xref: /openbmc/linux/mm/memory.c (revision 4e1a33b1)
1 /*
2  *  linux/mm/memory.c
3  *
4  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
5  */
6 
7 /*
8  * demand-loading started 01.12.91 - seems it is high on the list of
9  * things wanted, and it should be easy to implement. - Linus
10  */
11 
12 /*
13  * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
14  * pages started 02.12.91, seems to work. - Linus.
15  *
16  * Tested sharing by executing about 30 /bin/sh: under the old kernel it
17  * would have taken more than the 6M I have free, but it worked well as
18  * far as I could see.
19  *
20  * Also corrected some "invalidate()"s - I wasn't doing enough of them.
21  */
22 
23 /*
24  * Real VM (paging to/from disk) started 18.12.91. Much more work and
25  * thought has to go into this. Oh, well..
26  * 19.12.91  -  works, somewhat. Sometimes I get faults, don't know why.
27  *		Found it. Everything seems to work now.
28  * 20.12.91  -  Ok, making the swap-device changeable like the root.
29  */
30 
31 /*
32  * 05.04.94  -  Multi-page memory management added for v1.1.
33  *              Idea by Alex Bligh (alex@cconcepts.co.uk)
34  *
35  * 16.07.99  -  Support of BIGMEM added by Gerhard Wichert, Siemens AG
36  *		(Gerhard.Wichert@pdb.siemens.de)
37  *
38  * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
39  */
40 
41 #include <linux/kernel_stat.h>
42 #include <linux/mm.h>
43 #include <linux/hugetlb.h>
44 #include <linux/mman.h>
45 #include <linux/swap.h>
46 #include <linux/highmem.h>
47 #include <linux/pagemap.h>
48 #include <linux/ksm.h>
49 #include <linux/rmap.h>
50 #include <linux/export.h>
51 #include <linux/delayacct.h>
52 #include <linux/init.h>
53 #include <linux/pfn_t.h>
54 #include <linux/writeback.h>
55 #include <linux/memcontrol.h>
56 #include <linux/mmu_notifier.h>
57 #include <linux/kallsyms.h>
58 #include <linux/swapops.h>
59 #include <linux/elf.h>
60 #include <linux/gfp.h>
61 #include <linux/migrate.h>
62 #include <linux/string.h>
63 #include <linux/dma-debug.h>
64 #include <linux/debugfs.h>
65 #include <linux/userfaultfd_k.h>
66 #include <linux/dax.h>
67 
68 #include <asm/io.h>
69 #include <asm/mmu_context.h>
70 #include <asm/pgalloc.h>
71 #include <linux/uaccess.h>
72 #include <asm/tlb.h>
73 #include <asm/tlbflush.h>
74 #include <asm/pgtable.h>
75 
76 #include "internal.h"
77 
78 #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
79 #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
80 #endif
81 
82 #ifndef CONFIG_NEED_MULTIPLE_NODES
83 /* use the per-pgdat data instead for discontigmem - mbligh */
84 unsigned long max_mapnr;
85 EXPORT_SYMBOL(max_mapnr);
86 
87 struct page *mem_map;
88 EXPORT_SYMBOL(mem_map);
89 #endif
90 
91 /*
92  * A number of key systems in x86 including ioremap() rely on the assumption
93  * that high_memory defines the upper bound on direct map memory, then end
94  * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
95  * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
96  * and ZONE_HIGHMEM.
97  */
98 void *high_memory;
99 EXPORT_SYMBOL(high_memory);
100 
101 /*
102  * Randomize the address space (stacks, mmaps, brk, etc.).
103  *
104  * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
105  *   as ancient (libc5 based) binaries can segfault. )
106  */
107 int randomize_va_space __read_mostly =
108 #ifdef CONFIG_COMPAT_BRK
109 					1;
110 #else
111 					2;
112 #endif
113 
114 static int __init disable_randmaps(char *s)
115 {
116 	randomize_va_space = 0;
117 	return 1;
118 }
119 __setup("norandmaps", disable_randmaps);
120 
121 unsigned long zero_pfn __read_mostly;
122 EXPORT_SYMBOL(zero_pfn);
123 
124 unsigned long highest_memmap_pfn __read_mostly;
125 
126 /*
127  * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
128  */
129 static int __init init_zero_pfn(void)
130 {
131 	zero_pfn = page_to_pfn(ZERO_PAGE(0));
132 	return 0;
133 }
134 core_initcall(init_zero_pfn);
135 
136 
137 #if defined(SPLIT_RSS_COUNTING)
138 
139 void sync_mm_rss(struct mm_struct *mm)
140 {
141 	int i;
142 
143 	for (i = 0; i < NR_MM_COUNTERS; i++) {
144 		if (current->rss_stat.count[i]) {
145 			add_mm_counter(mm, i, current->rss_stat.count[i]);
146 			current->rss_stat.count[i] = 0;
147 		}
148 	}
149 	current->rss_stat.events = 0;
150 }
151 
152 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
153 {
154 	struct task_struct *task = current;
155 
156 	if (likely(task->mm == mm))
157 		task->rss_stat.count[member] += val;
158 	else
159 		add_mm_counter(mm, member, val);
160 }
161 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
162 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
163 
164 /* sync counter once per 64 page faults */
165 #define TASK_RSS_EVENTS_THRESH	(64)
166 static void check_sync_rss_stat(struct task_struct *task)
167 {
168 	if (unlikely(task != current))
169 		return;
170 	if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
171 		sync_mm_rss(task->mm);
172 }
173 #else /* SPLIT_RSS_COUNTING */
174 
175 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
176 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
177 
178 static void check_sync_rss_stat(struct task_struct *task)
179 {
180 }
181 
182 #endif /* SPLIT_RSS_COUNTING */
183 
184 #ifdef HAVE_GENERIC_MMU_GATHER
185 
186 static bool tlb_next_batch(struct mmu_gather *tlb)
187 {
188 	struct mmu_gather_batch *batch;
189 
190 	batch = tlb->active;
191 	if (batch->next) {
192 		tlb->active = batch->next;
193 		return true;
194 	}
195 
196 	if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
197 		return false;
198 
199 	batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
200 	if (!batch)
201 		return false;
202 
203 	tlb->batch_count++;
204 	batch->next = NULL;
205 	batch->nr   = 0;
206 	batch->max  = MAX_GATHER_BATCH;
207 
208 	tlb->active->next = batch;
209 	tlb->active = batch;
210 
211 	return true;
212 }
213 
214 /* tlb_gather_mmu
215  *	Called to initialize an (on-stack) mmu_gather structure for page-table
216  *	tear-down from @mm. The @fullmm argument is used when @mm is without
217  *	users and we're going to destroy the full address space (exit/execve).
218  */
219 void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end)
220 {
221 	tlb->mm = mm;
222 
223 	/* Is it from 0 to ~0? */
224 	tlb->fullmm     = !(start | (end+1));
225 	tlb->need_flush_all = 0;
226 	tlb->local.next = NULL;
227 	tlb->local.nr   = 0;
228 	tlb->local.max  = ARRAY_SIZE(tlb->__pages);
229 	tlb->active     = &tlb->local;
230 	tlb->batch_count = 0;
231 
232 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
233 	tlb->batch = NULL;
234 #endif
235 	tlb->page_size = 0;
236 
237 	__tlb_reset_range(tlb);
238 }
239 
240 static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
241 {
242 	if (!tlb->end)
243 		return;
244 
245 	tlb_flush(tlb);
246 	mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);
247 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
248 	tlb_table_flush(tlb);
249 #endif
250 	__tlb_reset_range(tlb);
251 }
252 
253 static void tlb_flush_mmu_free(struct mmu_gather *tlb)
254 {
255 	struct mmu_gather_batch *batch;
256 
257 	for (batch = &tlb->local; batch && batch->nr; batch = batch->next) {
258 		free_pages_and_swap_cache(batch->pages, batch->nr);
259 		batch->nr = 0;
260 	}
261 	tlb->active = &tlb->local;
262 }
263 
264 void tlb_flush_mmu(struct mmu_gather *tlb)
265 {
266 	tlb_flush_mmu_tlbonly(tlb);
267 	tlb_flush_mmu_free(tlb);
268 }
269 
270 /* tlb_finish_mmu
271  *	Called at the end of the shootdown operation to free up any resources
272  *	that were required.
273  */
274 void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
275 {
276 	struct mmu_gather_batch *batch, *next;
277 
278 	tlb_flush_mmu(tlb);
279 
280 	/* keep the page table cache within bounds */
281 	check_pgt_cache();
282 
283 	for (batch = tlb->local.next; batch; batch = next) {
284 		next = batch->next;
285 		free_pages((unsigned long)batch, 0);
286 	}
287 	tlb->local.next = NULL;
288 }
289 
290 /* __tlb_remove_page
291  *	Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
292  *	handling the additional races in SMP caused by other CPUs caching valid
293  *	mappings in their TLBs. Returns the number of free page slots left.
294  *	When out of page slots we must call tlb_flush_mmu().
295  *returns true if the caller should flush.
296  */
297 bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, int page_size)
298 {
299 	struct mmu_gather_batch *batch;
300 
301 	VM_BUG_ON(!tlb->end);
302 	VM_WARN_ON(tlb->page_size != page_size);
303 
304 	batch = tlb->active;
305 	/*
306 	 * Add the page and check if we are full. If so
307 	 * force a flush.
308 	 */
309 	batch->pages[batch->nr++] = page;
310 	if (batch->nr == batch->max) {
311 		if (!tlb_next_batch(tlb))
312 			return true;
313 		batch = tlb->active;
314 	}
315 	VM_BUG_ON_PAGE(batch->nr > batch->max, page);
316 
317 	return false;
318 }
319 
320 #endif /* HAVE_GENERIC_MMU_GATHER */
321 
322 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
323 
324 /*
325  * See the comment near struct mmu_table_batch.
326  */
327 
328 static void tlb_remove_table_smp_sync(void *arg)
329 {
330 	/* Simply deliver the interrupt */
331 }
332 
333 static void tlb_remove_table_one(void *table)
334 {
335 	/*
336 	 * This isn't an RCU grace period and hence the page-tables cannot be
337 	 * assumed to be actually RCU-freed.
338 	 *
339 	 * It is however sufficient for software page-table walkers that rely on
340 	 * IRQ disabling. See the comment near struct mmu_table_batch.
341 	 */
342 	smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
343 	__tlb_remove_table(table);
344 }
345 
346 static void tlb_remove_table_rcu(struct rcu_head *head)
347 {
348 	struct mmu_table_batch *batch;
349 	int i;
350 
351 	batch = container_of(head, struct mmu_table_batch, rcu);
352 
353 	for (i = 0; i < batch->nr; i++)
354 		__tlb_remove_table(batch->tables[i]);
355 
356 	free_page((unsigned long)batch);
357 }
358 
359 void tlb_table_flush(struct mmu_gather *tlb)
360 {
361 	struct mmu_table_batch **batch = &tlb->batch;
362 
363 	if (*batch) {
364 		call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
365 		*batch = NULL;
366 	}
367 }
368 
369 void tlb_remove_table(struct mmu_gather *tlb, void *table)
370 {
371 	struct mmu_table_batch **batch = &tlb->batch;
372 
373 	/*
374 	 * When there's less then two users of this mm there cannot be a
375 	 * concurrent page-table walk.
376 	 */
377 	if (atomic_read(&tlb->mm->mm_users) < 2) {
378 		__tlb_remove_table(table);
379 		return;
380 	}
381 
382 	if (*batch == NULL) {
383 		*batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
384 		if (*batch == NULL) {
385 			tlb_remove_table_one(table);
386 			return;
387 		}
388 		(*batch)->nr = 0;
389 	}
390 	(*batch)->tables[(*batch)->nr++] = table;
391 	if ((*batch)->nr == MAX_TABLE_BATCH)
392 		tlb_table_flush(tlb);
393 }
394 
395 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */
396 
397 /*
398  * Note: this doesn't free the actual pages themselves. That
399  * has been handled earlier when unmapping all the memory regions.
