2996 			page = __rmqueue_cma_fallback(zone, order);
2997 
2998 		if (!page && __rmqueue_fallback(zone, order, migratetype,
2999 								alloc_flags))
3000 			goto retry;
3001 	}
3002 out:
3003 	if (page)
3004 		trace_mm_page_alloc_zone_locked(page, order, migratetype);
3005 	return page;
3006 }
3007 
3008 /*
3009  * Obtain a specified number of elements from the buddy allocator, all under
3010  * a single hold of the lock, for efficiency.  Add them to the supplied list.
3011  * Returns the number of new pages which were placed at *list.
3012  */
3013 static int rmqueue_bulk(struct zone *zone, unsigned int order,
3014 			unsigned long count, struct list_head *list,
3015 			int migratetype, unsigned int alloc_flags)
3016 {
3017 	int i, allocated = 0;
3018 
3019 	/*
3020 	 * local_lock_irq held so equivalent to spin_lock_irqsave for
3021 	 * both PREEMPT_RT and non-PREEMPT_RT configurations.
3022 	 */
3023 	spin_lock(&zone->lock);
3024 	for (i = 0; i < count; ++i) {
3025 		struct page *page = __rmqueue(zone, order, migratetype,
3026 								alloc_flags);
3027 		if (unlikely(page == NULL))
3028 			break;
3029 
3030 		if (unlikely(check_pcp_refill(page)))
3031 			continue;
3032 
3033 		/*
3034 		 * Split buddy pages returned by expand() are received here in
3035 		 * physical page order. The page is added to the tail of
3036 		 * caller's list. From the callers perspective, the linked list
3037 		 * is ordered by page number under some conditions. This is
3038 		 * useful for IO devices that can forward direction from the
3039 		 * head, thus also in the physical page order. This is useful
3040 		 * for IO devices that can merge IO requests if the physical
3041 		 * pages are ordered properly.
3042 		 */
3043 		list_add_tail(&page->lru, list);
3044 		allocated++;
3045 		if (is_migrate_cma(get_pcppage_migratetype(page)))
3046 			__mod_zone_page_state(zone, NR_FREE_CMA_PAGES,
3047 					      -(1 << order));
3048 	}
3049 
3050 	/*
3051 	 * i pages were removed from the buddy list even if some leak due
3052 	 * to check_pcp_refill failing so adjust NR_FREE_PAGES based
3053 	 * on i. Do not confuse with 'allocated' which is the number of
3054 	 * pages added to the pcp list.
3055 	 */
3056 	__mod_zone_page_state(zone, NR_FREE_PAGES, -(i << order));
3057 	spin_unlock(&zone->lock);
3058 	return allocated;
3059 }
3060 
3061 #ifdef CONFIG_NUMA
3062 /*
3063  * Called from the vmstat counter updater to drain pagesets of this
3064  * currently executing processor on remote nodes after they have
3065  * expired.
3066  *
3067  * Note that this function must be called with the thread pinned to
3068  * a single processor.
3069  */
3070 void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
3071 {
3072 	unsigned long flags;
3073 	int to_drain, batch;
3074 
3075 	local_lock_irqsave(&pagesets.lock, flags);
3076 	batch = READ_ONCE(pcp->batch);
3077 	to_drain = min(pcp->count, batch);
3078 	if (to_drain > 0)
3079 		free_pcppages_bulk(zone, to_drain, pcp);
3080 	local_unlock_irqrestore(&pagesets.lock, flags);
3081 }
3082 #endif
3083 
3084 /*
3085  * Drain pcplists of the indicated processor and zone.
3086  *
3087  * The processor must either be the current processor and the
3088  * thread pinned to the current processor or a processor that
3089  * is not online.
3090  */
3091 static void drain_pages_zone(unsigned int cpu, struct zone *zone)
3092 {
3093 	unsigned long flags;
3094 	struct per_cpu_pages *pcp;
3095 
3096 	local_lock_irqsave(&pagesets.lock, flags);
3097 
3098 	pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
3099 	if (pcp->count)
3100 		free_pcppages_bulk(zone, pcp->count, pcp);
3101 
3102 	local_unlock_irqrestore(&pagesets.lock, flags);
3103 }
3104 
3105 /*
3106  * Drain pcplists of all zones on the indicated processor.
3107  *
3108  * The processor must either be the current processor and the
3109  * thread pinned to the current processor or a processor that
3110  * is not online.
3111  */
3112 static void drain_pages(unsigned int cpu)
3113 {
3114 	struct zone *zone;
3115 
3116 	for_each_populated_zone(zone) {
3117 		drain_pages_zone(cpu, zone);
3118 	}
3119 }
3120 
3121 /*
3122  * Spill all of this CPU's per-cpu pages back into the buddy allocator.
3123  *
3124  * The CPU has to be pinned. When zone parameter is non-NULL, spill just
3125  * the single zone's pages.
3126  */
3127 void drain_local_pages(struct zone *zone)
3128 {
3129 	int cpu = smp_processor_id();
3130 
3131 	if (zone)
3132 		drain_pages_zone(cpu, zone);
3133 	else
3134 		drain_pages(cpu);
3135 }
3136 
3137 static void drain_local_pages_wq(struct work_struct *work)
3138 {
3139 	struct pcpu_drain *drain;
3140 
3141 	drain = container_of(work, struct pcpu_drain, work);
3142 
3143 	/*
3144 	 * drain_all_pages doesn't use proper cpu hotplug protection so
3145 	 * we can race with cpu offline when the WQ can move this from
3146 	 * a cpu pinned worker to an unbound one. We can operate on a different
3147 	 * cpu which is alright but we also have to make sure to not move to
3148 	 * a different one.
3149 	 */
3150 	preempt_disable();
3151 	drain_local_pages(drain->zone);
3152 	preempt_enable();
3153 }
3154 
3155 /*
3156  * The implementation of drain_all_pages(), exposing an extra parameter to
3157  * drain on all cpus.
3158  *
3159  * drain_all_pages() is optimized to only execute on cpus where pcplists are
3160  * not empty. The check for non-emptiness can however race with a free to
3161  * pcplist that has not yet increased the pcp->count from 0 to 1. Callers
3162  * that need the guarantee that every CPU has drained can disable the
3163  * optimizing racy check.
3164  */
3165 static void __drain_all_pages(struct zone *zone, bool force_all_cpus)
3166 {
3167 	int cpu;
3168 
3169 	/*
3170 	 * Allocate in the BSS so we won't require allocation in
3171 	 * direct reclaim path for CONFIG_CPUMASK_OFFSTACK=y
3172 	 */
3173 	static cpumask_t cpus_with_pcps;
3174 
3175 	/*
3176 	 * Make sure nobody triggers this path before mm_percpu_wq is fully
3177 	 * initialized.
3178 	 */
3179 	if (WARN_ON_ONCE(!mm_percpu_wq))
3180 		return;
3181 
3182 	/*
3183 	 * Do not drain if one is already in progress unless it's specific to
3184 	 * a zone. Such callers are primarily CMA and memory hotplug and need
3185 	 * the drain to be complete when the call returns.
3186 	 */
3187 	if (unlikely(!mutex_trylock(&pcpu_drain_mutex))) {
3188 		if (!zone)
3189 			return;
3190 		mutex_lock(&pcpu_drain_mutex);
3191 	}
3192 
3193 	/*
3194 	 * We don't care about racing with CPU hotplug event
3195 	 * as offline notification will cause the notified
3196 	 * cpu to drain that CPU pcps and on_each_cpu_mask
3197 	 * disables preemption as part of its processing
3198 	 */
3199 	for_each_online_cpu(cpu) {
3200 		struct per_cpu_pages *pcp;
3201 		struct zone *z;
3202 		bool has_pcps = false;
3203 
3204 		if (force_all_cpus) {
3205 			/*
3206 			 * The pcp.count check is racy, some callers need a
3207 			 * guarantee that no cpu is missed.
3208 			 */
3209 			has_pcps = true;
3210 		} else if (zone) {
3211 			pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
3212 			if (pcp->count)
3213 				has_pcps = true;
3214 		} else {
3215 			for_each_populated_zone(z) {
3216 				pcp = per_cpu_ptr(z->per_cpu_pageset, cpu);
3217 				if (pcp->count) {
3218 					has_pcps = true;
3219 					break;
3220 				}
3221 			}
3222 		}
3223 
3224 		if (has_pcps)
3225 			cpumask_set_cpu(cpu, &cpus_with_pcps);
3226 		else
3227 			cpumask_clear_cpu(cpu, &cpus_with_pcps);
3228 	}
3229 
3230 	for_each_cpu(cpu, &cpus_with_pcps) {
3231 		struct pcpu_drain *drain = per_cpu_ptr(&pcpu_drain, cpu);
3232 
3233 		drain->zone = zone;
3234 		INIT_WORK(&drain->work, drain_local_pages_wq);
3235 		queue_work_on(cpu, mm_percpu_wq, &drain->work);
3236 	}
3237 	for_each_cpu(cpu, &cpus_with_pcps)
3238 		flush_work(&per_cpu_ptr(&pcpu_drain, cpu)->work);
3239 
3240 	mutex_unlock(&pcpu_drain_mutex);
3241 }
3242 
3243 /*
3244  * Spill all the per-cpu pages from all CPUs back into the buddy allocator.
3245  *
3246  * When zone parameter is non-NULL, spill just the single zone's pages.
3247  *
3248  * Note that this can be extremely slow as the draining happens in a workqueue.
3249  */
3250 void drain_all_pages(struct zone *zone)
3251 {
3252 	__drain_all_pages(zone, false);
3253 }
3254 
3255 #ifdef CONFIG_HIBERNATION
3256 
3257 /*
3258  * Touch the watchdog for every WD_PAGE_COUNT pages.
3259  */
3260 #define WD_PAGE_COUNT	(128*1024)
3261 
3262 void mark_free_pages(struct zone *zone)
3263 {
3264 	unsigned long pfn, max_zone_pfn, page_count = WD_PAGE_COUNT;
3265 	unsigned long flags;
3266 	unsigned int order, t;
3267 	struct page *page;
3268 
3269 	if (zone_is_empty(zone))
3270 		return;
3271 
3272 	spin_lock_irqsave(&zone->lock, flags);
3273 
3274 	max_zone_pfn = zone_end_pfn(zone);
3275 	for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
3276 		if (pfn_valid(pfn)) {
3277 			page = pfn_to_page(pfn);
3278 
3279 			if (!--page_count) {
3280 				touch_nmi_watchdog();
3281 				page_count = WD_PAGE_COUNT;
3282 			}
3283 
3284 			if (page_zone(page) != zone)
3285 				continue;
3286 
3287 			if (!swsusp_page_is_forbidden(page))
3288 				swsusp_unset_page_free(page);
3289 		}
3290 
3291 	for_each_migratetype_order(order, t) {
3292 		list_for_each_entry(page,
3293 				&zone->free_area[order].free_list[t], lru) {
3294 			unsigned long i;
3295 
3296 			pfn = page_to_pfn(page);
3297 			for (i = 0; i < (1UL << order); i++) {
3298 				if (!--page_count) {
3299 					touch_nmi_watchdog();
3300 					page_count = WD_PAGE_COUNT;
3301 				}
3302 				swsusp_set_page_free(pfn_to_page(pfn + i));
3303 			}
3304 		}
3305 	}
3306 	spin_unlock_irqrestore(&zone->lock, flags);
3307 }
3308 #endif /* CONFIG_PM */
3309 
3310 static bool free_unref_page_prepare(struct page *page, unsigned long pfn,
3311 							unsigned int order)
3312 {
3313 	int migratetype;
3314 
3315 	if (!free_pcp_prepare(page, order))
3316 		return false;
3317 
3318 	migratetype = get_pfnblock_migratetype(page, pfn);
3319 	set_pcppage_migratetype(page, migratetype);
3320 	return true;
3321 }
3322 
3323 static int nr_pcp_free(struct per_cpu_pages *pcp, int high, int batch)
3324 {
3325 	int min_nr_free, max_nr_free;
3326 
3327 	/* Check for PCP disabled or boot pageset */
3328 	if (unlikely(high < batch))
3329 		return 1;
3330 
3331 	/* Leave at least pcp->batch pages on the list */
3332 	min_nr_free = batch;
3333 	max_nr_free = high - batch;
3334 
3335 	/*
3336 	 * Double the number of pages freed each time there is subsequent
3337 	 * freeing of pages without any allocation.
3338 	 */
3339 	batch <<= pcp->free_factor;
3340 	if (batch < max_nr_free)
3341 		pcp->free_factor++;
3342 	batch = clamp(batch, min_nr_free, max_nr_free);
3343 
3344 	return batch;
3345 }
3346 
3347 static int nr_pcp_high(struct per_cpu_pages *pcp, struct zone *zone)
3348 {
3349 	int high = READ_ONCE(pcp->high);
3350 
3351 	if (unlikely(!high))
3352 		return 0;
3353 
3354 	if (!test_bit(ZONE_RECLAIM_ACTIVE, &zone->flags))
3355 		return high;
3356 
3357 	/*
3358 	 * If reclaim is active, limit the number of pages that can be
3359 	 * stored on pcp lists
3360 	 */
3361 	return min(READ_ONCE(pcp->batch) << 2, high);
3362 }
3363 
3364 static void free_unref_page_commit(struct page *page, unsigned long pfn,
3365 				   int migratetype, unsigned int order)
3366 {
3367 	struct zone *zone = page_zone(page);
3368 	struct per_cpu_pages *pcp;
3369 	int high;
3370 	int pindex;
3371 
3372 	__count_vm_event(PGFREE);
3373 	pcp = this_cpu_ptr(zone->per_cpu_pageset);
3374 	pindex = order_to_pindex(migratetype, order);
3375 	list_add(&page->lru, &pcp->lists[pindex]);
3376 	pcp->count += 1 << order;
3377 	high = nr_pcp_high(pcp, zone);
3378 	if (pcp->count >= high) {
3379 		int batch = READ_ONCE(pcp->batch);
3380 
3381 		free_pcppages_bulk(zone, nr_pcp_free(pcp, high, batch), pcp);
3382 	}
3383 }
3384 
3385 /*
3386  * Free a pcp page
3387  */
3388 void free_unref_page(struct page *page, unsigned int order)
3389 {
3390 	unsigned long flags;
3391 	unsigned long pfn = page_to_pfn(page);
3392 	int migratetype;
3393 
3394 	if (!free_unref_page_prepare(page, pfn, order))
3395 		return;
3396 
3397 	/*
3398 	 * We only track unmovable, reclaimable and movable on pcp lists.
3399 	 * Place ISOLATE pages on the isolated list because they are being
3400 	 * offlined but treat HIGHATOMIC as movable pages so we can get those
3401 	 * areas back if necessary. Otherwise, we may have to free
3402 	 * excessively into the page allocator
3403 	 */
3404 	migratetype = get_pcppage_migratetype(page);
3405 	if (unlikely(migratetype >= MIGRATE_PCPTYPES)) {
3406 		if (unlikely(is_migrate_isolate(migratetype))) {
3407 			free_one_page(page_zone(page), page, pfn, order, migratetype, FPI_NONE);
3408 			return;
3409 		}
3410 		migratetype = MIGRATE_MOVABLE;
3411 	}
3412 
3413 	local_lock_irqsave(&pagesets.lock, flags);
3414 	free_unref_page_commit(page, pfn, migratetype, order);
3415 	local_unlock_irqrestore(&pagesets.lock, flags);
3416 }
3417 
3418 /*
3419  * Free a list of 0-order pages
3420  */
3421 void free_unref_page_list(struct list_head *list)
3422 {
3423 	struct page *page, *next;
3424 	unsigned long flags, pfn;
3425 	int batch_count = 0;
3426 	int migratetype;
3427 
3428 	/* Prepare pages for freeing */
3429 	list_for_each_entry_safe(page, next, list, lru) {
3430 		pfn = page_to_pfn(page);
3431 		if (!free_unref_page_prepare(page, pfn, 0))
3432 			list_del(&page->lru);
3433 
3434 		/*
3435 		 * Free isolated pages directly to the allocator, see
3436 		 * comment in free_unref_page.
3437 		 */
3438 		migratetype = get_pcppage_migratetype(page);
3439 		if (unlikely(is_migrate_isolate(migratetype))) {
3440 			list_del(&page->lru);
3441 			free_one_page(page_zone(page), page, pfn, 0, migratetype, FPI_NONE);
3442 			continue;
3443 		}
3444 
3445 		set_page_private(page, pfn);
3446 	}
3447 
3448 	local_lock_irqsave(&pagesets.lock, flags);
3449 	list_for_each_entry_safe(page, next, list, lru) {
3450 		pfn = page_private(page);
3451 		set_page_private(page, 0);
3452 
3453 		/*
3454 		 * Non-isolated types over MIGRATE_PCPTYPES get added
3455 		 * to the MIGRATE_MOVABLE pcp list.
3456 		 */
3457 		migratetype = get_pcppage_migratetype(page);
3458 		if (unlikely(migratetype >= MIGRATE_PCPTYPES))
3459 			migratetype = MIGRATE_MOVABLE;
3460 
3461 		trace_mm_page_free_batched(page);
3462 		free_unref_page_commit(page, pfn, migratetype, 0);
3463 
3464 		/*
3465 		 * Guard against excessive IRQ disabled times when we get
3466 		 * a large list of pages to free.
3467 		 */
3468 		if (++batch_count == SWAP_CLUSTER_MAX) {
3469 			local_unlock_irqrestore(&pagesets.lock, flags);
3470 			batch_count = 0;
3471 			local_lock_irqsave(&pagesets.lock, flags);
3472 		}
3473 	}
3474 	local_unlock_irqrestore(&pagesets.lock, flags);
3475 }
3476 
3477 /*
3478  * split_page takes a non-compound higher-order page, and splits it into
3479  * n (1<<order) sub-pages: page[0..n]
3480  * Each sub-page must be freed individually.
3481  *
3482  * Note: this is probably too low level an operation for use in drivers.
3483  * Please consult with lkml before using this in your driver.
3484  */
3485 void split_page(struct page *page, unsigned int order)
3486 {
3487 	int i;
3488 
3489 	VM_BUG_ON_PAGE(PageCompound(page), page);
3490 	VM_BUG_ON_PAGE(!page_count(page), page);
3491 
3492 	for (i = 1; i < (1 << order); i++)
3493 		set_page_refcounted(page + i);
3494 	split_page_owner(page, 1 << order);
3495 	split_page_memcg(page, 1 << order);
3496 }
3497 EXPORT_SYMBOL_GPL(split_page);
3498 
3499 int __isolate_free_page(struct page *page, unsigned int order)
3500 {
3501 	unsigned long watermark;
3502 	struct zone *zone;
3503 	int mt;
3504 
3505 	BUG_ON(!PageBuddy(page));
3506 
3507 	zone = page_zone(page);
3508 	mt = get_pageblock_migratetype(page);
3509 
3510 	if (!is_migrate_isolate(mt)) {
3511 		/*
3512 		 * Obey watermarks as if the page was being allocated. We can
3513 		 * emulate a high-order watermark check with a raised order-0
3514 		 * watermark, because we already know our high-order page
3515 		 * exists.
3516 		 */
3517 		watermark = zone->_watermark[WMARK_MIN] + (1UL << order);
3518 		if (!zone_watermark_ok(zone, 0, watermark, 0, ALLOC_CMA))
3519 			return 0;
3520 
3521 		__mod_zone_freepage_state(zone, -(1UL << order), mt);
3522 	}
3523 
3524 	/* Remove page from free list */
3525 
3526 	del_page_from_free_list(page, zone, order);
3527 
3528 	/*
3529 	 * Set the pageblock if the isolated page is at least half of a
3530 	 * pageblock
3531 	 */
3532 	if (order >= pageblock_order - 1) {
3533 		struct page *endpage = page + (1 << order) - 1;
3534 		for (; page < endpage; page += pageblock_nr_pages) {
3535 			int mt = get_pageblock_migratetype(page);
3536 			if (!is_migrate_isolate(mt) && !is_migrate_cma(mt)
3537 			    && !is_migrate_highatomic(mt))
3538 				set_pageblock_migratetype(page,
3539 							  MIGRATE_MOVABLE);
3540 		}
3541 	}
3542 
3543 
3544 	return 1UL << order;
3545 }
3546 
3547 /**
3548  * __putback_isolated_page - Return a now-isolated page back where we got it
3549  * @page: Page that was isolated
3550  * @order: Order of the isolated page
3551  * @mt: The page's pageblock's migratetype
3552  *
3553  * This function is meant to return a page pulled from the free lists via
3554  * __isolate_free_page back to the free lists they were pulled from.
3555  */
3556 void __putback_isolated_page(struct page *page, unsigned int order, int mt)
3557 {
3558 	struct zone *zone = page_zone(page);
3559 
3560 	/* zone lock should be held when this function is called */
3561 	lockdep_assert_held(&zone->lock);
3562 
3563 	/* Return isolated page to tail of freelist. */
3564 	__free_one_page(page, page_to_pfn(page), zone, order, mt,
3565 			FPI_SKIP_REPORT_NOTIFY | FPI_TO_TAIL);
3566 }
3567 
3568 /*
3569  * Update NUMA hit/miss statistics
3570  *
3571  * Must be called with interrupts disabled.
3572  */
3573 static inline void zone_statistics(struct zone *preferred_zone, struct zone *z,
3574 				   long nr_account)
3575 {
3576 #ifdef CONFIG_NUMA
3577 	enum numa_stat_item local_stat = NUMA_LOCAL;
3578 
3579 	/* skip numa counters update if numa stats is disabled */
3580 	if (!static_branch_likely(&vm_numa_stat_key))
3581 		return;
3582 
3583 	if (zone_to_nid(z) != numa_node_id())
3584 		local_stat = NUMA_OTHER;
3585 
3586 	if (zone_to_nid(z) == zone_to_nid(preferred_zone))
3587 		__count_numa_events(z, NUMA_HIT, nr_account);
3588 	else {
3589 		__count_numa_events(z, NUMA_MISS, nr_account);
3590 		__count_numa_events(preferred_zone, NUMA_FOREIGN, nr_account);
3591 	}
3592 	__count_numa_events(z, local_stat, nr_account);
3593 #endif
3594 }
3595 
3596 /* Remove page from the per-cpu list, caller must protect the list */
3597 static inline
3598 struct page *__rmqueue_pcplist(struct zone *zone, unsigned int order,
3599 			int migratetype,
3600 			unsigned int alloc_flags,
3601 			struct per_cpu_pages *pcp,
3602 			struct list_head *list)
3603 {
3604 	struct page *page;
3605 
3606 	do {
3607 		if (list_empty(list)) {
3608 			int batch = READ_ONCE(pcp->batch);
3609 			int alloced;
3610 
3611 			/*
3612 			 * Scale batch relative to order if batch implies
3613 			 * free pages can be stored on the PCP. Batch can
3614 			 * be 1 for small zones or for boot pagesets which
3615 			 * should never store free pages as the pages may
3616 			 * belong to arbitrary zones.
3617 			 */
3618 			if (batch > 1)
3619 				batch = max(batch >> order, 2);
3620 			alloced = rmqueue_bulk(zone, order,
3621 					batch, list,
3622 					migratetype, alloc_flags);
3623 
3624 			pcp->count += alloced << order;
3625 			if (unlikely(list_empty(list)))
3626 				return NULL;
3627 		}
3628 
3629 		page = list_first_entry(list, struct page, lru);
3630 		list_del(&page->lru);
3631 		pcp->count -= 1 << order;
3632 	} while (check_new_pcp(page));
3633 
3634 	return page;
3635 }
3636 
3637 /* Lock and remove page from the per-cpu list */
3638 static struct page *rmqueue_pcplist(struct zone *preferred_zone,
3639 			struct zone *zone, unsigned int order,
3640 			gfp_t gfp_flags, int migratetype,
3641 			unsigned int alloc_flags)
3642 {
3643 	struct per_cpu_pages *pcp;
3644 	struct list_head *list;
3645 	struct page *page;
3646 	unsigned long flags;
3647 
3648 	local_lock_irqsave(&pagesets.lock, flags);
3649 
3650 	/*
3651 	 * On allocation, reduce the number of pages that are batch freed.
3652 	 * See nr_pcp_free() where free_factor is increased for subsequent
3653 	 * frees.
3654 	 */
3655 	pcp = this_cpu_ptr(zone->per_cpu_pageset);
3656 	pcp->free_factor >>= 1;
3657 	list = &pcp->lists[order_to_pindex(migratetype, order)];
3658 	page = __rmqueue_pcplist(zone, order, migratetype, alloc_flags, pcp, list);
3659 	local_unlock_irqrestore(&pagesets.lock, flags);
3660 	if (page) {
3661 		__count_zid_vm_events(PGALLOC, page_zonenum(page), 1);
3662 		zone_statistics(preferred_zone, zone, 1);
3663 	}
3664 	return page;
3665 }
3666 
3667 /*
3668  * Allocate a page from the given zone. Use pcplists for order-0 allocations.
3669  */
3670 static inline
3671 struct page *rmqueue(struct zone *preferred_zone,
3672 			struct zone *zone, unsigned int order,
3673 			gfp_t gfp_flags, unsigned int alloc_flags,
3674 			int migratetype)
3675 {
3676 	unsigned long flags;
3677 	struct page *page;
3678 
3679 	if (likely(pcp_allowed_order(order))) {
3680 		/*
3681 		 * MIGRATE_MOVABLE pcplist could have the pages on CMA area and
3682 		 * we need to skip it when CMA area isn't allowed.
3683 		 */
3684 		if (!IS_ENABLED(CONFIG_CMA) || alloc_flags & ALLOC_CMA ||
3685 				migratetype != MIGRATE_MOVABLE) {
3686 			page = rmqueue_pcplist(preferred_zone, zone, order,
3687 					gfp_flags, migratetype, alloc_flags);
3688 			goto out;
3689 		}
3690 	}
3691 
3692 	/*
3693 	 * We most definitely don't want callers attempting to
3694 	 * allocate greater than order-1 page units with __GFP_NOFAIL.
3695 	 */
3696 	WARN_ON_ONCE((gfp_flags & __GFP_NOFAIL) && (order > 1));
3697 	spin_lock_irqsave(&zone->lock, flags);
3698 
3699 	do {
3700 		page = NULL;
3701 		/*
3702 		 * order-0 request can reach here when the pcplist is skipped
3703 		 * due to non-CMA allocation context. HIGHATOMIC area is
3704 		 * reserved for high-order atomic allocation, so order-0
3705 		 * request should skip it.
3706 		 */
3707 		if (order > 0 && alloc_flags & ALLOC_HARDER) {
3708 			page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC);
3709 			if (page)
3710 				trace_mm_page_alloc_zone_locked(page, order, migratetype);
3711 		}
3712 		if (!page)
3713 			page = __rmqueue(zone, order, migratetype, alloc_flags);
3714 	} while (page && check_new_pages(page, order));
3715 	if (!page)
3716 		goto failed;
3717 
3718 	__mod_zone_freepage_state(zone, -(1 << order),
3719 				  get_pcppage_migratetype(page));
3720 	spin_unlock_irqrestore(&zone->lock, flags);
3721 
3722 	__count_zid_vm_events(PGALLOC, page_zonenum(page), 1 << order);
3723 	zone_statistics(preferred_zone, zone, 1);
3724 
3725 out:
3726 	/* Separate test+clear to avoid unnecessary atomics */
3727 	if (test_bit(ZONE_BOOSTED_WATERMARK, &zone->flags)) {
3728 		clear_bit(ZONE_BOOSTED_WATERMARK, &zone->flags);
3729 		wakeup_kswapd(zone, 0, 0, zone_idx(zone));
3730 	}
3731 
3732 	VM_BUG_ON_PAGE(page && bad_range(zone, page), page);
3733 	return page;
3734 
3735 failed:
3736 	spin_unlock_irqrestore(&zone->lock, flags);
3737 	return NULL;
3738 }
3739 
3740 #ifdef CONFIG_FAIL_PAGE_ALLOC
3741 
3742 static struct {
3743 	struct fault_attr attr;
3744 
3745 	bool ignore_gfp_highmem;
3746 	bool ignore_gfp_reclaim;
3747 	u32 min_order;
3748 } fail_page_alloc = {
3749 	.attr = FAULT_ATTR_INITIALIZER,
3750 	.ignore_gfp_reclaim = true,
3751 	.ignore_gfp_highmem = true,
3752 	.min_order = 1,
3753 };
3754 
3755 static int __init setup_fail_page_alloc(char *str)
3756 {
3757 	return setup_fault_attr(&fail_page_alloc.attr, str);
3758 }
3759 __setup("fail_page_alloc=", setup_fail_page_alloc);
3760 
3761 static bool __should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
3762 {
3763 	if (order < fail_page_alloc.min_order)
3764 		return false;
3765 	if (gfp_mask & __GFP_NOFAIL)
3766 		return false;
3767 	if (fail_page_alloc.ignore_gfp_highmem && (gfp_mask & __GFP_HIGHMEM))
3768 		return false;
3769 	if (fail_page_alloc.ignore_gfp_reclaim &&
3770 			(gfp_mask & __GFP_DIRECT_RECLAIM))
3771 		return false;
3772 
3773 	return should_fail(&fail_page_alloc.attr, 1 << order);
3774 }
3775 
3776 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
3777 
3778 static int __init fail_page_alloc_debugfs(void)
3779 {
3780 	umode_t mode = S_IFREG | 0600;
3781 	struct dentry *dir;
3782 
3783 	dir = fault_create_debugfs_attr("fail_page_alloc", NULL,
3784 					&fail_page_alloc.attr);
3785 
3786 	debugfs_create_bool("ignore-gfp-wait", mode, dir,
3787 			    &fail_page_alloc.ignore_gfp_reclaim);
3788 	debugfs_create_bool("ignore-gfp-highmem", mode, dir,
3789 			    &fail_page_alloc.ignore_gfp_highmem);
3790 	debugfs_create_u32("min-order", mode, dir, &fail_page_alloc.min_order);
3791 
3792 	return 0;
3793 }
3794 
3795 late_initcall(fail_page_alloc_debugfs);
3796 
3797 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
3798 
3799 #else /* CONFIG_FAIL_PAGE_ALLOC */
3800 
3801 static inline bool __should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
3802 {
3803 	return false;
3804 }
3805 
3806 #endif /* CONFIG_FAIL_PAGE_ALLOC */
3807 
3808 noinline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
3809 {
3810 	return __should_fail_alloc_page(gfp_mask, order);
3811 }
3812 ALLOW_ERROR_INJECTION(should_fail_alloc_page, TRUE);
3813 
3814 static inline long __zone_watermark_unusable_free(struct zone *z,
3815 				unsigned int order, unsigned int alloc_flags)
3816 {
3817 	const bool alloc_harder = (alloc_flags & (ALLOC_HARDER|ALLOC_OOM));
3818 	long unusable_free = (1 << order) - 1;
3819 
3820 	/*
3821 	 * If the caller does not have rights to ALLOC_HARDER then subtract
3822 	 * the high-atomic reserves. This will over-estimate the size of the
3823 	 * atomic reserve but it avoids a search.
3824 	 */
3825 	if (likely(!alloc_harder))
3826 		unusable_free += z->nr_reserved_highatomic;
3827 
3828 #ifdef CONFIG_CMA
3829 	/* If allocation can't use CMA areas don't use free CMA pages */
3830 	if (!(alloc_flags & ALLOC_CMA))
3831 		unusable_free += zone_page_state(z, NR_FREE_CMA_PAGES);
3832 #endif
3833 
3834 	return unusable_free;
3835 }
3836 
3837 /*
3838  * Return true if free base pages are above 'mark'. For high-order checks it
3839  * will return true of the order-0 watermark is reached and there is at least
3840  * one free page of a suitable size. Checking now avoids taking the zone lock
3841  * to check in the allocation paths if no pages are free.