400  */
401 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
402 			   unsigned long addr)
403 {
404 	pgtable_t token = pmd_pgtable(*pmd);
405 	pmd_clear(pmd);
406 	pte_free_tlb(tlb, token, addr);
407 	atomic_long_dec(&tlb->mm->nr_ptes);
408 }
409 
410 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
411 				unsigned long addr, unsigned long end,
412 				unsigned long floor, unsigned long ceiling)
413 {
414 	pmd_t *pmd;
415 	unsigned long next;
416 	unsigned long start;
417 
418 	start = addr;
419 	pmd = pmd_offset(pud, addr);
420 	do {
421 		next = pmd_addr_end(addr, end);
422 		if (pmd_none_or_clear_bad(pmd))
423 			continue;
424 		free_pte_range(tlb, pmd, addr);
425 	} while (pmd++, addr = next, addr != end);
426 
427 	start &= PUD_MASK;
428 	if (start < floor)
429 		return;
430 	if (ceiling) {
431 		ceiling &= PUD_MASK;
432 		if (!ceiling)
433 			return;
434 	}
435 	if (end - 1 > ceiling - 1)
436 		return;
437 
438 	pmd = pmd_offset(pud, start);
439 	pud_clear(pud);
440 	pmd_free_tlb(tlb, pmd, start);
441 	mm_dec_nr_pmds(tlb->mm);
442 }
443 
444 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
445 				unsigned long addr, unsigned long end,
446 				unsigned long floor, unsigned long ceiling)
447 {
448 	pud_t *pud;
449 	unsigned long next;
450 	unsigned long start;
451 
452 	start = addr;
453 	pud = pud_offset(pgd, addr);
454 	do {
455 		next = pud_addr_end(addr, end);
456 		if (pud_none_or_clear_bad(pud))
457 			continue;
458 		free_pmd_range(tlb, pud, addr, next, floor, ceiling);
459 	} while (pud++, addr = next, addr != end);
460 
461 	start &= PGDIR_MASK;
462 	if (start < floor)
463 		return;
464 	if (ceiling) {
465 		ceiling &= PGDIR_MASK;
466 		if (!ceiling)
467 			return;
468 	}
469 	if (end - 1 > ceiling - 1)
470 		return;
471 
472 	pud = pud_offset(pgd, start);
473 	pgd_clear(pgd);
474 	pud_free_tlb(tlb, pud, start);
475 }
476 
477 /*
478  * This function frees user-level page tables of a process.
479  */
480 void free_pgd_range(struct mmu_gather *tlb,
481 			unsigned long addr, unsigned long end,
482 			unsigned long floor, unsigned long ceiling)
483 {
484 	pgd_t *pgd;
485 	unsigned long next;
486 
487 	/*
488 	 * The next few lines have given us lots of grief...
489 	 *
490 	 * Why are we testing PMD* at this top level?  Because often
491 	 * there will be no work to do at all, and we'd prefer not to
492 	 * go all the way down to the bottom just to discover that.
493 	 *
494 	 * Why all these "- 1"s?  Because 0 represents both the bottom
495 	 * of the address space and the top of it (using -1 for the
496 	 * top wouldn't help much: the masks would do the wrong thing).
497 	 * The rule is that addr 0 and floor 0 refer to the bottom of
498 	 * the address space, but end 0 and ceiling 0 refer to the top
499 	 * Comparisons need to use "end - 1" and "ceiling - 1" (though
500 	 * that end 0 case should be mythical).
501 	 *
502 	 * Wherever addr is brought up or ceiling brought down, we must
503 	 * be careful to reject "the opposite 0" before it confuses the
504 	 * subsequent tests.  But what about where end is brought down
505 	 * by PMD_SIZE below? no, end can't go down to 0 there.
506 	 *
507 	 * Whereas we round start (addr) and ceiling down, by different
508 	 * masks at different levels, in order to test whether a table
509 	 * now has no other vmas using it, so can be freed, we don't
510 	 * bother to round floor or end up - the tests don't need that.
511 	 */
512 
513 	addr &= PMD_MASK;
514 	if (addr < floor) {
515 		addr += PMD_SIZE;
516 		if (!addr)
517 			return;
518 	}
519 	if (ceiling) {
520 		ceiling &= PMD_MASK;
521 		if (!ceiling)
522 			return;
523 	}
524 	if (end - 1 > ceiling - 1)
525 		end -= PMD_SIZE;
526 	if (addr > end - 1)
527 		return;
528 	/*
529 	 * We add page table cache pages with PAGE_SIZE,
530 	 * (see pte_free_tlb()), flush the tlb if we need
531 	 */
532 	tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
533 	pgd = pgd_offset(tlb->mm, addr);
534 	do {
535 		next = pgd_addr_end(addr, end);
536 		if (pgd_none_or_clear_bad(pgd))
537 			continue;
538 		free_pud_range(tlb, pgd, addr, next, floor, ceiling);
539 	} while (pgd++, addr = next, addr != end);
540 }
541 
542 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
543 		unsigned long floor, unsigned long ceiling)
544 {
545 	while (vma) {
546 		struct vm_area_struct *next = vma->vm_next;
547 		unsigned long addr = vma->vm_start;
548 
549 		/*
550 		 * Hide vma from rmap and truncate_pagecache before freeing
551 		 * pgtables
552 		 */
553 		unlink_anon_vmas(vma);
554 		unlink_file_vma(vma);
555 
556 		if (is_vm_hugetlb_page(vma)) {
557 			hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
558 				floor, next ? next->vm_start : ceiling);
559 		} else {
560 			/*
561 			 * Optimization: gather nearby vmas into one call down
562 			 */
563 			while (next && next->vm_start <= vma->vm_end + PMD_SIZE
564 			       && !is_vm_hugetlb_page(next)) {
565 				vma = next;
566 				next = vma->vm_next;
567 				unlink_anon_vmas(vma);
568 				unlink_file_vma(vma);
569 			}
570 			free_pgd_range(tlb, addr, vma->vm_end,
571 				floor, next ? next->vm_start : ceiling);
572 		}
573 		vma = next;
574 	}
575 }
576 
577 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
578 {
579 	spinlock_t *ptl;
580 	pgtable_t new = pte_alloc_one(mm, address);
581 	if (!new)
582 		return -ENOMEM;
583 
584 	/*
585 	 * Ensure all pte setup (eg. pte page lock and page clearing) are
586 	 * visible before the pte is made visible to other CPUs by being
587 	 * put into page tables.
588 	 *
589 	 * The other side of the story is the pointer chasing in the page
590 	 * table walking code (when walking the page table without locking;
591 	 * ie. most of the time). Fortunately, these data accesses consist
592 	 * of a chain of data-dependent loads, meaning most CPUs (alpha
593 	 * being the notable exception) will already guarantee loads are
594 	 * seen in-order. See the alpha page table accessors for the
595 	 * smp_read_barrier_depends() barriers in page table walking code.
596 	 */
597 	smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
598 
599 	ptl = pmd_lock(mm, pmd);
600 	if (likely(pmd_none(*pmd))) {	/* Has another populated it ? */
601 		atomic_long_inc(&mm->nr_ptes);
602 		pmd_populate(mm, pmd, new);
603 		new = NULL;
604 	}
605 	spin_unlock(ptl);
606 	if (new)
607 		pte_free(mm, new);
608 	return 0;
609 }
610 
611 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
612 {
613 	pte_t *new = pte_alloc_one_kernel(&init_mm, address);
614 	if (!new)
615 		return -ENOMEM;
616 
617 	smp_wmb(); /* See comment in __pte_alloc */
618 
619 	spin_lock(&init_mm.page_table_lock);
620 	if (likely(pmd_none(*pmd))) {	/* Has another populated it ? */
621 		pmd_populate_kernel(&init_mm, pmd, new);
622 		new = NULL;
623 	}
624 	spin_unlock(&init_mm.page_table_lock);
625 	if (new)
626 		pte_free_kernel(&init_mm, new);
627 	return 0;
628 }
629 
630 static inline void init_rss_vec(int *rss)
631 {
632 	memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
633 }
634 
635 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
636 {
637 	int i;
638 
639 	if (current->mm == mm)
640 		sync_mm_rss(mm);
641 	for (i = 0; i < NR_MM_COUNTERS; i++)
642 		if (rss[i])
643 			add_mm_counter(mm, i, rss[i]);
644 }
645 
646 /*
647  * This function is called to print an error when a bad pte
648  * is found. For example, we might have a PFN-mapped pte in
649  * a region that doesn't allow it.
650  *
651  * The calling function must still handle the error.
652  */
653 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
654 			  pte_t pte, struct page *page)
655 {
656 	pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
657 	pud_t *pud = pud_offset(pgd, addr);
658 	pmd_t *pmd = pmd_offset(pud, addr);
659 	struct address_space *mapping;
660 	pgoff_t index;
661 	static unsigned long resume;
662 	static unsigned long nr_shown;
663 	static unsigned long nr_unshown;
664 
665 	/*
666 	 * Allow a burst of 60 reports, then keep quiet for that minute;
667 	 * or allow a steady drip of one report per second.
668 	 */
669 	if (nr_shown == 60) {
670 		if (time_before(jiffies, resume)) {
671 			nr_unshown++;
672 			return;
673 		}
674 		if (nr_unshown) {
675 			pr_alert("BUG: Bad page map: %lu messages suppressed\n",
676 				 nr_unshown);
677 			nr_unshown = 0;
678 		}
679 		nr_shown = 0;
680 	}
681 	if (nr_shown++ == 0)
682 		resume = jiffies + 60 * HZ;
683 
684 	mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
685 	index = linear_page_index(vma, addr);
686 
687 	pr_alert("BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
688 		 current->comm,
689 		 (long long)pte_val(pte), (long long)pmd_val(*pmd));
690 	if (page)
691 		dump_page(page, "bad pte");
692 	pr_alert("addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
693 		 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
694 	/*
695 	 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
696 	 */
697 	pr_alert("file:%pD fault:%pf mmap:%pf readpage:%pf\n",
698 		 vma->vm_file,
699 		 vma->vm_ops ? vma->vm_ops->fault : NULL,
700 		 vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
701 		 mapping ? mapping->a_ops->readpage : NULL);
702 	dump_stack();
703 	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
704 }
705 
706 /*
707  * vm_normal_page -- This function gets the "struct page" associated with a pte.
708  *
709  * "Special" mappings do not wish to be associated with a "struct page" (either
710  * it doesn't exist, or it exists but they don't want to touch it). In this
711  * case, NULL is returned here. "Normal" mappings do have a struct page.
712  *
713  * There are 2 broad cases. Firstly, an architecture may define a pte_special()
714  * pte bit, in which case this function is trivial. Secondly, an architecture
715  * may not have a spare pte bit, which requires a more complicated scheme,
716  * described below.
717  *
718  * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
719  * special mapping (even if there are underlying and valid "struct pages").
720  * COWed pages of a VM_PFNMAP are always normal.
721  *
722  * The way we recognize COWed pages within VM_PFNMAP mappings is through the
723  * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
724  * set, and the vm_pgoff will point to the first PFN mapped: thus every special
725  * mapping will always honor the rule
726  *
727  *	pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
728  *
729  * And for normal mappings this is false.
730  *
731  * This restricts such mappings to be a linear translation from virtual address
732  * to pfn. To get around this restriction, we allow arbitrary mappings so long
733  * as the vma is not a COW mapping; in that case, we know that all ptes are
734  * special (because none can have been COWed).
735  *
736  *
737  * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
738  *
739  * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
740  * page" backing, however the difference is that _all_ pages with a struct
741  * page (that is, those where pfn_valid is true) are refcounted and considered
742  * normal pages by the VM. The disadvantage is that pages are refcounted
743  * (which can be slower and simply not an option for some PFNMAP users). The
744  * advantage is that we don't have to follow the strict linearity rule of
745  * PFNMAP mappings in order to support COWable mappings.
746  *
747  */
748 #ifdef __HAVE_ARCH_PTE_SPECIAL
749 # define HAVE_PTE_SPECIAL 1
750 #else
751 # define HAVE_PTE_SPECIAL 0
752 #endif
753 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
754 				pte_t pte)
755 {
756 	unsigned long pfn = pte_pfn(pte);
757 
758 	if (HAVE_PTE_SPECIAL) {
759 		if (likely(!pte_special(pte)))
760 			goto check_pfn;
761 		if (vma->vm_ops && vma->vm_ops->find_special_page)
762 			return vma->vm_ops->find_special_page(vma, addr);
763 		if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
764 			return NULL;
765 		if (!is_zero_pfn(pfn))
766 			print_bad_pte(vma, addr, pte, NULL);
767 		return NULL;
768 	}
769 
770 	/* !HAVE_PTE_SPECIAL case follows: */
771 
772 	if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
773 		if (vma->vm_flags & VM_MIXEDMAP) {
774 			if (!pfn_valid(pfn))
775 				return NULL;
776 			goto out;
777 		} else {
778 			unsigned long off;
779 			off = (addr - vma->vm_start) >> PAGE_SHIFT;
780 			if (pfn == vma->vm_pgoff + off)
781 				return NULL;
782 			if (!is_cow_mapping(vma->vm_flags))
783 				return NULL;
784 		}
785 	}
786 
787 	if (is_zero_pfn(pfn))
788 		return NULL;
789 check_pfn:
790 	if (unlikely(pfn > highest_memmap_pfn)) {
791 		print_bad_pte(vma, addr, pte, NULL);
792 		return NULL;
793 	}
794 
795 	/*
796 	 * NOTE! We still have PageReserved() pages in the page tables.
797 	 * eg. VDSO mappings can cause them to exist.
798 	 */
799 out:
800 	return pfn_to_page(pfn);
801 }
802 
803 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
804 struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
805 				pmd_t pmd)
806 {
807 	unsigned long pfn = pmd_pfn(pmd);
808 
809 	/*
810 	 * There is no pmd_special() but there may be special pmds, e.g.
811 	 * in a direct-access (dax) mapping, so let's just replicate the
812 	 * !HAVE_PTE_SPECIAL case from vm_normal_page() here.
813 	 */
814 	if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
815 		if (vma->vm_flags & VM_MIXEDMAP) {
816 			if (!pfn_valid(pfn))
817 				return NULL;
818 			goto out;
819 		} else {
820 			unsigned long off;
821 			off = (addr - vma->vm_start) >> PAGE_SHIFT;
822 			if (pfn == vma->vm_pgoff + off)
823 				return NULL;
824 			if (!is_cow_mapping(vma->vm_flags))
825 				return NULL;
826 		}
827 	}
828 
829 	if (is_zero_pfn(pfn))
830 		return NULL;
831 	if (unlikely(pfn > highest_memmap_pfn))
832 		return NULL;
833 
834 	/*
835 	 * NOTE! We still have PageReserved() pages in the page tables.
836 	 * eg. VDSO mappings can cause them to exist.
837 	 */
838 out:
839 	return pfn_to_page(pfn);
840 }
841 #endif
842 
843 /*
844  * copy one vm_area from one task to the other. Assumes the page tables
845  * already present in the new task to be cleared in the whole range
846  * covered by this vma.
847  */
848 
849 static inline unsigned long
850 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
851 		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
852 		unsigned long addr, int *rss)
853 {
854 	unsigned long vm_flags = vma->vm_flags;
855 	pte_t pte = *src_pte;
856 	struct page *page;
857 
858 	/* pte contains position in swap or file, so copy. */
859 	if (unlikely(!pte_present(pte))) {
860 		swp_entry_t entry = pte_to_swp_entry(pte);
861 
862 		if (likely(!non_swap_entry(entry))) {
863 			if (swap_duplicate(entry) < 0)
864 				return entry.val;
865 
866 			/* make sure dst_mm is on swapoff's mmlist. */
867 			if (unlikely(list_empty(&dst_mm->mmlist))) {
868 				spin_lock(&mmlist_lock);
869 				if (list_empty(&dst_mm->mmlist))
870 					list_add(&dst_mm->mmlist,
871 							&src_mm->mmlist);
872 				spin_unlock(&mmlist_lock);
873 			}
874 			rss[MM_SWAPENTS]++;
875 		} else if (is_migration_entry(entry)) {
876 			page = migration_entry_to_page(entry);
877 
878 			rss[mm_counter(page)]++;
879 
880 			if (is_write_migration_entry(entry) &&
881 					is_cow_mapping(vm_flags)) {
882 				/*
883 				 * COW mappings require pages in both
884 				 * parent and child to be set to read.
885 				 */
886 				make_migration_entry_read(&entry);
887 				pte = swp_entry_to_pte(entry);
888 				if (pte_swp_soft_dirty(*src_pte))
889 					pte = pte_swp_mksoft_dirty(pte);
890 				set_pte_at(src_mm, addr, src_pte, pte);
891 			}
892 		}
893 		goto out_set_pte;
894 	}
895 
896 	/*
897 	 * If it's a COW mapping, write protect it both
898 	 * in the parent and the child
899 	 */
900 	if (is_cow_mapping(vm_flags)) {
901 		ptep_set_wrprotect(src_mm, addr, src_pte);
902 		pte = pte_wrprotect(pte);
903 	}
904 
905 	/*
906 	 * If it's a shared mapping, mark it clean in
907 	 * the child
908 	 */
909 	if (vm_flags & VM_SHARED)
910 		pte = pte_mkclean(pte);
911 	pte = pte_mkold(pte);
912 
913 	page = vm_normal_page(vma, addr, pte);
914 	if (page) {
915 		get_page(page);
916 		page_dup_rmap(page, false);
917 		rss[mm_counter(page)]++;
918 	}
919 
920 out_set_pte:
921 	set_pte_at(dst_mm, addr, dst_pte, pte);
922 	return 0;
923 }
924 
925 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
926 		   pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
927 		   unsigned long addr, unsigned long end)
928 {
929 	pte_t *orig_src_pte, *orig_dst_pte;
930 	pte_t *src_pte, *dst_pte;
931 	spinlock_t *src_ptl, *dst_ptl;
932 	int progress = 0;
933 	int rss[NR_MM_COUNTERS];
934 	swp_entry_t entry = (swp_entry_t){0};
935 
936 again:
937 	init_rss_vec(rss);
938 
939 	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
940 	if (!dst_pte)
941 		return -ENOMEM;
942 	src_pte = pte_offset_map(src_pmd, addr);
943 	src_ptl = pte_lockptr(src_mm, src_pmd);
944 	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
945 	orig_src_pte = src_pte;
946 	orig_dst_pte = dst_pte;
947 	arch_enter_lazy_mmu_mode();
948 
949 	do {
950 		/*
951 		 * We are holding two locks at this point - either of them
952 		 * could generate latencies in another task on another CPU.
953 		 */
954 		if (progress >= 32) {
955 			progress = 0;
956 			if (need_resched() ||
957 			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
958 				break;
959 		}
960 		if (pte_none(*src_pte)) {
961 			progress++;
962 			continue;
963 		}
964 		entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
965 							vma, addr, rss);
966 		if (entry.val)
967 			break;
968 		progress += 8;
969 	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
970 
971 	arch_leave_lazy_mmu_mode();
972 	spin_unlock(src_ptl);
973 	pte_unmap(orig_src_pte);
974 	add_mm_rss_vec(dst_mm, rss);
975 	pte_unmap_unlock(orig_dst_pte, dst_ptl);
976 	cond_resched();
977 
978 	if (entry.val) {
979 		if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
980 			return -ENOMEM;
981 		progress = 0;
982 	}
983 	if (addr != end)
984 		goto again;
985 	return 0;
986 }
987 
988 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
989 		pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
990 		unsigned long addr, unsigned long end)
991 {
992 	pmd_t *src_pmd, *dst_pmd;
993 	unsigned long next;
994 
995 	dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
996 	if (!dst_pmd)
997 		return -ENOMEM;
998 	src_pmd = pmd_offset(src_pud, addr);
999 	do {
1000 		next = pmd_addr_end(addr, end);
1001 		if (pmd_trans_huge(*src_pmd) || pmd_devmap(*src_pmd)) {
1002 			int err;
1003 			VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, vma);
1004 			err = copy_huge_pmd(dst_mm, src_mm,
1005 					    dst_pmd, src_pmd, addr, vma);
1006 			if (err == -ENOMEM)
1007 				return -ENOMEM;
1008 			if (!err)
1009 				continue;
1010 			/* fall through */
1011 		}
1012 		if (pmd_none_or_clear_bad(src_pmd))
1013 			continue;
1014 		if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
1015 						vma, addr, next))
1016 			return -ENOMEM;
1017 	} while (dst_pmd++, src_pmd++, addr = next, addr != end);
1018 	return 0;
1019 }
1020 
1021 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1022 		pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
1023 		unsigned long addr, unsigned long end)
1024 {
1025 	pud_t *src_pud, *dst_pud;
1026 	unsigned long next;
1027 
1028 	dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
1029 	if (!dst_pud)
1030 		return -ENOMEM;
1031 	src_pud = pud_offset(src_pgd, addr);
1032 	do {
1033 		next = pud_addr_end(addr, end);
1034 		if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
1035 			int err;
1036 
1037 			VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, vma);
1038 			err = copy_huge_pud(dst_mm, src_mm,
1039 					    dst_pud, src_pud, addr, vma);
1040 			if (err == -ENOMEM)
1041 				return -ENOMEM;
1042 			if (!err)
1043 				continue;
1044 			/* fall through */
1045 		}
1046 		if (pud_none_or_clear_bad(src_pud))
1047 			continue;
1048 		if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1049 						vma, addr, next))
1050 			return -ENOMEM;
1051 	} while (dst_pud++, src_pud++, addr = next, addr != end);
1052 	return 0;
1053 }
1054 
1055 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1056 		struct vm_area_struct *vma)
1057 {
1058 	pgd_t *src_pgd, *dst_pgd;
1059 	unsigned long next;
1060 	unsigned long addr = vma->vm_start;
1061 	unsigned long end = vma->vm_end;
1062 	unsigned long mmun_start;	/* For mmu_notifiers */
1063 	unsigned long mmun_end;		/* For mmu_notifiers */
1064 	bool is_cow;
1065 	int ret;
1066 
1067 	/*
1068 	 * Don't copy ptes where a page fault will fill them correctly.
1069 	 * Fork becomes much lighter when there are big shared or private
1070 	 * readonly mappings. The tradeoff is that copy_page_range is more
1071 	 * efficient than faulting.
1072 	 */
1073 	if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
1074 			!vma->anon_vma)
1075 		return 0;
1076 
1077 	if (is_vm_hugetlb_page(vma))
1078 		return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1079 
1080 	if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1081 		/*
1082 		 * We do not free on error cases below as remove_vma
1083 		 * gets called on error from higher level routine
1084 		 */
1085 		ret = track_pfn_copy(vma);
1086 		if (ret)
1087 			return ret;
1088 	}
1089 
1090 	/*
1091 	 * We need to invalidate the secondary MMU mappings only when
1092 	 * there could be a permission downgrade on the ptes of the
1093 	 * parent mm. And a permission downgrade will only happen if
1094 	 * is_cow_mapping() returns true.