3842  */
3843 bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
3844 			 int highest_zoneidx, unsigned int alloc_flags,
3845 			 long free_pages)
3846 {
3847 	long min = mark;
3848 	int o;
3849 	const bool alloc_harder = (alloc_flags & (ALLOC_HARDER|ALLOC_OOM));
3850 
3851 	/* free_pages may go negative - that's OK */
3852 	free_pages -= __zone_watermark_unusable_free(z, order, alloc_flags);
3853 
3854 	if (alloc_flags & ALLOC_HIGH)
3855 		min -= min / 2;
3856 
3857 	if (unlikely(alloc_harder)) {
3858 		/*
3859 		 * OOM victims can try even harder than normal ALLOC_HARDER
3860 		 * users on the grounds that it's definitely going to be in
3861 		 * the exit path shortly and free memory. Any allocation it
3862 		 * makes during the free path will be small and short-lived.
3863 		 */
3864 		if (alloc_flags & ALLOC_OOM)
3865 			min -= min / 2;
3866 		else
3867 			min -= min / 4;
3868 	}
3869 
3870 	/*
3871 	 * Check watermarks for an order-0 allocation request. If these
3872 	 * are not met, then a high-order request also cannot go ahead
3873 	 * even if a suitable page happened to be free.
3874 	 */
3875 	if (free_pages <= min + z->lowmem_reserve[highest_zoneidx])
3876 		return false;
3877 
3878 	/* If this is an order-0 request then the watermark is fine */
3879 	if (!order)
3880 		return true;
3881 
3882 	/* For a high-order request, check at least one suitable page is free */
3883 	for (o = order; o < MAX_ORDER; o++) {
3884 		struct free_area *area = &z->free_area[o];
3885 		int mt;
3886 
3887 		if (!area->nr_free)
3888 			continue;
3889 
3890 		for (mt = 0; mt < MIGRATE_PCPTYPES; mt++) {
3891 			if (!free_area_empty(area, mt))
3892 				return true;
3893 		}
3894 
3895 #ifdef CONFIG_CMA
3896 		if ((alloc_flags & ALLOC_CMA) &&
3897 		    !free_area_empty(area, MIGRATE_CMA)) {
3898 			return true;
3899 		}
3900 #endif
3901 		if (alloc_harder && !free_area_empty(area, MIGRATE_HIGHATOMIC))
3902 			return true;
3903 	}
3904 	return false;
3905 }
3906 
3907 bool zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
3908 		      int highest_zoneidx, unsigned int alloc_flags)
3909 {
3910 	return __zone_watermark_ok(z, order, mark, highest_zoneidx, alloc_flags,
3911 					zone_page_state(z, NR_FREE_PAGES));
3912 }
3913 
3914 static inline bool zone_watermark_fast(struct zone *z, unsigned int order,
3915 				unsigned long mark, int highest_zoneidx,
3916 				unsigned int alloc_flags, gfp_t gfp_mask)
3917 {
3918 	long free_pages;
3919 
3920 	free_pages = zone_page_state(z, NR_FREE_PAGES);
3921 
3922 	/*
3923 	 * Fast check for order-0 only. If this fails then the reserves
3924 	 * need to be calculated.
3925 	 */
3926 	if (!order) {
3927 		long fast_free;
3928 
3929 		fast_free = free_pages;
3930 		fast_free -= __zone_watermark_unusable_free(z, 0, alloc_flags);
3931 		if (fast_free > mark + z->lowmem_reserve[highest_zoneidx])
3932 			return true;
3933 	}
3934 
3935 	if (__zone_watermark_ok(z, order, mark, highest_zoneidx, alloc_flags,
3936 					free_pages))
3937 		return true;
3938 	/*
3939 	 * Ignore watermark boosting for GFP_ATOMIC order-0 allocations
3940 	 * when checking the min watermark. The min watermark is the
3941 	 * point where boosting is ignored so that kswapd is woken up
3942 	 * when below the low watermark.
3943 	 */
3944 	if (unlikely(!order && (gfp_mask & __GFP_ATOMIC) && z->watermark_boost
3945 		&& ((alloc_flags & ALLOC_WMARK_MASK) == WMARK_MIN))) {
3946 		mark = z->_watermark[WMARK_MIN];
3947 		return __zone_watermark_ok(z, order, mark, highest_zoneidx,
3948 					alloc_flags, free_pages);
3949 	}
3950 
3951 	return false;
3952 }
3953 
3954 bool zone_watermark_ok_safe(struct zone *z, unsigned int order,
3955 			unsigned long mark, int highest_zoneidx)
3956 {
3957 	long free_pages = zone_page_state(z, NR_FREE_PAGES);
3958 
3959 	if (z->percpu_drift_mark && free_pages < z->percpu_drift_mark)
3960 		free_pages = zone_page_state_snapshot(z, NR_FREE_PAGES);
3961 
3962 	return __zone_watermark_ok(z, order, mark, highest_zoneidx, 0,
3963 								free_pages);
3964 }
3965 
3966 #ifdef CONFIG_NUMA
3967 static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
3968 {
3969 	return node_distance(zone_to_nid(local_zone), zone_to_nid(zone)) <=
3970 				node_reclaim_distance;
3971 }
3972 #else	/* CONFIG_NUMA */
3973 static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
3974 {
3975 	return true;
3976 }
3977 #endif	/* CONFIG_NUMA */
3978 
3979 /*
3980  * The restriction on ZONE_DMA32 as being a suitable zone to use to avoid
3981  * fragmentation is subtle. If the preferred zone was HIGHMEM then
3982  * premature use of a lower zone may cause lowmem pressure problems that
3983  * are worse than fragmentation. If the next zone is ZONE_DMA then it is
3984  * probably too small. It only makes sense to spread allocations to avoid
3985  * fragmentation between the Normal and DMA32 zones.
3986  */
3987 static inline unsigned int
3988 alloc_flags_nofragment(struct zone *zone, gfp_t gfp_mask)
3989 {
3990 	unsigned int alloc_flags;
3991 
3992 	/*
3993 	 * __GFP_KSWAPD_RECLAIM is assumed to be the same as ALLOC_KSWAPD
3994 	 * to save a branch.
3995 	 */
3996 	alloc_flags = (__force int) (gfp_mask & __GFP_KSWAPD_RECLAIM);
3997 
3998 #ifdef CONFIG_ZONE_DMA32
3999 	if (!zone)
4000 		return alloc_flags;
4001 
4002 	if (zone_idx(zone) != ZONE_NORMAL)
4003 		return alloc_flags;
4004 
4005 	/*
4006 	 * If ZONE_DMA32 exists, assume it is the one after ZONE_NORMAL and
4007 	 * the pointer is within zone->zone_pgdat->node_zones[]. Also assume
4008 	 * on UMA that if Normal is populated then so is DMA32.
4009 	 */
4010 	BUILD_BUG_ON(ZONE_NORMAL - ZONE_DMA32 != 1);
4011 	if (nr_online_nodes > 1 && !populated_zone(--zone))
4012 		return alloc_flags;
4013 
4014 	alloc_flags |= ALLOC_NOFRAGMENT;
4015 #endif /* CONFIG_ZONE_DMA32 */
4016 	return alloc_flags;
4017 }
4018 
4019 /* Must be called after current_gfp_context() which can change gfp_mask */
4020 static inline unsigned int gfp_to_alloc_flags_cma(gfp_t gfp_mask,
4021 						  unsigned int alloc_flags)
4022 {
4023 #ifdef CONFIG_CMA
4024 	if (gfp_migratetype(gfp_mask) == MIGRATE_MOVABLE)
4025 		alloc_flags |= ALLOC_CMA;
4026 #endif
4027 	return alloc_flags;
4028 }
4029 
4030 /*
4031  * get_page_from_freelist goes through the zonelist trying to allocate
4032  * a page.
4033  */
4034 static struct page *
4035 get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
4036 						const struct alloc_context *ac)
4037 {
4038 	struct zoneref *z;
4039 	struct zone *zone;
4040 	struct pglist_data *last_pgdat_dirty_limit = NULL;
4041 	bool no_fallback;
4042 
4043 retry:
4044 	/*
4045 	 * Scan zonelist, looking for a zone with enough free.
4046 	 * See also __cpuset_node_allowed() comment in kernel/cpuset.c.
4047 	 */
4048 	no_fallback = alloc_flags & ALLOC_NOFRAGMENT;
4049 	z = ac->preferred_zoneref;
4050 	for_next_zone_zonelist_nodemask(zone, z, ac->highest_zoneidx,
4051 					ac->nodemask) {
4052 		struct page *page;
4053 		unsigned long mark;
4054 
4055 		if (cpusets_enabled() &&
4056 			(alloc_flags & ALLOC_CPUSET) &&
4057 			!__cpuset_zone_allowed(zone, gfp_mask))
4058 				continue;
4059 		/*
4060 		 * When allocating a page cache page for writing, we
4061 		 * want to get it from a node that is within its dirty
4062 		 * limit, such that no single node holds more than its
4063 		 * proportional share of globally allowed dirty pages.
4064 		 * The dirty limits take into account the node's
4065 		 * lowmem reserves and high watermark so that kswapd
4066 		 * should be able to balance it without having to
4067 		 * write pages from its LRU list.
4068 		 *
4069 		 * XXX: For now, allow allocations to potentially
4070 		 * exceed the per-node dirty limit in the slowpath
4071 		 * (spread_dirty_pages unset) before going into reclaim,
4072 		 * which is important when on a NUMA setup the allowed
4073 		 * nodes are together not big enough to reach the
4074 		 * global limit.  The proper fix for these situations
4075 		 * will require awareness of nodes in the
4076 		 * dirty-throttling and the flusher threads.
4077 		 */
4078 		if (ac->spread_dirty_pages) {
4079 			if (last_pgdat_dirty_limit == zone->zone_pgdat)
4080 				continue;
4081 
4082 			if (!node_dirty_ok(zone->zone_pgdat)) {
4083 				last_pgdat_dirty_limit = zone->zone_pgdat;
4084 				continue;
4085 			}
4086 		}
4087 
4088 		if (no_fallback && nr_online_nodes > 1 &&
4089 		    zone != ac->preferred_zoneref->zone) {
4090 			int local_nid;
4091 
4092 			/*
4093 			 * If moving to a remote node, retry but allow
4094 			 * fragmenting fallbacks. Locality is more important
4095 			 * than fragmentation avoidance.
4096 			 */
4097 			local_nid = zone_to_nid(ac->preferred_zoneref->zone);
4098 			if (zone_to_nid(zone) != local_nid) {
4099 				alloc_flags &= ~ALLOC_NOFRAGMENT;
4100 				goto retry;
4101 			}
4102 		}
4103 
4104 		mark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK);
4105 		if (!zone_watermark_fast(zone, order, mark,
4106 				       ac->highest_zoneidx, alloc_flags,
4107 				       gfp_mask)) {
4108 			int ret;
4109 
4110 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
4111 			/*
4112 			 * Watermark failed for this zone, but see if we can
4113 			 * grow this zone if it contains deferred pages.
4114 			 */
4115 			if (static_branch_unlikely(&deferred_pages)) {
4116 				if (_deferred_grow_zone(zone, order))
4117 					goto try_this_zone;
4118 			}
4119 #endif
4120 			/* Checked here to keep the fast path fast */
4121 			BUILD_BUG_ON(ALLOC_NO_WATERMARKS < NR_WMARK);
4122 			if (alloc_flags & ALLOC_NO_WATERMARKS)
4123 				goto try_this_zone;
4124 
4125 			if (!node_reclaim_enabled() ||
4126 			    !zone_allows_reclaim(ac->preferred_zoneref->zone, zone))
4127 				continue;
4128 
4129 			ret = node_reclaim(zone->zone_pgdat, gfp_mask, order);
4130 			switch (ret) {
4131 			case NODE_RECLAIM_NOSCAN:
4132 				/* did not scan */
4133 				continue;
4134 			case NODE_RECLAIM_FULL:
4135 				/* scanned but unreclaimable */
4136 				continue;
4137 			default:
4138 				/* did we reclaim enough */
4139 				if (zone_watermark_ok(zone, order, mark,
4140 					ac->highest_zoneidx, alloc_flags))
4141 					goto try_this_zone;
4142 
4143 				continue;
4144 			}
4145 		}
4146 
4147 try_this_zone:
4148 		page = rmqueue(ac->preferred_zoneref->zone, zone, order,
4149 				gfp_mask, alloc_flags, ac->migratetype);
4150 		if (page) {
4151 			prep_new_page(page, order, gfp_mask, alloc_flags);
4152 
4153 			/*
4154 			 * If this is a high-order atomic allocation then check
4155 			 * if the pageblock should be reserved for the future
4156 			 */
4157 			if (unlikely(order && (alloc_flags & ALLOC_HARDER)))
4158 				reserve_highatomic_pageblock(page, zone, order);
4159 
4160 			return page;
4161 		} else {
4162 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
4163 			/* Try again if zone has deferred pages */
4164 			if (static_branch_unlikely(&deferred_pages)) {
4165 				if (_deferred_grow_zone(zone, order))
4166 					goto try_this_zone;
4167 			}
4168 #endif
4169 		}
4170 	}
4171 
4172 	/*
4173 	 * It's possible on a UMA machine to get through all zones that are
4174 	 * fragmented. If avoiding fragmentation, reset and try again.
4175 	 */
4176 	if (no_fallback) {
4177 		alloc_flags &= ~ALLOC_NOFRAGMENT;
4178 		goto retry;
4179 	}
4180 
4181 	return NULL;
4182 }
4183 
4184 static void warn_alloc_show_mem(gfp_t gfp_mask, nodemask_t *nodemask)
4185 {
4186 	unsigned int filter = SHOW_MEM_FILTER_NODES;
4187 
4188 	/*
4189 	 * This documents exceptions given to allocations in certain
4190 	 * contexts that are allowed to allocate outside current's set
4191 	 * of allowed nodes.
4192 	 */
4193 	if (!(gfp_mask & __GFP_NOMEMALLOC))
4194 		if (tsk_is_oom_victim(current) ||
4195 		    (current->flags & (PF_MEMALLOC | PF_EXITING)))
4196 			filter &= ~SHOW_MEM_FILTER_NODES;
4197 	if (in_interrupt() || !(gfp_mask & __GFP_DIRECT_RECLAIM))
4198 		filter &= ~SHOW_MEM_FILTER_NODES;
4199 
4200 	show_mem(filter, nodemask);
4201 }
4202 
4203 void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...)
4204 {
4205 	struct va_format vaf;
4206 	va_list args;
4207 	static DEFINE_RATELIMIT_STATE(nopage_rs, 10*HZ, 1);
4208 
4209 	if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs))
4210 		return;
4211 
4212 	va_start(args, fmt);
4213 	vaf.fmt = fmt;
4214 	vaf.va = &args;
4215 	pr_warn("%s: %pV, mode:%#x(%pGg), nodemask=%*pbl",
4216 			current->comm, &vaf, gfp_mask, &gfp_mask,
4217 			nodemask_pr_args(nodemask));
4218 	va_end(args);
4219 
4220 	cpuset_print_current_mems_allowed();
4221 	pr_cont("\n");
4222 	dump_stack();
4223 	warn_alloc_show_mem(gfp_mask, nodemask);
4224 }
4225 
4226 static inline struct page *
4227 __alloc_pages_cpuset_fallback(gfp_t gfp_mask, unsigned int order,
4228 			      unsigned int alloc_flags,
4229 			      const struct alloc_context *ac)
4230 {
4231 	struct page *page;
4232 
4233 	page = get_page_from_freelist(gfp_mask, order,
4234 			alloc_flags|ALLOC_CPUSET, ac);
4235 	/*
4236 	 * fallback to ignore cpuset restriction if our nodes
4237 	 * are depleted
4238 	 */
4239 	if (!page)
4240 		page = get_page_from_freelist(gfp_mask, order,
4241 				alloc_flags, ac);
4242 
4243 	return page;
4244 }
4245 
4246 static inline struct page *
4247 __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
4248 	const struct alloc_context *ac, unsigned long *did_some_progress)
4249 {
4250 	struct oom_control oc = {
4251 		.zonelist = ac->zonelist,
4252 		.nodemask = ac->nodemask,
4253 		.memcg = NULL,
4254 		.gfp_mask = gfp_mask,
4255 		.order = order,
4256 	};
4257 	struct page *page;
4258 
4259 	*did_some_progress = 0;
4260 
4261 	/*
4262 	 * Acquire the oom lock.  If that fails, somebody else is
4263 	 * making progress for us.
4264 	 */
4265 	if (!mutex_trylock(&oom_lock)) {
4266 		*did_some_progress = 1;
4267 		schedule_timeout_uninterruptible(1);
4268 		return NULL;
4269 	}
4270 
4271 	/*
4272 	 * Go through the zonelist yet one more time, keep very high watermark
4273 	 * here, this is only to catch a parallel oom killing, we must fail if
4274 	 * we're still under heavy pressure. But make sure that this reclaim
4275 	 * attempt shall not depend on __GFP_DIRECT_RECLAIM && !__GFP_NORETRY
4276 	 * allocation which will never fail due to oom_lock already held.
4277 	 */
4278 	page = get_page_from_freelist((gfp_mask | __GFP_HARDWALL) &
4279 				      ~__GFP_DIRECT_RECLAIM, order,
4280 				      ALLOC_WMARK_HIGH|ALLOC_CPUSET, ac);
4281 	if (page)
4282 		goto out;
4283 
4284 	/* Coredumps can quickly deplete all memory reserves */
4285 	if (current->flags & PF_DUMPCORE)
4286 		goto out;
4287 	/* The OOM killer will not help higher order allocs */
4288 	if (order > PAGE_ALLOC_COSTLY_ORDER)
4289 		goto out;
4290 	/*
4291 	 * We have already exhausted all our reclaim opportunities without any
4292 	 * success so it is time to admit defeat. We will skip the OOM killer
4293 	 * because it is very likely that the caller has a more reasonable
4294 	 * fallback than shooting a random task.
4295 	 *
4296 	 * The OOM killer may not free memory on a specific node.
4297 	 */
4298 	if (gfp_mask & (__GFP_RETRY_MAYFAIL | __GFP_THISNODE))
4299 		goto out;
4300 	/* The OOM killer does not needlessly kill tasks for lowmem */
4301 	if (ac->highest_zoneidx < ZONE_NORMAL)
4302 		goto out;
4303 	if (pm_suspended_storage())
4304 		goto out;
4305 	/*
4306 	 * XXX: GFP_NOFS allocations should rather fail than rely on
4307 	 * other request to make a forward progress.
4308 	 * We are in an unfortunate situation where out_of_memory cannot
4309 	 * do much for this context but let's try it to at least get
4310 	 * access to memory reserved if the current task is killed (see
4311 	 * out_of_memory). Once filesystems are ready to handle allocation
4312 	 * failures more gracefully we should just bail out here.
4313 	 */
4314 
4315 	/* Exhausted what can be done so it's blame time */
4316 	if (out_of_memory(&oc) || WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL)) {
4317 		*did_some_progress = 1;
4318 
4319 		/*
4320 		 * Help non-failing allocations by giving them access to memory
4321 		 * reserves
4322 		 */
4323 		if (gfp_mask & __GFP_NOFAIL)
4324 			page = __alloc_pages_cpuset_fallback(gfp_mask, order,
4325 					ALLOC_NO_WATERMARKS, ac);
4326 	}
4327 out:
4328 	mutex_unlock(&oom_lock);
4329 	return page;
4330 }
4331 
4332 /*
4333  * Maximum number of compaction retries with a progress before OOM
4334  * killer is consider as the only way to move forward.
4335  */
4336 #define MAX_COMPACT_RETRIES 16
4337 
4338 #ifdef CONFIG_COMPACTION
4339 /* Try memory compaction for high-order allocations before reclaim */
4340 static struct page *
4341 __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
4342 		unsigned int alloc_flags, const struct alloc_context *ac,
4343 		enum compact_priority prio, enum compact_result *compact_result)
4344 {
4345 	struct page *page = NULL;
4346 	unsigned long pflags;
4347 	unsigned int noreclaim_flag;
4348 
4349 	if (!order)
4350 		return NULL;
4351 
4352 	psi_memstall_enter(&pflags);
4353 	noreclaim_flag = memalloc_noreclaim_save();
4354 
4355 	*compact_result = try_to_compact_pages(gfp_mask, order, alloc_flags, ac,
4356 								prio, &page);
4357 
4358 	memalloc_noreclaim_restore(noreclaim_flag);
4359 	psi_memstall_leave(&pflags);
4360 
4361 	if (*compact_result == COMPACT_SKIPPED)
4362 		return NULL;
4363 	/*
4364 	 * At least in one zone compaction wasn't deferred or skipped, so let's
4365 	 * count a compaction stall
4366 	 */
4367 	count_vm_event(COMPACTSTALL);
4368 
4369 	/* Prep a captured page if available */
4370 	if (page)
4371 		prep_new_page(page, order, gfp_mask, alloc_flags);
4372 
4373 	/* Try get a page from the freelist if available */
4374 	if (!page)
4375 		page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
4376 
4377 	if (page) {
4378 		struct zone *zone = page_zone(page);
4379 
4380 		zone->compact_blockskip_flush = false;
4381 		compaction_defer_reset(zone, order, true);
4382 		count_vm_event(COMPACTSUCCESS);
4383 		return page;
4384 	}
4385 
4386 	/*
4387 	 * It's bad if compaction run occurs and fails. The most likely reason
4388 	 * is that pages exist, but not enough to satisfy watermarks.
4389 	 */
4390 	count_vm_event(COMPACTFAIL);
4391 
4392 	cond_resched();
4393 
4394 	return NULL;
4395 }
4396 
4397 static inline bool
4398 should_compact_retry(struct alloc_context *ac, int order, int alloc_flags,
4399 		     enum compact_result compact_result,
4400 		     enum compact_priority *compact_priority,
4401 		     int *compaction_retries)
4402 {
4403 	int max_retries = MAX_COMPACT_RETRIES;
4404 	int min_priority;
4405 	bool ret = false;
4406 	int retries = *compaction_retries;
4407 	enum compact_priority priority = *compact_priority;
4408 
4409 	if (!order)
4410 		return false;
4411 
4412 	if (fatal_signal_pending(current))
4413 		return false;
4414 
4415 	if (compaction_made_progress(compact_result))
4416 		(*compaction_retries)++;
4417 
4418 	/*
4419 	 * compaction considers all the zone as desperately out of memory
4420 	 * so it doesn't really make much sense to retry except when the
4421 	 * failure could be caused by insufficient priority
4422 	 */
4423 	if (compaction_failed(compact_result))
4424 		goto check_priority;
4425 
4426 	/*
4427 	 * compaction was skipped because there are not enough order-0 pages
4428 	 * to work with, so we retry only if it looks like reclaim can help.
4429 	 */
4430 	if (compaction_needs_reclaim(compact_result)) {
4431 		ret = compaction_zonelist_suitable(ac, order, alloc_flags);
4432 		goto out;
4433 	}
4434 
4435 	/*
4436 	 * make sure the compaction wasn't deferred or didn't bail out early
4437 	 * due to locks contention before we declare that we should give up.
4438 	 * But the next retry should use a higher priority if allowed, so
4439 	 * we don't just keep bailing out endlessly.
4440 	 */
4441 	if (compaction_withdrawn(compact_result)) {
4442 		goto check_priority;
4443 	}
4444 
4445 	/*
4446 	 * !costly requests are much more important than __GFP_RETRY_MAYFAIL
4447 	 * costly ones because they are de facto nofail and invoke OOM
4448 	 * killer to move on while costly can fail and users are ready
4449 	 * to cope with that. 1/4 retries is rather arbitrary but we
4450 	 * would need much more detailed feedback from compaction to
4451 	 * make a better decision.
4452 	 */
4453 	if (order > PAGE_ALLOC_COSTLY_ORDER)
4454 		max_retries /= 4;
4455 	if (*compaction_retries <= max_retries) {
4456 		ret = true;
4457 		goto out;
4458 	}
4459 
4460 	/*
4461 	 * Make sure there are attempts at the highest priority if we exhausted
4462 	 * all retries or failed at the lower priorities.
4463 	 */
4464 check_priority:
4465 	min_priority = (order > PAGE_ALLOC_COSTLY_ORDER) ?
4466 			MIN_COMPACT_COSTLY_PRIORITY : MIN_COMPACT_PRIORITY;
4467 
4468 	if (*compact_priority > min_priority) {
4469 		(*compact_priority)--;
4470 		*compaction_retries = 0;
4471 		ret = true;
4472 	}
4473 out:
4474 	trace_compact_retry(order, priority, compact_result, retries, max_retries, ret);
4475 	return ret;
4476 }
4477 #else
4478 static inline struct page *
4479 __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
4480 		unsigned int alloc_flags, const struct alloc_context *ac,
4481 		enum compact_priority prio, enum compact_result *compact_result)
4482 {
4483 	*compact_result = COMPACT_SKIPPED;
4484 	return NULL;
4485 }
4486 
4487 static inline bool
4488 should_compact_retry(struct alloc_context *ac, unsigned int order, int alloc_flags,
4489 		     enum compact_result compact_result,
4490 		     enum compact_priority *compact_priority,
4491 		     int *compaction_retries)
4492 {
4493 	struct zone *zone;
4494 	struct zoneref *z;
4495 
4496 	if (!order || order > PAGE_ALLOC_COSTLY_ORDER)
4497 		return false;
4498 
4499 	/*
4500 	 * There are setups with compaction disabled which would prefer to loop
4501 	 * inside the allocator rather than hit the oom killer prematurely.
4502 	 * Let's give them a good hope and keep retrying while the order-0
4503 	 * watermarks are OK.
4504 	 */
4505 	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist,
4506 				ac->highest_zoneidx, ac->nodemask) {
4507 		if (zone_watermark_ok(zone, 0, min_wmark_pages(zone),
4508 					ac->highest_zoneidx, alloc_flags))
4509 			return true;
4510 	}
4511 	return false;
4512 }
4513 #endif /* CONFIG_COMPACTION */
4514 
4515 #ifdef CONFIG_LOCKDEP
4516 static struct lockdep_map __fs_reclaim_map =
4517 	STATIC_LOCKDEP_MAP_INIT("fs_reclaim", &__fs_reclaim_map);
4518 
4519 static bool __need_reclaim(gfp_t gfp_mask)
4520 {
4521 	/* no reclaim without waiting on it */
4522 	if (!(gfp_mask & __GFP_DIRECT_RECLAIM))
4523 		return false;
4524 
4525 	/* this guy won't enter reclaim */
4526 	if (current->flags & PF_MEMALLOC)
4527 		return false;
4528 
4529 	if (gfp_mask & __GFP_NOLOCKDEP)
4530 		return false;
4531 
4532 	return true;
4533 }
4534 
4535 void __fs_reclaim_acquire(void)
4536 {
4537 	lock_map_acquire(&__fs_reclaim_map);
4538 }
4539 
4540 void __fs_reclaim_release(void)
4541 {
4542 	lock_map_release(&__fs_reclaim_map);
4543 }
4544 
4545 void fs_reclaim_acquire(gfp_t gfp_mask)
4546 {
4547 	gfp_mask = current_gfp_context(gfp_mask);
4548 
4549 	if (__need_reclaim(gfp_mask)) {
4550 		if (gfp_mask & __GFP_FS)
4551 			__fs_reclaim_acquire();
4552 
4553 #ifdef CONFIG_MMU_NOTIFIER
4554 		lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
4555 		lock_map_release(&__mmu_notifier_invalidate_range_start_map);
4556 #endif
4557 
4558 	}
4559 }
4560 EXPORT_SYMBOL_GPL(fs_reclaim_acquire);
4561 
4562 void fs_reclaim_release(gfp_t gfp_mask)
4563 {
4564 	gfp_mask = current_gfp_context(gfp_mask);
4565 
4566 	if (__need_reclaim(gfp_mask)) {
4567 		if (gfp_mask & __GFP_FS)
4568 			__fs_reclaim_release();
4569 	}
4570 }
4571 EXPORT_SYMBOL_GPL(fs_reclaim_release);
4572 #endif
4573 
4574 /* Perform direct synchronous page reclaim */
4575 static unsigned long
4576 __perform_reclaim(gfp_t gfp_mask, unsigned int order,
4577 					const struct alloc_context *ac)
4578 {
4579 	unsigned int noreclaim_flag;
4580 	unsigned long pflags, progress;
4581 
4582 	cond_resched();
4583 
4584 	/* We now go into synchronous reclaim */
4585 	cpuset_memory_pressure_bump();
4586 	psi_memstall_enter(&pflags);
4587 	fs_reclaim_acquire(gfp_mask);
4588 	noreclaim_flag = memalloc_noreclaim_save();
4589 
4590 	progress = try_to_free_pages(ac->zonelist, order, gfp_mask,
4591 								ac->nodemask);
4592 
4593 	memalloc_noreclaim_restore(noreclaim_flag);
4594 	fs_reclaim_release(gfp_mask);
4595 	psi_memstall_leave(&pflags);
4596 
4597 	cond_resched();
4598 
4599 	return progress;
4600 }
4601 
4602 /* The really slow allocator path where we enter direct reclaim */
4603 static inline struct page *
4604 __alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order,
4605 		unsigned int alloc_flags, const struct alloc_context *ac,
4606 		unsigned long *did_some_progress)
4607 {
4608 	struct page *page = NULL;
4609 	bool drained = false;
4610 
4611 	*did_some_progress = __perform_reclaim(gfp_mask, order, ac);
4612 	if (unlikely(!(*did_some_progress)))
4613 		return NULL;
4614 
4615 retry:
4616 	page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
4617 
4618 	/*
4619 	 * If an allocation failed after direct reclaim, it could be because
4620 	 * pages are pinned on the per-cpu lists or in high alloc reserves.
4621 	 * Shrink them and try again
4622 	 */
4623 	if (!page && !drained) {
4624 		unreserve_highatomic_pageblock(ac, false);
4625 		drain_all_pages(NULL);
4626 		drained = true;
4627 		goto retry;
4628 	}
4629 
4630 	return page;
4631 }
4632 
4633 static void wake_all_kswapds(unsigned int order, gfp_t gfp_mask,
4634 			     const struct alloc_context *ac)
4635 {
4636 	struct zoneref *z;
4637 	struct zone *zone;
4638 	pg_data_t *last_pgdat = NULL;
4639 	enum zone_type highest_zoneidx = ac->highest_zoneidx;
4640 
4641 	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, highest_zoneidx,
4642 					ac->nodemask) {
4643 		if (last_pgdat != zone->zone_pgdat)
4644 			wakeup_kswapd(zone, gfp_mask, order, highest_zoneidx);
4645 		last_pgdat = zone->zone_pgdat;
4646 	}
4647 }
4648 
4649 static inline unsigned int
4650 gfp_to_alloc_flags(gfp_t gfp_mask)
4651 {
4652 	unsigned int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET;
4653 
4654 	/*
4655 	 * __GFP_HIGH is assumed to be the same as ALLOC_HIGH
4656 	 * and __GFP_KSWAPD_RECLAIM is assumed to be the same as ALLOC_KSWAPD
4657 	 * to save two branches.
4658 	 */
4659 	BUILD_BUG_ON(__GFP_HIGH != (__force gfp_t) ALLOC_HIGH);
4660 	BUILD_BUG_ON(__GFP_KSWAPD_RECLAIM != (__force gfp_t) ALLOC_KSWAPD);
4661 
4662 	/*
4663 	 * The caller may dip into page reserves a bit more if the caller
4664 	 * cannot run direct reclaim, or if the caller has realtime scheduling
4665 	 * policy or is asking for __GFP_HIGH memory.  GFP_ATOMIC requests will
4666 	 * set both ALLOC_HARDER (__GFP_ATOMIC) and ALLOC_HIGH (__GFP_HIGH).