1095 	 */
1096 	is_cow = is_cow_mapping(vma->vm_flags);
1097 	mmun_start = addr;
1098 	mmun_end   = end;
1099 	if (is_cow)
1100 		mmu_notifier_invalidate_range_start(src_mm, mmun_start,
1101 						    mmun_end);
1102 
1103 	ret = 0;
1104 	dst_pgd = pgd_offset(dst_mm, addr);
1105 	src_pgd = pgd_offset(src_mm, addr);
1106 	do {
1107 		next = pgd_addr_end(addr, end);
1108 		if (pgd_none_or_clear_bad(src_pgd))
1109 			continue;
1110 		if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
1111 					    vma, addr, next))) {
1112 			ret = -ENOMEM;
1113 			break;
1114 		}
1115 	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
1116 
1117 	if (is_cow)
1118 		mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
1119 	return ret;
1120 }
1121 
1122 static unsigned long zap_pte_range(struct mmu_gather *tlb,
1123 				struct vm_area_struct *vma, pmd_t *pmd,
1124 				unsigned long addr, unsigned long end,
1125 				struct zap_details *details)
1126 {
1127 	struct mm_struct *mm = tlb->mm;
1128 	int force_flush = 0;
1129 	int rss[NR_MM_COUNTERS];
1130 	spinlock_t *ptl;
1131 	pte_t *start_pte;
1132 	pte_t *pte;
1133 	swp_entry_t entry;
1134 
1135 	tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
1136 again:
1137 	init_rss_vec(rss);
1138 	start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1139 	pte = start_pte;
1140 	arch_enter_lazy_mmu_mode();
1141 	do {
1142 		pte_t ptent = *pte;
1143 		if (pte_none(ptent))
1144 			continue;
1145 
1146 		if (pte_present(ptent)) {
1147 			struct page *page;
1148 
1149 			page = vm_normal_page(vma, addr, ptent);
1150 			if (unlikely(details) && page) {
1151 				/*
1152 				 * unmap_shared_mapping_pages() wants to
1153 				 * invalidate cache without truncating:
1154 				 * unmap shared but keep private pages.
1155 				 */
1156 				if (details->check_mapping &&
1157 				    details->check_mapping != page_rmapping(page))
1158 					continue;
1159 			}
1160 			ptent = ptep_get_and_clear_full(mm, addr, pte,
1161 							tlb->fullmm);
1162 			tlb_remove_tlb_entry(tlb, pte, addr);
1163 			if (unlikely(!page))
1164 				continue;
1165 
1166 			if (!PageAnon(page)) {
1167 				if (pte_dirty(ptent)) {
1168 					force_flush = 1;
1169 					set_page_dirty(page);
1170 				}
1171 				if (pte_young(ptent) &&
1172 				    likely(!(vma->vm_flags & VM_SEQ_READ)))
1173 					mark_page_accessed(page);
1174 			}
1175 			rss[mm_counter(page)]--;
1176 			page_remove_rmap(page, false);
1177 			if (unlikely(page_mapcount(page) < 0))
1178 				print_bad_pte(vma, addr, ptent, page);
1179 			if (unlikely(__tlb_remove_page(tlb, page))) {
1180 				force_flush = 1;
1181 				addr += PAGE_SIZE;
1182 				break;
1183 			}
1184 			continue;
1185 		}
1186 		/* If details->check_mapping, we leave swap entries. */
1187 		if (unlikely(details))
1188 			continue;
1189 
1190 		entry = pte_to_swp_entry(ptent);
1191 		if (!non_swap_entry(entry))
1192 			rss[MM_SWAPENTS]--;
1193 		else if (is_migration_entry(entry)) {
1194 			struct page *page;
1195 
1196 			page = migration_entry_to_page(entry);
1197 			rss[mm_counter(page)]--;
1198 		}
1199 		if (unlikely(!free_swap_and_cache(entry)))
1200 			print_bad_pte(vma, addr, ptent, NULL);
1201 		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1202 	} while (pte++, addr += PAGE_SIZE, addr != end);
1203 
1204 	add_mm_rss_vec(mm, rss);
1205 	arch_leave_lazy_mmu_mode();
1206 
1207 	/* Do the actual TLB flush before dropping ptl */
1208 	if (force_flush)
1209 		tlb_flush_mmu_tlbonly(tlb);
1210 	pte_unmap_unlock(start_pte, ptl);
1211 
1212 	/*
1213 	 * If we forced a TLB flush (either due to running out of
1214 	 * batch buffers or because we needed to flush dirty TLB
1215 	 * entries before releasing the ptl), free the batched
1216 	 * memory too. Restart if we didn't do everything.
1217 	 */
1218 	if (force_flush) {
1219 		force_flush = 0;
1220 		tlb_flush_mmu_free(tlb);
1221 		if (addr != end)
1222 			goto again;
1223 	}
1224 
1225 	return addr;
1226 }
1227 
1228 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1229 				struct vm_area_struct *vma, pud_t *pud,
1230 				unsigned long addr, unsigned long end,
1231 				struct zap_details *details)
1232 {
1233 	pmd_t *pmd;
1234 	unsigned long next;
1235 
1236 	pmd = pmd_offset(pud, addr);
1237 	do {
1238 		next = pmd_addr_end(addr, end);
1239 		if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1240 			if (next - addr != HPAGE_PMD_SIZE) {
1241 				VM_BUG_ON_VMA(vma_is_anonymous(vma) &&
1242 				    !rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1243 				__split_huge_pmd(vma, pmd, addr, false, NULL);
1244 			} else if (zap_huge_pmd(tlb, vma, pmd, addr))
1245 				goto next;
1246 			/* fall through */
1247 		}
1248 		/*
1249 		 * Here there can be other concurrent MADV_DONTNEED or
1250 		 * trans huge page faults running, and if the pmd is
1251 		 * none or trans huge it can change under us. This is
1252 		 * because MADV_DONTNEED holds the mmap_sem in read
1253 		 * mode.
1254 		 */
1255 		if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1256 			goto next;
1257 		next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1258 next:
1259 		cond_resched();
1260 	} while (pmd++, addr = next, addr != end);
1261 
1262 	return addr;
1263 }
1264 
1265 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1266 				struct vm_area_struct *vma, pgd_t *pgd,
1267 				unsigned long addr, unsigned long end,
1268 				struct zap_details *details)
1269 {
1270 	pud_t *pud;
1271 	unsigned long next;
1272 
1273 	pud = pud_offset(pgd, addr);
1274 	do {
1275 		next = pud_addr_end(addr, end);
1276 		if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
1277 			if (next - addr != HPAGE_PUD_SIZE) {
1278 				VM_BUG_ON_VMA(!rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1279 				split_huge_pud(vma, pud, addr);
1280 			} else if (zap_huge_pud(tlb, vma, pud, addr))
1281 				goto next;
1282 			/* fall through */
1283 		}
1284 		if (pud_none_or_clear_bad(pud))
1285 			continue;
1286 		next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1287 next:
1288 		cond_resched();
1289 	} while (pud++, addr = next, addr != end);
1290 
1291 	return addr;
1292 }
1293 
1294 void unmap_page_range(struct mmu_gather *tlb,
1295 			     struct vm_area_struct *vma,
1296 			     unsigned long addr, unsigned long end,
1297 			     struct zap_details *details)
1298 {
1299 	pgd_t *pgd;
1300 	unsigned long next;
1301 
1302 	BUG_ON(addr >= end);
1303 	tlb_start_vma(tlb, vma);
1304 	pgd = pgd_offset(vma->vm_mm, addr);
1305 	do {
1306 		next = pgd_addr_end(addr, end);
1307 		if (pgd_none_or_clear_bad(pgd))
1308 			continue;
1309 		next = zap_pud_range(tlb, vma, pgd, addr, next, details);
1310 	} while (pgd++, addr = next, addr != end);
1311 	tlb_end_vma(tlb, vma);
1312 }
1313 
1314 
1315 static void unmap_single_vma(struct mmu_gather *tlb,
1316 		struct vm_area_struct *vma, unsigned long start_addr,
1317 		unsigned long end_addr,
1318 		struct zap_details *details)
1319 {
1320 	unsigned long start = max(vma->vm_start, start_addr);
1321 	unsigned long end;
1322 
1323 	if (start >= vma->vm_end)
1324 		return;
1325 	end = min(vma->vm_end, end_addr);
1326 	if (end <= vma->vm_start)
1327 		return;
1328 
1329 	if (vma->vm_file)
1330 		uprobe_munmap(vma, start, end);
1331 
1332 	if (unlikely(vma->vm_flags & VM_PFNMAP))
1333 		untrack_pfn(vma, 0, 0);
1334 
1335 	if (start != end) {
1336 		if (unlikely(is_vm_hugetlb_page(vma))) {
1337 			/*
1338 			 * It is undesirable to test vma->vm_file as it
1339 			 * should be non-null for valid hugetlb area.
1340 			 * However, vm_file will be NULL in the error
1341 			 * cleanup path of mmap_region. When
1342 			 * hugetlbfs ->mmap method fails,
1343 			 * mmap_region() nullifies vma->vm_file
1344 			 * before calling this function to clean up.
1345 			 * Since no pte has actually been setup, it is
1346 			 * safe to do nothing in this case.
1347 			 */
1348 			if (vma->vm_file) {
1349 				i_mmap_lock_write(vma->vm_file->f_mapping);
1350 				__unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1351 				i_mmap_unlock_write(vma->vm_file->f_mapping);
1352 			}
1353 		} else
1354 			unmap_page_range(tlb, vma, start, end, details);
1355 	}
1356 }
1357 
1358 /**
1359  * unmap_vmas - unmap a range of memory covered by a list of vma's
1360  * @tlb: address of the caller's struct mmu_gather
1361  * @vma: the starting vma
1362  * @start_addr: virtual address at which to start unmapping
1363  * @end_addr: virtual address at which to end unmapping
1364  *
1365  * Unmap all pages in the vma list.
1366  *
1367  * Only addresses between `start' and `end' will be unmapped.
1368  *
1369  * The VMA list must be sorted in ascending virtual address order.
1370  *
1371  * unmap_vmas() assumes that the caller will flush the whole unmapped address
1372  * range after unmap_vmas() returns.  So the only responsibility here is to
1373  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1374  * drops the lock and schedules.
1375  */
1376 void unmap_vmas(struct mmu_gather *tlb,
1377 		struct vm_area_struct *vma, unsigned long start_addr,
1378 		unsigned long end_addr)
1379 {
1380 	struct mm_struct *mm = vma->vm_mm;
1381 
1382 	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1383 	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1384 		unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1385 	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1386 }
1387 
1388 /**
1389  * zap_page_range - remove user pages in a given range
1390  * @vma: vm_area_struct holding the applicable pages
1391  * @start: starting address of pages to zap
1392  * @size: number of bytes to zap
1393  *
1394  * Caller must protect the VMA list
1395  */
1396 void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1397 		unsigned long size)
1398 {
1399 	struct mm_struct *mm = vma->vm_mm;
1400 	struct mmu_gather tlb;
1401 	unsigned long end = start + size;
1402 
1403 	lru_add_drain();
1404 	tlb_gather_mmu(&tlb, mm, start, end);
1405 	update_hiwater_rss(mm);
1406 	mmu_notifier_invalidate_range_start(mm, start, end);
1407 	for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
1408 		unmap_single_vma(&tlb, vma, start, end, NULL);
1409 	mmu_notifier_invalidate_range_end(mm, start, end);
1410 	tlb_finish_mmu(&tlb, start, end);
1411 }
1412 
1413 /**
1414  * zap_page_range_single - remove user pages in a given range
1415  * @vma: vm_area_struct holding the applicable pages
1416  * @address: starting address of pages to zap
1417  * @size: number of bytes to zap
1418  * @details: details of shared cache invalidation
1419  *
1420  * The range must fit into one VMA.