4667 	 */
4668 	alloc_flags |= (__force int)
4669 		(gfp_mask & (__GFP_HIGH | __GFP_KSWAPD_RECLAIM));
4670 
4671 	if (gfp_mask & __GFP_ATOMIC) {
4672 		/*
4673 		 * Not worth trying to allocate harder for __GFP_NOMEMALLOC even
4674 		 * if it can't schedule.
4675 		 */
4676 		if (!(gfp_mask & __GFP_NOMEMALLOC))
4677 			alloc_flags |= ALLOC_HARDER;
4678 		/*
4679 		 * Ignore cpuset mems for GFP_ATOMIC rather than fail, see the
4680 		 * comment for __cpuset_node_allowed().
4681 		 */
4682 		alloc_flags &= ~ALLOC_CPUSET;
4683 	} else if (unlikely(rt_task(current)) && !in_interrupt())
4684 		alloc_flags |= ALLOC_HARDER;
4685 
4686 	alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, alloc_flags);
4687 
4688 	return alloc_flags;
4689 }
4690 
4691 static bool oom_reserves_allowed(struct task_struct *tsk)
4692 {
4693 	if (!tsk_is_oom_victim(tsk))
4694 		return false;
4695 
4696 	/*
4697 	 * !MMU doesn't have oom reaper so give access to memory reserves
4698 	 * only to the thread with TIF_MEMDIE set
4699 	 */
4700 	if (!IS_ENABLED(CONFIG_MMU) && !test_thread_flag(TIF_MEMDIE))
4701 		return false;
4702 
4703 	return true;
4704 }
4705 
4706 /*
4707  * Distinguish requests which really need access to full memory
4708  * reserves from oom victims which can live with a portion of it
4709  */
4710 static inline int __gfp_pfmemalloc_flags(gfp_t gfp_mask)
4711 {
4712 	if (unlikely(gfp_mask & __GFP_NOMEMALLOC))
4713 		return 0;
4714 	if (gfp_mask & __GFP_MEMALLOC)
4715 		return ALLOC_NO_WATERMARKS;
4716 	if (in_serving_softirq() && (current->flags & PF_MEMALLOC))
4717 		return ALLOC_NO_WATERMARKS;
4718 	if (!in_interrupt()) {
4719 		if (current->flags & PF_MEMALLOC)
4720 			return ALLOC_NO_WATERMARKS;
4721 		else if (oom_reserves_allowed(current))
4722 			return ALLOC_OOM;
4723 	}
4724 
4725 	return 0;
4726 }
4727 
4728 bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
4729 {
4730 	return !!__gfp_pfmemalloc_flags(gfp_mask);
4731 }
4732 
4733 /*
4734  * Checks whether it makes sense to retry the reclaim to make a forward progress
4735  * for the given allocation request.
4736  *
4737  * We give up when we either have tried MAX_RECLAIM_RETRIES in a row
4738  * without success, or when we couldn't even meet the watermark if we
4739  * reclaimed all remaining pages on the LRU lists.
4740  *
4741  * Returns true if a retry is viable or false to enter the oom path.
4742  */
4743 static inline bool
4744 should_reclaim_retry(gfp_t gfp_mask, unsigned order,
4745 		     struct alloc_context *ac, int alloc_flags,
4746 		     bool did_some_progress, int *no_progress_loops)
4747 {
4748 	struct zone *zone;
4749 	struct zoneref *z;
4750 	bool ret = false;
4751 
4752 	/*
4753 	 * Costly allocations might have made a progress but this doesn't mean
4754 	 * their order will become available due to high fragmentation so
4755 	 * always increment the no progress counter for them
4756 	 */
4757 	if (did_some_progress && order <= PAGE_ALLOC_COSTLY_ORDER)
4758 		*no_progress_loops = 0;
4759 	else
4760 		(*no_progress_loops)++;
4761 
4762 	/*
4763 	 * Make sure we converge to OOM if we cannot make any progress
4764 	 * several times in the row.
4765 	 */
4766 	if (*no_progress_loops > MAX_RECLAIM_RETRIES) {
4767 		/* Before OOM, exhaust highatomic_reserve */
4768 		return unreserve_highatomic_pageblock(ac, true);
4769 	}
4770 
4771 	/*
4772 	 * Keep reclaiming pages while there is a chance this will lead
4773 	 * somewhere.  If none of the target zones can satisfy our allocation
4774 	 * request even if all reclaimable pages are considered then we are
4775 	 * screwed and have to go OOM.
4776 	 */
4777 	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist,
4778 				ac->highest_zoneidx, ac->nodemask) {
4779 		unsigned long available;
4780 		unsigned long reclaimable;
4781 		unsigned long min_wmark = min_wmark_pages(zone);
4782 		bool wmark;
4783 
4784 		available = reclaimable = zone_reclaimable_pages(zone);
4785 		available += zone_page_state_snapshot(zone, NR_FREE_PAGES);
4786 
4787 		/*
4788 		 * Would the allocation succeed if we reclaimed all
4789 		 * reclaimable pages?
4790 		 */
4791 		wmark = __zone_watermark_ok(zone, order, min_wmark,
4792 				ac->highest_zoneidx, alloc_flags, available);
4793 		trace_reclaim_retry_zone(z, order, reclaimable,
4794 				available, min_wmark, *no_progress_loops, wmark);
4795 		if (wmark) {
4796 			/*
4797 			 * If we didn't make any progress and have a lot of
4798 			 * dirty + writeback pages then we should wait for
4799 			 * an IO to complete to slow down the reclaim and
4800 			 * prevent from pre mature OOM
4801 			 */
4802 			if (!did_some_progress) {
4803 				unsigned long write_pending;
4804 
4805 				write_pending = zone_page_state_snapshot(zone,
4806 							NR_ZONE_WRITE_PENDING);
4807 
4808 				if (2 * write_pending > reclaimable) {
4809 					congestion_wait(BLK_RW_ASYNC, HZ/10);
4810 					return true;
4811 				}
4812 			}
4813 
4814 			ret = true;
4815 			goto out;
4816 		}
4817 	}
4818 
4819 out:
4820 	/*
4821 	 * Memory allocation/reclaim might be called from a WQ context and the
4822 	 * current implementation of the WQ concurrency control doesn't
4823 	 * recognize that a particular WQ is congested if the worker thread is
4824 	 * looping without ever sleeping. Therefore we have to do a short sleep
4825 	 * here rather than calling cond_resched().
4826 	 */
4827 	if (current->flags & PF_WQ_WORKER)
4828 		schedule_timeout_uninterruptible(1);
4829 	else
4830 		cond_resched();
4831 	return ret;
4832 }
4833 
4834 static inline bool
4835 check_retry_cpuset(int cpuset_mems_cookie, struct alloc_context *ac)
4836 {
4837 	/*
4838 	 * It's possible that cpuset's mems_allowed and the nodemask from
4839 	 * mempolicy don't intersect. This should be normally dealt with by
4840 	 * policy_nodemask(), but it's possible to race with cpuset update in
4841 	 * such a way the check therein was true, and then it became false
4842 	 * before we got our cpuset_mems_cookie here.
4843 	 * This assumes that for all allocations, ac->nodemask can come only
4844 	 * from MPOL_BIND mempolicy (whose documented semantics is to be ignored
4845 	 * when it does not intersect with the cpuset restrictions) or the
4846 	 * caller can deal with a violated nodemask.
4847 	 */
4848 	if (cpusets_enabled() && ac->nodemask &&
4849 			!cpuset_nodemask_valid_mems_allowed(ac->nodemask)) {
4850 		ac->nodemask = NULL;
4851 		return true;
4852 	}
4853 
4854 	/*
4855 	 * When updating a task's mems_allowed or mempolicy nodemask, it is
4856 	 * possible to race with parallel threads in such a way that our
4857 	 * allocation can fail while the mask is being updated. If we are about
4858 	 * to fail, check if the cpuset changed during allocation and if so,
4859 	 * retry.
4860 	 */
4861 	if (read_mems_allowed_retry(cpuset_mems_cookie))
4862 		return true;
4863 
4864 	return false;
4865 }
4866 
4867 static inline struct page *
4868 __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
4869 						struct alloc_context *ac)
4870 {
4871 	bool can_direct_reclaim = gfp_mask & __GFP_DIRECT_RECLAIM;
4872 	const bool costly_order = order > PAGE_ALLOC_COSTLY_ORDER;
4873 	struct page *page = NULL;
4874 	unsigned int alloc_flags;
4875 	unsigned long did_some_progress;
4876 	enum compact_priority compact_priority;
4877 	enum compact_result compact_result;
4878 	int compaction_retries;
4879 	int no_progress_loops;
4880 	unsigned int cpuset_mems_cookie;
4881 	int reserve_flags;
4882 
4883 	/*
4884 	 * We also sanity check to catch abuse of atomic reserves being used by
4885 	 * callers that are not in atomic context.
4886 	 */
4887 	if (WARN_ON_ONCE((gfp_mask & (__GFP_ATOMIC|__GFP_DIRECT_RECLAIM)) ==
4888 				(__GFP_ATOMIC|__GFP_DIRECT_RECLAIM)))
4889 		gfp_mask &= ~__GFP_ATOMIC;
4890 
4891 retry_cpuset:
4892 	compaction_retries = 0;
4893 	no_progress_loops = 0;
4894 	compact_priority = DEF_COMPACT_PRIORITY;
4895 	cpuset_mems_cookie = read_mems_allowed_begin();
4896 
4897 	/*
4898 	 * The fast path uses conservative alloc_flags to succeed only until
4899 	 * kswapd needs to be woken up, and to avoid the cost of setting up
4900 	 * alloc_flags precisely. So we do that now.
4901 	 */
4902 	alloc_flags = gfp_to_alloc_flags(gfp_mask);
4903 
4904 	/*
4905 	 * We need to recalculate the starting point for the zonelist iterator
4906 	 * because we might have used different nodemask in the fast path, or
4907 	 * there was a cpuset modification and we are retrying - otherwise we
4908 	 * could end up iterating over non-eligible zones endlessly.
4909 	 */
4910 	ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
4911 					ac->highest_zoneidx, ac->nodemask);
4912 	if (!ac->preferred_zoneref->zone)
4913 		goto nopage;
4914 
4915 	if (alloc_flags & ALLOC_KSWAPD)
4916 		wake_all_kswapds(order, gfp_mask, ac);
4917 
4918 	/*
4919 	 * The adjusted alloc_flags might result in immediate success, so try
4920 	 * that first
4921 	 */
4922 	page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
4923 	if (page)
4924 		goto got_pg;
4925 
4926 	/*
4927 	 * For costly allocations, try direct compaction first, as it's likely
4928 	 * that we have enough base pages and don't need to reclaim. For non-
4929 	 * movable high-order allocations, do that as well, as compaction will
4930 	 * try prevent permanent fragmentation by migrating from blocks of the
4931 	 * same migratetype.
4932 	 * Don't try this for allocations that are allowed to ignore
4933 	 * watermarks, as the ALLOC_NO_WATERMARKS attempt didn't yet happen.
4934 	 */
4935 	if (can_direct_reclaim &&
4936 			(costly_order ||
4937 			   (order > 0 && ac->migratetype != MIGRATE_MOVABLE))
4938 			&& !gfp_pfmemalloc_allowed(gfp_mask)) {
4939 		page = __alloc_pages_direct_compact(gfp_mask, order,
4940 						alloc_flags, ac,
4941 						INIT_COMPACT_PRIORITY,
4942 						&compact_result);
4943 		if (page)
4944 			goto got_pg;
4945 
4946 		/*
4947 		 * Checks for costly allocations with __GFP_NORETRY, which
4948 		 * includes some THP page fault allocations
4949 		 */
4950 		if (costly_order && (gfp_mask & __GFP_NORETRY)) {
4951 			/*
4952 			 * If allocating entire pageblock(s) and compaction
4953 			 * failed because all zones are below low watermarks
4954 			 * or is prohibited because it recently failed at this
4955 			 * order, fail immediately unless the allocator has
4956 			 * requested compaction and reclaim retry.
4957 			 *
4958 			 * Reclaim is
4959 			 *  - potentially very expensive because zones are far
4960 			 *    below their low watermarks or this is part of very
4961 			 *    bursty high order allocations,
4962 			 *  - not guaranteed to help because isolate_freepages()
4963 			 *    may not iterate over freed pages as part of its
4964 			 *    linear scan, and
4965 			 *  - unlikely to make entire pageblocks free on its
4966 			 *    own.
4967 			 */
4968 			if (compact_result == COMPACT_SKIPPED ||
4969 			    compact_result == COMPACT_DEFERRED)
4970 				goto nopage;
4971 
4972 			/*
4973 			 * Looks like reclaim/compaction is worth trying, but
4974 			 * sync compaction could be very expensive, so keep
4975 			 * using async compaction.
4976 			 */
4977 			compact_priority = INIT_COMPACT_PRIORITY;
4978 		}
4979 	}
4980 
4981 retry:
4982 	/* Ensure kswapd doesn't accidentally go to sleep as long as we loop */
4983 	if (alloc_flags & ALLOC_KSWAPD)
4984 		wake_all_kswapds(order, gfp_mask, ac);
4985 
4986 	reserve_flags = __gfp_pfmemalloc_flags(gfp_mask);
4987 	if (reserve_flags)
4988 		alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, reserve_flags);
4989 
4990 	/*
4991 	 * Reset the nodemask and zonelist iterators if memory policies can be
4992 	 * ignored. These allocations are high priority and system rather than
4993 	 * user oriented.
4994 	 */
4995 	if (!(alloc_flags & ALLOC_CPUSET) || reserve_flags) {
4996 		ac->nodemask = NULL;
4997 		ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
4998 					ac->highest_zoneidx, ac->nodemask);
4999 	}
5000 
5001 	/* Attempt with potentially adjusted zonelist and alloc_flags */
5002 	page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
5003 	if (page)
5004 		goto got_pg;
5005 
5006 	/* Caller is not willing to reclaim, we can't balance anything */
5007 	if (!can_direct_reclaim)
5008 		goto nopage;
5009 
5010 	/* Avoid recursion of direct reclaim */
5011 	if (current->flags & PF_MEMALLOC)
5012 		goto nopage;
5013 
5014 	/* Try direct reclaim and then allocating */
5015 	page = __alloc_pages_direct_reclaim(gfp_mask, order, alloc_flags, ac,
5016 							&did_some_progress);
5017 	if (page)
5018 		goto got_pg;
5019 
5020 	/* Try direct compaction and then allocating */
5021 	page = __alloc_pages_direct_compact(gfp_mask, order, alloc_flags, ac,
5022 					compact_priority, &compact_result);
5023 	if (page)
5024 		goto got_pg;
5025 
5026 	/* Do not loop if specifically requested */
5027 	if (gfp_mask & __GFP_NORETRY)
5028 		goto nopage;
5029 
5030 	/*
5031 	 * Do not retry costly high order allocations unless they are
5032 	 * __GFP_RETRY_MAYFAIL
5033 	 */
5034 	if (costly_order && !(gfp_mask & __GFP_RETRY_MAYFAIL))
5035 		goto nopage;
5036 
5037 	if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags,
5038 				 did_some_progress > 0, &no_progress_loops))
5039 		goto retry;
5040 
5041 	/*
5042 	 * It doesn't make any sense to retry for the compaction if the order-0
5043 	 * reclaim is not able to make any progress because the current
5044 	 * implementation of the compaction depends on the sufficient amount
5045 	 * of free memory (see __compaction_suitable)
5046 	 */
5047 	if (did_some_progress > 0 &&
5048 			should_compact_retry(ac, order, alloc_flags,
5049 				compact_result, &compact_priority,
5050 				&compaction_retries))
5051 		goto retry;
5052 
5053 
5054 	/* Deal with possible cpuset update races before we start OOM killing */
5055 	if (check_retry_cpuset(cpuset_mems_cookie, ac))
5056 		goto retry_cpuset;
5057 
5058 	/* Reclaim has failed us, start killing things */
5059 	page = __alloc_pages_may_oom(gfp_mask, order, ac, &did_some_progress);
5060 	if (page)
5061 		goto got_pg;
5062 
5063 	/* Avoid allocations with no watermarks from looping endlessly */
5064 	if (tsk_is_oom_victim(current) &&
5065 	    (alloc_flags & ALLOC_OOM ||
5066 	     (gfp_mask & __GFP_NOMEMALLOC)))
5067 		goto nopage;
5068 
5069 	/* Retry as long as the OOM killer is making progress */
5070 	if (did_some_progress) {
5071 		no_progress_loops = 0;
5072 		goto retry;
5073 	}
5074 
5075 nopage:
5076 	/* Deal with possible cpuset update races before we fail */
5077 	if (check_retry_cpuset(cpuset_mems_cookie, ac))
5078 		goto retry_cpuset;
5079 
5080 	/*
5081 	 * Make sure that __GFP_NOFAIL request doesn't leak out and make sure
5082 	 * we always retry
5083 	 */
5084 	if (gfp_mask & __GFP_NOFAIL) {
5085 		/*
5086 		 * All existing users of the __GFP_NOFAIL are blockable, so warn
5087 		 * of any new users that actually require GFP_NOWAIT
5088 		 */
5089 		if (WARN_ON_ONCE(!can_direct_reclaim))
5090 			goto fail;
5091 
5092 		/*
5093 		 * PF_MEMALLOC request from this context is rather bizarre
5094 		 * because we cannot reclaim anything and only can loop waiting
5095 		 * for somebody to do a work for us
5096 		 */
5097 		WARN_ON_ONCE(current->flags & PF_MEMALLOC);
5098 
5099 		/*
5100 		 * non failing costly orders are a hard requirement which we
5101 		 * are not prepared for much so let's warn about these users
5102 		 * so that we can identify them and convert them to something
5103 		 * else.
5104 		 */
5105 		WARN_ON_ONCE(order > PAGE_ALLOC_COSTLY_ORDER);
5106 
5107 		/*
5108 		 * Help non-failing allocations by giving them access to memory
5109 		 * reserves but do not use ALLOC_NO_WATERMARKS because this
5110 		 * could deplete whole memory reserves which would just make
5111 		 * the situation worse
5112 		 */
5113 		page = __alloc_pages_cpuset_fallback(gfp_mask, order, ALLOC_HARDER, ac);
5114 		if (page)
5115 			goto got_pg;
5116 
5117 		cond_resched();
5118 		goto retry;
5119 	}
5120 fail:
5121 	warn_alloc(gfp_mask, ac->nodemask,
5122 			"page allocation failure: order:%u", order);
5123 got_pg:
5124 	return page;
5125 }
5126 
5127 static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order,
5128 		int preferred_nid, nodemask_t *nodemask,
5129 		struct alloc_context *ac, gfp_t *alloc_gfp,
5130 		unsigned int *alloc_flags)
5131 {
5132 	ac->highest_zoneidx = gfp_zone(gfp_mask);
5133 	ac->zonelist = node_zonelist(preferred_nid, gfp_mask);
5134 	ac->nodemask = nodemask;
5135 	ac->migratetype = gfp_migratetype(gfp_mask);
5136 
5137 	if (cpusets_enabled()) {
5138 		*alloc_gfp |= __GFP_HARDWALL;
5139 		/*
5140 		 * When we are in the interrupt context, it is irrelevant
5141 		 * to the current task context. It means that any node ok.
5142 		 */
5143 		if (!in_interrupt() && !ac->nodemask)
5144 			ac->nodemask = &cpuset_current_mems_allowed;
5145 		else
5146 			*alloc_flags |= ALLOC_CPUSET;
5147 	}
5148 
5149 	fs_reclaim_acquire(gfp_mask);
5150 	fs_reclaim_release(gfp_mask);
5151 
5152 	might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
5153 
5154 	if (should_fail_alloc_page(gfp_mask, order))
5155 		return false;
5156 
5157 	*alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, *alloc_flags);
5158 
5159 	/* Dirty zone balancing only done in the fast path */
5160 	ac->spread_dirty_pages = (gfp_mask & __GFP_WRITE);
5161 
5162 	/*
5163 	 * The preferred zone is used for statistics but crucially it is
5164 	 * also used as the starting point for the zonelist iterator. It
5165 	 * may get reset for allocations that ignore memory policies.
5166 	 */
5167 	ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
5168 					ac->highest_zoneidx, ac->nodemask);
5169 
5170 	return true;
5171 }
5172 
5173 /*
5174  * __alloc_pages_bulk - Allocate a number of order-0 pages to a list or array
5175  * @gfp: GFP flags for the allocation
5176  * @preferred_nid: The preferred NUMA node ID to allocate from
5177  * @nodemask: Set of nodes to allocate from, may be NULL
5178  * @nr_pages: The number of pages desired on the list or array
5179  * @page_list: Optional list to store the allocated pages
5180  * @page_array: Optional array to store the pages
5181  *
5182  * This is a batched version of the page allocator that attempts to
5183  * allocate nr_pages quickly. Pages are added to page_list if page_list
5184  * is not NULL, otherwise it is assumed that the page_array is valid.
5185  *
5186  * For lists, nr_pages is the number of pages that should be allocated.
5187  *
5188  * For arrays, only NULL elements are populated with pages and nr_pages
5189  * is the maximum number of pages that will be stored in the array.
5190  *
5191  * Returns the number of pages on the list or array.
5192  */
5193 unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid,
5194 			nodemask_t *nodemask, int nr_pages,
5195 			struct list_head *page_list,
5196 			struct page **page_array)
5197 {
5198 	struct page *page;
5199 	unsigned long flags;
5200 	struct zone *zone;
5201 	struct zoneref *z;
5202 	struct per_cpu_pages *pcp;
5203 	struct list_head *pcp_list;
5204 	struct alloc_context ac;
5205 	gfp_t alloc_gfp;
5206 	unsigned int alloc_flags = ALLOC_WMARK_LOW;
5207 	int nr_populated = 0, nr_account = 0;
5208 
5209 	/*
5210 	 * Skip populated array elements to determine if any pages need
5211 	 * to be allocated before disabling IRQs.
5212 	 */
5213 	while (page_array && nr_populated < nr_pages && page_array[nr_populated])
5214 		nr_populated++;
5215 
5216 	/* No pages requested? */
5217 	if (unlikely(nr_pages <= 0))
5218 		goto out;
5219 
5220 	/* Already populated array? */
5221 	if (unlikely(page_array && nr_pages - nr_populated == 0))
5222 		goto out;
5223 
5224 	/* Use the single page allocator for one page. */
5225 	if (nr_pages - nr_populated == 1)
5226 		goto failed;
5227 
5228 #ifdef CONFIG_PAGE_OWNER
5229 	/*
5230 	 * PAGE_OWNER may recurse into the allocator to allocate space to
5231 	 * save the stack with pagesets.lock held. Releasing/reacquiring
5232 	 * removes much of the performance benefit of bulk allocation so
5233 	 * force the caller to allocate one page at a time as it'll have
5234 	 * similar performance to added complexity to the bulk allocator.
5235 	 */
5236 	if (static_branch_unlikely(&page_owner_inited))
5237 		goto failed;
5238 #endif
5239 
5240 	/* May set ALLOC_NOFRAGMENT, fragmentation will return 1 page. */
5241 	gfp &= gfp_allowed_mask;
5242 	alloc_gfp = gfp;
5243 	if (!prepare_alloc_pages(gfp, 0, preferred_nid, nodemask, &ac, &alloc_gfp, &alloc_flags))
5244 		goto out;
5245 	gfp = alloc_gfp;
5246 
5247 	/* Find an allowed local zone that meets the low watermark. */
5248 	for_each_zone_zonelist_nodemask(zone, z, ac.zonelist, ac.highest_zoneidx, ac.nodemask) {
5249 		unsigned long mark;
5250 
5251 		if (cpusets_enabled() && (alloc_flags & ALLOC_CPUSET) &&
5252 		    !__cpuset_zone_allowed(zone, gfp)) {
5253 			continue;
5254 		}
5255 
5256 		if (nr_online_nodes > 1 && zone != ac.preferred_zoneref->zone &&
5257 		    zone_to_nid(zone) != zone_to_nid(ac.preferred_zoneref->zone)) {
5258 			goto failed;
5259 		}
5260 
5261 		mark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK) + nr_pages;
5262 		if (zone_watermark_fast(zone, 0,  mark,
5263 				zonelist_zone_idx(ac.preferred_zoneref),
5264 				alloc_flags, gfp)) {
5265 			break;
5266 		}
5267 	}
5268 
5269 	/*
5270 	 * If there are no allowed local zones that meets the watermarks then
5271 	 * try to allocate a single page and reclaim if necessary.
5272 	 */
5273 	if (unlikely(!zone))
5274 		goto failed;
5275 
5276 	/* Attempt the batch allocation */
5277 	local_lock_irqsave(&pagesets.lock, flags);
5278 	pcp = this_cpu_ptr(zone->per_cpu_pageset);
5279 	pcp_list = &pcp->lists[order_to_pindex(ac.migratetype, 0)];
5280 
5281 	while (nr_populated < nr_pages) {
5282 
5283 		/* Skip existing pages */
5284 		if (page_array && page_array[nr_populated]) {
5285 			nr_populated++;
5286 			continue;
5287 		}
5288 
5289 		page = __rmqueue_pcplist(zone, 0, ac.migratetype, alloc_flags,
5290 								pcp, pcp_list);
5291 		if (unlikely(!page)) {
5292 			/* Try and get at least one page */
5293 			if (!nr_populated)
5294 				goto failed_irq;
5295 			break;
5296 		}
5297 		nr_account++;
5298 
5299 		prep_new_page(page, 0, gfp, 0);
5300 		if (page_list)
5301 			list_add(&page->lru, page_list);
5302 		else
5303 			page_array[nr_populated] = page;
5304 		nr_populated++;
5305 	}
5306 
5307 	local_unlock_irqrestore(&pagesets.lock, flags);
5308 
5309 	__count_zid_vm_events(PGALLOC, zone_idx(zone), nr_account);
5310 	zone_statistics(ac.preferred_zoneref->zone, zone, nr_account);
5311 
5312 out:
5313 	return nr_populated;
5314 
5315 failed_irq:
5316 	local_unlock_irqrestore(&pagesets.lock, flags);
5317 
5318 failed:
5319 	page = __alloc_pages(gfp, 0, preferred_nid, nodemask);
5320 	if (page) {
5321 		if (page_list)
5322 			list_add(&page->lru, page_list);
5323 		else
5324 			page_array[nr_populated] = page;
5325 		nr_populated++;
5326 	}
5327 
5328 	goto out;
5329 }
5330 EXPORT_SYMBOL_GPL(__alloc_pages_bulk);
5331 
5332 /*
5333  * This is the 'heart' of the zoned buddy allocator.
5334  */
5335 struct page *__alloc_pages(gfp_t gfp, unsigned int order, int preferred_nid,
5336 							nodemask_t *nodemask)
5337 {
5338 	struct page *page;
5339 	unsigned int alloc_flags = ALLOC_WMARK_LOW;
5340 	gfp_t alloc_gfp; /* The gfp_t that was actually used for allocation */
5341 	struct alloc_context ac = { };
5342 
5343 	/*
5344 	 * There are several places where we assume that the order value is sane
5345 	 * so bail out early if the request is out of bound.
5346 	 */
5347 	if (unlikely(order >= MAX_ORDER)) {
5348 		WARN_ON_ONCE(!(gfp & __GFP_NOWARN));
5349 		return NULL;
5350 	}
5351 
5352 	gfp &= gfp_allowed_mask;
5353 	/*
5354 	 * Apply scoped allocation constraints. This is mainly about GFP_NOFS
5355 	 * resp. GFP_NOIO which has to be inherited for all allocation requests
5356 	 * from a particular context which has been marked by
5357 	 * memalloc_no{fs,io}_{save,restore}. And PF_MEMALLOC_PIN which ensures
5358 	 * movable zones are not used during allocation.
5359 	 */
5360 	gfp = current_gfp_context(gfp);
5361 	alloc_gfp = gfp;
5362 	if (!prepare_alloc_pages(gfp, order, preferred_nid, nodemask, &ac,
5363 			&alloc_gfp, &alloc_flags))
5364 		return NULL;
5365 
5366 	/*
5367 	 * Forbid the first pass from falling back to types that fragment
5368 	 * memory until all local zones are considered.
5369 	 */
5370 	alloc_flags |= alloc_flags_nofragment(ac.preferred_zoneref->zone, gfp);
5371 
5372 	/* First allocation attempt */
5373 	page = get_page_from_freelist(alloc_gfp, order, alloc_flags, &ac);
5374 	if (likely(page))
5375 		goto out;
5376 
5377 	alloc_gfp = gfp;
5378 	ac.spread_dirty_pages = false;
5379 
5380 	/*
5381 	 * Restore the original nodemask if it was potentially replaced with
5382 	 * &cpuset_current_mems_allowed to optimize the fast-path attempt.
5383 	 */
5384 	ac.nodemask = nodemask;
5385 
5386 	page = __alloc_pages_slowpath(alloc_gfp, order, &ac);
5387 
5388 out:
5389 	if (memcg_kmem_enabled() && (gfp & __GFP_ACCOUNT) && page &&
5390 	    unlikely(__memcg_kmem_charge_page(page, gfp, order) != 0)) {
5391 		__free_pages(page, order);
5392 		page = NULL;
5393 	}
5394 
5395 	trace_mm_page_alloc(page, order, alloc_gfp, ac.migratetype);
5396 
5397 	return page;
5398 }
5399 EXPORT_SYMBOL(__alloc_pages);
5400 
5401 /*
5402  * Common helper functions. Never use with __GFP_HIGHMEM because the returned
5403  * address cannot represent highmem pages. Use alloc_pages and then kmap if
5404  * you need to access high mem.
5405  */
5406 unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order)
5407 {
5408 	struct page *page;
5409 
5410 	page = alloc_pages(gfp_mask & ~__GFP_HIGHMEM, order);
5411 	if (!page)
5412 		return 0;
5413 	return (unsigned long) page_address(page);
5414 }
5415 EXPORT_SYMBOL(__get_free_pages);
5416 
5417 unsigned long get_zeroed_page(gfp_t gfp_mask)
5418 {
5419 	return __get_free_pages(gfp_mask | __GFP_ZERO, 0);
5420 }
5421 EXPORT_SYMBOL(get_zeroed_page);
5422 
5423 /**
5424  * __free_pages - Free pages allocated with alloc_pages().
5425  * @page: The page pointer returned from alloc_pages().
5426  * @order: The order of the allocation.
5427  *
5428  * This function can free multi-page allocations that are not compound
5429  * pages.  It does not check that the @order passed in matches that of
5430  * the allocation, so it is easy to leak memory.  Freeing more memory
5431  * than was allocated will probably emit a warning.
5432  *
5433  * If the last reference to this page is speculative, it will be released
5434  * by put_page() which only frees the first page of a non-compound
5435  * allocation.  To prevent the remaining pages from being leaked, we free
5436  * the subsequent pages here.  If you want to use the page's reference
5437  * count to decide when to free the allocation, you should allocate a
5438  * compound page, and use put_page() instead of __free_pages().
5439  *
5440  * Context: May be called in interrupt context or while holding a normal
5441  * spinlock, but not in NMI context or while holding a raw spinlock.
5442  */
5443 void __free_pages(struct page *page, unsigned int order)
5444 {
5445 	if (put_page_testzero(page))
5446 		free_the_page(page, order);
5447 	else if (!PageHead(page))
5448 		while (order-- > 0)
5449 			free_the_page(page + (1 << order), order);
5450 }
5451 EXPORT_SYMBOL(__free_pages);
5452 
5453 void free_pages(unsigned long addr, unsigned int order)
5454 {
5455 	if (addr != 0) {
5456 		VM_BUG_ON(!virt_addr_valid((void *)addr));
5457 		__free_pages(virt_to_page((void *)addr), order);
5458 	}
5459 }
5460 
5461 EXPORT_SYMBOL(free_pages);
5462 
5463 /*
5464  * Page Fragment:
5465  *  An arbitrary-length arbitrary-offset area of memory which resides
5466  *  within a 0 or higher order page.  Multiple fragments within that page
5467  *  are individually refcounted, in the page's reference counter.
5468  *
5469  * The page_frag functions below provide a simple allocation framework for
5470  * page fragments.  This is used by the network stack and network device
5471  * drivers to provide a backing region of memory for use as either an
5472  * sk_buff->head, or to be used in the "frags" portion of skb_shared_info.
5473  */
5474 static struct page *__page_frag_cache_refill(struct page_frag_cache *nc,
5475 					     gfp_t gfp_mask)
5476 {
5477 	struct page *page = NULL;
5478 	gfp_t gfp = gfp_mask;
5479 
5480 #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
5481 	gfp_mask |= __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY |
5482 		    __GFP_NOMEMALLOC;
5483 	page = alloc_pages_node(NUMA_NO_NODE, gfp_mask,
5484 				PAGE_FRAG_CACHE_MAX_ORDER);
5485 	nc->size = page ? PAGE_FRAG_CACHE_MAX_SIZE : PAGE_SIZE;
5486 #endif
5487 	if (unlikely(!page))
5488 		page = alloc_pages_node(NUMA_NO_NODE, gfp, 0);
5489 
5490 	nc->va = page ? page_address(page) : NULL;
5491 
5492 	return page;
5493 }
5494 
5495 void __page_frag_cache_drain(struct page *page, unsigned int count)
5496 {
5497 	VM_BUG_ON_PAGE(page_ref_count(page) == 0, page);
5498 
5499 	if (page_ref_sub_and_test(page, count))
5500 		free_the_page(page, compound_order(page));
5501 }
5502 EXPORT_SYMBOL(__page_frag_cache_drain);
5503 
5504 void *page_frag_alloc_align(struct page_frag_cache *nc,
5505 		      unsigned int fragsz, gfp_t gfp_mask,
5506 		      unsigned int align_mask)
5507 {
5508 	unsigned int size = PAGE_SIZE;
5509 	struct page *page;
5510 	int offset;
5511 
5512 	if (unlikely(!nc->va)) {
5513 refill:
5514 		page = __page_frag_cache_refill(nc, gfp_mask);
5515 		if (!page)
5516 			return NULL;
5517 
5518 #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
5519 		/* if size can vary use size else just use PAGE_SIZE */
5520 		size = nc->size;
5521 #endif
5522 		/* Even if we own the page, we do not use atomic_set().
5523 		 * This would break get_page_unless_zero() users.
5524 		 */
5525 		page_ref_add(page, PAGE_FRAG_CACHE_MAX_SIZE);
5526 
5527 		/* reset page count bias and offset to start of new frag */
5528 		nc->pfmemalloc = page_is_pfmemalloc(page);
5529 		nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1;
5530 		nc->offset = size;
5531 	}
5532 
5533 	offset = nc->offset - fragsz;
5534 	if (unlikely(offset < 0)) {
5535 		page = virt_to_page(nc->va);
5536 
5537 		if (!page_ref_sub_and_test(page, nc->pagecnt_bias))
5538 			goto refill;
5539 
5540 		if (unlikely(nc->pfmemalloc)) {
5541 			free_the_page(page, compound_order(page));
5542 			goto refill;
5543 		}
5544 
5545 #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
5546 		/* if size can vary use size else just use PAGE_SIZE */
5547 		size = nc->size;
5548 #endif
5549 		/* OK, page count is 0, we can safely set it */
5550 		set_page_count(page, PAGE_FRAG_CACHE_MAX_SIZE + 1);
5551 
5552 		/* reset page count bias and offset to start of new frag */
5553 		nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1;
5554 		offset = size - fragsz;
5555 	}
5556 
5557 	nc->pagecnt_bias--;
5558 	offset &= align_mask;
5559 	nc->offset = offset;
5560 
5561 	return nc->va + offset;
5562 }
5563 EXPORT_SYMBOL(page_frag_alloc_align);
5564 
5565 /*
5566  * Frees a page fragment allocated out of either a compound or order 0 page.
5567  */
5568 void page_frag_free(void *addr)
5569 {
5570 	struct page *page = virt_to_head_page(addr);
5571 
5572 	if (unlikely(put_page_testzero(page)))
5573 		free_the_page(page, compound_order(page));
5574 }
5575 EXPORT_SYMBOL(page_frag_free);
5576 
5577 static void *make_alloc_exact(unsigned long addr, unsigned int order,
5578 		size_t size)
5579 {
5580 	if (addr) {
5581 		unsigned long alloc_end = addr + (PAGE_SIZE << order);
5582 		unsigned long used = addr + PAGE_ALIGN(size);
5583 
5584 		split_page(virt_to_page((void *)addr), order);
5585 		while (used < alloc_end) {
5586 			free_page(used);
5587 			used += PAGE_SIZE;
5588 		}
5589 	}
5590 	return (void *)addr;
5591 }
5592 
5593 /**
5594  * alloc_pages_exact - allocate an exact number physically-contiguous pages.
5595  * @size: the number of bytes to allocate
5596  * @gfp_mask: GFP flags for the allocation, must not contain __GFP_COMP
5597  *
5598  * This function is similar to alloc_pages(), except that it allocates the
5599  * minimum number of pages to satisfy the request.  alloc_pages() can only
5600  * allocate memory in power-of-two pages.
5601  *
5602  * This function is also limited by MAX_ORDER.
5603  *
5604  * Memory allocated by this function must be released by free_pages_exact().
5605  *
5606  * Return: pointer to the allocated area or %NULL in case of error.
5607  */
5608 void *alloc_pages_exact(size_t size, gfp_t gfp_mask)
5609 {
5610 	unsigned int order = get_order(size);
5611 	unsigned long addr;
5612 
5613 	if (WARN_ON_ONCE(gfp_mask & __GFP_COMP))
5614 		gfp_mask &= ~__GFP_COMP;
5615 
5616 	addr = __get_free_pages(gfp_mask, order);
5617 	return make_alloc_exact(addr, order, size);
5618 }
5619 EXPORT_SYMBOL(alloc_pages_exact);
5620 
5621 /**
5622  * alloc_pages_exact_nid - allocate an exact number of physically-contiguous
5623  *			   pages on a node.
5624  * @nid: the preferred node ID where memory should be allocated
5625  * @size: the number of bytes to allocate
5626  * @gfp_mask: GFP flags for the allocation, must not contain __GFP_COMP
5627  *
5628  * Like alloc_pages_exact(), but try to allocate on node nid first before falling
5629  * back.
5630  *
5631  * Return: pointer to the allocated area or %NULL in case of error.
5632  */
5633 void * __meminit alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask)
5634 {
5635 	unsigned int order = get_order(size);
5636 	struct page *p;
5637 
5638 	if (WARN_ON_ONCE(gfp_mask & __GFP_COMP))
5639 		gfp_mask &= ~__GFP_COMP;
5640 
5641 	p = alloc_pages_node(nid, gfp_mask, order);
5642 	if (!p)
5643 		return NULL;
5644 	return make_alloc_exact((unsigned long)page_address(p), order, size);
5645 }
5646 
5647 /**
5648  * free_pages_exact - release memory allocated via alloc_pages_exact()
5649  * @virt: the value returned by alloc_pages_exact.
5650  * @size: size of allocation, same value as passed to alloc_pages_exact().
5651  *
5652  * Release the memory allocated by a previous call to alloc_pages_exact.
5653  */
5654 void free_pages_exact(void *virt, size_t size)
5655 {
5656 	unsigned long addr = (unsigned long)virt;
5657 	unsigned long end = addr + PAGE_ALIGN(size);
5658 
5659 	while (addr < end) {
5660 		free_page(addr);
5661 		addr += PAGE_SIZE;
5662 	}
5663 }
5664 EXPORT_SYMBOL(free_pages_exact);
5665 
5666 /**
5667  * nr_free_zone_pages - count number of pages beyond high watermark
5668  * @offset: The zone index of the highest zone
5669  *
5670  * nr_free_zone_pages() counts the number of pages which are beyond the
5671  * high watermark within all zones at or below a given zone index.  For each
5672  * zone, the number of pages is calculated as:
5673  *
5674  *     nr_free_zone_pages = managed_pages - high_pages
5675  *
5676  * Return: number of pages beyond high watermark.
5677  */
5678 static unsigned long nr_free_zone_pages(int offset)
5679 {
5680 	struct zoneref *z;
5681 	struct zone *zone;
5682 
5683 	/* Just pick one node, since fallback list is circular */
5684 	unsigned long sum = 0;
5685 
5686 	struct zonelist *zonelist = node_zonelist(numa_node_id(), GFP_KERNEL);
5687 
5688 	for_each_zone_zonelist(zone, z, zonelist, offset) {
5689 		unsigned long size = zone_managed_pages(zone);
5690 		unsigned long high = high_wmark_pages(zone);
5691 		if (size > high)
5692 			sum += size - high;
5693 	}
5694 
5695 	return sum;
5696 }
5697 
5698 /**
5699  * nr_free_buffer_pages - count number of pages beyond high watermark
5700  *
5701  * nr_free_buffer_pages() counts the number of pages which are beyond the high
5702  * watermark within ZONE_DMA and ZONE_NORMAL.
5703  *
5704  * Return: number of pages beyond high watermark within ZONE_DMA and
5705  * ZONE_NORMAL.
5706  */
5707 unsigned long nr_free_buffer_pages(void)
5708 {
5709 	return nr_free_zone_pages(gfp_zone(GFP_USER));
5710 }
5711 EXPORT_SYMBOL_GPL(nr_free_buffer_pages);
5712 
5713 static inline void show_node(struct zone *zone)
5714 {
5715 	if (IS_ENABLED(CONFIG_NUMA))
5716 		printk("Node %d ", zone_to_nid(zone));
5717 }
5718 
5719 long si_mem_available(void)
5720 {
5721 	long available;
5722 	unsigned long pagecache;
5723 	unsigned long wmark_low = 0;
5724 	unsigned long pages[NR_LRU_LISTS];
5725 	unsigned long reclaimable;
5726 	struct zone *zone;
5727 	int lru;
5728 
5729 	for (lru = LRU_BASE; lru < NR_LRU_LISTS; lru++)
5730 		pages[lru] = global_node_page_state(NR_LRU_BASE + lru);
5731 
5732 	for_each_zone(zone)
5733 		wmark_low += low_wmark_pages(zone);
5734 
5735 	/*
5736 	 * Estimate the amount of memory available for userspace allocations,
5737 	 * without causing swapping.
5738 	 */
5739 	available = global_zone_page_state(NR_FREE_PAGES) - totalreserve_pages;
5740 
5741 	/*
5742 	 * Not all the page cache can be freed, otherwise the system will
5743 	 * start swapping. Assume at least half of the page cache, or the
5744 	 * low watermark worth of cache, needs to stay.
5745 	 */
5746 	pagecache = pages[LRU_ACTIVE_FILE] + pages[LRU_INACTIVE_FILE];
5747 	pagecache -= min(pagecache / 2, wmark_low);
5748 	available += pagecache;
5749 
5750 	/*
5751 	 * Part of the reclaimable slab and other kernel memory consists of
5752 	 * items that are in use, and cannot be freed. Cap this estimate at the
5753 	 * low watermark.
5754 	 */
5755 	reclaimable = global_node_page_state_pages(NR_SLAB_RECLAIMABLE_B) +
5756 		global_node_page_state(NR_KERNEL_MISC_RECLAIMABLE);
5757 	available += reclaimable - min(reclaimable / 2, wmark_low);
5758 
5759 	if (available < 0)
5760 		available = 0;
5761 	return available;
5762 }
5763 EXPORT_SYMBOL_GPL(si_mem_available);
5764 
5765 void si_meminfo(struct sysinfo *val)
5766 {
5767 	val->totalram = totalram_pages();
5768 	val->sharedram = global_node_page_state(NR_SHMEM);
5769 	val->freeram = global_zone_page_state(NR_FREE_PAGES);
5770 	val->bufferram = nr_blockdev_pages();
5771 	val->totalhigh = totalhigh_pages();
5772 	val->freehigh = nr_free_highpages();
5773 	val->mem_unit = PAGE_SIZE;
5774 }
5775 
5776 EXPORT_SYMBOL(si_meminfo);
5777 
5778 #ifdef CONFIG_NUMA
5779 void si_meminfo_node(struct sysinfo *val, int nid)
5780 {
5781 	int zone_type;		/* needs to be signed */
5782 	unsigned long managed_pages = 0;
5783 	unsigned long managed_highpages = 0;
5784 	unsigned long free_highpages = 0;
5785 	pg_data_t *pgdat = NODE_DATA(nid);
5786 
5787 	for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++)
5788 		managed_pages += zone_managed_pages(&pgdat->node_zones[zone_type]);
5789 	val->totalram = managed_pages;
5790 	val->sharedram = node_page_state(pgdat, NR_SHMEM);
5791 	val->freeram = sum_zone_node_page_state(nid, NR_FREE_PAGES);
5792 #ifdef CONFIG_HIGHMEM
5793 	for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++) {
5794 		struct zone *zone = &pgdat->node_zones[zone_type];
5795 
5796 		if (is_highmem(zone)) {
5797 			managed_highpages += zone_managed_pages(zone);
5798 			free_highpages += zone_page_state(zone, NR_FREE_PAGES);
5799 		}
5800 	}
5801 	val->totalhigh = managed_highpages;
5802 	val->freehigh = free_highpages;
5803 #else
5804 	val->totalhigh = managed_highpages;
5805 	val->freehigh = free_highpages;
5806 #endif
5807 	val->mem_unit = PAGE_SIZE;
5808 }
5809 #endif
5810 
5811 /*
5812  * Determine whether the node should be displayed or not, depending on whether
5813  * SHOW_MEM_FILTER_NODES was passed to show_free_areas().
5814  */
5815 static bool show_mem_node_skip(unsigned int flags, int nid, nodemask_t *nodemask)
5816 {
5817 	if (!(flags & SHOW_MEM_FILTER_NODES))
5818 		return false;
5819 
5820 	/*
5821 	 * no node mask - aka implicit memory numa policy. Do not bother with
5822 	 * the synchronization - read_mems_allowed_begin - because we do not
5823 	 * have to be precise here.
5824 	 */
5825 	if (!nodemask)
5826 		nodemask = &cpuset_current_mems_allowed;
5827 
5828 	return !node_isset(nid, *nodemask);
5829 }
5830 
5831 #define K(x) ((x) << (PAGE_SHIFT-10))
5832 
5833 static void show_migration_types(unsigned char type)
5834 {
5835 	static const char types[MIGRATE_TYPES] = {
5836 		[MIGRATE_UNMOVABLE]	= 'U',
5837 		[MIGRATE_MOVABLE]	= 'M',
5838 		[MIGRATE_RECLAIMABLE]	= 'E',
5839 		[MIGRATE_HIGHATOMIC]	= 'H',
5840 #ifdef CONFIG_CMA
5841 		[MIGRATE_CMA]		= 'C',
5842 #endif
5843 #ifdef CONFIG_MEMORY_ISOLATION
5844 		[MIGRATE_ISOLATE]	= 'I',
5845 #endif
5846 	};
5847 	char tmp[MIGRATE_TYPES + 1];
5848 	char *p = tmp;
5849 	int i;
5850 
5851 	for (i = 0; i < MIGRATE_TYPES; i++) {
5852 		if (type & (1 << i))
5853 			*p++ = types[i];
5854 	}
5855 
5856 	*p = '\0';
5857 	printk(KERN_CONT "(%s) ", tmp);
5858 }
5859 
5860 /*
5861  * Show free area list (used inside shift_scroll-lock stuff)
5862  * We also calculate the percentage fragmentation. We do this by counting the
5863  * memory on each free list with the exception of the first item on the list.
5864  *
5865  * Bits in @filter:
5866  * SHOW_MEM_FILTER_NODES: suppress nodes that are not allowed by current's
5867  *   cpuset.
5868  */
5869 void show_free_areas(unsigned int filter, nodemask_t *nodemask)
5870 {
5871 	unsigned long free_pcp = 0;
5872 	int cpu;
5873 	struct zone *zone;
5874 	pg_data_t *pgdat;
5875 
5876 	for_each_populated_zone(zone) {
5877 		if (show_mem_node_skip(filter, zone_to_nid(zone), nodemask))
5878 			continue;
5879 
5880 		for_each_online_cpu(cpu)
5881 			free_pcp += per_cpu_ptr(zone->per_cpu_pageset, cpu)->count;
5882 	}
5883 
5884 	printk("active_anon:%lu inactive_anon:%lu isolated_anon:%lu\n"
5885 		" active_file:%lu inactive_file:%lu isolated_file:%lu\n"
5886 		" unevictable:%lu dirty:%lu writeback:%lu\n"
5887 		" slab_reclaimable:%lu slab_unreclaimable:%lu\n"
5888 		" mapped:%lu shmem:%lu pagetables:%lu bounce:%lu\n"
5889 		" free:%lu free_pcp:%lu free_cma:%lu\n",
5890 		global_node_page_state(NR_ACTIVE_ANON),
5891 		global_node_page_state(NR_INACTIVE_ANON),
5892 		global_node_page_state(NR_ISOLATED_ANON),
5893 		global_node_page_state(NR_ACTIVE_FILE),
5894 		global_node_page_state(NR_INACTIVE_FILE),
5895 		global_node_page_state(NR_ISOLATED_FILE),
5896 		global_node_page_state(NR_UNEVICTABLE),
5897 		global_node_page_state(NR_FILE_DIRTY),
5898 		global_node_page_state(NR_WRITEBACK),
5899 		global_node_page_state_pages(NR_SLAB_RECLAIMABLE_B),
5900 		global_node_page_state_pages(NR_SLAB_UNRECLAIMABLE_B),
5901 		global_node_page_state(NR_FILE_MAPPED),
5902 		global_node_page_state(NR_SHMEM),
5903 		global_node_page_state(NR_PAGETABLE),
5904 		global_zone_page_state(NR_BOUNCE),
5905 		global_zone_page_state(NR_FREE_PAGES),
5906 		free_pcp,
5907 		global_zone_page_state(NR_FREE_CMA_PAGES));
5908 
5909 	for_each_online_pgdat(pgdat) {
5910 		if (show_mem_node_skip(filter, pgdat->node_id, nodemask))
5911 			continue;
5912 
5913 		printk("Node %d"
5914 			" active_anon:%lukB"
5915 			" inactive_anon:%lukB"
5916 			" active_file:%lukB"
5917 			" inactive_file:%lukB"
5918 			" unevictable:%lukB"
5919 			" isolated(anon):%lukB"
5920 			" isolated(file):%lukB"
5921 			" mapped:%lukB"
5922 			" dirty:%lukB"
5923 			" writeback:%lukB"
5924 			" shmem:%lukB"
5925 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
5926 			" shmem_thp: %lukB"
5927 			" shmem_pmdmapped: %lukB"
5928 			" anon_thp: %lukB"
5929 #endif
5930 			" writeback_tmp:%lukB"
5931 			" kernel_stack:%lukB"
5932 #ifdef CONFIG_SHADOW_CALL_STACK
5933 			" shadow_call_stack:%lukB"
5934 #endif
5935 			" pagetables:%lukB"
5936 			" all_unreclaimable? %s"
5937 			"\n",
5938 			pgdat->node_id,
5939 			K(node_page_state(pgdat, NR_ACTIVE_ANON)),
5940 			K(node_page_state(pgdat, NR_INACTIVE_ANON)),
5941 			K(node_page_state(pgdat, NR_ACTIVE_FILE)),
5942 			K(node_page_state(pgdat, NR_INACTIVE_FILE)),
5943 			K(node_page_state(pgdat, NR_UNEVICTABLE)),
5944 			K(node_page_state(pgdat, NR_ISOLATED_ANON)),
5945 			K(node_page_state(pgdat, NR_ISOLATED_FILE)),
5946 			K(node_page_state(pgdat, NR_FILE_MAPPED)),
5947 			K(node_page_state(pgdat, NR_FILE_DIRTY)),
5948 			K(node_page_state(pgdat, NR_WRITEBACK)),
5949 			K(node_page_state(pgdat, NR_SHMEM)),
5950 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
5951 			K(node_page_state(pgdat, NR_SHMEM_THPS)),
5952 			K(node_page_state(pgdat, NR_SHMEM_PMDMAPPED)),
5953 			K(node_page_state(pgdat, NR_ANON_THPS)),
5954 #endif
5955 			K(node_page_state(pgdat, NR_WRITEBACK_TEMP)),
5956 			node_page_state(pgdat, NR_KERNEL_STACK_KB),
5957 #ifdef CONFIG_SHADOW_CALL_STACK
5958 			node_page_state(pgdat, NR_KERNEL_SCS_KB),
5959 #endif
5960 			K(node_page_state(pgdat, NR_PAGETABLE)),
5961 			pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES ?
5962 				"yes" : "no");
5963 	}
5964 
5965 	for_each_populated_zone(zone) {
5966 		int i;
5967 
5968 		if (show_mem_node_skip(filter, zone_to_nid(zone), nodemask))
5969 			continue;
5970 
5971 		free_pcp = 0;
5972 		for_each_online_cpu(cpu)
5973 			free_pcp += per_cpu_ptr(zone->per_cpu_pageset, cpu)->count;
5974 
5975 		show_node(zone);
5976 		printk(KERN_CONT
5977 			"%s"
5978 			" free:%lukB"
5979 			" min:%lukB"
5980 			" low:%lukB"
5981 			" high:%lukB"
5982 			" reserved_highatomic:%luKB"
5983 			" active_anon:%lukB"
5984 			" inactive_anon:%lukB"
5985 			" active_file:%lukB"
5986 			" inactive_file:%lukB"
5987 			" unevictable:%lukB"
5988 			" writepending:%lukB"
5989 			" present:%lukB"
5990 			" managed:%lukB"
5991 			" mlocked:%lukB"
5992 			" bounce:%lukB"
5993 			" free_pcp:%lukB"
5994 			" local_pcp:%ukB"
5995 			" free_cma:%lukB"
5996 			"\n",
5997 			zone->name,
5998 			K(zone_page_state(zone, NR_FREE_PAGES)),
5999 			K(min_wmark_pages(zone)),
6000 			K(low_wmark_pages(zone)),
6001 			K(high_wmark_pages(zone)),
6002 			K(zone->nr_reserved_highatomic),
6003 			K(zone_page_state(zone, NR_ZONE_ACTIVE_ANON)),
6004 			K(zone_page_state(zone, NR_ZONE_INACTIVE_ANON)),
6005 			K(zone_page_state(zone, NR_ZONE_ACTIVE_FILE)),
6006 			K(zone_page_state(zone, NR_ZONE_INACTIVE_FILE)),
6007 			K(zone_page_state(zone, NR_ZONE_UNEVICTABLE)),
6008 			K(zone_page_state(zone, NR_ZONE_WRITE_PENDING)),
6009 			K(zone->present_pages),
6010 			K(zone_managed_pages(zone)),
6011 			K(zone_page_state(zone, NR_MLOCK)),
6012 			K(zone_page_state(zone, NR_BOUNCE)),
6013 			K(free_pcp),
6014 			K(this_cpu_read(zone->per_cpu_pageset->count)),
6015 			K(zone_page_state(zone, NR_FREE_CMA_PAGES)));
6016 		printk("lowmem_reserve[]:");
6017 		for (i = 0; i < MAX_NR_ZONES; i++)
6018 			printk(KERN_CONT " %ld", zone->lowmem_reserve[i]);
6019 		printk(KERN_CONT "\n");
6020 	}
6021 
6022 	for_each_populated_zone(zone) {
6023 		unsigned int order;
6024 		unsigned long nr[MAX_ORDER], flags, total = 0;
6025 		unsigned char types[MAX_ORDER];
6026 
6027 		if (show_mem_node_skip(filter, zone_to_nid(zone), nodemask))
6028 			continue;
6029 		show_node(zone);
6030 		printk(KERN_CONT "%s: ", zone->name);
6031 
6032 		spin_lock_irqsave(&zone->lock, flags);
6033 		for (order = 0; order < MAX_ORDER; order++) {
6034 			struct free_area *area = &zone->free_area[order];
6035 			int type;
6036 
6037 			nr[order] = area->nr_free;
6038 			total += nr[order] << order;
6039 
6040 			types[order] = 0;
6041 			for (type = 0; type < MIGRATE_TYPES; type++) {
6042 				if (!free_area_empty(area, type))
6043 					types[order] |= 1 << type;
6044 			}
6045 		}
6046 		spin_unlock_irqrestore(&zone->lock, flags);
6047 		for (order = 0; order < MAX_ORDER; order++) {
6048 			printk(KERN_CONT "%lu*%lukB ",
6049 			       nr[order], K(1UL) << order);
6050 			if (nr[order])
6051 				show_migration_types(types[order]);
6052 		}
6053 		printk(KERN_CONT "= %lukB\n", K(total));
6054 	}
6055 
6056 	hugetlb_show_meminfo();
6057 
6058 	printk("%ld total pagecache pages\n", global_node_page_state(NR_FILE_PAGES));
6059 
6060 	show_swap_cache_info();
6061 }
6062 
6063 static void zoneref_set_zone(struct zone *zone, struct zoneref *zoneref)
6064 {
6065 	zoneref->zone = zone;
6066 	zoneref->zone_idx = zone_idx(zone);
6067 }
6068 
6069 /*
6070  * Builds allocation fallback zone lists.
6071  *
6072  * Add all populated zones of a node to the zonelist.
6073  */
6074 static int build_zonerefs_node(pg_data_t *pgdat, struct zoneref *zonerefs)
6075 {
6076 	struct zone *zone;
6077 	enum zone_type zone_type = MAX_NR_ZONES;
6078 	int nr_zones = 0;
6079 
6080 	do {
6081 		zone_type--;
6082 		zone = pgdat->node_zones + zone_type;
6083 		if (managed_zone(zone)) {
6084 			zoneref_set_zone(zone, &zonerefs[nr_zones++]);
6085 			check_highest_zone(zone_type);
6086 		}
6087 	} while (zone_type);
6088 
6089 	return nr_zones;
6090 }
6091 
6092 #ifdef CONFIG_NUMA
6093 
6094 static int __parse_numa_zonelist_order(char *s)
6095 {
6096 	/*
6097 	 * We used to support different zonelists modes but they turned
6098 	 * out to be just not useful. Let's keep the warning in place
6099 	 * if somebody still use the cmd line parameter so that we do
6100 	 * not fail it silently
6101 	 */
6102 	if (!(*s == 'd' || *s == 'D' || *s == 'n' || *s == 'N')) {
6103 		pr_warn("Ignoring unsupported numa_zonelist_order value:  %s\n", s);
6104 		return -EINVAL;
6105 	}
6106 	return 0;
6107 }
6108 
6109 char numa_zonelist_order[] = "Node";
6110 
6111 /*
6112  * sysctl handler for numa_zonelist_order
6113  */
6114 int numa_zonelist_order_handler(struct ctl_table *table, int write,
6115 		void *buffer, size_t *length, loff_t *ppos)
6116 {
6117 	if (write)
6118 		return __parse_numa_zonelist_order(buffer);
6119 	return proc_dostring(table, write, buffer, length, ppos);
6120 }
6121 
6122 
6123 #define MAX_NODE_LOAD (nr_online_nodes)
6124 static int node_load[MAX_NUMNODES];
6125 
6126 /**
6127  * find_next_best_node - find the next node that should appear in a given node's fallback list
6128  * @node: node whose fallback list we're appending
6129  * @used_node_mask: nodemask_t of already used nodes
6130  *
6131  * We use a number of factors to determine which is the next node that should
6132  * appear on a given node's fallback list.  The node should not have appeared
6133  * already in @node's fallback list, and it should be the next closest node
6134  * according to the distance array (which contains arbitrary distance values
6135  * from each node to each node in the system), and should also prefer nodes
6136  * with no CPUs, since presumably they'll have very little allocation pressure
6137  * on them otherwise.
6138  *
6139  * Return: node id of the found node or %NUMA_NO_NODE if no node is found.
6140  */
6141 static int find_next_best_node(int node, nodemask_t *used_node_mask)
6142 {
6143 	int n, val;
6144 	int min_val = INT_MAX;
6145 	int best_node = NUMA_NO_NODE;
6146 
6147 	/* Use the local node if we haven't already */
6148 	if (!node_isset(node, *used_node_mask)) {
6149 		node_set(node, *used_node_mask);
6150 		return node;
6151 	}
6152 
6153 	for_each_node_state(n, N_MEMORY) {
6154 
6155 		/* Don't want a node to appear more than once */
6156 		if (node_isset(n, *used_node_mask))
6157 			continue;
6158 
6159 		/* Use the distance array to find the distance */
6160 		val = node_distance(node, n);
6161 
6162 		/* Penalize nodes under us ("prefer the next node") */
6163 		val += (n < node);
6164 
6165 		/* Give preference to headless and unused nodes */
6166 		if (!cpumask_empty(cpumask_of_node(n)))
6167 			val += PENALTY_FOR_NODE_WITH_CPUS;
6168 
6169 		/* Slight preference for less loaded node */
6170 		val *= (MAX_NODE_LOAD*MAX_NUMNODES);
6171 		val += node_load[n];
6172 
6173 		if (val < min_val) {
6174 			min_val = val;
6175 			best_node = n;
6176 		}
6177 	}
6178 
6179 	if (best_node >= 0)
6180 		node_set(best_node, *used_node_mask);
6181 
6182 	return best_node;
6183 }
6184 
6185 
6186 /*
6187  * Build zonelists ordered by node and zones within node.
6188  * This results in maximum locality--normal zone overflows into local
6189  * DMA zone, if any--but risks exhausting DMA zone.
6190  */
6191 static void build_zonelists_in_node_order(pg_data_t *pgdat, int *node_order,
6192 		unsigned nr_nodes)
6193 {
6194 	struct zoneref *zonerefs;
6195 	int i;
6196 
6197 	zonerefs = pgdat->node_zonelists[ZONELIST_FALLBACK]._zonerefs;
6198 
6199 	for (i = 0; i < nr_nodes; i++) {
6200 		int nr_zones;
6201 
6202 		pg_data_t *node = NODE_DATA(node_order[i]);
6203 
6204 		nr_zones = build_zonerefs_node(node, zonerefs);
6205 		zonerefs += nr_zones;
6206 	}
6207 	zonerefs->zone = NULL;
6208 	zonerefs->zone_idx = 0;
6209 }
6210 
6211 /*
6212  * Build gfp_thisnode zonelists
6213  */
6214 static void build_thisnode_zonelists(pg_data_t *pgdat)
6215 {
6216 	struct zoneref *zonerefs;
6217 	int nr_zones;
6218 
6219 	zonerefs = pgdat->node_zonelists[ZONELIST_NOFALLBACK]._zonerefs;
6220 	nr_zones = build_zonerefs_node(pgdat, zonerefs);
6221 	zonerefs += nr_zones;
6222 	zonerefs->zone = NULL;
6223 	zonerefs->zone_idx = 0;
6224 }
6225 
6226 /*
6227  * Build zonelists ordered by zone and nodes within zones.
6228  * This results in conserving DMA zone[s] until all Normal memory is
6229  * exhausted, but results in overflowing to remote node while memory
6230  * may still exist in local DMA zone.
6231  */
6232 
6233 static void build_zonelists(pg_data_t *pgdat)
6234 {
6235 	static int node_order[MAX_NUMNODES];
6236 	int node, load, nr_nodes = 0;
6237 	nodemask_t used_mask = NODE_MASK_NONE;
6238 	int local_node, prev_node;
6239 
6240 	/* NUMA-aware ordering of nodes */
6241 	local_node = pgdat->node_id;
6242 	load = nr_online_nodes;
6243 	prev_node = local_node;
6244 
6245 	memset(node_order, 0, sizeof(node_order));
6246 	while ((node = find_next_best_node(local_node, &used_mask)) >= 0) {
6247 		/*
6248 		 * We don't want to pressure a particular node.