1421  */
1422 static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1423 		unsigned long size, struct zap_details *details)
1424 {
1425 	struct mm_struct *mm = vma->vm_mm;
1426 	struct mmu_gather tlb;
1427 	unsigned long end = address + size;
1428 
1429 	lru_add_drain();
1430 	tlb_gather_mmu(&tlb, mm, address, end);
1431 	update_hiwater_rss(mm);
1432 	mmu_notifier_invalidate_range_start(mm, address, end);
1433 	unmap_single_vma(&tlb, vma, address, end, details);
1434 	mmu_notifier_invalidate_range_end(mm, address, end);
1435 	tlb_finish_mmu(&tlb, address, end);
1436 }
1437 
1438 /**
1439  * zap_vma_ptes - remove ptes mapping the vma
1440  * @vma: vm_area_struct holding ptes to be zapped
1441  * @address: starting address of pages to zap
1442  * @size: number of bytes to zap
1443  *
1444  * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1445  *
1446  * The entire address range must be fully contained within the vma.
1447  *
1448  * Returns 0 if successful.
1449  */
1450 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1451 		unsigned long size)
1452 {
1453 	if (address < vma->vm_start || address + size > vma->vm_end ||
1454 	    		!(vma->vm_flags & VM_PFNMAP))
1455 		return -1;
1456 	zap_page_range_single(vma, address, size, NULL);
1457 	return 0;
1458 }
1459 EXPORT_SYMBOL_GPL(zap_vma_ptes);
1460 
1461 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1462 			spinlock_t **ptl)
1463 {
1464 	pgd_t *pgd = pgd_offset(mm, addr);
1465 	pud_t *pud = pud_alloc(mm, pgd, addr);
1466 	if (pud) {
1467 		pmd_t *pmd = pmd_alloc(mm, pud, addr);
1468 		if (pmd) {
1469 			VM_BUG_ON(pmd_trans_huge(*pmd));
1470 			return pte_alloc_map_lock(mm, pmd, addr, ptl);
1471 		}
1472 	}
1473 	return NULL;
1474 }
1475 
1476 /*
1477  * This is the old fallback for page remapping.
1478  *
1479  * For historical reasons, it only allows reserved pages. Only
1480  * old drivers should use this, and they needed to mark their
1481  * pages reserved for the old functions anyway.
1482  */
1483 static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1484 			struct page *page, pgprot_t prot)
1485 {
1486 	struct mm_struct *mm = vma->vm_mm;
1487 	int retval;
1488 	pte_t *pte;
1489 	spinlock_t *ptl;
1490 
1491 	retval = -EINVAL;
1492 	if (PageAnon(page))
1493 		goto out;
1494 	retval = -ENOMEM;
1495 	flush_dcache_page(page);
1496 	pte = get_locked_pte(mm, addr, &ptl);
1497 	if (!pte)
1498 		goto out;
1499 	retval = -EBUSY;
1500 	if (!pte_none(*pte))
1501 		goto out_unlock;
1502 
1503 	/* Ok, finally just insert the thing.. */
1504 	get_page(page);
1505 	inc_mm_counter_fast(mm, mm_counter_file(page));
1506 	page_add_file_rmap(page, false);
1507 	set_pte_at(mm, addr, pte, mk_pte(page, prot));
1508 
1509 	retval = 0;
1510 	pte_unmap_unlock(pte, ptl);
1511 	return retval;
1512 out_unlock:
1513 	pte_unmap_unlock(pte, ptl);
1514 out:
1515 	return retval;
1516 }
1517 
1518 /**
1519  * vm_insert_page - insert single page into user vma
1520  * @vma: user vma to map to
1521  * @addr: target user address of this page
1522  * @page: source kernel page
1523  *
1524  * This allows drivers to insert individual pages they've allocated
1525  * into a user vma.
1526  *
1527  * The page has to be a nice clean _individual_ kernel allocation.
1528  * If you allocate a compound page, you need to have marked it as
1529  * such (__GFP_COMP), or manually just split the page up yourself
1530  * (see split_page()).
1531  *
1532  * NOTE! Traditionally this was done with "remap_pfn_range()" which
1533  * took an arbitrary page protection parameter. This doesn't allow
1534  * that. Your vma protection will have to be set up correctly, which
1535  * means that if you want a shared writable mapping, you'd better
1536  * ask for a shared writable mapping!
1537  *
1538  * The page does not need to be reserved.
1539  *
1540  * Usually this function is called from f_op->mmap() handler
1541  * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
1542  * Caller must set VM_MIXEDMAP on vma if it wants to call this
1543  * function from other places, for example from page-fault handler.
1544  */
1545 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1546 			struct page *page)
1547 {
1548 	if (addr < vma->vm_start || addr >= vma->vm_end)
1549 		return -EFAULT;
1550 	if (!page_count(page))
1551 		return -EINVAL;
1552 	if (!(vma->vm_flags & VM_MIXEDMAP)) {
1553 		BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
1554 		BUG_ON(vma->vm_flags & VM_PFNMAP);
1555 		vma->vm_flags |= VM_MIXEDMAP;
1556 	}
1557 	return insert_page(vma, addr, page, vma->vm_page_prot);
1558 }
1559 EXPORT_SYMBOL(vm_insert_page);
1560 
1561 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1562 			pfn_t pfn, pgprot_t prot)
1563 {
1564 	struct mm_struct *mm = vma->vm_mm;
1565 	int retval;
1566 	pte_t *pte, entry;
1567 	spinlock_t *ptl;
1568 
1569 	retval = -ENOMEM;
1570 	pte = get_locked_pte(mm, addr, &ptl);
1571 	if (!pte)
1572 		goto out;
1573 	retval = -EBUSY;
1574 	if (!pte_none(*pte))
1575 		goto out_unlock;
1576 
1577 	/* Ok, finally just insert the thing.. */
1578 	if (pfn_t_devmap(pfn))
1579 		entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
1580 	else
1581 		entry = pte_mkspecial(pfn_t_pte(pfn, prot));
1582 	set_pte_at(mm, addr, pte, entry);
1583 	update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
1584 
1585 	retval = 0;
1586 out_unlock:
1587 	pte_unmap_unlock(pte, ptl);
1588 out:
1589 	return retval;
1590 }
1591 
1592 /**
1593  * vm_insert_pfn - insert single pfn into user vma
1594  * @vma: user vma to map to
1595  * @addr: target user address of this page
1596  * @pfn: source kernel pfn
1597  *
1598  * Similar to vm_insert_page, this allows drivers to insert individual pages
1599  * they've allocated into a user vma. Same comments apply.
1600  *
1601  * This function should only be called from a vm_ops->fault handler, and
1602  * in that case the handler should return NULL.
1603  *
1604  * vma cannot be a COW mapping.
1605  *
1606  * As this is called only for pages that do not currently exist, we
1607  * do not need to flush old virtual caches or the TLB.
1608  */
1609 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1610 			unsigned long pfn)
1611 {
1612 	return vm_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
1613 }
1614 EXPORT_SYMBOL(vm_insert_pfn);
1615 
1616 /**
1617  * vm_insert_pfn_prot - insert single pfn into user vma with specified pgprot
1618  * @vma: user vma to map to
1619  * @addr: target user address of this page
1620  * @pfn: source kernel pfn
1621  * @pgprot: pgprot flags for the inserted page
1622  *
1623  * This is exactly like vm_insert_pfn, except that it allows drivers to
1624  * to override pgprot on a per-page basis.
1625  *
1626  * This only makes sense for IO mappings, and it makes no sense for
1627  * cow mappings.  In general, using multiple vmas is preferable;
1628  * vm_insert_pfn_prot should only be used if using multiple VMAs is
1629  * impractical.
1630  */
1631 int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
1632 			unsigned long pfn, pgprot_t pgprot)
1633 {
1634 	int ret;
1635 	/*
1636 	 * Technically, architectures with pte_special can avoid all these
1637 	 * restrictions (same for remap_pfn_range).  However we would like
1638 	 * consistency in testing and feature parity among all, so we should
1639 	 * try to keep these invariants in place for everybody.
1640 	 */
1641 	BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1642 	BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1643 						(VM_PFNMAP|VM_MIXEDMAP));
1644 	BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1645 	BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1646 
1647 	if (addr < vma->vm_start || addr >= vma->vm_end)
1648 		return -EFAULT;
1649 
1650 	track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
1651 
1652 	ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot);
1653 
1654 	return ret;
1655 }
1656 EXPORT_SYMBOL(vm_insert_pfn_prot);
1657 
1658 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1659 			pfn_t pfn)
1660 {
1661 	pgprot_t pgprot = vma->vm_page_prot;
1662 
1663 	BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
1664 
1665 	if (addr < vma->vm_start || addr >= vma->vm_end)
1666 		return -EFAULT;
1667 
1668 	track_pfn_insert(vma, &pgprot, pfn);
1669 
1670 	/*
1671 	 * If we don't have pte special, then we have to use the pfn_valid()
1672 	 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1673 	 * refcount the page if pfn_valid is true (hence insert_page rather
1674 	 * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
1675 	 * without pte special, it would there be refcounted as a normal page.
1676 	 */
1677 	if (!HAVE_PTE_SPECIAL && !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
1678 		struct page *page;
1679 
1680 		/*
1681 		 * At this point we are committed to insert_page()
1682 		 * regardless of whether the caller specified flags that
1683 		 * result in pfn_t_has_page() == false.
1684 		 */
1685 		page = pfn_to_page(pfn_t_to_pfn(pfn));
1686 		return insert_page(vma, addr, page, pgprot);
1687 	}
1688 	return insert_pfn(vma, addr, pfn, pgprot);
1689 }
1690 EXPORT_SYMBOL(vm_insert_mixed);
1691 
1692 /*
1693  * maps a range of physical memory into the requested pages. the old
1694  * mappings are removed. any references to nonexistent pages results
1695  * in null mappings (currently treated as "copy-on-access")
1696  */
1697 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1698 			unsigned long addr, unsigned long end,
1699 			unsigned long pfn, pgprot_t prot)
1700 {
1701 	pte_t *pte;
1702 	spinlock_t *ptl;
1703 
1704 	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1705 	if (!pte)
1706 		return -ENOMEM;
1707 	arch_enter_lazy_mmu_mode();
1708 	do {
1709 		BUG_ON(!pte_none(*pte));
1710 		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
1711 		pfn++;
1712 	} while (pte++, addr += PAGE_SIZE, addr != end);
1713 	arch_leave_lazy_mmu_mode();
1714 	pte_unmap_unlock(pte - 1, ptl);
1715 	return 0;
1716 }
1717 
1718 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1719 			unsigned long addr, unsigned long end,
1720 			unsigned long pfn, pgprot_t prot)
1721 {
1722 	pmd_t *pmd;
1723 	unsigned long next;
1724 
1725 	pfn -= addr >> PAGE_SHIFT;
1726 	pmd = pmd_alloc(mm, pud, addr);
1727 	if (!pmd)
1728 		return -ENOMEM;
1729 	VM_BUG_ON(pmd_trans_huge(*pmd));
1730 	do {
1731 		next = pmd_addr_end(addr, end);
1732 		if (remap_pte_range(mm, pmd, addr, next,
1733 				pfn + (addr >> PAGE_SHIFT), prot))
1734 			return -ENOMEM;
1735 	} while (pmd++, addr = next, addr != end);
1736 	return 0;
1737 }
1738 
1739 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1740 			unsigned long addr, unsigned long end,
1741 			unsigned long pfn, pgprot_t prot)
1742 {
1743 	pud_t *pud;
1744 	unsigned long next;
1745 
1746 	pfn -= addr >> PAGE_SHIFT;
1747 	pud = pud_alloc(mm, pgd, addr);
1748 	if (!pud)
1749 		return -ENOMEM;
1750 	do {
1751 		next = pud_addr_end(addr, end);
1752 		if (remap_pmd_range(mm, pud, addr, next,
1753 				pfn + (addr >> PAGE_SHIFT), prot))
1754 			return -ENOMEM;
1755 	} while (pud++, addr = next, addr != end);
1756 	return 0;
1757 }
1758 
1759 /**
1760  * remap_pfn_range - remap kernel memory to userspace
1761  * @vma: user vma to map to
1762  * @addr: target user address to start at
1763  * @pfn: physical address of kernel memory
1764  * @size: size of map area
1765  * @prot: page protection flags for this mapping
1766  *
1767  *  Note: this is only safe if the mm semaphore is held when called.