6249 		 * So adding penalty to the first node in same
6250 		 * distance group to make it round-robin.
6251 		 */
6252 		if (node_distance(local_node, node) !=
6253 		    node_distance(local_node, prev_node))
6254 			node_load[node] = load;
6255 
6256 		node_order[nr_nodes++] = node;
6257 		prev_node = node;
6258 		load--;
6259 	}
6260 
6261 	build_zonelists_in_node_order(pgdat, node_order, nr_nodes);
6262 	build_thisnode_zonelists(pgdat);
6263 }
6264 
6265 #ifdef CONFIG_HAVE_MEMORYLESS_NODES
6266 /*
6267  * Return node id of node used for "local" allocations.
6268  * I.e., first node id of first zone in arg node's generic zonelist.
6269  * Used for initializing percpu 'numa_mem', which is used primarily
6270  * for kernel allocations, so use GFP_KERNEL flags to locate zonelist.
6271  */
6272 int local_memory_node(int node)
6273 {
6274 	struct zoneref *z;
6275 
6276 	z = first_zones_zonelist(node_zonelist(node, GFP_KERNEL),
6277 				   gfp_zone(GFP_KERNEL),
6278 				   NULL);
6279 	return zone_to_nid(z->zone);
6280 }
6281 #endif
6282 
6283 static void setup_min_unmapped_ratio(void);
6284 static void setup_min_slab_ratio(void);
6285 #else	/* CONFIG_NUMA */
6286 
6287 static void build_zonelists(pg_data_t *pgdat)
6288 {
6289 	int node, local_node;
6290 	struct zoneref *zonerefs;
6291 	int nr_zones;
6292 
6293 	local_node = pgdat->node_id;
6294 
6295 	zonerefs = pgdat->node_zonelists[ZONELIST_FALLBACK]._zonerefs;
6296 	nr_zones = build_zonerefs_node(pgdat, zonerefs);
6297 	zonerefs += nr_zones;
6298 
6299 	/*
6300 	 * Now we build the zonelist so that it contains the zones
6301 	 * of all the other nodes.
6302 	 * We don't want to pressure a particular node, so when
6303 	 * building the zones for node N, we make sure that the
6304 	 * zones coming right after the local ones are those from
6305 	 * node N+1 (modulo N)
6306 	 */
6307 	for (node = local_node + 1; node < MAX_NUMNODES; node++) {
6308 		if (!node_online(node))
6309 			continue;
6310 		nr_zones = build_zonerefs_node(NODE_DATA(node), zonerefs);
6311 		zonerefs += nr_zones;
6312 	}
6313 	for (node = 0; node < local_node; node++) {
6314 		if (!node_online(node))
6315 			continue;
6316 		nr_zones = build_zonerefs_node(NODE_DATA(node), zonerefs);
6317 		zonerefs += nr_zones;
6318 	}
6319 
6320 	zonerefs->zone = NULL;
6321 	zonerefs->zone_idx = 0;
6322 }
6323 
6324 #endif	/* CONFIG_NUMA */
6325 
6326 /*
6327  * Boot pageset table. One per cpu which is going to be used for all
6328  * zones and all nodes. The parameters will be set in such a way
6329  * that an item put on a list will immediately be handed over to
6330  * the buddy list. This is safe since pageset manipulation is done
6331  * with interrupts disabled.
6332  *
6333  * The boot_pagesets must be kept even after bootup is complete for
6334  * unused processors and/or zones. They do play a role for bootstrapping
6335  * hotplugged processors.
6336  *
6337  * zoneinfo_show() and maybe other functions do
6338  * not check if the processor is online before following the pageset pointer.
6339  * Other parts of the kernel may not check if the zone is available.
6340  */
6341 static void per_cpu_pages_init(struct per_cpu_pages *pcp, struct per_cpu_zonestat *pzstats);
6342 /* These effectively disable the pcplists in the boot pageset completely */
6343 #define BOOT_PAGESET_HIGH	0
6344 #define BOOT_PAGESET_BATCH	1
6345 static DEFINE_PER_CPU(struct per_cpu_pages, boot_pageset);
6346 static DEFINE_PER_CPU(struct per_cpu_zonestat, boot_zonestats);
6347 static DEFINE_PER_CPU(struct per_cpu_nodestat, boot_nodestats);
6348 
6349 static void __build_all_zonelists(void *data)
6350 {
6351 	int nid;
6352 	int __maybe_unused cpu;
6353 	pg_data_t *self = data;
6354 	static DEFINE_SPINLOCK(lock);
6355 
6356 	spin_lock(&lock);
6357 
6358 #ifdef CONFIG_NUMA
6359 	memset(node_load, 0, sizeof(node_load));
6360 #endif
6361 
6362 	/*
6363 	 * This node is hotadded and no memory is yet present.   So just
6364 	 * building zonelists is fine - no need to touch other nodes.
6365 	 */
6366 	if (self && !node_online(self->node_id)) {
6367 		build_zonelists(self);
6368 	} else {
6369 		for_each_online_node(nid) {
6370 			pg_data_t *pgdat = NODE_DATA(nid);
6371 
6372 			build_zonelists(pgdat);
6373 		}
6374 
6375 #ifdef CONFIG_HAVE_MEMORYLESS_NODES
6376 		/*
6377 		 * We now know the "local memory node" for each node--
6378 		 * i.e., the node of the first zone in the generic zonelist.
6379 		 * Set up numa_mem percpu variable for on-line cpus.  During
6380 		 * boot, only the boot cpu should be on-line;  we'll init the
6381 		 * secondary cpus' numa_mem as they come on-line.  During
6382 		 * node/memory hotplug, we'll fixup all on-line cpus.
6383 		 */
6384 		for_each_online_cpu(cpu)
6385 			set_cpu_numa_mem(cpu, local_memory_node(cpu_to_node(cpu)));
6386 #endif
6387 	}
6388 
6389 	spin_unlock(&lock);
6390 }
6391 
6392 static noinline void __init
6393 build_all_zonelists_init(void)
6394 {
6395 	int cpu;
6396 
6397 	__build_all_zonelists(NULL);
6398 
6399 	/*
6400 	 * Initialize the boot_pagesets that are going to be used
6401 	 * for bootstrapping processors. The real pagesets for
6402 	 * each zone will be allocated later when the per cpu
6403 	 * allocator is available.
6404 	 *
6405 	 * boot_pagesets are used also for bootstrapping offline
6406 	 * cpus if the system is already booted because the pagesets
6407 	 * are needed to initialize allocators on a specific cpu too.
6408 	 * F.e. the percpu allocator needs the page allocator which
6409 	 * needs the percpu allocator in order to allocate its pagesets
6410 	 * (a chicken-egg dilemma).
6411 	 */
6412 	for_each_possible_cpu(cpu)
6413 		per_cpu_pages_init(&per_cpu(boot_pageset, cpu), &per_cpu(boot_zonestats, cpu));
6414 
6415 	mminit_verify_zonelist();
6416 	cpuset_init_current_mems_allowed();
6417 }
6418 
6419 /*
6420  * unless system_state == SYSTEM_BOOTING.
6421  *
6422  * __ref due to call of __init annotated helper build_all_zonelists_init
6423  * [protected by SYSTEM_BOOTING].
6424  */
6425 void __ref build_all_zonelists(pg_data_t *pgdat)
6426 {
6427 	unsigned long vm_total_pages;
6428 
6429 	if (system_state == SYSTEM_BOOTING) {
6430 		build_all_zonelists_init();
6431 	} else {
6432 		__build_all_zonelists(pgdat);
6433 		/* cpuset refresh routine should be here */
6434 	}
6435 	/* Get the number of free pages beyond high watermark in all zones. */
6436 	vm_total_pages = nr_free_zone_pages(gfp_zone(GFP_HIGHUSER_MOVABLE));
6437 	/*
6438 	 * Disable grouping by mobility if the number of pages in the
6439 	 * system is too low to allow the mechanism to work. It would be
6440 	 * more accurate, but expensive to check per-zone. This check is
6441 	 * made on memory-hotadd so a system can start with mobility
6442 	 * disabled and enable it later
6443 	 */
6444 	if (vm_total_pages < (pageblock_nr_pages * MIGRATE_TYPES))
6445 		page_group_by_mobility_disabled = 1;
6446 	else
6447 		page_group_by_mobility_disabled = 0;
6448 
6449 	pr_info("Built %u zonelists, mobility grouping %s.  Total pages: %ld\n",
6450 		nr_online_nodes,
6451 		page_group_by_mobility_disabled ? "off" : "on",
6452 		vm_total_pages);
6453 #ifdef CONFIG_NUMA
6454 	pr_info("Policy zone: %s\n", zone_names[policy_zone]);
6455 #endif
6456 }
6457 
6458 /* If zone is ZONE_MOVABLE but memory is mirrored, it is an overlapped init */
6459 static bool __meminit
6460 overlap_memmap_init(unsigned long zone, unsigned long *pfn)
6461 {
6462 	static struct memblock_region *r;
6463 
6464 	if (mirrored_kernelcore && zone == ZONE_MOVABLE) {
6465 		if (!r || *pfn >= memblock_region_memory_end_pfn(r)) {
6466 			for_each_mem_region(r) {
6467 				if (*pfn < memblock_region_memory_end_pfn(r))
6468 					break;
6469 			}
6470 		}
6471 		if (*pfn >= memblock_region_memory_base_pfn(r) &&
6472 		    memblock_is_mirror(r)) {
6473 			*pfn = memblock_region_memory_end_pfn(r);
6474 			return true;
6475 		}
6476 	}
6477 	return false;
6478 }
6479 
6480 /*
6481  * Initially all pages are reserved - free ones are freed
6482  * up by memblock_free_all() once the early boot process is
6483  * done. Non-atomic initialization, single-pass.
6484  *
6485  * All aligned pageblocks are initialized to the specified migratetype
6486  * (usually MIGRATE_MOVABLE). Besides setting the migratetype, no related
6487  * zone stats (e.g., nr_isolate_pageblock) are touched.
6488  */
6489 void __meminit memmap_init_range(unsigned long size, int nid, unsigned long zone,
6490 		unsigned long start_pfn, unsigned long zone_end_pfn,
6491 		enum meminit_context context,
6492 		struct vmem_altmap *altmap, int migratetype)
6493 {
6494 	unsigned long pfn, end_pfn = start_pfn + size;
6495 	struct page *page;
6496 
6497 	if (highest_memmap_pfn < end_pfn - 1)
6498 		highest_memmap_pfn = end_pfn - 1;
6499 
6500 #ifdef CONFIG_ZONE_DEVICE
6501 	/*
6502 	 * Honor reservation requested by the driver for this ZONE_DEVICE
6503 	 * memory. We limit the total number of pages to initialize to just
6504 	 * those that might contain the memory mapping. We will defer the
6505 	 * ZONE_DEVICE page initialization until after we have released
6506 	 * the hotplug lock.
6507 	 */
6508 	if (zone == ZONE_DEVICE) {
6509 		if (!altmap)
6510 			return;
6511 
6512 		if (start_pfn == altmap->base_pfn)
6513 			start_pfn += altmap->reserve;
6514 		end_pfn = altmap->base_pfn + vmem_altmap_offset(altmap);
6515 	}
6516 #endif
6517 
6518 	for (pfn = start_pfn; pfn < end_pfn; ) {
6519 		/*
6520 		 * There can be holes in boot-time mem_map[]s handed to this
6521 		 * function.  They do not exist on hotplugged memory.
6522 		 */
6523 		if (context == MEMINIT_EARLY) {
6524 			if (overlap_memmap_init(zone, &pfn))
6525 				continue;
6526 			if (defer_init(nid, pfn, zone_end_pfn))
6527 				break;
6528 		}
6529 
6530 		page = pfn_to_page(pfn);
6531 		__init_single_page(page, pfn, zone, nid);
6532 		if (context == MEMINIT_HOTPLUG)
6533 			__SetPageReserved(page);
6534 
6535 		/*
6536 		 * Usually, we want to mark the pageblock MIGRATE_MOVABLE,
6537 		 * such that unmovable allocations won't be scattered all
6538 		 * over the place during system boot.
6539 		 */
6540 		if (IS_ALIGNED(pfn, pageblock_nr_pages)) {
6541 			set_pageblock_migratetype(page, migratetype);
6542 			cond_resched();
6543 		}
6544 		pfn++;
6545 	}
6546 }
6547 
6548 #ifdef CONFIG_ZONE_DEVICE
6549 void __ref memmap_init_zone_device(struct zone *zone,
6550 				   unsigned long start_pfn,
6551 				   unsigned long nr_pages,
6552 				   struct dev_pagemap *pgmap)
6553 {
6554 	unsigned long pfn, end_pfn = start_pfn + nr_pages;
6555 	struct pglist_data *pgdat = zone->zone_pgdat;
6556 	struct vmem_altmap *altmap = pgmap_altmap(pgmap);
6557 	unsigned long zone_idx = zone_idx(zone);
6558 	unsigned long start = jiffies;
6559 	int nid = pgdat->node_id;
6560 
6561 	if (WARN_ON_ONCE(!pgmap || zone_idx(zone) != ZONE_DEVICE))
6562 		return;
6563 
6564 	/*
6565 	 * The call to memmap_init should have already taken care
6566 	 * of the pages reserved for the memmap, so we can just jump to
6567 	 * the end of that region and start processing the device pages.
6568 	 */
6569 	if (altmap) {
6570 		start_pfn = altmap->base_pfn + vmem_altmap_offset(altmap);
6571 		nr_pages = end_pfn - start_pfn;
6572 	}
6573 
6574 	for (pfn = start_pfn; pfn < end_pfn; pfn++) {
6575 		struct page *page = pfn_to_page(pfn);
6576 
6577 		__init_single_page(page, pfn, zone_idx, nid);
6578 
6579 		/*
6580 		 * Mark page reserved as it will need to wait for onlining
6581 		 * phase for it to be fully associated with a zone.
6582 		 *
6583 		 * We can use the non-atomic __set_bit operation for setting
6584 		 * the flag as we are still initializing the pages.
6585 		 */
6586 		__SetPageReserved(page);
6587 
6588 		/*
6589 		 * ZONE_DEVICE pages union ->lru with a ->pgmap back pointer
6590 		 * and zone_device_data.  It is a bug if a ZONE_DEVICE page is
6591 		 * ever freed or placed on a driver-private list.
6592 		 */
6593 		page->pgmap = pgmap;
6594 		page->zone_device_data = NULL;
6595 
6596 		/*
6597 		 * Mark the block movable so that blocks are reserved for
6598 		 * movable at startup. This will force kernel allocations
6599 		 * to reserve their blocks rather than leaking throughout
6600 		 * the address space during boot when many long-lived
6601 		 * kernel allocations are made.
6602 		 *
6603 		 * Please note that MEMINIT_HOTPLUG path doesn't clear memmap
6604 		 * because this is done early in section_activate()
6605 		 */
6606 		if (IS_ALIGNED(pfn, pageblock_nr_pages)) {
6607 			set_pageblock_migratetype(page, MIGRATE_MOVABLE);
6608 			cond_resched();
6609 		}
6610 	}
6611 
6612 	pr_info("%s initialised %lu pages in %ums\n", __func__,
6613 		nr_pages, jiffies_to_msecs(jiffies - start));
6614 }
6615 
6616 #endif
6617 static void __meminit zone_init_free_lists(struct zone *zone)
6618 {
6619 	unsigned int order, t;
6620 	for_each_migratetype_order(order, t) {
6621 		INIT_LIST_HEAD(&zone->free_area[order].free_list[t]);
6622 		zone->free_area[order].nr_free = 0;
6623 	}
6624 }
6625 
6626 #if !defined(CONFIG_FLATMEM)
6627 /*
6628  * Only struct pages that correspond to ranges defined by memblock.memory
6629  * are zeroed and initialized by going through __init_single_page() during
6630  * memmap_init_zone_range().
6631  *
6632  * But, there could be struct pages that correspond to holes in
6633  * memblock.memory. This can happen because of the following reasons:
6634  * - physical memory bank size is not necessarily the exact multiple of the
6635  *   arbitrary section size
6636  * - early reserved memory may not be listed in memblock.memory
6637  * - memory layouts defined with memmap= kernel parameter may not align
6638  *   nicely with memmap sections
6639  *
6640  * Explicitly initialize those struct pages so that:
6641  * - PG_Reserved is set
6642  * - zone and node links point to zone and node that span the page if the
6643  *   hole is in the middle of a zone
6644  * - zone and node links point to adjacent zone/node if the hole falls on
6645  *   the zone boundary; the pages in such holes will be prepended to the
6646  *   zone/node above the hole except for the trailing pages in the last
6647  *   section that will be appended to the zone/node below.
6648  */
6649 static void __init init_unavailable_range(unsigned long spfn,
6650 					  unsigned long epfn,
6651 					  int zone, int node)
6652 {
6653 	unsigned long pfn;
6654 	u64 pgcnt = 0;
6655 
6656 	for (pfn = spfn; pfn < epfn; pfn++) {
6657 		if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages))) {
6658 			pfn = ALIGN_DOWN(pfn, pageblock_nr_pages)
6659 				+ pageblock_nr_pages - 1;
6660 			continue;
6661 		}
6662 		__init_single_page(pfn_to_page(pfn), pfn, zone, node);
6663 		__SetPageReserved(pfn_to_page(pfn));
6664 		pgcnt++;
6665 	}
6666 
6667 	if (pgcnt)
6668 		pr_info("On node %d, zone %s: %lld pages in unavailable ranges",
6669 			node, zone_names[zone], pgcnt);
6670 }
6671 #else
6672 static inline void init_unavailable_range(unsigned long spfn,
6673 					  unsigned long epfn,
6674 					  int zone, int node)
6675 {
6676 }
6677 #endif
6678 
6679 static void __init memmap_init_zone_range(struct zone *zone,
6680 					  unsigned long start_pfn,
6681 					  unsigned long end_pfn,
6682 					  unsigned long *hole_pfn)
6683 {
6684 	unsigned long zone_start_pfn = zone->zone_start_pfn;
6685 	unsigned long zone_end_pfn = zone_start_pfn + zone->spanned_pages;
6686 	int nid = zone_to_nid(zone), zone_id = zone_idx(zone);
6687 
6688 	start_pfn = clamp(start_pfn, zone_start_pfn, zone_end_pfn);
6689 	end_pfn = clamp(end_pfn, zone_start_pfn, zone_end_pfn);
6690 
6691 	if (start_pfn >= end_pfn)
6692 		return;
6693 
6694 	memmap_init_range(end_pfn - start_pfn, nid, zone_id, start_pfn,
6695 			  zone_end_pfn, MEMINIT_EARLY, NULL, MIGRATE_MOVABLE);
6696 
6697 	if (*hole_pfn < start_pfn)
6698 		init_unavailable_range(*hole_pfn, start_pfn, zone_id, nid);
6699 
6700 	*hole_pfn = end_pfn;
6701 }
6702 
6703 static void __init memmap_init(void)
6704 {
6705 	unsigned long start_pfn, end_pfn;
6706 	unsigned long hole_pfn = 0;
6707 	int i, j, zone_id, nid;
6708 
6709 	for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) {
6710 		struct pglist_data *node = NODE_DATA(nid);
6711 
6712 		for (j = 0; j < MAX_NR_ZONES; j++) {
6713 			struct zone *zone = node->node_zones + j;
6714 
6715 			if (!populated_zone(zone))
6716 				continue;
6717 
6718 			memmap_init_zone_range(zone, start_pfn, end_pfn,
6719 					       &hole_pfn);
6720 			zone_id = j;
6721 		}
6722 	}
6723 
6724 #ifdef CONFIG_SPARSEMEM
6725 	/*
6726 	 * Initialize the memory map for hole in the range [memory_end,
6727 	 * section_end].
6728 	 * Append the pages in this hole to the highest zone in the last
6729 	 * node.
6730 	 * The call to init_unavailable_range() is outside the ifdef to
6731 	 * silence the compiler warining about zone_id set but not used;
6732 	 * for FLATMEM it is a nop anyway
6733 	 */
6734 	end_pfn = round_up(end_pfn, PAGES_PER_SECTION);
6735 	if (hole_pfn < end_pfn)
6736 #endif
6737 		init_unavailable_range(hole_pfn, end_pfn, zone_id, nid);
6738 }
6739 
6740 static int zone_batchsize(struct zone *zone)
6741 {
6742 #ifdef CONFIG_MMU
6743 	int batch;
6744 
6745 	/*
6746 	 * The number of pages to batch allocate is either ~0.1%
6747 	 * of the zone or 1MB, whichever is smaller. The batch
6748 	 * size is striking a balance between allocation latency
6749 	 * and zone lock contention.
6750 	 */
6751 	batch = min(zone_managed_pages(zone) >> 10, (1024 * 1024) / PAGE_SIZE);
6752 	batch /= 4;		/* We effectively *= 4 below */
6753 	if (batch < 1)
6754 		batch = 1;
6755 
6756 	/*
6757 	 * Clamp the batch to a 2^n - 1 value. Having a power
6758 	 * of 2 value was found to be more likely to have
6759 	 * suboptimal cache aliasing properties in some cases.
6760 	 *
6761 	 * For example if 2 tasks are alternately allocating
6762 	 * batches of pages, one task can end up with a lot
6763 	 * of pages of one half of the possible page colors
6764 	 * and the other with pages of the other colors.
6765 	 */
6766 	batch = rounddown_pow_of_two(batch + batch/2) - 1;
6767 
6768 	return batch;
6769 
6770 #else
6771 	/* The deferral and batching of frees should be suppressed under NOMMU
6772 	 * conditions.
6773 	 *
6774 	 * The problem is that NOMMU needs to be able to allocate large chunks
6775 	 * of contiguous memory as there's no hardware page translation to
6776 	 * assemble apparent contiguous memory from discontiguous pages.
6777 	 *
6778 	 * Queueing large contiguous runs of pages for batching, however,
6779 	 * causes the pages to actually be freed in smaller chunks.  As there
6780 	 * can be a significant delay between the individual batches being
6781 	 * recycled, this leads to the once large chunks of space being
6782 	 * fragmented and becoming unavailable for high-order allocations.
6783 	 */
6784 	return 0;
6785 #endif
6786 }
6787 
6788 static int zone_highsize(struct zone *zone, int batch, int cpu_online)
6789 {
6790 #ifdef CONFIG_MMU
6791 	int high;
6792 	int nr_split_cpus;
6793 	unsigned long total_pages;
6794 
6795 	if (!percpu_pagelist_high_fraction) {
6796 		/*
6797 		 * By default, the high value of the pcp is based on the zone
6798 		 * low watermark so that if they are full then background
6799 		 * reclaim will not be started prematurely.
6800 		 */
6801 		total_pages = low_wmark_pages(zone);
6802 	} else {
6803 		/*
6804 		 * If percpu_pagelist_high_fraction is configured, the high
6805 		 * value is based on a fraction of the managed pages in the
6806 		 * zone.
6807 		 */
6808 		total_pages = zone_managed_pages(zone) / percpu_pagelist_high_fraction;
6809 	}
6810 
6811 	/*
6812 	 * Split the high value across all online CPUs local to the zone. Note
6813 	 * that early in boot that CPUs may not be online yet and that during
6814 	 * CPU hotplug that the cpumask is not yet updated when a CPU is being
6815 	 * onlined. For memory nodes that have no CPUs, split pcp->high across
6816 	 * all online CPUs to mitigate the risk that reclaim is triggered
6817 	 * prematurely due to pages stored on pcp lists.
6818 	 */
6819 	nr_split_cpus = cpumask_weight(cpumask_of_node(zone_to_nid(zone))) + cpu_online;
6820 	if (!nr_split_cpus)
6821 		nr_split_cpus = num_online_cpus();
6822 	high = total_pages / nr_split_cpus;
6823 
6824 	/*
6825 	 * Ensure high is at least batch*4. The multiple is based on the
6826 	 * historical relationship between high and batch.
6827 	 */
6828 	high = max(high, batch << 2);
6829 
6830 	return high;
6831 #else
6832 	return 0;
6833 #endif
6834 }
6835 
6836 /*
6837  * pcp->high and pcp->batch values are related and generally batch is lower
6838  * than high. They are also related to pcp->count such that count is lower
6839  * than high, and as soon as it reaches high, the pcplist is flushed.
6840  *
6841  * However, guaranteeing these relations at all times would require e.g. write
6842  * barriers here but also careful usage of read barriers at the read side, and
6843  * thus be prone to error and bad for performance. Thus the update only prevents
6844  * store tearing. Any new users of pcp->batch and pcp->high should ensure they
6845  * can cope with those fields changing asynchronously, and fully trust only the
6846  * pcp->count field on the local CPU with interrupts disabled.
6847  *
6848  * mutex_is_locked(&pcp_batch_high_lock) required when calling this function
6849  * outside of boot time (or some other assurance that no concurrent updaters
6850  * exist).
6851  */
6852 static void pageset_update(struct per_cpu_pages *pcp, unsigned long high,
6853 		unsigned long batch)
6854 {
6855 	WRITE_ONCE(pcp->batch, batch);
6856 	WRITE_ONCE(pcp->high, high);
6857 }
6858 
6859 static void per_cpu_pages_init(struct per_cpu_pages *pcp, struct per_cpu_zonestat *pzstats)
6860 {
6861 	int pindex;
6862 
6863 	memset(pcp, 0, sizeof(*pcp));
6864 	memset(pzstats, 0, sizeof(*pzstats));
6865 
6866 	for (pindex = 0; pindex < NR_PCP_LISTS; pindex++)
6867 		INIT_LIST_HEAD(&pcp->lists[pindex]);
6868 
6869 	/*
6870 	 * Set batch and high values safe for a boot pageset. A true percpu
6871 	 * pageset's initialization will update them subsequently. Here we don't
6872 	 * need to be as careful as pageset_update() as nobody can access the
6873 	 * pageset yet.
6874 	 */
6875 	pcp->high = BOOT_PAGESET_HIGH;
6876 	pcp->batch = BOOT_PAGESET_BATCH;
6877 	pcp->free_factor = 0;
6878 }
6879 
6880 static void __zone_set_pageset_high_and_batch(struct zone *zone, unsigned long high,
6881 		unsigned long batch)
6882 {
6883 	struct per_cpu_pages *pcp;
6884 	int cpu;
6885 
6886 	for_each_possible_cpu(cpu) {
6887 		pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
6888 		pageset_update(pcp, high, batch);
6889 	}
6890 }
6891 
6892 /*
6893  * Calculate and set new high and batch values for all per-cpu pagesets of a
6894  * zone based on the zone's size.
6895  */
6896 static void zone_set_pageset_high_and_batch(struct zone *zone, int cpu_online)
6897 {
6898 	int new_high, new_batch;
6899 
6900 	new_batch = max(1, zone_batchsize(zone));
6901 	new_high = zone_highsize(zone, new_batch, cpu_online);
6902 
6903 	if (zone->pageset_high == new_high &&
6904 	    zone->pageset_batch == new_batch)
6905 		return;
6906 
6907 	zone->pageset_high = new_high;
6908 	zone->pageset_batch = new_batch;
6909 
6910 	__zone_set_pageset_high_and_batch(zone, new_high, new_batch);
6911 }
6912 
6913 void __meminit setup_zone_pageset(struct zone *zone)
6914 {
6915 	int cpu;
6916 
6917 	/* Size may be 0 on !SMP && !NUMA */
6918 	if (sizeof(struct per_cpu_zonestat) > 0)
6919 		zone->per_cpu_zonestats = alloc_percpu(struct per_cpu_zonestat);
6920 
6921 	zone->per_cpu_pageset = alloc_percpu(struct per_cpu_pages);
6922 	for_each_possible_cpu(cpu) {
6923 		struct per_cpu_pages *pcp;
6924 		struct per_cpu_zonestat *pzstats;
6925 
6926 		pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
6927 		pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu);
6928 		per_cpu_pages_init(pcp, pzstats);
6929 	}
6930 
6931 	zone_set_pageset_high_and_batch(zone, 0);
6932 }
6933 
6934 /*
6935  * Allocate per cpu pagesets and initialize them.
6936  * Before this call only boot pagesets were available.
6937  */
6938 void __init setup_per_cpu_pageset(void)
6939 {
6940 	struct pglist_data *pgdat;
6941 	struct zone *zone;
6942 	int __maybe_unused cpu;
6943 
6944 	for_each_populated_zone(zone)
6945 		setup_zone_pageset(zone);
6946 
6947 #ifdef CONFIG_NUMA
6948 	/*
6949 	 * Unpopulated zones continue using the boot pagesets.
6950 	 * The numa stats for these pagesets need to be reset.
6951 	 * Otherwise, they will end up skewing the stats of
6952 	 * the nodes these zones are associated with.
6953 	 */
6954 	for_each_possible_cpu(cpu) {
6955 		struct per_cpu_zonestat *pzstats = &per_cpu(boot_zonestats, cpu);
6956 		memset(pzstats->vm_numa_event, 0,
6957 		       sizeof(pzstats->vm_numa_event));
6958 	}
6959 #endif
6960 
6961 	for_each_online_pgdat(pgdat)
6962 		pgdat->per_cpu_nodestats =
6963 			alloc_percpu(struct per_cpu_nodestat);
6964 }
6965 
6966 static __meminit void zone_pcp_init(struct zone *zone)
6967 {
6968 	/*
6969 	 * per cpu subsystem is not up at this point. The following code
6970 	 * relies on the ability of the linker to provide the
6971 	 * offset of a (static) per cpu variable into the per cpu area.
6972 	 */
6973 	zone->per_cpu_pageset = &boot_pageset;
6974 	zone->per_cpu_zonestats = &boot_zonestats;
6975 	zone->pageset_high = BOOT_PAGESET_HIGH;
6976 	zone->pageset_batch = BOOT_PAGESET_BATCH;
6977 
6978 	if (populated_zone(zone))
6979 		pr_debug("  %s zone: %lu pages, LIFO batch:%u\n", zone->name,
6980 			 zone->present_pages, zone_batchsize(zone));
6981 }
6982 
6983 void __meminit init_currently_empty_zone(struct zone *zone,
6984 					unsigned long zone_start_pfn,
6985 					unsigned long size)
6986 {
6987 	struct pglist_data *pgdat = zone->zone_pgdat;
6988 	int zone_idx = zone_idx(zone) + 1;
6989 
6990 	if (zone_idx > pgdat->nr_zones)
6991 		pgdat->nr_zones = zone_idx;
6992 
6993 	zone->zone_start_pfn = zone_start_pfn;
6994 
6995 	mminit_dprintk(MMINIT_TRACE, "memmap_init",
6996 			"Initialising map node %d zone %lu pfns %lu -> %lu\n",
6997 			pgdat->node_id,
6998 			(unsigned long)zone_idx(zone),
6999 			zone_start_pfn, (zone_start_pfn + size));
7000 
7001 	zone_init_free_lists(zone);
7002 	zone->initialized = 1;
7003 }
7004 
7005 /**
7006  * get_pfn_range_for_nid - Return the start and end page frames for a node
7007  * @nid: The nid to return the range for. If MAX_NUMNODES, the min and max PFN are returned.
7008  * @start_pfn: Passed by reference. On return, it will have the node start_pfn.
7009  * @end_pfn: Passed by reference. On return, it will have the node end_pfn.
7010  *
7011  * It returns the start and end page frame of a node based on information
7012  * provided by memblock_set_node(). If called for a node
7013  * with no available memory, a warning is printed and the start and end
7014  * PFNs will be 0.