1768  */
1769 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1770 		    unsigned long pfn, unsigned long size, pgprot_t prot)
1771 {
1772 	pgd_t *pgd;
1773 	unsigned long next;
1774 	unsigned long end = addr + PAGE_ALIGN(size);
1775 	struct mm_struct *mm = vma->vm_mm;
1776 	unsigned long remap_pfn = pfn;
1777 	int err;
1778 
1779 	/*
1780 	 * Physically remapped pages are special. Tell the
1781 	 * rest of the world about it:
1782 	 *   VM_IO tells people not to look at these pages
1783 	 *	(accesses can have side effects).
1784 	 *   VM_PFNMAP tells the core MM that the base pages are just
1785 	 *	raw PFN mappings, and do not have a "struct page" associated
1786 	 *	with them.
1787 	 *   VM_DONTEXPAND
1788 	 *      Disable vma merging and expanding with mremap().
1789 	 *   VM_DONTDUMP
1790 	 *      Omit vma from core dump, even when VM_IO turned off.
1791 	 *
1792 	 * There's a horrible special case to handle copy-on-write
1793 	 * behaviour that some programs depend on. We mark the "original"
1794 	 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1795 	 * See vm_normal_page() for details.
1796 	 */
1797 	if (is_cow_mapping(vma->vm_flags)) {
1798 		if (addr != vma->vm_start || end != vma->vm_end)
1799 			return -EINVAL;
1800 		vma->vm_pgoff = pfn;
1801 	}
1802 
1803 	err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size));
1804 	if (err)
1805 		return -EINVAL;
1806 
1807 	vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
1808 
1809 	BUG_ON(addr >= end);
1810 	pfn -= addr >> PAGE_SHIFT;
1811 	pgd = pgd_offset(mm, addr);
1812 	flush_cache_range(vma, addr, end);
1813 	do {
1814 		next = pgd_addr_end(addr, end);
1815 		err = remap_pud_range(mm, pgd, addr, next,
1816 				pfn + (addr >> PAGE_SHIFT), prot);
1817 		if (err)
1818 			break;
1819 	} while (pgd++, addr = next, addr != end);
1820 
1821 	if (err)
1822 		untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size));
1823 
1824 	return err;
1825 }
1826 EXPORT_SYMBOL(remap_pfn_range);
1827 
1828 /**
1829  * vm_iomap_memory - remap memory to userspace
1830  * @vma: user vma to map to
1831  * @start: start of area
1832  * @len: size of area
1833  *
1834  * This is a simplified io_remap_pfn_range() for common driver use. The
1835  * driver just needs to give us the physical memory range to be mapped,
1836  * we'll figure out the rest from the vma information.
1837  *
1838  * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
1839  * whatever write-combining details or similar.
1840  */
1841 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
1842 {
1843 	unsigned long vm_len, pfn, pages;
1844 
1845 	/* Check that the physical memory area passed in looks valid */
1846 	if (start + len < start)
1847 		return -EINVAL;
1848 	/*
1849 	 * You *really* shouldn't map things that aren't page-aligned,
1850 	 * but we've historically allowed it because IO memory might
1851 	 * just have smaller alignment.
1852 	 */
1853 	len += start & ~PAGE_MASK;
1854 	pfn = start >> PAGE_SHIFT;
1855 	pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
1856 	if (pfn + pages < pfn)
1857 		return -EINVAL;
1858 
1859 	/* We start the mapping 'vm_pgoff' pages into the area */
1860 	if (vma->vm_pgoff > pages)
1861 		return -EINVAL;
1862 	pfn += vma->vm_pgoff;
1863 	pages -= vma->vm_pgoff;
1864 
1865 	/* Can we fit all of the mapping? */
1866 	vm_len = vma->vm_end - vma->vm_start;
1867 	if (vm_len >> PAGE_SHIFT > pages)
1868 		return -EINVAL;
1869 
1870 	/* Ok, let it rip */
1871 	return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
1872 }
1873 EXPORT_SYMBOL(vm_iomap_memory);
1874 
1875 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
1876 				     unsigned long addr, unsigned long end,
1877 				     pte_fn_t fn, void *data)
1878 {
1879 	pte_t *pte;
1880 	int err;
1881 	pgtable_t token;
1882 	spinlock_t *uninitialized_var(ptl);
1883 
1884 	pte = (mm == &init_mm) ?
1885 		pte_alloc_kernel(pmd, addr) :
1886 		pte_alloc_map_lock(mm, pmd, addr, &ptl);
1887 	if (!pte)
1888 		return -ENOMEM;
1889 
1890 	BUG_ON(pmd_huge(*pmd));
1891 
1892 	arch_enter_lazy_mmu_mode();
1893 
1894 	token = pmd_pgtable(*pmd);
1895 
1896 	do {
1897 		err = fn(pte++, token, addr, data);
1898 		if (err)
1899 			break;
1900 	} while (addr += PAGE_SIZE, addr != end);
1901 
1902 	arch_leave_lazy_mmu_mode();
1903 
1904 	if (mm != &init_mm)
1905 		pte_unmap_unlock(pte-1, ptl);
1906 	return err;
1907 }
1908 
1909 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
1910 				     unsigned long addr, unsigned long end,
1911 				     pte_fn_t fn, void *data)
1912 {
1913 	pmd_t *pmd;
1914 	unsigned long next;
1915 	int err;
1916 
1917 	BUG_ON(pud_huge(*pud));
1918 
1919 	pmd = pmd_alloc(mm, pud, addr);
1920 	if (!pmd)
1921 		return -ENOMEM;
1922 	do {
1923 		next = pmd_addr_end(addr, end);
1924 		err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
1925 		if (err)
1926 			break;
1927 	} while (pmd++, addr = next, addr != end);
1928 	return err;
1929 }
1930 
1931 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
1932 				     unsigned long addr, unsigned long end,
1933 				     pte_fn_t fn, void *data)
1934 {
1935 	pud_t *pud;
1936 	unsigned long next;
1937 	int err;
1938 
1939 	pud = pud_alloc(mm, pgd, addr);
1940 	if (!pud)
1941 		return -ENOMEM;
1942 	do {
1943 		next = pud_addr_end(addr, end);
1944 		err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
1945 		if (err)
1946 			break;
1947 	} while (pud++, addr = next, addr != end);
1948 	return err;
1949 }
1950 
1951 /*
1952  * Scan a region of virtual memory, filling in page tables as necessary
1953  * and calling a provided function on each leaf page table.
1954  */
1955 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
1956 			unsigned long size, pte_fn_t fn, void *data)
1957 {
1958 	pgd_t *pgd;
1959 	unsigned long next;
1960 	unsigned long end = addr + size;
1961 	int err;
1962 
1963 	if (WARN_ON(addr >= end))
1964 		return -EINVAL;
1965 
1966 	pgd = pgd_offset(mm, addr);
1967 	do {
1968 		next = pgd_addr_end(addr, end);
1969 		err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
1970 		if (err)
1971 			break;
1972 	} while (pgd++, addr = next, addr != end);
1973 
1974 	return err;
1975 }
1976 EXPORT_SYMBOL_GPL(apply_to_page_range);
1977 
1978 /*
1979  * handle_pte_fault chooses page fault handler according to an entry which was
1980  * read non-atomically.  Before making any commitment, on those architectures
1981  * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
1982  * parts, do_swap_page must check under lock before unmapping the pte and
1983  * proceeding (but do_wp_page is only called after already making such a check;
1984  * and do_anonymous_page can safely check later on).
1985  */
1986 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1987 				pte_t *page_table, pte_t orig_pte)
1988 {
1989 	int same = 1;
1990 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
1991 	if (sizeof(pte_t) > sizeof(unsigned long)) {
1992 		spinlock_t *ptl = pte_lockptr(mm, pmd);
1993 		spin_lock(ptl);
1994 		same = pte_same(*page_table, orig_pte);
1995 		spin_unlock(ptl);
1996 	}
1997 #endif
1998 	pte_unmap(page_table);
1999 	return same;
2000 }
2001 
2002 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2003 {
2004 	debug_dma_assert_idle(src);
2005 
2006 	/*
2007 	 * If the source page was a PFN mapping, we don't have
2008 	 * a "struct page" for it. We do a best-effort copy by
2009 	 * just copying from the original user address. If that
2010 	 * fails, we just zero-fill it. Live with it.
2011 	 */
2012 	if (unlikely(!src)) {
2013 		void *kaddr = kmap_atomic(dst);
2014 		void __user *uaddr = (void __user *)(va & PAGE_MASK);
2015 
2016 		/*
2017 		 * This really shouldn't fail, because the page is there
2018 		 * in the page tables. But it might just be unreadable,
2019 		 * in which case we just give up and fill the result with
2020 		 * zeroes.
2021 		 */
2022 		if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2023 			clear_page(kaddr);
2024 		kunmap_atomic(kaddr);
2025 		flush_dcache_page(dst);
2026 	} else
2027 		copy_user_highpage(dst, src, va, vma);
2028 }
2029 
2030 static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
2031 {
2032 	struct file *vm_file = vma->vm_file;
2033 
2034 	if (vm_file)
2035 		return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
2036 
2037 	/*
2038 	 * Special mappings (e.g. VDSO) do not have any file so fake
2039 	 * a default GFP_KERNEL for them.
2040 	 */
2041 	return GFP_KERNEL;
2042 }
2043 
2044 /*
2045  * Notify the address space that the page is about to become writable so that
2046  * it can prohibit this or wait for the page to get into an appropriate state.
2047  *
2048  * We do this without the lock held, so that it can sleep if it needs to.
2049  */
2050 static int do_page_mkwrite(struct vm_fault *vmf)
2051 {
2052 	int ret;
2053 	struct page *page = vmf->page;
2054 	unsigned int old_flags = vmf->flags;
2055 
2056 	vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2057 
2058 	ret = vmf->vma->vm_ops->page_mkwrite(vmf);
2059 	/* Restore original flags so that caller is not surprised */
2060 	vmf->flags = old_flags;
2061 	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2062 		return ret;
2063 	if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2064 		lock_page(page);
2065 		if (!page->mapping) {
2066 			unlock_page(page);
2067 			return 0; /* retry */
2068 		}
2069 		ret |= VM_FAULT_LOCKED;
2070 	} else
2071 		VM_BUG_ON_PAGE(!PageLocked(page), page);
2072 	return ret;
2073 }
2074 
2075 /*
2076  * Handle dirtying of a page in shared file mapping on a write fault.
2077  *
2078  * The function expects the page to be locked and unlocks it.
2079  */
2080 static void fault_dirty_shared_page(struct vm_area_struct *vma,
2081 				    struct page *page)
2082 {
2083 	struct address_space *mapping;
2084 	bool dirtied;
2085 	bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
2086 
2087 	dirtied = set_page_dirty(page);
2088 	VM_BUG_ON_PAGE(PageAnon(page), page);
2089 	/*
2090 	 * Take a local copy of the address_space - page.mapping may be zeroed
2091 	 * by truncate after unlock_page().   The address_space itself remains
2092 	 * pinned by vma->vm_file's reference.  We rely on unlock_page()'s
2093 	 * release semantics to prevent the compiler from undoing this copying.
2094 	 */
2095 	mapping = page_rmapping(page);
2096 	unlock_page(page);
2097 
2098 	if ((dirtied || page_mkwrite) && mapping) {
2099 		/*
2100 		 * Some device drivers do not set page.mapping
2101 		 * but still dirty their pages
2102 		 */
2103 		balance_dirty_pages_ratelimited(mapping);
2104 	}
2105 
2106 	if (!page_mkwrite)
2107 		file_update_time(vma->vm_file);
2108 }
2109 
2110 /*
2111  * Handle write page faults for pages that can be reused in the current vma
2112  *
2113  * This can happen either due to the mapping being with the VM_SHARED flag,
2114  * or due to us being the last reference standing to the page. In either
2115  * case, all we need to do here is to mark the page as writable and update
2116  * any related book-keeping.
2117  */
2118 static inline void wp_page_reuse(struct vm_fault *vmf)
2119 	__releases(vmf->ptl)
2120 {
2121 	struct vm_area_struct *vma = vmf->vma;
2122 	struct page *page = vmf->page;
2123 	pte_t entry;
2124 	/*
2125 	 * Clear the pages cpupid information as the existing
2126 	 * information potentially belongs to a now completely
2127 	 * unrelated process.
2128 	 */
2129 	if (page)
2130 		page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
2131 
2132 	flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2133 	entry = pte_mkyoung(vmf->orig_pte);
2134 	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2135 	if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
2136 		update_mmu_cache(vma, vmf->address, vmf->pte);
2137 	pte_unmap_unlock(vmf->pte, vmf->ptl);
2138 }
2139 
2140 /*
2141  * Handle the case of a page which we actually need to copy to a new page.
2142  *
2143  * Called with mmap_sem locked and the old page referenced, but
2144  * without the ptl held.
2145  *
2146  * High level logic flow:
2147  *
2148  * - Allocate a page, copy the content of the old page to the new one.
2149  * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
2150  * - Take the PTL. If the pte changed, bail out and release the allocated page
2151  * - If the pte is still the way we remember it, update the page table and all
2152  *   relevant references. This includes dropping the reference the page-table
2153  *   held to the old page, as well as updating the rmap.
2154  * - In any case, unlock the PTL and drop the reference we took to the old page.
2155  */
2156 static int wp_page_copy(struct vm_fault *vmf)
2157 {
2158 	struct vm_area_struct *vma = vmf->vma;
2159 	struct mm_struct *mm = vma->vm_mm;
2160 	struct page *old_page = vmf->page;
2161 	struct page *new_page = NULL;
2162 	pte_t entry;
2163 	int page_copied = 0;
2164 	const unsigned long mmun_start = vmf->address & PAGE_MASK;
2165 	const unsigned long mmun_end = mmun_start + PAGE_SIZE;
2166 	struct mem_cgroup *memcg;
2167 
2168 	if (unlikely(anon_vma_prepare(vma)))
2169 		goto oom;
2170 
2171 	if (is_zero_pfn(pte_pfn(vmf->orig_pte))) {
2172 		new_page = alloc_zeroed_user_highpage_movable(vma,
2173 							      vmf->address);
2174 		if (!new_page)
2175 			goto oom;
2176 	} else {
2177 		new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
2178 				vmf->address);
2179 		if (!new_page)
2180 			goto oom;
2181 		cow_user_page(new_page, old_page, vmf->address, vma);
2182 	}
2183 
2184 	if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false))
2185 		goto oom_free_new;
2186 
2187 	__SetPageUptodate(new_page);
2188 
2189 	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2190 
2191 	/*
2192 	 * Re-check the pte - we dropped the lock
2193 	 */
2194 	vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
2195 	if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2196 		if (old_page) {
2197 			if (!PageAnon(old_page)) {
2198 				dec_mm_counter_fast(mm,
2199 						mm_counter_file(old_page));
2200 				inc_mm_counter_fast(mm, MM_ANONPAGES);
2201 			}
2202 		} else {
2203 			inc_mm_counter_fast(mm, MM_ANONPAGES);
2204 		}
2205 		flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2206 		entry = mk_pte(new_page, vma->vm_page_prot);
2207 		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2208 		/*
2209 		 * Clear the pte entry and flush it first, before updating the
2210 		 * pte with the new entry. This will avoid a race condition
2211 		 * seen in the presence of one thread doing SMC and another
2212 		 * thread doing COW.
2213 		 */
2214 		ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
2215 		page_add_new_anon_rmap(new_page, vma, vmf->address, false);
2216 		mem_cgroup_commit_charge(new_page, memcg, false, false);
2217 		lru_cache_add_active_or_unevictable(new_page, vma);
2218 		/*
2219 		 * We call the notify macro here because, when using secondary
2220 		 * mmu page tables (such as kvm shadow page tables), we want the
2221 		 * new page to be mapped directly into the secondary page table.
2222 		 */
2223 		set_pte_at_notify(mm, vmf->address, vmf->pte, entry);
2224 		update_mmu_cache(vma, vmf->address, vmf->pte);
2225 		if (old_page) {
2226 			/*
2227 			 * Only after switching the pte to the new page may
2228 			 * we remove the mapcount here. Otherwise another
2229 			 * process may come and find the rmap count decremented
2230 			 * before the pte is switched to the new page, and
2231 			 * "reuse" the old page writing into it while our pte
2232 			 * here still points into it and can be read by other
2233 			 * threads.
2234 			 *
2235 			 * The critical issue is to order this
2236 			 * page_remove_rmap with the ptp_clear_flush above.
2237 			 * Those stores are ordered by (if nothing else,)
2238 			 * the barrier present in the atomic_add_negative
2239 			 * in page_remove_rmap.
2240 			 *
2241 			 * Then the TLB flush in ptep_clear_flush ensures that
2242 			 * no process can access the old page before the
2243 			 * decremented mapcount is visible. And the old page
2244 			 * cannot be reused until after the decremented
2245 			 * mapcount is visible. So transitively, TLBs to
2246 			 * old page will be flushed before it can be reused.
2247 			 */
2248 			page_remove_rmap(old_page, false);
2249 		}
2250 
2251 		/* Free the old page.. */
2252 		new_page = old_page;
2253 		page_copied = 1;
2254 	} else {
2255 		mem_cgroup_cancel_charge(new_page, memcg, false);
2256 	}
2257 
2258 	if (new_page)
2259 		put_page(new_page);
2260 
2261 	pte_unmap_unlock(vmf->pte, vmf->ptl);
2262 	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2263 	if (old_page) {
2264 		/*
2265 		 * Don't let another task, with possibly unlocked vma,
2266 		 * keep the mlocked page.
2267 		 */
2268 		if (page_copied && (vma->vm_flags & VM_LOCKED)) {
2269 			lock_page(old_page);	/* LRU manipulation */
2270 			if (PageMlocked(old_page))
2271 				munlock_vma_page(old_page);
2272 			unlock_page(old_page);
2273 		}
2274 		put_page(old_page);
2275 	}
2276 	return page_copied ? VM_FAULT_WRITE : 0;
2277 oom_free_new:
2278 	put_page(new_page);
2279 oom:
2280 	if (old_page)
2281 		put_page(old_page);
2282 	return VM_FAULT_OOM;
2283 }
2284 
2285 /**
2286  * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
2287  *			  writeable once the page is prepared
2288  *
2289  * @vmf: structure describing the fault
2290  *
2291  * This function handles all that is needed to finish a write page fault in a
2292  * shared mapping due to PTE being read-only once the mapped page is prepared.
2293  * It handles locking of PTE and modifying it. The function returns
2294  * VM_FAULT_WRITE on success, 0 when PTE got changed before we acquired PTE
2295  * lock.
2296  *
2297  * The function expects the page to be locked or other protection against
2298  * concurrent faults / writeback (such as DAX radix tree locks).
2299  */
2300 int finish_mkwrite_fault(struct vm_fault *vmf)
2301 {
2302 	WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
2303 	vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
2304 				       &vmf->ptl);
2305 	/*
2306 	 * We might have raced with another page fault while we released the
2307 	 * pte_offset_map_lock.
2308 	 */
2309 	if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2310 		pte_unmap_unlock(vmf->pte, vmf->ptl);
2311 		return VM_FAULT_NOPAGE;
2312 	}
2313 	wp_page_reuse(vmf);
2314 	return 0;
2315 }
2316 
2317 /*
2318  * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
2319  * mapping
2320  */
2321 static int wp_pfn_shared(struct vm_fault *vmf)
2322 {
2323 	struct vm_area_struct *vma = vmf->vma;
2324 
2325 	if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
2326 		int ret;
2327 
2328 		pte_unmap_unlock(vmf->pte, vmf->ptl);
2329 		vmf->flags |= FAULT_FLAG_MKWRITE;
2330 		ret = vma->vm_ops->pfn_mkwrite(vmf);
2331 		if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
2332 			return ret;
2333 		return finish_mkwrite_fault(vmf);
2334 	}
2335 	wp_page_reuse(vmf);
2336 	return VM_FAULT_WRITE;
2337 }
2338 
2339 static int wp_page_shared(struct vm_fault *vmf)
2340 	__releases(vmf->ptl)
2341 {
2342 	struct vm_area_struct *vma = vmf->vma;
2343 
2344 	get_page(vmf->page);
2345 
2346 	if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2347 		int tmp;
2348 
2349 		pte_unmap_unlock(vmf->pte, vmf->ptl);
2350 		tmp = do_page_mkwrite(vmf);
2351 		if (unlikely(!tmp || (tmp &
2352 				      (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
2353 			put_page(vmf->page);
2354 			return tmp;
2355 		}
2356 		tmp = finish_mkwrite_fault(vmf);
2357 		if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2358 			unlock_page(vmf->page);
2359 			put_page(vmf->page);
2360 			return tmp;
2361 		}
2362 	} else {
2363 		wp_page_reuse(vmf);
2364 		lock_page(vmf->page);
2365 	}
2366 	fault_dirty_shared_page(vma, vmf->page);
2367 	put_page(vmf->page);
2368 
2369 	return VM_FAULT_WRITE;
2370 }
2371 
2372 /*
2373  * This routine handles present pages, when users try to write
2374  * to a shared page. It is done by copying the page to a new address
2375  * and decrementing the shared-page counter for the old page.
2376  *
2377  * Note that this routine assumes that the protection checks have been
2378  * done by the caller (the low-level page fault routine in most cases).
2379  * Thus we can safely just mark it writable once we've done any necessary
2380  * COW.
2381  *
2382  * We also mark the page dirty at this point even though the page will
2383  * change only once the write actually happens. This avoids a few races,
2384  * and potentially makes it more efficient.
2385  *
2386  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2387  * but allow concurrent faults), with pte both mapped and locked.
2388  * We return with mmap_sem still held, but pte unmapped and unlocked.
2389  */
2390 static int do_wp_page(struct vm_fault *vmf)
2391 	__releases(vmf->ptl)
2392 {
2393 	struct vm_area_struct *vma = vmf->vma;
2394 
2395 	vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
2396 	if (!vmf->page) {
2397 		/*
2398 		 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
2399 		 * VM_PFNMAP VMA.
2400 		 *
2401 		 * We should not cow pages in a shared writeable mapping.
2402 		 * Just mark the pages writable and/or call ops->pfn_mkwrite.