7015  */
7016 void __init get_pfn_range_for_nid(unsigned int nid,
7017 			unsigned long *start_pfn, unsigned long *end_pfn)
7018 {
7019 	unsigned long this_start_pfn, this_end_pfn;
7020 	int i;
7021 
7022 	*start_pfn = -1UL;
7023 	*end_pfn = 0;
7024 
7025 	for_each_mem_pfn_range(i, nid, &this_start_pfn, &this_end_pfn, NULL) {
7026 		*start_pfn = min(*start_pfn, this_start_pfn);
7027 		*end_pfn = max(*end_pfn, this_end_pfn);
7028 	}
7029 
7030 	if (*start_pfn == -1UL)
7031 		*start_pfn = 0;
7032 }
7033 
7034 /*
7035  * This finds a zone that can be used for ZONE_MOVABLE pages. The
7036  * assumption is made that zones within a node are ordered in monotonic
7037  * increasing memory addresses so that the "highest" populated zone is used
7038  */
7039 static void __init find_usable_zone_for_movable(void)
7040 {
7041 	int zone_index;
7042 	for (zone_index = MAX_NR_ZONES - 1; zone_index >= 0; zone_index--) {
7043 		if (zone_index == ZONE_MOVABLE)
7044 			continue;
7045 
7046 		if (arch_zone_highest_possible_pfn[zone_index] >
7047 				arch_zone_lowest_possible_pfn[zone_index])
7048 			break;
7049 	}
7050 
7051 	VM_BUG_ON(zone_index == -1);
7052 	movable_zone = zone_index;
7053 }
7054 
7055 /*
7056  * The zone ranges provided by the architecture do not include ZONE_MOVABLE
7057  * because it is sized independent of architecture. Unlike the other zones,
7058  * the starting point for ZONE_MOVABLE is not fixed. It may be different
7059  * in each node depending on the size of each node and how evenly kernelcore
7060  * is distributed. This helper function adjusts the zone ranges
7061  * provided by the architecture for a given node by using the end of the
7062  * highest usable zone for ZONE_MOVABLE. This preserves the assumption that
7063  * zones within a node are in order of monotonic increases memory addresses
7064  */
7065 static void __init adjust_zone_range_for_zone_movable(int nid,
7066 					unsigned long zone_type,
7067 					unsigned long node_start_pfn,
7068 					unsigned long node_end_pfn,
7069 					unsigned long *zone_start_pfn,
7070 					unsigned long *zone_end_pfn)
7071 {
7072 	/* Only adjust if ZONE_MOVABLE is on this node */
7073 	if (zone_movable_pfn[nid]) {
7074 		/* Size ZONE_MOVABLE */
7075 		if (zone_type == ZONE_MOVABLE) {
7076 			*zone_start_pfn = zone_movable_pfn[nid];
7077 			*zone_end_pfn = min(node_end_pfn,
7078 				arch_zone_highest_possible_pfn[movable_zone]);
7079 
7080 		/* Adjust for ZONE_MOVABLE starting within this range */
7081 		} else if (!mirrored_kernelcore &&
7082 			*zone_start_pfn < zone_movable_pfn[nid] &&
7083 			*zone_end_pfn > zone_movable_pfn[nid]) {
7084 			*zone_end_pfn = zone_movable_pfn[nid];
7085 
7086 		/* Check if this whole range is within ZONE_MOVABLE */
7087 		} else if (*zone_start_pfn >= zone_movable_pfn[nid])
7088 			*zone_start_pfn = *zone_end_pfn;
7089 	}
7090 }
7091 
7092 /*
7093  * Return the number of pages a zone spans in a node, including holes
7094  * present_pages = zone_spanned_pages_in_node() - zone_absent_pages_in_node()
7095  */
7096 static unsigned long __init zone_spanned_pages_in_node(int nid,
7097 					unsigned long zone_type,
7098 					unsigned long node_start_pfn,
7099 					unsigned long node_end_pfn,
7100 					unsigned long *zone_start_pfn,
7101 					unsigned long *zone_end_pfn)
7102 {
7103 	unsigned long zone_low = arch_zone_lowest_possible_pfn[zone_type];
7104 	unsigned long zone_high = arch_zone_highest_possible_pfn[zone_type];
7105 	/* When hotadd a new node from cpu_up(), the node should be empty */
7106 	if (!node_start_pfn && !node_end_pfn)
7107 		return 0;
7108 
7109 	/* Get the start and end of the zone */
7110 	*zone_start_pfn = clamp(node_start_pfn, zone_low, zone_high);
7111 	*zone_end_pfn = clamp(node_end_pfn, zone_low, zone_high);
7112 	adjust_zone_range_for_zone_movable(nid, zone_type,
7113 				node_start_pfn, node_end_pfn,
7114 				zone_start_pfn, zone_end_pfn);
7115 
7116 	/* Check that this node has pages within the zone's required range */
7117 	if (*zone_end_pfn < node_start_pfn || *zone_start_pfn > node_end_pfn)
7118 		return 0;
7119 
7120 	/* Move the zone boundaries inside the node if necessary */
7121 	*zone_end_pfn = min(*zone_end_pfn, node_end_pfn);
7122 	*zone_start_pfn = max(*zone_start_pfn, node_start_pfn);
7123 
7124 	/* Return the spanned pages */
7125 	return *zone_end_pfn - *zone_start_pfn;
7126 }
7127 
7128 /*
7129  * Return the number of holes in a range on a node. If nid is MAX_NUMNODES,
7130  * then all holes in the requested range will be accounted for.
7131  */
7132 unsigned long __init __absent_pages_in_range(int nid,
7133 				unsigned long range_start_pfn,
7134 				unsigned long range_end_pfn)
7135 {
7136 	unsigned long nr_absent = range_end_pfn - range_start_pfn;
7137 	unsigned long start_pfn, end_pfn;
7138 	int i;
7139 
7140 	for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) {
7141 		start_pfn = clamp(start_pfn, range_start_pfn, range_end_pfn);
7142 		end_pfn = clamp(end_pfn, range_start_pfn, range_end_pfn);
7143 		nr_absent -= end_pfn - start_pfn;
7144 	}
7145 	return nr_absent;
7146 }
7147 
7148 /**
7149  * absent_pages_in_range - Return number of page frames in holes within a range
7150  * @start_pfn: The start PFN to start searching for holes
7151  * @end_pfn: The end PFN to stop searching for holes
7152  *
7153  * Return: the number of pages frames in memory holes within a range.
7154  */
7155 unsigned long __init absent_pages_in_range(unsigned long start_pfn,
7156 							unsigned long end_pfn)
7157 {
7158 	return __absent_pages_in_range(MAX_NUMNODES, start_pfn, end_pfn);
7159 }
7160 
7161 /* Return the number of page frames in holes in a zone on a node */
7162 static unsigned long __init zone_absent_pages_in_node(int nid,
7163 					unsigned long zone_type,
7164 					unsigned long node_start_pfn,
7165 					unsigned long node_end_pfn)
7166 {
7167 	unsigned long zone_low = arch_zone_lowest_possible_pfn[zone_type];
7168 	unsigned long zone_high = arch_zone_highest_possible_pfn[zone_type];
7169 	unsigned long zone_start_pfn, zone_end_pfn;
7170 	unsigned long nr_absent;
7171 
7172 	/* When hotadd a new node from cpu_up(), the node should be empty */
7173 	if (!node_start_pfn && !node_end_pfn)
7174 		return 0;
7175 
7176 	zone_start_pfn = clamp(node_start_pfn, zone_low, zone_high);
7177 	zone_end_pfn = clamp(node_end_pfn, zone_low, zone_high);
7178 
7179 	adjust_zone_range_for_zone_movable(nid, zone_type,
7180 			node_start_pfn, node_end_pfn,
7181 			&zone_start_pfn, &zone_end_pfn);
7182 	nr_absent = __absent_pages_in_range(nid, zone_start_pfn, zone_end_pfn);
7183 
7184 	/*
7185 	 * ZONE_MOVABLE handling.
7186 	 * Treat pages to be ZONE_MOVABLE in ZONE_NORMAL as absent pages
7187 	 * and vice versa.
7188 	 */
7189 	if (mirrored_kernelcore && zone_movable_pfn[nid]) {
7190 		unsigned long start_pfn, end_pfn;
7191 		struct memblock_region *r;
7192 
7193 		for_each_mem_region(r) {
7194 			start_pfn = clamp(memblock_region_memory_base_pfn(r),
7195 					  zone_start_pfn, zone_end_pfn);
7196 			end_pfn = clamp(memblock_region_memory_end_pfn(r),
7197 					zone_start_pfn, zone_end_pfn);
7198 
7199 			if (zone_type == ZONE_MOVABLE &&
7200 			    memblock_is_mirror(r))
7201 				nr_absent += end_pfn - start_pfn;
7202 
7203 			if (zone_type == ZONE_NORMAL &&
7204 			    !memblock_is_mirror(r))
7205 				nr_absent += end_pfn - start_pfn;
7206 		}
7207 	}
7208 
7209 	return nr_absent;
7210 }
7211 
7212 static void __init calculate_node_totalpages(struct pglist_data *pgdat,
7213 						unsigned long node_start_pfn,
7214 						unsigned long node_end_pfn)
7215 {
7216 	unsigned long realtotalpages = 0, totalpages = 0;
7217 	enum zone_type i;
7218 
7219 	for (i = 0; i < MAX_NR_ZONES; i++) {
7220 		struct zone *zone = pgdat->node_zones + i;
7221 		unsigned long zone_start_pfn, zone_end_pfn;
7222 		unsigned long spanned, absent;
7223 		unsigned long size, real_size;
7224 
7225 		spanned = zone_spanned_pages_in_node(pgdat->node_id, i,
7226 						     node_start_pfn,
7227 						     node_end_pfn,
7228 						     &zone_start_pfn,
7229 						     &zone_end_pfn);
7230 		absent = zone_absent_pages_in_node(pgdat->node_id, i,
7231 						   node_start_pfn,
7232 						   node_end_pfn);
7233 
7234 		size = spanned;
7235 		real_size = size - absent;
7236 
7237 		if (size)
7238 			zone->zone_start_pfn = zone_start_pfn;
7239 		else
7240 			zone->zone_start_pfn = 0;
7241 		zone->spanned_pages = size;
7242 		zone->present_pages = real_size;
7243 #if defined(CONFIG_MEMORY_HOTPLUG)
7244 		zone->present_early_pages = real_size;
7245 #endif
7246 
7247 		totalpages += size;
7248 		realtotalpages += real_size;
7249 	}
7250 
7251 	pgdat->node_spanned_pages = totalpages;
7252 	pgdat->node_present_pages = realtotalpages;
7253 	pr_debug("On node %d totalpages: %lu\n", pgdat->node_id, realtotalpages);
7254 }
7255 
7256 #ifndef CONFIG_SPARSEMEM
7257 /*
7258  * Calculate the size of the zone->blockflags rounded to an unsigned long
7259  * Start by making sure zonesize is a multiple of pageblock_order by rounding
7260  * up. Then use 1 NR_PAGEBLOCK_BITS worth of bits per pageblock, finally
7261  * round what is now in bits to nearest long in bits, then return it in
7262  * bytes.
7263  */
7264 static unsigned long __init usemap_size(unsigned long zone_start_pfn, unsigned long zonesize)
7265 {
7266 	unsigned long usemapsize;
7267 
7268 	zonesize += zone_start_pfn & (pageblock_nr_pages-1);
7269 	usemapsize = roundup(zonesize, pageblock_nr_pages);
7270 	usemapsize = usemapsize >> pageblock_order;
7271 	usemapsize *= NR_PAGEBLOCK_BITS;
7272 	usemapsize = roundup(usemapsize, 8 * sizeof(unsigned long));
7273 
7274 	return usemapsize / 8;
7275 }
7276 
7277 static void __ref setup_usemap(struct zone *zone)
7278 {
7279 	unsigned long usemapsize = usemap_size(zone->zone_start_pfn,
7280 					       zone->spanned_pages);
7281 	zone->pageblock_flags = NULL;
7282 	if (usemapsize) {
7283 		zone->pageblock_flags =
7284 			memblock_alloc_node(usemapsize, SMP_CACHE_BYTES,
7285 					    zone_to_nid(zone));
7286 		if (!zone->pageblock_flags)
7287 			panic("Failed to allocate %ld bytes for zone %s pageblock flags on node %d\n",
7288 			      usemapsize, zone->name, zone_to_nid(zone));
7289 	}
7290 }
7291 #else
7292 static inline void setup_usemap(struct zone *zone) {}
7293 #endif /* CONFIG_SPARSEMEM */
7294 
7295 #ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
7296 
7297 /* Initialise the number of pages represented by NR_PAGEBLOCK_BITS */
7298 void __init set_pageblock_order(void)
7299 {
7300 	unsigned int order;
7301 
7302 	/* Check that pageblock_nr_pages has not already been setup */
7303 	if (pageblock_order)
7304 		return;
7305 
7306 	if (HPAGE_SHIFT > PAGE_SHIFT)
7307 		order = HUGETLB_PAGE_ORDER;
7308 	else
7309 		order = MAX_ORDER - 1;
7310 
7311 	/*
7312 	 * Assume the largest contiguous order of interest is a huge page.
7313 	 * This value may be variable depending on boot parameters on IA64 and
7314 	 * powerpc.
7315 	 */
7316 	pageblock_order = order;
7317 }
7318 #else /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
7319 
7320 /*
7321  * When CONFIG_HUGETLB_PAGE_SIZE_VARIABLE is not set, set_pageblock_order()
7322  * is unused as pageblock_order is set at compile-time. See
7323  * include/linux/pageblock-flags.h for the values of pageblock_order based on
7324  * the kernel config
7325  */
7326 void __init set_pageblock_order(void)
7327 {
7328 }
7329 
7330 #endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
7331 
7332 static unsigned long __init calc_memmap_size(unsigned long spanned_pages,
7333 						unsigned long present_pages)
7334 {
7335 	unsigned long pages = spanned_pages;
7336 
7337 	/*
7338 	 * Provide a more accurate estimation if there are holes within
7339 	 * the zone and SPARSEMEM is in use. If there are holes within the
7340 	 * zone, each populated memory region may cost us one or two extra
7341 	 * memmap pages due to alignment because memmap pages for each
7342 	 * populated regions may not be naturally aligned on page boundary.
7343 	 * So the (present_pages >> 4) heuristic is a tradeoff for that.
7344 	 */
7345 	if (spanned_pages > present_pages + (present_pages >> 4) &&
7346 	    IS_ENABLED(CONFIG_SPARSEMEM))
7347 		pages = present_pages;
7348 
7349 	return PAGE_ALIGN(pages * sizeof(struct page)) >> PAGE_SHIFT;
7350 }
7351 
7352 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
7353 static void pgdat_init_split_queue(struct pglist_data *pgdat)
7354 {
7355 	struct deferred_split *ds_queue = &pgdat->deferred_split_queue;
7356 
7357 	spin_lock_init(&ds_queue->split_queue_lock);
7358 	INIT_LIST_HEAD(&ds_queue->split_queue);
7359 	ds_queue->split_queue_len = 0;
7360 }
7361 #else
7362 static void pgdat_init_split_queue(struct pglist_data *pgdat) {}
7363 #endif
7364 
7365 #ifdef CONFIG_COMPACTION
7366 static void pgdat_init_kcompactd(struct pglist_data *pgdat)
7367 {
7368 	init_waitqueue_head(&pgdat->kcompactd_wait);
7369 }
7370 #else
7371 static void pgdat_init_kcompactd(struct pglist_data *pgdat) {}
7372 #endif
7373 
7374 static void __meminit pgdat_init_internals(struct pglist_data *pgdat)
7375 {
7376 	pgdat_resize_init(pgdat);
7377 
7378 	pgdat_init_split_queue(pgdat);
7379 	pgdat_init_kcompactd(pgdat);
7380 
7381 	init_waitqueue_head(&pgdat->kswapd_wait);
7382 	init_waitqueue_head(&pgdat->pfmemalloc_wait);
7383 
7384 	pgdat_page_ext_init(pgdat);
7385 	lruvec_init(&pgdat->__lruvec);
7386 }
7387 
7388 static void __meminit zone_init_internals(struct zone *zone, enum zone_type idx, int nid,
7389 							unsigned long remaining_pages)
7390 {
7391 	atomic_long_set(&zone->managed_pages, remaining_pages);
7392 	zone_set_nid(zone, nid);
7393 	zone->name = zone_names[idx];
7394 	zone->zone_pgdat = NODE_DATA(nid);
7395 	spin_lock_init(&zone->lock);
7396 	zone_seqlock_init(zone);
7397 	zone_pcp_init(zone);
7398 }
7399 
7400 /*
7401  * Set up the zone data structures
7402  * - init pgdat internals
7403  * - init all zones belonging to this node
7404  *
7405  * NOTE: this function is only called during memory hotplug
7406  */
7407 #ifdef CONFIG_MEMORY_HOTPLUG
7408 void __ref free_area_init_core_hotplug(int nid)
7409 {
7410 	enum zone_type z;
7411 	pg_data_t *pgdat = NODE_DATA(nid);
7412 
7413 	pgdat_init_internals(pgdat);
7414 	for (z = 0; z < MAX_NR_ZONES; z++)
7415 		zone_init_internals(&pgdat->node_zones[z], z, nid, 0);
7416 }
7417 #endif
7418 
7419 /*
7420  * Set up the zone data structures:
7421  *   - mark all pages reserved
7422  *   - mark all memory queues empty
7423  *   - clear the memory bitmaps
7424  *
7425  * NOTE: pgdat should get zeroed by caller.
7426  * NOTE: this function is only called during early init.
7427  */
7428 static void __init free_area_init_core(struct pglist_data *pgdat)
7429 {
7430 	enum zone_type j;
7431 	int nid = pgdat->node_id;
7432 
7433 	pgdat_init_internals(pgdat);
7434 	pgdat->per_cpu_nodestats = &boot_nodestats;
7435 
7436 	for (j = 0; j < MAX_NR_ZONES; j++) {
7437 		struct zone *zone = pgdat->node_zones + j;
7438 		unsigned long size, freesize, memmap_pages;
7439 
7440 		size = zone->spanned_pages;
7441 		freesize = zone->present_pages;
7442 
7443 		/*
7444 		 * Adjust freesize so that it accounts for how much memory
7445 		 * is used by this zone for memmap. This affects the watermark
7446 		 * and per-cpu initialisations
7447 		 */
7448 		memmap_pages = calc_memmap_size(size, freesize);
7449 		if (!is_highmem_idx(j)) {
7450 			if (freesize >= memmap_pages) {
7451 				freesize -= memmap_pages;
7452 				if (memmap_pages)
7453 					pr_debug("  %s zone: %lu pages used for memmap\n",
7454 						 zone_names[j], memmap_pages);
7455 			} else
7456 				pr_warn("  %s zone: %lu memmap pages exceeds freesize %lu\n",
7457 					zone_names[j], memmap_pages, freesize);
7458 		}
7459 
7460 		/* Account for reserved pages */
7461 		if (j == 0 && freesize > dma_reserve) {
7462 			freesize -= dma_reserve;
7463 			pr_debug("  %s zone: %lu pages reserved\n", zone_names[0], dma_reserve);
7464 		}
7465 
7466 		if (!is_highmem_idx(j))
7467 			nr_kernel_pages += freesize;
7468 		/* Charge for highmem memmap if there are enough kernel pages */
7469 		else if (nr_kernel_pages > memmap_pages * 2)
7470 			nr_kernel_pages -= memmap_pages;
7471 		nr_all_pages += freesize;
7472 
7473 		/*
7474 		 * Set an approximate value for lowmem here, it will be adjusted
7475 		 * when the bootmem allocator frees pages into the buddy system.
7476 		 * And all highmem pages will be managed by the buddy system.
7477 		 */
7478 		zone_init_internals(zone, j, nid, freesize);
7479 
7480 		if (!size)
7481 			continue;
7482 
7483 		set_pageblock_order();
7484 		setup_usemap(zone);
7485 		init_currently_empty_zone(zone, zone->zone_start_pfn, size);
7486 	}
7487 }
7488 
7489 #ifdef CONFIG_FLATMEM
7490 static void __ref alloc_node_mem_map(struct pglist_data *pgdat)
7491 {
7492 	unsigned long __maybe_unused start = 0;
7493 	unsigned long __maybe_unused offset = 0;
7494 
7495 	/* Skip empty nodes */
7496 	if (!pgdat->node_spanned_pages)
7497 		return;
7498 
7499 	start = pgdat->node_start_pfn & ~(MAX_ORDER_NR_PAGES - 1);
7500 	offset = pgdat->node_start_pfn - start;
7501 	/* ia64 gets its own node_mem_map, before this, without bootmem */
7502 	if (!pgdat->node_mem_map) {
7503 		unsigned long size, end;
7504 		struct page *map;
7505 
7506 		/*
7507 		 * The zone's endpoints aren't required to be MAX_ORDER
7508 		 * aligned but the node_mem_map endpoints must be in order
7509 		 * for the buddy allocator to function correctly.
7510 		 */
7511 		end = pgdat_end_pfn(pgdat);
7512 		end = ALIGN(end, MAX_ORDER_NR_PAGES);
7513 		size =  (end - start) * sizeof(struct page);
7514 		map = memblock_alloc_node(size, SMP_CACHE_BYTES,
7515 					  pgdat->node_id);
7516 		if (!map)
7517 			panic("Failed to allocate %ld bytes for node %d memory map\n",
7518 			      size, pgdat->node_id);
7519 		pgdat->node_mem_map = map + offset;
7520 	}
7521 	pr_debug("%s: node %d, pgdat %08lx, node_mem_map %08lx\n",
7522 				__func__, pgdat->node_id, (unsigned long)pgdat,
7523 				(unsigned long)pgdat->node_mem_map);
7524 #ifndef CONFIG_NUMA
7525 	/*
7526 	 * With no DISCONTIG, the global mem_map is just set as node 0's
7527 	 */
7528 	if (pgdat == NODE_DATA(0)) {
7529 		mem_map = NODE_DATA(0)->node_mem_map;
7530 		if (page_to_pfn(mem_map) != pgdat->node_start_pfn)
7531 			mem_map -= offset;
7532 	}
7533 #endif
7534 }
7535 #else
7536 static void __ref alloc_node_mem_map(struct pglist_data *pgdat) { }
7537 #endif /* CONFIG_FLATMEM */
7538 
7539 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
7540 static inline void pgdat_set_deferred_range(pg_data_t *pgdat)
7541 {
7542 	pgdat->first_deferred_pfn = ULONG_MAX;
7543 }
7544 #else
7545 static inline void pgdat_set_deferred_range(pg_data_t *pgdat) {}
7546 #endif
7547 
7548 static void __init free_area_init_node(int nid)
7549 {
7550 	pg_data_t *pgdat = NODE_DATA(nid);
7551 	unsigned long start_pfn = 0;
7552 	unsigned long end_pfn = 0;
7553 
7554 	/* pg_data_t should be reset to zero when it's allocated */
7555 	WARN_ON(pgdat->nr_zones || pgdat->kswapd_highest_zoneidx);
7556 
7557 	get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);
7558 
7559 	pgdat->node_id = nid;
7560 	pgdat->node_start_pfn = start_pfn;
7561 	pgdat->per_cpu_nodestats = NULL;
7562 
7563 	pr_info("Initmem setup node %d [mem %#018Lx-%#018Lx]\n", nid,
7564 		(u64)start_pfn << PAGE_SHIFT,
7565 		end_pfn ? ((u64)end_pfn << PAGE_SHIFT) - 1 : 0);
7566 	calculate_node_totalpages(pgdat, start_pfn, end_pfn);
7567 
7568 	alloc_node_mem_map(pgdat);
7569 	pgdat_set_deferred_range(pgdat);
7570 
7571 	free_area_init_core(pgdat);
7572 }
7573 
7574 void __init free_area_init_memoryless_node(int nid)
7575 {
7576 	free_area_init_node(nid);
7577 }
7578 
7579 #if MAX_NUMNODES > 1
7580 /*
7581  * Figure out the number of possible node ids.
7582  */
7583 void __init setup_nr_node_ids(void)
7584 {
7585 	unsigned int highest;
7586 
7587 	highest = find_last_bit(node_possible_map.bits, MAX_NUMNODES);
7588 	nr_node_ids = highest + 1;
7589 }
7590 #endif
7591 
7592 /**
7593  * node_map_pfn_alignment - determine the maximum internode alignment
7594  *
7595  * This function should be called after node map is populated and sorted.
7596  * It calculates the maximum power of two alignment which can distinguish
7597  * all the nodes.
7598  *
7599  * For example, if all nodes are 1GiB and aligned to 1GiB, the return value
7600  * would indicate 1GiB alignment with (1 << (30 - PAGE_SHIFT)).  If the
7601  * nodes are shifted by 256MiB, 256MiB.  Note that if only the last node is
7602  * shifted, 1GiB is enough and this function will indicate so.
7603  *
7604  * This is used to test whether pfn -> nid mapping of the chosen memory
7605  * model has fine enough granularity to avoid incorrect mapping for the
7606  * populated node map.
7607  *
7608  * Return: the determined alignment in pfn's.  0 if there is no alignment
7609  * requirement (single node).
7610  */
7611 unsigned long __init node_map_pfn_alignment(void)
7612 {
7613 	unsigned long accl_mask = 0, last_end = 0;
7614 	unsigned long start, end, mask;
7615 	int last_nid = NUMA_NO_NODE;
7616 	int i, nid;
7617 
7618 	for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, &nid) {
7619 		if (!start || last_nid < 0 || last_nid == nid) {
7620 			last_nid = nid;
7621 			last_end = end;
7622 			continue;
7623 		}
7624 
7625 		/*
7626 		 * Start with a mask granular enough to pin-point to the
7627 		 * start pfn and tick off bits one-by-one until it becomes
7628 		 * too coarse to separate the current node from the last.
7629 		 */
7630 		mask = ~((1 << __ffs(start)) - 1);
7631 		while (mask && last_end <= (start & (mask << 1)))
7632 			mask <<= 1;
7633 
7634 		/* accumulate all internode masks */
7635 		accl_mask |= mask;
7636 	}
7637 
7638 	/* convert mask to number of pages */
7639 	return ~accl_mask + 1;
7640 }
7641 
7642 /**
7643  * find_min_pfn_with_active_regions - Find the minimum PFN registered
7644  *
7645  * Return: the minimum PFN based on information provided via
7646  * memblock_set_node().
7647  */
7648 unsigned long __init find_min_pfn_with_active_regions(void)
7649 {
7650 	return PHYS_PFN(memblock_start_of_DRAM());
7651 }
7652 
7653 /*
7654  * early_calculate_totalpages()
7655  * Sum pages in active regions for movable zone.
7656  * Populate N_MEMORY for calculating usable_nodes.
7657  */
7658 static unsigned long __init early_calculate_totalpages(void)
7659 {
7660 	unsigned long totalpages = 0;
7661 	unsigned long start_pfn, end_pfn;
7662 	int i, nid;
7663 
7664 	for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) {
7665 		unsigned long pages = end_pfn - start_pfn;
7666 
7667 		totalpages += pages;
7668 		if (pages)
7669 			node_set_state(nid, N_MEMORY);
7670 	}
7671 	return totalpages;
7672 }
7673 
7674 /*
7675  * Find the PFN the Movable zone begins in each node. Kernel memory
7676  * is spread evenly between nodes as long as the nodes have enough
7677  * memory. When they don't, some nodes will have more kernelcore than
7678  * others
7679  */
7680 static void __init find_zone_movable_pfns_for_nodes(void)
7681 {
7682 	int i, nid;
7683 	unsigned long usable_startpfn;
7684 	unsigned long kernelcore_node, kernelcore_remaining;
7685 	/* save the state before borrow the nodemask */
7686 	nodemask_t saved_node_state = node_states[N_MEMORY];
7687 	unsigned long totalpages = early_calculate_totalpages();
7688 	int usable_nodes = nodes_weight(node_states[N_MEMORY]);
7689 	struct memblock_region *r;
7690 
7691 	/* Need to find movable_zone earlier when movable_node is specified. */
7692 	find_usable_zone_for_movable();
7693 
7694 	/*
7695 	 * If movable_node is specified, ignore kernelcore and movablecore
7696 	 * options.
7697 	 */
7698 	if (movable_node_is_enabled()) {
7699 		for_each_mem_region(r) {
7700 			if (!memblock_is_hotpluggable(r))
7701 				continue;
7702 
7703 			nid = memblock_get_region_node(r);
7704 
7705 			usable_startpfn = PFN_DOWN(r->base);
7706 			zone_movable_pfn[nid] = zone_movable_pfn[nid] ?
7707 				min(usable_startpfn, zone_movable_pfn[nid]) :
7708 				usable_startpfn;
7709 		}
7710 
7711 		goto out2;
7712 	}
7713 
7714 	/*
7715 	 * If kernelcore=mirror is specified, ignore movablecore option
7716 	 */
7717 	if (mirrored_kernelcore) {
7718 		bool mem_below_4gb_not_mirrored = false;
7719 
7720 		for_each_mem_region(r) {
7721 			if (memblock_is_mirror(r))
7722 				continue;
7723 
7724 			nid = memblock_get_region_node(r);
7725 
7726 			usable_startpfn = memblock_region_memory_base_pfn(r);
7727 
7728 			if (usable_startpfn < 0x100000) {
7729 				mem_below_4gb_not_mirrored = true;
7730 				continue;
7731 			}
7732 
7733 			zone_movable_pfn[nid] = zone_movable_pfn[nid] ?
7734 				min(usable_startpfn, zone_movable_pfn[nid]) :
7735 				usable_startpfn;
7736 		}
7737 
7738 		if (mem_below_4gb_not_mirrored)
7739 			pr_warn("This configuration results in unmirrored kernel memory.\n");
7740 
7741 		goto out2;
7742 	}
7743 
7744 	/*
7745 	 * If kernelcore=nn% or movablecore=nn% was specified, calculate the
7746 	 * amount of necessary memory.
7747 	 */
7748 	if (required_kernelcore_percent)
7749 		required_kernelcore = (totalpages * 100 * required_kernelcore_percent) /
7750 				       10000UL;
7751 	if (required_movablecore_percent)
7752 		required_movablecore = (totalpages * 100 * required_movablecore_percent) /
7753 					10000UL;
7754 
7755 	/*
7756 	 * If movablecore= was specified, calculate what size of
7757 	 * kernelcore that corresponds so that memory usable for
7758 	 * any allocation type is evenly spread. If both kernelcore
7759 	 * and movablecore are specified, then the value of kernelcore
7760 	 * will be used for required_kernelcore if it's greater than
7761 	 * what movablecore would have allowed.
7762 	 */
7763 	if (required_movablecore) {
7764 		unsigned long corepages;
7765 
7766 		/*
7767 		 * Round-up so that ZONE_MOVABLE is at least as large as what
7768 		 * was requested by the user
7769 		 */
7770 		required_movablecore =
7771 			roundup(required_movablecore, MAX_ORDER_NR_PAGES);
7772 		required_movablecore = min(totalpages, required_movablecore);
7773 		corepages = totalpages - required_movablecore;
7774 
7775 		required_kernelcore = max(required_kernelcore, corepages);
7776 	}
7777 
7778 	/*
7779 	 * If kernelcore was not specified or kernelcore size is larger
7780 	 * than totalpages, there is no ZONE_MOVABLE.
7781 	 */
7782 	if (!required_kernelcore || required_kernelcore >= totalpages)
7783 		goto out;
7784 
7785 	/* usable_startpfn is the lowest possible pfn ZONE_MOVABLE can be at */
7786 	usable_startpfn = arch_zone_lowest_possible_pfn[movable_zone];
7787 
7788 restart:
7789 	/* Spread kernelcore memory as evenly as possible throughout nodes */
7790 	kernelcore_node = required_kernelcore / usable_nodes;
7791 	for_each_node_state(nid, N_MEMORY) {
7792 		unsigned long start_pfn, end_pfn;
7793 
7794 		/*
7795 		 * Recalculate kernelcore_node if the division per node
7796 		 * now exceeds what is necessary to satisfy the requested
7797 		 * amount of memory for the kernel
7798 		 */
7799 		if (required_kernelcore < kernelcore_node)
7800 			kernelcore_node = required_kernelcore / usable_nodes;
7801 
7802 		/*
7803 		 * As the map is walked, we track how much memory is usable
7804 		 * by the kernel using kernelcore_remaining. When it is
7805 		 * 0, the rest of the node is usable by ZONE_MOVABLE
7806 		 */
7807 		kernelcore_remaining = kernelcore_node;
7808 
7809 		/* Go through each range of PFNs within this node */
7810 		for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) {
7811 			unsigned long size_pages;
7812 
7813 			start_pfn = max(start_pfn, zone_movable_pfn[nid]);
7814 			if (start_pfn >= end_pfn)
7815 				continue;
7816 
7817 			/* Account for what is only usable for kernelcore */
7818 			if (start_pfn < usable_startpfn) {
7819 				unsigned long kernel_pages;
7820 				kernel_pages = min(end_pfn, usable_startpfn)
7821 								- start_pfn;
7822 
7823 				kernelcore_remaining -= min(kernel_pages,
7824 							kernelcore_remaining);
7825 				required_kernelcore -= min(kernel_pages,
7826 							required_kernelcore);
7827 
7828 				/* Continue if range is now fully accounted */
7829 				if (end_pfn <= usable_startpfn) {
7830 
7831 					/*
7832 					 * Push zone_movable_pfn to the end so
7833 					 * that if we have to rebalance
7834 					 * kernelcore across nodes, we will
7835 					 * not double account here
7836 					 */
7837 					zone_movable_pfn[nid] = end_pfn;
7838 					continue;
7839 				}
7840 				start_pfn = usable_startpfn;
7841 			}
7842 
7843 			/*
7844 			 * The usable PFN range for ZONE_MOVABLE is from
7845 			 * start_pfn->end_pfn. Calculate size_pages as the
7846 			 * number of pages used as kernelcore
7847 			 */
7848 			size_pages = end_pfn - start_pfn;
7849 			if (size_pages > kernelcore_remaining)
7850 				size_pages = kernelcore_remaining;
7851 			zone_movable_pfn[nid] = start_pfn + size_pages;
7852 
7853 			/*
7854 			 * Some kernelcore has been met, update counts and
7855 			 * break if the kernelcore for this node has been
7856 			 * satisfied
7857 			 */
7858 			required_kernelcore -= min(required_kernelcore,
7859 								size_pages);
7860 			kernelcore_remaining -= size_pages;
7861 			if (!kernelcore_remaining)
7862 				break;
7863 		}
7864 	}
7865 
7866 	/*
7867 	 * If there is still required_kernelcore, we do another pass with one
7868 	 * less node in the count. This will push zone_movable_pfn[nid] further
7869 	 * along on the nodes that still have memory until kernelcore is
7870 	 * satisfied
7871 	 */
7872 	usable_nodes--;
7873 	if (usable_nodes && required_kernelcore > usable_nodes)
7874 		goto restart;
7875 
7876 out2:
7877 	/* Align start of ZONE_MOVABLE on all nids to MAX_ORDER_NR_PAGES */
7878 	for (nid = 0; nid < MAX_NUMNODES; nid++)
7879 		zone_movable_pfn[nid] =
7880 			roundup(zone_movable_pfn[nid], MAX_ORDER_NR_PAGES);
7881 
7882 out:
7883 	/* restore the node_state */
7884 	node_states[N_MEMORY] = saved_node_state;
7885 }
7886 
7887 /* Any regular or high memory on that node ? */
7888 static void check_for_memory(pg_data_t *pgdat, int nid)
7889 {
7890 	enum zone_type zone_type;
7891 
7892 	for (zone_type = 0; zone_type <= ZONE_MOVABLE - 1; zone_type++) {
7893 		struct zone *zone = &pgdat->node_zones[zone_type];
7894 		if (populated_zone(zone)) {
7895 			if (IS_ENABLED(CONFIG_HIGHMEM))
7896 				node_set_state(nid, N_HIGH_MEMORY);
7897 			if (zone_type <= ZONE_NORMAL)
7898 				node_set_state(nid, N_NORMAL_MEMORY);
7899 			break;
7900 		}
7901 	}
7902 }
7903 
7904 /*
7905  * Some architectures, e.g. ARC may have ZONE_HIGHMEM below ZONE_NORMAL. For
7906  * such cases we allow max_zone_pfn sorted in the descending order
7907  */
7908 bool __weak arch_has_descending_max_zone_pfns(void)
7909 {
7910 	return false;
7911 }
7912 
7913 /**
7914  * free_area_init - Initialise all pg_data_t and zone data
7915  * @max_zone_pfn: an array of max PFNs for each zone
7916  *
7917  * This will call free_area_init_node() for each active node in the system.
7918  * Using the page ranges provided by memblock_set_node(), the size of each
7919  * zone in each node and their holes is calculated. If the maximum PFN
7920  * between two adjacent zones match, it is assumed that the zone is empty.
7921  * For example, if arch_max_dma_pfn == arch_max_dma32_pfn, it is assumed
7922  * that arch_max_dma32_pfn has no pages. It is also assumed that a zone
7923  * starts where the previous one ended. For example, ZONE_DMA32 starts
7924  * at arch_max_dma_pfn.
7925  */
7926 void __init free_area_init(unsigned long *max_zone_pfn)
7927 {
7928 	unsigned long start_pfn, end_pfn;
7929 	int i, nid, zone;
7930 	bool descending;
7931 
7932 	/* Record where the zone boundaries are */
7933 	memset(arch_zone_lowest_possible_pfn, 0,
7934 				sizeof(arch_zone_lowest_possible_pfn));
7935 	memset(arch_zone_highest_possible_pfn, 0,
7936 				sizeof(arch_zone_highest_possible_pfn));
7937 
7938 	start_pfn = find_min_pfn_with_active_regions();
7939 	descending = arch_has_descending_max_zone_pfns();
7940 
7941 	for (i = 0; i < MAX_NR_ZONES; i++) {
7942 		if (descending)
7943 			zone = MAX_NR_ZONES - i - 1;
7944 		else
7945 			zone = i;
7946 
7947 		if (zone == ZONE_MOVABLE)
7948 			continue;
7949 
7950 		end_pfn = max(max_zone_pfn[zone], start_pfn);
7951 		arch_zone_lowest_possible_pfn[zone] = start_pfn;
7952 		arch_zone_highest_possible_pfn[zone] = end_pfn;
7953 
7954 		start_pfn = end_pfn;
7955 	}
7956 
7957 	/* Find the PFNs that ZONE_MOVABLE begins at in each node */
7958 	memset(zone_movable_pfn, 0, sizeof(zone_movable_pfn));
7959 	find_zone_movable_pfns_for_nodes();
7960 
7961 	/* Print out the zone ranges */
7962 	pr_info("Zone ranges:\n");
7963 	for (i = 0; i < MAX_NR_ZONES; i++) {
7964 		if (i == ZONE_MOVABLE)
7965 			continue;
7966 		pr_info("  %-8s ", zone_names[i]);
7967 		if (arch_zone_lowest_possible_pfn[i] ==
7968 				arch_zone_highest_possible_pfn[i])
7969 			pr_cont("empty\n");
7970 		else
7971 			pr_cont("[mem %#018Lx-%#018Lx]\n",
7972 				(u64)arch_zone_lowest_possible_pfn[i]
7973 					<< PAGE_SHIFT,
7974 				((u64)arch_zone_highest_possible_pfn[i]
7975 					<< PAGE_SHIFT) - 1);
7976 	}
7977 
7978 	/* Print out the PFNs ZONE_MOVABLE begins at in each node */
7979 	pr_info("Movable zone start for each node\n");
7980 	for (i = 0; i < MAX_NUMNODES; i++) {
7981 		if (zone_movable_pfn[i])
7982 			pr_info("  Node %d: %#018Lx\n", i,
7983 			       (u64)zone_movable_pfn[i] << PAGE_SHIFT);
7984 	}
7985 
7986 	/*
7987 	 * Print out the early node map, and initialize the
7988 	 * subsection-map relative to active online memory ranges to
7989 	 * enable future "sub-section" extensions of the memory map.
7990 	 */
7991 	pr_info("Early memory node ranges\n");
7992 	for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) {
7993 		pr_info("  node %3d: [mem %#018Lx-%#018Lx]\n", nid,
7994 			(u64)start_pfn << PAGE_SHIFT,
7995 			((u64)end_pfn << PAGE_SHIFT) - 1);
7996 		subsection_map_init(start_pfn, end_pfn - start_pfn);
7997 	}
7998 
7999 	/* Initialise every node */
8000 	mminit_verify_pageflags_layout();
8001 	setup_nr_node_ids();
8002 	for_each_online_node(nid) {
8003 		pg_data_t *pgdat = NODE_DATA(nid);
8004 		free_area_init_node(nid);
8005 
8006 		/* Any memory on that node */
8007 		if (pgdat->node_present_pages)
8008 			node_set_state(nid, N_MEMORY);
8009 		check_for_memory(pgdat, nid);
8010 	}
8011 
8012 	memmap_init();
8013 }
8014 
8015 static int __init cmdline_parse_core(char *p, unsigned long *core,
8016 				     unsigned long *percent)
8017 {
8018 	unsigned long long coremem;
8019 	char *endptr;
8020 
8021 	if (!p)
8022 		return -EINVAL;
8023 
8024 	/* Value may be a percentage of total memory, otherwise bytes */
8025 	coremem = simple_strtoull(p, &endptr, 0);
8026 	if (*endptr == '%') {
8027 		/* Paranoid check for percent values greater than 100 */
8028 		WARN_ON(coremem > 100);
8029 
8030 		*percent = coremem;
8031 	} else {
8032 		coremem = memparse(p, &p);
8033 		/* Paranoid check that UL is enough for the coremem value */
8034 		WARN_ON((coremem >> PAGE_SHIFT) > ULONG_MAX);
8035 
8036 		*core = coremem >> PAGE_SHIFT;
8037 		*percent = 0UL;
8038 	}
8039 	return 0;
8040 }
8041 
8042 /*
8043  * kernelcore=size sets the amount of memory for use for allocations that
8044  * cannot be reclaimed or migrated.
8045  */
8046 static int __init cmdline_parse_kernelcore(char *p)
8047 {
8048 	/* parse kernelcore=mirror */
8049 	if (parse_option_str(p, "mirror")) {
8050 		mirrored_kernelcore = true;
8051 		return 0;
8052 	}
8053 
8054 	return cmdline_parse_core(p, &required_kernelcore,
8055 				  &required_kernelcore_percent);
8056 }
8057 
8058 /*
8059  * movablecore=size sets the amount of memory for use for allocations that
8060  * can be reclaimed or migrated.
8061  */
8062 static int __init cmdline_parse_movablecore(char *p)
8063 {
8064 	return cmdline_parse_core(p, &required_movablecore,
8065 				  &required_movablecore_percent);
8066 }
8067 
8068 early_param("kernelcore", cmdline_parse_kernelcore);
8069 early_param("movablecore", cmdline_parse_movablecore);
8070 
8071 void adjust_managed_page_count(struct page *page, long count)
8072 {
8073 	atomic_long_add(count, &page_zone(page)->managed_pages);
8074 	totalram_pages_add(count);
8075 #ifdef CONFIG_HIGHMEM
8076 	if (PageHighMem(page))
8077 		totalhigh_pages_add(count);
8078 #endif
8079 }
8080 EXPORT_SYMBOL(adjust_managed_page_count);
8081 
8082 unsigned long free_reserved_area(void *start, void *end, int poison, const char *s)
8083 {
8084 	void *pos;
8085 	unsigned long pages = 0;
8086 
8087 	start = (void *)PAGE_ALIGN((unsigned long)start);
8088 	end = (void *)((unsigned long)end & PAGE_MASK);
8089 	for (pos = start; pos < end; pos += PAGE_SIZE, pages++) {
8090 		struct page *page = virt_to_page(pos);
8091 		void *direct_map_addr;
8092 
8093 		/*
8094 		 * 'direct_map_addr' might be different from 'pos'
8095 		 * because some architectures' virt_to_page()
8096 		 * work with aliases.  Getting the direct map
8097 		 * address ensures that we get a _writeable_
8098 		 * alias for the memset().
8099 		 */
8100 		direct_map_addr = page_address(page);
8101 		/*
8102 		 * Perform a kasan-unchecked memset() since this memory
8103 		 * has not been initialized.
8104 		 */
8105 		direct_map_addr = kasan_reset_tag(direct_map_addr);
8106 		if ((unsigned int)poison <= 0xFF)
8107 			memset(direct_map_addr, poison, PAGE_SIZE);
8108 
8109 		free_reserved_page(page);
8110 	}
8111 
8112 	if (pages && s)
8113 		pr_info("Freeing %s memory: %ldK\n",
8114 			s, pages << (PAGE_SHIFT - 10));
8115 
8116 	return pages;
8117 }
8118 
8119 void __init mem_init_print_info(void)
8120 {
8121 	unsigned long physpages, codesize, datasize, rosize, bss_size;
8122 	unsigned long init_code_size, init_data_size;
8123 
8124 	physpages = get_num_physpages();
8125 	codesize = _etext - _stext;
8126 	datasize = _edata - _sdata;
8127 	rosize = __end_rodata - __start_rodata;
8128 	bss_size = __bss_stop - __bss_start;
8129 	init_data_size = __init_end - __init_begin;
8130 	init_code_size = _einittext - _sinittext;
8131 
8132 	/*
8133 	 * Detect special cases and adjust section sizes accordingly:
8134 	 * 1) .init.* may be embedded into .data sections
8135 	 * 2) .init.text.* may be out of [__init_begin, __init_end],
8136 	 *    please refer to arch/tile/kernel/vmlinux.lds.S.
8137 	 * 3) .rodata.* may be embedded into .text or .data sections.
8138 	 */
8139 #define adj_init_size(start, end, size, pos, adj) \
8140 	do { \
8141 		if (start <= pos && pos < end && size > adj) \
8142 			size -= adj; \
8143 	} while (0)
8144 
8145 	adj_init_size(__init_begin, __init_end, init_data_size,
8146 		     _sinittext, init_code_size);
8147 	adj_init_size(_stext, _etext, codesize, _sinittext, init_code_size);
8148 	adj_init_size(_sdata, _edata, datasize, __init_begin, init_data_size);
8149 	adj_init_size(_stext, _etext, codesize, __start_rodata, rosize);
8150 	adj_init_size(_sdata, _edata, datasize, __start_rodata, rosize);
8151 
8152 #undef	adj_init_size
8153 
8154 	pr_info("Memory: %luK/%luK available (%luK kernel code, %luK rwdata, %luK rodata, %luK init, %luK bss, %luK reserved, %luK cma-reserved"
8155 #ifdef	CONFIG_HIGHMEM
8156 		", %luK highmem"
8157 #endif
8158 		")\n",
8159 		nr_free_pages() << (PAGE_SHIFT - 10),
8160 		physpages << (PAGE_SHIFT - 10),
8161 		codesize >> 10, datasize >> 10, rosize >> 10,
8162 		(init_data_size + init_code_size) >> 10, bss_size >> 10,
8163 		(physpages - totalram_pages() - totalcma_pages) << (PAGE_SHIFT - 10),
8164 		totalcma_pages << (PAGE_SHIFT - 10)
8165 #ifdef	CONFIG_HIGHMEM
8166 		, totalhigh_pages() << (PAGE_SHIFT - 10)
8167 #endif
8168 		);
8169 }
8170 
8171 /**
8172  * set_dma_reserve - set the specified number of pages reserved in the first zone
8173  * @new_dma_reserve: The number of pages to mark reserved
8174  *
8175  * The per-cpu batchsize and zone watermarks are determined by managed_pages.
8176  * In the DMA zone, a significant percentage may be consumed by kernel image
8177  * and other unfreeable allocations which can skew the watermarks badly. This
8178  * function may optionally be used to account for unfreeable pages in the
8179  * first zone (e.g., ZONE_DMA). The effect will be lower watermarks and
8180  * smaller per-cpu batchsize.
8181  */
8182 void __init set_dma_reserve(unsigned long new_dma_reserve)
8183 {
8184 	dma_reserve = new_dma_reserve;
8185 }
8186 
8187 static int page_alloc_cpu_dead(unsigned int cpu)
8188 {
8189 	struct zone *zone;
8190 
8191 	lru_add_drain_cpu(cpu);
8192 	drain_pages(cpu);
8193 
8194 	/*
8195 	 * Spill the event counters of the dead processor
8196 	 * into the current processors event counters.
8197 	 * This artificially elevates the count of the current
8198 	 * processor.
8199 	 */
8200 	vm_events_fold_cpu(cpu);
8201 
8202 	/*
8203 	 * Zero the differential counters of the dead processor
8204 	 * so that the vm statistics are consistent.
8205 	 *
8206 	 * This is only okay since the processor is dead and cannot
8207 	 * race with what we are doing.
8208 	 */
8209 	cpu_vm_stats_fold(cpu);
8210 
8211 	for_each_populated_zone(zone)
8212 		zone_pcp_update(zone, 0);
8213 
8214 	return 0;
8215 }
8216 
8217 static int page_alloc_cpu_online(unsigned int cpu)
8218 {
8219 	struct zone *zone;
8220 
8221 	for_each_populated_zone(zone)
8222 		zone_pcp_update(zone, 1);
8223 	return 0;
8224 }
8225 
8226 #ifdef CONFIG_NUMA
8227 int hashdist = HASHDIST_DEFAULT;
8228 
8229 static int __init set_hashdist(char *str)
8230 {
8231 	if (!str)
8232 		return 0;
8233 	hashdist = simple_strtoul(str, &str, 0);
8234 	return 1;
8235 }
8236 __setup("hashdist=", set_hashdist);
8237 #endif
8238 
8239 void __init page_alloc_init(void)
8240 {
8241 	int ret;
8242 
8243 #ifdef CONFIG_NUMA
8244 	if (num_node_state(N_MEMORY) == 1)
8245 		hashdist = 0;
8246 #endif
8247 
8248 	ret = cpuhp_setup_state_nocalls(CPUHP_PAGE_ALLOC,
8249 					"mm/page_alloc:pcp",
8250 					page_alloc_cpu_online,
8251 					page_alloc_cpu_dead);
8252 	WARN_ON(ret < 0);
8253 }
8254 
8255 /*
8256  * calculate_totalreserve_pages - called when sysctl_lowmem_reserve_ratio
8257  *	or min_free_kbytes changes.
8258  */
8259 static void calculate_totalreserve_pages(void)
8260 {
8261 	struct pglist_data *pgdat;
8262 	unsigned long reserve_pages = 0;
8263 	enum zone_type i, j;
8264 
8265 	for_each_online_pgdat(pgdat) {
8266 
8267 		pgdat->totalreserve_pages = 0;
8268 
8269 		for (i = 0; i < MAX_NR_ZONES; i++) {
8270 			struct zone *zone = pgdat->node_zones + i;
8271 			long max = 0;
8272 			unsigned long managed_pages = zone_managed_pages(zone);
8273 
8274 			/* Find valid and maximum lowmem_reserve in the zone */
8275 			for (j = i; j < MAX_NR_ZONES; j++) {
8276 				if (zone->lowmem_reserve[j] > max)
8277 					max = zone->lowmem_reserve[j];
8278 			}
8279 
8280 			/* we treat the high watermark as reserved pages. */
8281 			max += high_wmark_pages(zone);
8282 
8283 			if (max > managed_pages)
8284 				max = managed_pages;
8285 
8286 			pgdat->totalreserve_pages += max;
8287 
8288 			reserve_pages += max;
8289 		}
8290 	}
8291 	totalreserve_pages = reserve_pages;
8292 }
8293 
8294 /*
8295  * setup_per_zone_lowmem_reserve - called whenever
8296  *	sysctl_lowmem_reserve_ratio changes.  Ensures that each zone
8297  *	has a correct pages reserved value, so an adequate number of
8298  *	pages are left in the zone after a successful __alloc_pages().
8299  */
8300 static void setup_per_zone_lowmem_reserve(void)
8301 {
8302 	struct pglist_data *pgdat;
8303 	enum zone_type i, j;
8304 
8305 	for_each_online_pgdat(pgdat) {
8306 		for (i = 0; i < MAX_NR_ZONES - 1; i++) {
8307 			struct zone *zone = &pgdat->node_zones[i];
8308 			int ratio = sysctl_lowmem_reserve_ratio[i];
8309 			bool clear = !ratio || !zone_managed_pages(zone);
8310 			unsigned long managed_pages = 0;
8311 
8312 			for (j = i + 1; j < MAX_NR_ZONES; j++) {
8313 				struct zone *upper_zone = &pgdat->node_zones[j];
8314 
8315 				managed_pages += zone_managed_pages(upper_zone);
8316 
8317 				if (clear)
8318 					zone->lowmem_reserve[j] = 0;
8319 				else
8320 					zone->lowmem_reserve[j] = managed_pages / ratio;
8321 			}
8322 		}
8323 	}
8324 
8325 	/* update totalreserve_pages */
8326 	calculate_totalreserve_pages();
8327 }
8328 
8329 static void __setup_per_zone_wmarks(void)
8330 {
8331 	unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10);
8332 	unsigned long lowmem_pages = 0;
8333 	struct zone *zone;
8334 	unsigned long flags;
8335 
8336 	/* Calculate total number of !ZONE_HIGHMEM pages */
8337 	for_each_zone(zone) {
8338 		if (!is_highmem(zone))
8339 			lowmem_pages += zone_managed_pages(zone);
8340 	}
8341 
8342 	for_each_zone(zone) {
8343 		u64 tmp;
8344 
8345 		spin_lock_irqsave(&zone->lock, flags);
8346 		tmp = (u64)pages_min * zone_managed_pages(zone);
8347 		do_div(tmp, lowmem_pages);
8348 		if (is_highmem(zone)) {
8349 			/*
8350 			 * __GFP_HIGH and PF_MEMALLOC allocations usually don't
8351 			 * need highmem pages, so cap pages_min to a small
8352 			 * value here.
8353 			 *
8354 			 * The WMARK_HIGH-WMARK_LOW and (WMARK_LOW-WMARK_MIN)
8355 			 * deltas control async page reclaim, and so should
8356 			 * not be capped for highmem.
8357 			 */
8358 			unsigned long min_pages;
8359 
8360 			min_pages = zone_managed_pages(zone) / 1024;
8361 			min_pages = clamp(min_pages, SWAP_CLUSTER_MAX, 128UL);
8362 			zone->_watermark[WMARK_MIN] = min_pages;
8363 		} else {
8364 			/*
8365 			 * If it's a lowmem zone, reserve a number of pages
8366 			 * proportionate to the zone's size.
8367 			 */
8368 			zone->_watermark[WMARK_MIN] = tmp;
8369 		}
8370 
8371 		/*
8372 		 * Set the kswapd watermarks distance according to the
8373 		 * scale factor in proportion to available memory, but
8374 		 * ensure a minimum size on small systems.
8375 		 */
8376 		tmp = max_t(u64, tmp >> 2,
8377 			    mult_frac(zone_managed_pages(zone),
8378 				      watermark_scale_factor, 10000));
8379 
8380 		zone->watermark_boost = 0;
8381 		zone->_watermark[WMARK_LOW]  = min_wmark_pages(zone) + tmp;
8382 		zone->_watermark[WMARK_HIGH] = min_wmark_pages(zone) + tmp * 2;
8383 
8384 		spin_unlock_irqrestore(&zone->lock, flags);
8385 	}
8386 
8387 	/* update totalreserve_pages */
8388 	calculate_totalreserve_pages();
8389 }
8390 
8391 /**
8392  * setup_per_zone_wmarks - called when min_free_kbytes changes
8393  * or when memory is hot-{added|removed}
8394  *
8395  * Ensures that the watermark[min,low,high] values for each zone are set
8396  * correctly with respect to min_free_kbytes.
8397  */
8398 void setup_per_zone_wmarks(void)
8399 {
8400 	struct zone *zone;
8401 	static DEFINE_SPINLOCK(lock);
8402 
8403 	spin_lock(&lock);
8404 	__setup_per_zone_wmarks();
8405 	spin_unlock(&lock);
8406 
8407 	/*
8408 	 * The watermark size have changed so update the pcpu batch
8409 	 * and high limits or the limits may be inappropriate.
8410 	 */
8411 	for_each_zone(zone)
8412 		zone_pcp_update(zone, 0);
8413 }
8414 
8415 /*
8416  * Initialise min_free_kbytes.
8417  *
8418  * For small machines we want it small (128k min).  For large machines
8419  * we want it large (256MB max).  But it is not linear, because network
8420  * bandwidth does not increase linearly with machine size.  We use
8421  *
8422  *	min_free_kbytes = 4 * sqrt(lowmem_kbytes), for better accuracy:
8423  *	min_free_kbytes = sqrt(lowmem_kbytes * 16)
8424  *
8425  * which yields
8426  *
8427  * 16MB:	512k
8428  * 32MB:	724k
8429  * 64MB:	1024k
8430  * 128MB:	1448k
8431  * 256MB:	2048k
8432  * 512MB:	2896k
8433  * 1024MB:	4096k
8434  * 2048MB:	5792k
8435  * 4096MB:	8192k
8436  * 8192MB:	11584k
8437  * 16384MB:	16384k
8438  */
8439 int __meminit init_per_zone_wmark_min(void)
8440 {
8441 	unsigned long lowmem_kbytes;
8442 	int new_min_free_kbytes;
8443 
8444 	lowmem_kbytes = nr_free_buffer_pages() * (PAGE_SIZE >> 10);
8445 	new_min_free_kbytes = int_sqrt(lowmem_kbytes * 16);
8446 
8447 	if (new_min_free_kbytes > user_min_free_kbytes) {
8448 		min_free_kbytes = new_min_free_kbytes;
8449 		if (min_free_kbytes < 128)
8450 			min_free_kbytes = 128;
8451 		if (min_free_kbytes > 262144)
8452 			min_free_kbytes = 262144;
8453 	} else {
8454 		pr_warn("min_free_kbytes is not updated to %d because user defined value %d is preferred\n",
8455 				new_min_free_kbytes, user_min_free_kbytes);
8456 	}
8457 	setup_per_zone_wmarks();
8458 	refresh_zone_stat_thresholds();
8459 	setup_per_zone_lowmem_reserve();
8460 
8461 #ifdef CONFIG_NUMA
8462 	setup_min_unmapped_ratio();
8463 	setup_min_slab_ratio();
8464 #endif
8465 
8466 	khugepaged_min_free_kbytes_update();
8467 
8468 	return 0;
8469 }
8470 postcore_initcall(init_per_zone_wmark_min)
8471 
8472 /*
8473  * min_free_kbytes_sysctl_handler - just a wrapper around proc_dointvec() so
8474  *	that we can call two helper functions whenever min_free_kbytes
8475  *	changes.
8476  */
8477 int min_free_kbytes_sysctl_handler(struct ctl_table *table, int write,
8478 		void *buffer, size_t *length, loff_t *ppos)
8479 {
8480 	int rc;
8481 
8482 	rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
8483 	if (rc)
8484 		return rc;
8485 
8486 	if (write) {
8487 		user_min_free_kbytes = min_free_kbytes;
8488 		setup_per_zone_wmarks();
8489 	}
8490 	return 0;
8491 }
8492 
8493 int watermark_scale_factor_sysctl_handler(struct ctl_table *table, int write,
8494 		void *buffer, size_t *length, loff_t *ppos)
8495 {
8496 	int rc;
8497 
8498 	rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
8499 	if (rc)
8500 		return rc;
8501 
8502 	if (write)
8503 		setup_per_zone_wmarks();
8504 
8505 	return 0;
8506 }
8507 
8508 #ifdef CONFIG_NUMA
8509 static void setup_min_unmapped_ratio(void)
8510 {
8511 	pg_data_t *pgdat;
8512 	struct zone *zone;
8513 
8514 	for_each_online_pgdat(pgdat)
8515 		pgdat->min_unmapped_pages = 0;
8516 
8517 	for_each_zone(zone)
8518 		zone->zone_pgdat->min_unmapped_pages += (zone_managed_pages(zone) *
8519 						         sysctl_min_unmapped_ratio) / 100;
8520 }
8521 
8522 
8523 int sysctl_min_unmapped_ratio_sysctl_handler(struct ctl_table *table, int write,
8524 		void *buffer, size_t *length, loff_t *ppos)
8525 {
8526 	int rc;
8527 
8528 	rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
8529 	if (rc)
8530 		return rc;
8531 
8532 	setup_min_unmapped_ratio();
8533 
8534 	return 0;
8535 }
8536 
8537 static void setup_min_slab_ratio(void)
8538 {
8539 	pg_data_t *pgdat;
8540 	struct zone *zone;
8541 
8542 	for_each_online_pgdat(pgdat)
8543 		pgdat->min_slab_pages = 0;
8544 
8545 	for_each_zone(zone)
8546 		zone->zone_pgdat->min_slab_pages += (zone_managed_pages(zone) *
8547 						     sysctl_min_slab_ratio) / 100;
8548 }
8549 
8550 int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *table, int write,
8551 		void *buffer, size_t *length, loff_t *ppos)
8552 {
8553 	int rc;
8554 
8555 	rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
8556 	if (rc)
8557 		return rc;
8558 
8559 	setup_min_slab_ratio();
8560 
8561 	return 0;
8562 }
8563 #endif
8564 
8565 /*
8566  * lowmem_reserve_ratio_sysctl_handler - just a wrapper around
8567  *	proc_dointvec() so that we can call setup_per_zone_lowmem_reserve()
8568  *	whenever sysctl_lowmem_reserve_ratio changes.
8569  *
8570  * The reserve ratio obviously has absolutely no relation with the
8571  * minimum watermarks. The lowmem reserve ratio can only make sense
8572  * if in function of the boot time zone sizes.
8573  */
8574 int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *table, int write,
8575 		void *buffer, size_t *length, loff_t *ppos)
8576 {
8577 	int i;
8578 
8579 	proc_dointvec_minmax(table, write, buffer, length, ppos);
8580 
8581 	for (i = 0; i < MAX_NR_ZONES; i++) {
8582 		if (sysctl_lowmem_reserve_ratio[i] < 1)
8583 			sysctl_lowmem_reserve_ratio[i] = 0;
8584 	}
8585 
8586 	setup_per_zone_lowmem_reserve();
8587 	return 0;
8588 }
8589 
8590 /*
8591  * percpu_pagelist_high_fraction - changes the pcp->high for each zone on each
8592  * cpu. It is the fraction of total pages in each zone that a hot per cpu
8593  * pagelist can have before it gets flushed back to buddy allocator.
8594  */
8595 int percpu_pagelist_high_fraction_sysctl_handler(struct ctl_table *table,
8596 		int write, void *buffer, size_t *length, loff_t *ppos)
8597 {
8598 	struct zone *zone;
8599 	int old_percpu_pagelist_high_fraction;
8600 	int ret;
8601 
8602 	mutex_lock(&pcp_batch_high_lock);
8603 	old_percpu_pagelist_high_fraction = percpu_pagelist_high_fraction;
8604 
8605 	ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
8606 	if (!write || ret < 0)
8607 		goto out;
8608 
8609 	/* Sanity checking to avoid pcp imbalance */
8610 	if (percpu_pagelist_high_fraction &&
8611 	    percpu_pagelist_high_fraction < MIN_PERCPU_PAGELIST_HIGH_FRACTION) {
8612 		percpu_pagelist_high_fraction = old_percpu_pagelist_high_fraction;
8613 		ret = -EINVAL;
8614 		goto out;
8615 	}
8616 
8617 	/* No change? */
8618 	if (percpu_pagelist_high_fraction == old_percpu_pagelist_high_fraction)
8619 		goto out;
8620 
8621 	for_each_populated_zone(zone)
8622 		zone_set_pageset_high_and_batch(zone, 0);
8623 out:
8624 	mutex_unlock(&pcp_batch_high_lock);
8625 	return ret;
8626 }
8627 
8628 #ifndef __HAVE_ARCH_RESERVED_KERNEL_PAGES
8629 /*
8630  * Returns the number of pages that arch has reserved but
8631  * is not known to alloc_large_system_hash().
8632  */
8633 static unsigned long __init arch_reserved_kernel_pages(void)
8634 {
8635 	return 0;
8636 }
8637 #endif
8638 
8639 /*
8640  * Adaptive scale is meant to reduce sizes of hash tables on large memory
8641  * machines. As memory size is increased the scale is also increased but at
8642  * slower pace.  Starting from ADAPT_SCALE_BASE (64G), every time memory
8643  * quadruples the scale is increased by one, which means the size of hash table
8644  * only doubles, instead of quadrupling as well.
8645  * Because 32-bit systems cannot have large physical memory, where this scaling
8646  * makes sense, it is disabled on such platforms.
8647  */
8648 #if __BITS_PER_LONG > 32
8649 #define ADAPT_SCALE_BASE	(64ul << 30)
8650 #define ADAPT_SCALE_SHIFT	2
8651 #define ADAPT_SCALE_NPAGES	(ADAPT_SCALE_BASE >> PAGE_SHIFT)
8652 #endif
8653 
8654 /*
8655  * allocate a large system hash table from bootmem
8656  * - it is assumed that the hash table must contain an exact power-of-2
8657  *   quantity of entries
8658  * - limit is the number of hash buckets, not the total allocation size
8659  */
8660 void *__init alloc_large_system_hash(const char *tablename,
8661 				     unsigned long bucketsize,
8662 				     unsigned long numentries,
8663 				     int scale,
8664 				     int flags,
8665 				     unsigned int *_hash_shift,
8666 				     unsigned int *_hash_mask,
8667 				     unsigned long low_limit,
8668 				     unsigned long high_limit)
8669 {
8670 	unsigned long long max = high_limit;
8671 	unsigned long log2qty, size;
8672 	void *table = NULL;
8673 	gfp_t gfp_flags;
8674 	bool virt;
8675 	bool huge;
8676 
8677 	/* allow the kernel cmdline to have a say */
8678 	if (!numentries) {
8679 		/* round applicable memory size up to nearest megabyte */
8680 		numentries = nr_kernel_pages;
8681 		numentries -= arch_reserved_kernel_pages();
8682 
8683 		/* It isn't necessary when PAGE_SIZE >= 1MB */
8684 		if (PAGE_SHIFT < 20)
8685 			numentries = round_up(numentries, (1<<20)/PAGE_SIZE);
8686 
8687 #if __BITS_PER_LONG > 32
8688 		if (!high_limit) {
8689 			unsigned long adapt;
8690 
8691 			for (adapt = ADAPT_SCALE_NPAGES; adapt < numentries;
8692 			     adapt <<= ADAPT_SCALE_SHIFT)
8693 				scale++;
8694 		}
8695 #endif
8696 
8697 		/* limit to 1 bucket per 2^scale bytes of low memory */
8698 		if (scale > PAGE_SHIFT)
8699 			numentries >>= (scale - PAGE_SHIFT);
8700 		else
8701 			numentries <<= (PAGE_SHIFT - scale);
8702 
8703 		/* Make sure we've got at least a 0-order allocation.. */
8704 		if (unlikely(flags & HASH_SMALL)) {
8705 			/* Makes no sense without HASH_EARLY */
8706 			WARN_ON(!(flags & HASH_EARLY));
8707 			if (!(numentries >> *_hash_shift)) {
8708 				numentries = 1UL << *_hash_shift;
8709 				BUG_ON(!numentries);
8710 			}
8711 		} else if (unlikely((numentries * bucketsize) < PAGE_SIZE))
8712 			numentries = PAGE_SIZE / bucketsize;
8713 	}
8714 	numentries = roundup_pow_of_two(numentries);
8715 
8716 	/* limit allocation size to 1/16 total memory by default */
8717 	if (max == 0) {
8718 		max = ((unsigned long long)nr_all_pages << PAGE_SHIFT) >> 4;
8719 		do_div(max, bucketsize);
8720 	}
8721 	max = min(max, 0x80000000ULL);
8722 
8723 	if (numentries < low_limit)
8724 		numentries = low_limit;
8725 	if (numentries > max)
8726 		numentries = max;
8727 
8728 	log2qty = ilog2(numentries);
8729 
8730 	gfp_flags = (flags & HASH_ZERO) ? GFP_ATOMIC | __GFP_ZERO : GFP_ATOMIC;
8731 	do {
8732 		virt = false;
8733 		size = bucketsize << log2qty;
8734 		if (flags & HASH_EARLY) {
8735 			if (flags & HASH_ZERO)
8736 				table = memblock_alloc(size, SMP_CACHE_BYTES);
8737 			else
8738 				table = memblock_alloc_raw(size,
8739 							   SMP_CACHE_BYTES);
8740 		} else if (get_order(size) >= MAX_ORDER || hashdist) {
8741 			table = __vmalloc(size, gfp_flags);
8742 			virt = true;
8743 			huge = is_vm_area_hugepages(table);
8744 		} else {
8745 			/*
8746 			 * If bucketsize is not a power-of-two, we may free
8747 			 * some pages at the end of hash table which
8748 			 * alloc_pages_exact() automatically does
8749 			 */
8750 			table = alloc_pages_exact(size, gfp_flags);
8751 			kmemleak_alloc(table, size, 1, gfp_flags);
8752 		}
8753 	} while (!table && size > PAGE_SIZE && --log2qty);
8754 
8755 	if (!table)
8756 		panic("Failed to allocate %s hash table\n", tablename);
8757 
8758 	pr_info("%s hash table entries: %ld (order: %d, %lu bytes, %s)\n",
8759 		tablename, 1UL << log2qty, ilog2(size) - PAGE_SHIFT, size,
8760 		virt ? (huge ? "vmalloc hugepage" : "vmalloc") : "linear");
8761 
8762 	if (_hash_shift)
8763 		*_hash_shift = log2qty;
8764 	if (_hash_mask)
8765 		*_hash_mask = (1 << log2qty) - 1;
8766 
8767 	return table;
8768 }
8769 
8770 /*
8771  * This function checks whether pageblock includes unmovable pages or not.
8772  *
8773  * PageLRU check without isolation or lru_lock could race so that
8774  * MIGRATE_MOVABLE block might include unmovable pages. And __PageMovable
8775  * check without lock_page also may miss some movable non-lru pages at
8776  * race condition. So you can't expect this function should be exact.
8777  *
8778  * Returns a page without holding a reference. If the caller wants to
8779  * dereference that page (e.g., dumping), it has to make sure that it
8780  * cannot get removed (e.g., via memory unplug) concurrently.
8781  *
8782  */
8783 struct page *has_unmovable_pages(struct zone *zone, struct page *page,
8784 				 int migratetype, int flags)
8785 {
8786 	unsigned long iter = 0;
8787 	unsigned long pfn = page_to_pfn(page);
8788 	unsigned long offset = pfn % pageblock_nr_pages;
8789 
8790 	if (is_migrate_cma_page(page)) {
8791 		/*
8792 		 * CMA allocations (alloc_contig_range) really need to mark
8793 		 * isolate CMA pageblocks even when they are not movable in fact
8794 		 * so consider them movable here.
8795 		 */
8796 		if (is_migrate_cma(migratetype))
8797 			return NULL;
8798 
8799 		return page;
8800 	}
8801 
8802 	for (; iter < pageblock_nr_pages - offset; iter++) {
8803 		page = pfn_to_page(pfn + iter);
8804 
8805 		/*
8806 		 * Both, bootmem allocations and memory holes are marked
8807 		 * PG_reserved and are unmovable. We can even have unmovable
8808 		 * allocations inside ZONE_MOVABLE, for example when
8809 		 * specifying "movablecore".
8810 		 */
8811 		if (PageReserved(page))
8812 			return page;
8813 
8814 		/*
8815 		 * If the zone is movable and we have ruled out all reserved
8816 		 * pages then it should be reasonably safe to assume the rest
8817 		 * is movable.
8818 		 */
8819 		if (zone_idx(zone) == ZONE_MOVABLE)
8820 			continue;
8821 
8822 		/*
8823 		 * Hugepages are not in LRU lists, but they're movable.
8824 		 * THPs are on the LRU, but need to be counted as #small pages.
8825 		 * We need not scan over tail pages because we don't
8826 		 * handle each tail page individually in migration.
8827 		 */
8828 		if (PageHuge(page) || PageTransCompound(page)) {
8829 			struct page *head = compound_head(page);
8830 			unsigned int skip_pages;
8831 
8832 			if (PageHuge(page)) {
8833 				if (!hugepage_migration_supported(page_hstate(head)))
8834 					return page;
8835 			} else if (!PageLRU(head) && !__PageMovable(head)) {
8836 				return page;
8837 			}
8838 
8839 			skip_pages = compound_nr(head) - (page - head);
8840 			iter += skip_pages - 1;
8841 			continue;
8842 		}
8843 
8844 		/*
8845 		 * We can't use page_count without pin a page
8846 		 * because another CPU can free compound page.
8847 		 * This check already skips compound tails of THP
8848 		 * because their page->_refcount is zero at all time.
8849 		 */
8850 		if (!page_ref_count(page)) {
8851 			if (PageBuddy(page))
8852 				iter += (1 << buddy_order(page)) - 1;
8853 			continue;
8854 		}
8855 
8856 		/*
8857 		 * The HWPoisoned page may be not in buddy system, and
8858 		 * page_count() is not 0.
8859 		 */
8860 		if ((flags & MEMORY_OFFLINE) && PageHWPoison(page))
8861 			continue;
8862 
8863 		/*
8864 		 * We treat all PageOffline() pages as movable when offlining
8865 		 * to give drivers a chance to decrement their reference count
8866 		 * in MEM_GOING_OFFLINE in order to indicate that these pages
8867 		 * can be offlined as there are no direct references anymore.
8868 		 * For actually unmovable PageOffline() where the driver does
8869 		 * not support this, we will fail later when trying to actually
8870 		 * move these pages that still have a reference count > 0.
8871 		 * (false negatives in this function only)
8872 		 */
8873 		if ((flags & MEMORY_OFFLINE) && PageOffline(page))
8874 			continue;
8875 
8876 		if (__PageMovable(page) || PageLRU(page))
8877 			continue;
8878 
8879 		/*
8880 		 * If there are RECLAIMABLE pages, we need to check
8881 		 * it.  But now, memory offline itself doesn't call
8882 		 * shrink_node_slabs() and it still to be fixed.
8883 		 */
8884 		return page;
8885 	}
8886 	return NULL;
8887 }
8888 
8889 #ifdef CONFIG_CONTIG_ALLOC
8890 static unsigned long pfn_max_align_down(unsigned long pfn)
8891 {
8892 	return pfn & ~(max_t(unsigned long, MAX_ORDER_NR_PAGES,
8893 			     pageblock_nr_pages) - 1);
8894 }
8895 
8896 static unsigned long pfn_max_align_up(unsigned long pfn)
8897 {
8898 	return ALIGN(pfn, max_t(unsigned long, MAX_ORDER_NR_PAGES,
8899 				pageblock_nr_pages));
8900 }
8901 
8902 #if defined(CONFIG_DYNAMIC_DEBUG) || \
8903 	(defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE))
8904 /* Usage: See admin-guide/dynamic-debug-howto.rst */
8905 static void alloc_contig_dump_pages(struct list_head *page_list)
8906 {
8907 	DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, "migrate failure");
8908 
8909 	if (DYNAMIC_DEBUG_BRANCH(descriptor)) {
8910 		struct page *page;
8911 
8912 		dump_stack();
8913 		list_for_each_entry(page, page_list, lru)
8914 			dump_page(page, "migration failure");
8915 	}
8916 }
8917 #else
8918 static inline void alloc_contig_dump_pages(struct list_head *page_list)
8919 {
8920 }
8921 #endif
8922 
8923 /* [start, end) must belong to a single zone. */
8924 static int __alloc_contig_migrate_range(struct compact_control *cc,
8925 					unsigned long start, unsigned long end)
8926 {
8927 	/* This function is based on compact_zone() from compaction.c. */
8928 	unsigned int nr_reclaimed;
8929 	unsigned long pfn = start;
8930 	unsigned int tries = 0;
8931 	int ret = 0;
8932 	struct migration_target_control mtc = {
8933 		.nid = zone_to_nid(cc->zone),
8934 		.gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,
8935 	};
8936 
8937 	lru_cache_disable();
8938 
8939 	while (pfn < end || !list_empty(&cc->migratepages)) {
8940 		if (fatal_signal_pending(current)) {
8941 			ret = -EINTR;
8942 			break;
8943 		}
8944 
8945 		if (list_empty(&cc->migratepages)) {
8946 			cc->nr_migratepages = 0;
8947 			ret = isolate_migratepages_range(cc, pfn, end);
8948 			if (ret && ret != -EAGAIN)
8949 				break;
8950 			pfn = cc->migrate_pfn;
8951 			tries = 0;
8952 		} else if (++tries == 5) {
8953 			ret = -EBUSY;
8954 			break;
8955 		}
8956 
8957 		nr_reclaimed = reclaim_clean_pages_from_list(cc->zone,
8958 							&cc->migratepages);
8959 		cc->nr_migratepages -= nr_reclaimed;
8960 
8961 		ret = migrate_pages(&cc->migratepages, alloc_migration_target,
8962 				NULL, (unsigned long)&mtc, cc->mode, MR_CONTIG_RANGE);
8963 
8964 		/*
8965 		 * On -ENOMEM, migrate_pages() bails out right away. It is pointless
8966 		 * to retry again over this error, so do the same here.
8967 		 */
8968 		if (ret == -ENOMEM)
8969 			break;
8970 	}
8971 
8972 	lru_cache_enable();
8973 	if (ret < 0) {
8974 		if (ret == -EBUSY)
8975 			alloc_contig_dump_pages(&cc->migratepages);
8976 		putback_movable_pages(&cc->migratepages);
8977 		return ret;
8978 	}
8979 	return 0;
8980 }
8981 
8982 /**
8983  * alloc_contig_range() -- tries to allocate given range of pages
8984  * @start:	start PFN to allocate
8985  * @end:	one-past-the-last PFN to allocate
8986  * @migratetype:	migratetype of the underlying pageblocks (either
8987  *			#MIGRATE_MOVABLE or #MIGRATE_CMA).  All pageblocks
8988  *			in range must have the same migratetype and it must
8989  *			be either of the two.
8990  * @gfp_mask:	GFP mask to use during compaction
8991  *
8992  * The PFN range does not have to be pageblock or MAX_ORDER_NR_PAGES
8993  * aligned.  The PFN range must belong to a single zone.
8994  *
8995  * The first thing this routine does is attempt to MIGRATE_ISOLATE all
8996  * pageblocks in the range.  Once isolated, the pageblocks should not
8997  * be modified by others.
8998  *
8999  * Return: zero on success or negative error code.  On success all
9000  * pages which PFN is in [start, end) are allocated for the caller and
9001  * need to be freed with free_contig_range().
9002  */
9003 int alloc_contig_range(unsigned long start, unsigned long end,
9004 		       unsigned migratetype, gfp_t gfp_mask)
9005 {
9006 	unsigned long outer_start, outer_end;
9007 	unsigned int order;
9008 	int ret = 0;
9009 
9010 	struct compact_control cc = {
9011 		.nr_migratepages = 0,
9012 		.order = -1,
9013 		.zone = page_zone(pfn_to_page(start)),
9014 		.mode = MIGRATE_SYNC,
9015 		.ignore_skip_hint = true,
9016 		.no_set_skip_hint = true,
9017 		.gfp_mask = current_gfp_context(gfp_mask),
9018 		.alloc_contig = true,
9019 	};
9020 	INIT_LIST_HEAD(&cc.migratepages);
9021 
9022 	/*
9023 	 * What we do here is we mark all pageblocks in range as
9024 	 * MIGRATE_ISOLATE.  Because pageblock and max order pages may
9025 	 * have different sizes, and due to the way page allocator
9026 	 * work, we align the range to biggest of the two pages so
9027 	 * that page allocator won't try to merge buddies from
9028 	 * different pageblocks and change MIGRATE_ISOLATE to some
9029 	 * other migration type.
9030 	 *
9031 	 * Once the pageblocks are marked as MIGRATE_ISOLATE, we
9032 	 * migrate the pages from an unaligned range (ie. pages that
9033 	 * we are interested in).  This will put all the pages in
9034 	 * range back to page allocator as MIGRATE_ISOLATE.
9035 	 *
9036 	 * When this is done, we take the pages in range from page
9037 	 * allocator removing them from the buddy system.  This way
9038 	 * page allocator will never consider using them.
9039 	 *
9040 	 * This lets us mark the pageblocks back as
9041 	 * MIGRATE_CMA/MIGRATE_MOVABLE so that free pages in the
9042 	 * aligned range but not in the unaligned, original range are
9043 	 * put back to page allocator so that buddy can use them.
9044 	 */
9045 
9046 	ret = start_isolate_page_range(pfn_max_align_down(start),
9047 				       pfn_max_align_up(end), migratetype, 0);
9048 	if (ret)
9049 		return ret;
9050 
9051 	drain_all_pages(cc.zone);
9052 
9053 	/*
9054 	 * In case of -EBUSY, we'd like to know which page causes problem.
9055 	 * So, just fall through. test_pages_isolated() has a tracepoint
9056 	 * which will report the busy page.
9057 	 *
9058 	 * It is possible that busy pages could become available before
9059 	 * the call to test_pages_isolated, and the range will actually be
9060 	 * allocated.  So, if we fall through be sure to clear ret so that
9061 	 * -EBUSY is not accidentally used or returned to caller.
9062 	 */
9063 	ret = __alloc_contig_migrate_range(&cc, start, end);
9064 	if (ret && ret != -EBUSY)
9065 		goto done;
9066 	ret = 0;
9067 
9068 	/*
9069 	 * Pages from [start, end) are within a MAX_ORDER_NR_PAGES
9070 	 * aligned blocks that are marked as MIGRATE_ISOLATE.  What's
9071 	 * more, all pages in [start, end) are free in page allocator.
9072 	 * What we are going to do is to allocate all pages from
9073 	 * [start, end) (that is remove them from page allocator).
9074 	 *
9075 	 * The only problem is that pages at the beginning and at the
9076 	 * end of interesting range may be not aligned with pages that
9077 	 * page allocator holds, ie. they can be part of higher order
9078 	 * pages.  Because of this, we reserve the bigger range and
9079 	 * once this is done free the pages we are not interested in.
9080 	 *
9081 	 * We don't have to hold zone->lock here because the pages are
9082 	 * isolated thus they won't get removed from buddy.
9083 	 */
9084 
9085 	order = 0;
9086 	outer_start = start;
9087 	while (!PageBuddy(pfn_to_page(outer_start))) {
9088 		if (++order >= MAX_ORDER) {
9089 			outer_start = start;
9090 			break;
9091 		}
9092 		outer_start &= ~0UL << order;
9093 	}
9094 
9095 	if (outer_start != start) {
9096 		order = buddy_order(pfn_to_page(outer_start));
9097 
9098 		/*
9099 		 * outer_start page could be small order buddy page and
9100 		 * it doesn't include start page. Adjust outer_start
9101 		 * in this case to report failed page properly
9102 		 * on tracepoint in test_pages_isolated()
9103 		 */
9104 		if (outer_start + (1UL << order) <= start)
9105 			outer_start = start;
9106 	}
9107 
9108 	/* Make sure the range is really isolated. */
9109 	if (test_pages_isolated(outer_start, end, 0)) {
9110 		ret = -EBUSY;
9111 		goto done;
9112 	}
9113 
9114 	/* Grab isolated pages from freelists. */
9115 	outer_end = isolate_freepages_range(&cc, outer_start, end);
9116 	if (!outer_end) {
9117 		ret = -EBUSY;
9118 		goto done;
9119 	}
9120 
9121 	/* Free head and tail (if any) */
9122 	if (start != outer_start)
9123 		free_contig_range(outer_start, start - outer_start);
9124 	if (end != outer_end)
9125 		free_contig_range(end, outer_end - end);
9126 
9127 done:
9128 	undo_isolate_page_range(pfn_max_align_down(start),
9129 				pfn_max_align_up(end), migratetype);
9130 	return ret;
9131 }
9132 EXPORT_SYMBOL(alloc_contig_range);
9133 
9134 static int __alloc_contig_pages(unsigned long start_pfn,
9135 				unsigned long nr_pages, gfp_t gfp_mask)
9136 {
9137 	unsigned long end_pfn = start_pfn + nr_pages;
9138 
9139 	return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE,
9140 				  gfp_mask);
9141 }
9142 
9143 static bool pfn_range_valid_contig(struct zone *z, unsigned long start_pfn,
9144 				   unsigned long nr_pages)
9145 {
9146 	unsigned long i, end_pfn = start_pfn + nr_pages;
9147 	struct page *page;
9148 
9149 	for (i = start_pfn; i < end_pfn; i++) {
9150 		page = pfn_to_online_page(i);
9151 		if (!page)
9152 			return false;
9153 
9154 		if (page_zone(page) != z)
9155 			return false;
9156 
9157 		if (PageReserved(page))
9158 			return false;
9159 	}
9160 	return true;
9161 }
9162 
9163 static bool zone_spans_last_pfn(const struct zone *zone,
9164 				unsigned long start_pfn, unsigned long nr_pages)
9165 {
9166 	unsigned long last_pfn = start_pfn + nr_pages - 1;
9167 
9168 	return zone_spans_pfn(zone, last_pfn);
9169 }
9170 
9171 /**
9172  * alloc_contig_pages() -- tries to find and allocate contiguous range of pages
9173  * @nr_pages:	Number of contiguous pages to allocate
9174  * @gfp_mask:	GFP mask to limit search and used during compaction
9175  * @nid:	Target node
9176  * @nodemask:	Mask for other possible nodes
9177  *
9178  * This routine is a wrapper around alloc_contig_range(). It scans over zones
9179  * on an applicable zonelist to find a contiguous pfn range which can then be
9180  * tried for allocation with alloc_contig_range(). This routine is intended
9181  * for allocation requests which can not be fulfilled with the buddy allocator.
9182  *
9183  * The allocated memory is always aligned to a page boundary. If nr_pages is a
9184  * power of two then the alignment is guaranteed to be to the given nr_pages
9185  * (e.g. 1GB request would be aligned to 1GB).
9186  *
9187  * Allocated pages can be freed with free_contig_range() or by manually calling
9188  * __free_page() on each allocated page.
9189  *
9190  * Return: pointer to contiguous pages on success, or NULL if not successful.
9191  */
9192 struct page *alloc_contig_pages(unsigned long nr_pages, gfp_t gfp_mask,
9193 				int nid, nodemask_t *nodemask)
9194 {
9195 	unsigned long ret, pfn, flags;
9196 	struct zonelist *zonelist;
9197 	struct zone *zone;
9198 	struct zoneref *z;
9199 
9200 	zonelist = node_zonelist(nid, gfp_mask);
9201 	for_each_zone_zonelist_nodemask(zone, z, zonelist,
9202 					gfp_zone(gfp_mask), nodemask) {
9203 		spin_lock_irqsave(&zone->lock, flags);
9204 
9205 		pfn = ALIGN(zone->zone_start_pfn, nr_pages);
9206 		while (zone_spans_last_pfn(zone, pfn, nr_pages)) {
9207 			if (pfn_range_valid_contig(zone, pfn, nr_pages)) {
9208 				/*
9209 				 * We release the zone lock here because
9210 				 * alloc_contig_range() will also lock the zone
9211 				 * at some point. If there's an allocation
9212 				 * spinning on this lock, it may win the race
9213 				 * and cause alloc_contig_range() to fail...
9214 				 */
9215 				spin_unlock_irqrestore(&zone->lock, flags);
9216 				ret = __alloc_contig_pages(pfn, nr_pages,
9217 							gfp_mask);
9218 				if (!ret)
9219 					return pfn_to_page(pfn);
9220 				spin_lock_irqsave(&zone->lock, flags);
9221 			}
9222 			pfn += nr_pages;
9223 		}
9224 		spin_unlock_irqrestore(&zone->lock, flags);
9225 	}
9226 	return NULL;
9227 }
9228 #endif /* CONFIG_CONTIG_ALLOC */
9229 
9230 void free_contig_range(unsigned long pfn, unsigned long nr_pages)
9231 {
9232 	unsigned long count = 0;
9233 
9234 	for (; nr_pages--; pfn++) {
9235 		struct page *page = pfn_to_page(pfn);
9236 
9237 		count += page_count(page) != 1;
9238 		__free_page(page);
9239 	}
9240 	WARN(count != 0, "%lu pages are still in use!\n", count);
9241 }
9242 EXPORT_SYMBOL(free_contig_range);
9243 
9244 /*
9245  * The zone indicated has a new number of managed_pages; batch sizes and percpu
9246  * page high values need to be recalculated.
9247  */
9248 void zone_pcp_update(struct zone *zone, int cpu_online)
9249 {
9250 	mutex_lock(&pcp_batch_high_lock);
9251 	zone_set_pageset_high_and_batch(zone, cpu_online);
9252 	mutex_unlock(&pcp_batch_high_lock);
9253 }
9254 
9255 /*
9256  * Effectively disable pcplists for the zone by setting the high limit to 0
9257  * and draining all cpus. A concurrent page freeing on another CPU that's about
9258  * to put the page on pcplist will either finish before the drain and the page
9259  * will be drained, or observe the new high limit and skip the pcplist.
9260  *
9261  * Must be paired with a call to zone_pcp_enable().
9262  */
9263 void zone_pcp_disable(struct zone *zone)
9264 {
9265 	mutex_lock(&pcp_batch_high_lock);
9266 	__zone_set_pageset_high_and_batch(zone, 0, 1);
9267 	__drain_all_pages(zone, true);
9268 }
9269 
9270 void zone_pcp_enable(struct zone *zone)
9271 {
9272 	__zone_set_pageset_high_and_batch(zone, zone->pageset_high, zone->pageset_batch);
9273 	mutex_unlock(&pcp_batch_high_lock);
9274 }
9275 
9276 void zone_pcp_reset(struct zone *zone)
9277 {
9278 	int cpu;
9279 	struct per_cpu_zonestat *pzstats;
9280 
9281 	if (zone->per_cpu_pageset != &boot_pageset) {
9282 		for_each_online_cpu(cpu) {
9283 			pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu);
9284 			drain_zonestat(zone, pzstats);
9285 		}
9286 		free_percpu(zone->per_cpu_pageset);
9287 		free_percpu(zone->per_cpu_zonestats);
9288 		zone->per_cpu_pageset = &boot_pageset;
9289 		zone->per_cpu_zonestats = &boot_zonestats;
9290 	}
9291 }
9292 
9293 #ifdef CONFIG_MEMORY_HOTREMOVE
9294 /*
9295  * All pages in the range must be in a single zone, must not contain holes,
9296  * must span full sections, and must be isolated before calling this function.
9297  */
9298 void __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
9299 {
9300 	unsigned long pfn = start_pfn;
9301 	struct page *page;
9302 	struct zone *zone;
9303 	unsigned int order;
9304 	unsigned long flags;
9305 
9306 	offline_mem_sections(pfn, end_pfn);
9307 	zone = page_zone(pfn_to_page(pfn));
9308 	spin_lock_irqsave(&zone->lock, flags);
9309 	while (pfn < end_pfn) {
9310 		page = pfn_to_page(pfn);
9311 		/*
9312 		 * The HWPoisoned page may be not in buddy system, and
9313 		 * page_count() is not 0.
9314 		 */
9315 		if (unlikely(!PageBuddy(page) && PageHWPoison(page))) {
9316 			pfn++;
9317 			continue;
9318 		}
9319 		/*
9320 		 * At this point all remaining PageOffline() pages have a
9321 		 * reference count of 0 and can simply be skipped.
9322 		 */
9323 		if (PageOffline(page)) {
9324 			BUG_ON(page_count(page));
9325 			BUG_ON(PageBuddy(page));
9326 			pfn++;
9327 			continue;
9328 		}
9329 
9330 		BUG_ON(page_count(page));
9331 		BUG_ON(!PageBuddy(page));
9332 		order = buddy_order(page);
9333 		del_page_from_free_list(page, zone, order);
9334 		pfn += (1 << order);
9335 	}
9336 	spin_unlock_irqrestore(&zone->lock, flags);
9337 }
9338 #endif
9339 
9340 bool is_free_buddy_page(struct page *page)
9341 {
9342 	struct zone *zone = page_zone(page);
9343 	unsigned long pfn = page_to_pfn(page);
9344 	unsigned long flags;
9345 	unsigned int order;
9346 
9347 	spin_lock_irqsave(&zone->lock, flags);
9348 	for (order = 0; order < MAX_ORDER; order++) {
9349 		struct page *page_head = page - (pfn & ((1 << order) - 1));
9350 
9351 		if (PageBuddy(page_head) && buddy_order(page_head) >= order)
9352 			break;
9353 	}
9354 	spin_unlock_irqrestore(&zone->lock, flags);
9355 
9356 	return order < MAX_ORDER;
9357 }
9358 
9359 #ifdef CONFIG_MEMORY_FAILURE
9360 /*
9361  * Break down a higher-order page in sub-pages, and keep our target out of
9362  * buddy allocator.
9363  */
9364 static void break_down_buddy_pages(struct zone *zone, struct page *page,
9365 				   struct page *target, int low, int high,
9366 				   int migratetype)
9367 {
9368 	unsigned long size = 1 << high;
9369 	struct page *current_buddy, *next_page;
9370 
9371 	while (high > low) {
9372 		high--;
9373 		size >>= 1;
9374 
9375 		if (target >= &page[size]) {
9376 			next_page = page + size;
9377 			current_buddy = page;
9378 		} else {
9379 			next_page = page;
9380 			current_buddy = page + size;
9381 		}
9382 
9383 		if (set_page_guard(zone, current_buddy, high, migratetype))
9384 			continue;
9385 
9386 		if (current_buddy != target) {
9387 			add_to_free_list(current_buddy, zone, high, migratetype);
9388 			set_buddy_order(current_buddy, high);
9389 			page = next_page;
9390 		}
9391 	}
9392 }
9393 
9394 /*
9395  * Take a page that will be marked as poisoned off the buddy allocator.
9396  */
9397 bool take_page_off_buddy(struct page *page)
9398 {
9399 	struct zone *zone = page_zone(page);
9400 	unsigned long pfn = page_to_pfn(page);
9401 	unsigned long flags;
9402 	unsigned int order;
9403 	bool ret = false;
9404 
9405 	spin_lock_irqsave(&zone->lock, flags);
9406 	for (order = 0; order < MAX_ORDER; order++) {
9407 		struct page *page_head = page - (pfn & ((1 << order) - 1));
9408 		int page_order = buddy_order(page_head);
9409 
9410 		if (PageBuddy(page_head) && page_order >= order) {
9411 			unsigned long pfn_head = page_to_pfn(page_head);
9412 			int migratetype = get_pfnblock_migratetype(page_head,
9413 								   pfn_head);
9414 
9415 			del_page_from_free_list(page_head, zone, page_order);
9416 			break_down_buddy_pages(zone, page_head, page, 0,
9417 						page_order, migratetype);
9418 			if (!is_migrate_isolate(migratetype))
9419 				__mod_zone_freepage_state(zone, -1, migratetype);
9420 			ret = true;
9421 			break;
9422 		}
9423 		if (page_count(page_head) > 0)
9424 			break;
9425 	}
9426 	spin_unlock_irqrestore(&zone->lock, flags);
9427 	return ret;
9428 }
9429 #endif
9430