2403 		 */
2404 		if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2405 				     (VM_WRITE|VM_SHARED))
2406 			return wp_pfn_shared(vmf);
2407 
2408 		pte_unmap_unlock(vmf->pte, vmf->ptl);
2409 		return wp_page_copy(vmf);
2410 	}
2411 
2412 	/*
2413 	 * Take out anonymous pages first, anonymous shared vmas are
2414 	 * not dirty accountable.
2415 	 */
2416 	if (PageAnon(vmf->page) && !PageKsm(vmf->page)) {
2417 		int total_mapcount;
2418 		if (!trylock_page(vmf->page)) {
2419 			get_page(vmf->page);
2420 			pte_unmap_unlock(vmf->pte, vmf->ptl);
2421 			lock_page(vmf->page);
2422 			vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2423 					vmf->address, &vmf->ptl);
2424 			if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2425 				unlock_page(vmf->page);
2426 				pte_unmap_unlock(vmf->pte, vmf->ptl);
2427 				put_page(vmf->page);
2428 				return 0;
2429 			}
2430 			put_page(vmf->page);
2431 		}
2432 		if (reuse_swap_page(vmf->page, &total_mapcount)) {
2433 			if (total_mapcount == 1) {
2434 				/*
2435 				 * The page is all ours. Move it to
2436 				 * our anon_vma so the rmap code will
2437 				 * not search our parent or siblings.
2438 				 * Protected against the rmap code by
2439 				 * the page lock.
2440 				 */
2441 				page_move_anon_rmap(vmf->page, vma);
2442 			}
2443 			unlock_page(vmf->page);
2444 			wp_page_reuse(vmf);
2445 			return VM_FAULT_WRITE;
2446 		}
2447 		unlock_page(vmf->page);
2448 	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2449 					(VM_WRITE|VM_SHARED))) {
2450 		return wp_page_shared(vmf);
2451 	}
2452 
2453 	/*
2454 	 * Ok, we need to copy. Oh, well..
2455 	 */
2456 	get_page(vmf->page);
2457 
2458 	pte_unmap_unlock(vmf->pte, vmf->ptl);
2459 	return wp_page_copy(vmf);
2460 }
2461 
2462 static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2463 		unsigned long start_addr, unsigned long end_addr,
2464 		struct zap_details *details)
2465 {
2466 	zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
2467 }
2468 
2469 static inline void unmap_mapping_range_tree(struct rb_root *root,
2470 					    struct zap_details *details)
2471 {
2472 	struct vm_area_struct *vma;
2473 	pgoff_t vba, vea, zba, zea;
2474 
2475 	vma_interval_tree_foreach(vma, root,
2476 			details->first_index, details->last_index) {
2477 
2478 		vba = vma->vm_pgoff;
2479 		vea = vba + vma_pages(vma) - 1;
2480 		zba = details->first_index;
2481 		if (zba < vba)
2482 			zba = vba;
2483 		zea = details->last_index;
2484 		if (zea > vea)
2485 			zea = vea;
2486 
2487 		unmap_mapping_range_vma(vma,
2488 			((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2489 			((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2490 				details);
2491 	}
2492 }
2493 
2494 /**
2495  * unmap_mapping_range - unmap the portion of all mmaps in the specified
2496  * address_space corresponding to the specified page range in the underlying
2497  * file.
2498  *
2499  * @mapping: the address space containing mmaps to be unmapped.
2500  * @holebegin: byte in first page to unmap, relative to the start of
2501  * the underlying file.  This will be rounded down to a PAGE_SIZE
2502  * boundary.  Note that this is different from truncate_pagecache(), which
2503  * must keep the partial page.  In contrast, we must get rid of
2504  * partial pages.
2505  * @holelen: size of prospective hole in bytes.  This will be rounded
2506  * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
2507  * end of the file.
2508  * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2509  * but 0 when invalidating pagecache, don't throw away private data.
2510  */
2511 void unmap_mapping_range(struct address_space *mapping,
2512 		loff_t const holebegin, loff_t const holelen, int even_cows)
2513 {
2514 	struct zap_details details = { };
2515 	pgoff_t hba = holebegin >> PAGE_SHIFT;
2516 	pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2517 
2518 	/* Check for overflow. */
2519 	if (sizeof(holelen) > sizeof(hlen)) {
2520 		long long holeend =
2521 			(holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2522 		if (holeend & ~(long long)ULONG_MAX)
2523 			hlen = ULONG_MAX - hba + 1;
2524 	}
2525 
2526 	details.check_mapping = even_cows ? NULL : mapping;
2527 	details.first_index = hba;
2528 	details.last_index = hba + hlen - 1;
2529 	if (details.last_index < details.first_index)
2530 		details.last_index = ULONG_MAX;
2531 
2532 	i_mmap_lock_write(mapping);
2533 	if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
2534 		unmap_mapping_range_tree(&mapping->i_mmap, &details);
2535 	i_mmap_unlock_write(mapping);
2536 }
2537 EXPORT_SYMBOL(unmap_mapping_range);
2538 
2539 /*
2540  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2541  * but allow concurrent faults), and pte mapped but not yet locked.
2542  * We return with pte unmapped and unlocked.
2543  *
2544  * We return with the mmap_sem locked or unlocked in the same cases
2545  * as does filemap_fault().
2546  */
2547 int do_swap_page(struct vm_fault *vmf)
2548 {
2549 	struct vm_area_struct *vma = vmf->vma;
2550 	struct page *page, *swapcache;
2551 	struct mem_cgroup *memcg;
2552 	swp_entry_t entry;
2553 	pte_t pte;
2554 	int locked;
2555 	int exclusive = 0;
2556 	int ret = 0;
2557 
2558 	if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
2559 		goto out;
2560 
2561 	entry = pte_to_swp_entry(vmf->orig_pte);
2562 	if (unlikely(non_swap_entry(entry))) {
2563 		if (is_migration_entry(entry)) {
2564 			migration_entry_wait(vma->vm_mm, vmf->pmd,
2565 					     vmf->address);
2566 		} else if (is_hwpoison_entry(entry)) {
2567 			ret = VM_FAULT_HWPOISON;
2568 		} else {
2569 			print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
2570 			ret = VM_FAULT_SIGBUS;
2571 		}
2572 		goto out;
2573 	}
2574 	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2575 	page = lookup_swap_cache(entry);
2576 	if (!page) {
2577 		page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, vma,
2578 					vmf->address);
2579 		if (!page) {
2580 			/*
2581 			 * Back out if somebody else faulted in this pte
2582 			 * while we released the pte lock.
2583 			 */
2584 			vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2585 					vmf->address, &vmf->ptl);
2586 			if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
2587 				ret = VM_FAULT_OOM;
2588 			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2589 			goto unlock;
2590 		}
2591 
2592 		/* Had to read the page from swap area: Major fault */
2593 		ret = VM_FAULT_MAJOR;
2594 		count_vm_event(PGMAJFAULT);
2595 		mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
2596 	} else if (PageHWPoison(page)) {
2597 		/*
2598 		 * hwpoisoned dirty swapcache pages are kept for killing
2599 		 * owner processes (which may be unknown at hwpoison time)
2600 		 */
2601 		ret = VM_FAULT_HWPOISON;
2602 		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2603 		swapcache = page;
2604 		goto out_release;
2605 	}
2606 
2607 	swapcache = page;
2608 	locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
2609 
2610 	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2611 	if (!locked) {
2612 		ret |= VM_FAULT_RETRY;
2613 		goto out_release;
2614 	}
2615 
2616 	/*
2617 	 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2618 	 * release the swapcache from under us.  The page pin, and pte_same
2619 	 * test below, are not enough to exclude that.  Even if it is still
2620 	 * swapcache, we need to check that the page's swap has not changed.
2621 	 */
2622 	if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
2623 		goto out_page;
2624 
2625 	page = ksm_might_need_to_copy(page, vma, vmf->address);
2626 	if (unlikely(!page)) {
2627 		ret = VM_FAULT_OOM;
2628 		page = swapcache;
2629 		goto out_page;
2630 	}
2631 
2632 	if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL,
2633 				&memcg, false)) {
2634 		ret = VM_FAULT_OOM;
2635 		goto out_page;
2636 	}
2637 
2638 	/*
2639 	 * Back out if somebody else already faulted in this pte.
2640 	 */
2641 	vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
2642 			&vmf->ptl);
2643 	if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
2644 		goto out_nomap;
2645 
2646 	if (unlikely(!PageUptodate(page))) {
2647 		ret = VM_FAULT_SIGBUS;
2648 		goto out_nomap;
2649 	}
2650 
2651 	/*
2652 	 * The page isn't present yet, go ahead with the fault.
2653 	 *
2654 	 * Be careful about the sequence of operations here.
2655 	 * To get its accounting right, reuse_swap_page() must be called
2656 	 * while the page is counted on swap but not yet in mapcount i.e.
2657 	 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2658 	 * must be called after the swap_free(), or it will never succeed.
2659 	 */
2660 
2661 	inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
2662 	dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
2663 	pte = mk_pte(page, vma->vm_page_prot);
2664 	if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
2665 		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2666 		vmf->flags &= ~FAULT_FLAG_WRITE;
2667 		ret |= VM_FAULT_WRITE;
2668 		exclusive = RMAP_EXCLUSIVE;
2669 	}
2670 	flush_icache_page(vma, page);
2671 	if (pte_swp_soft_dirty(vmf->orig_pte))
2672 		pte = pte_mksoft_dirty(pte);
2673 	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
2674 	vmf->orig_pte = pte;
2675 	if (page == swapcache) {
2676 		do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
2677 		mem_cgroup_commit_charge(page, memcg, true, false);
2678 		activate_page(page);
2679 	} else { /* ksm created a completely new copy */
2680 		page_add_new_anon_rmap(page, vma, vmf->address, false);
2681 		mem_cgroup_commit_charge(page, memcg, false, false);
2682 		lru_cache_add_active_or_unevictable(page, vma);
2683 	}
2684 
2685 	swap_free(entry);
2686 	if (mem_cgroup_swap_full(page) ||
2687 	    (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2688 		try_to_free_swap(page);
2689 	unlock_page(page);
2690 	if (page != swapcache) {
2691 		/*
2692 		 * Hold the lock to avoid the swap entry to be reused
2693 		 * until we take the PT lock for the pte_same() check
2694 		 * (to avoid false positives from pte_same). For
2695 		 * further safety release the lock after the swap_free
2696 		 * so that the swap count won't change under a
2697 		 * parallel locked swapcache.
2698 		 */
2699 		unlock_page(swapcache);
2700 		put_page(swapcache);
2701 	}
2702 
2703 	if (vmf->flags & FAULT_FLAG_WRITE) {
2704 		ret |= do_wp_page(vmf);
2705 		if (ret & VM_FAULT_ERROR)
2706 			ret &= VM_FAULT_ERROR;
2707 		goto out;
2708 	}
2709 
2710 	/* No need to invalidate - it was non-present before */
2711 	update_mmu_cache(vma, vmf->address, vmf->pte);
2712 unlock:
2713 	pte_unmap_unlock(vmf->pte, vmf->ptl);
2714 out:
2715 	return ret;
2716 out_nomap:
2717 	mem_cgroup_cancel_charge(page, memcg, false);
2718 	pte_unmap_unlock(vmf->pte, vmf->ptl);
2719 out_page:
2720 	unlock_page(page);
2721 out_release:
2722 	put_page(page);
2723 	if (page != swapcache) {
2724 		unlock_page(swapcache);
2725 		put_page(swapcache);
2726 	}
2727 	return ret;
2728 }
2729 
2730 /*
2731  * This is like a special single-page "expand_{down|up}wards()",
2732  * except we must first make sure that 'address{-|+}PAGE_SIZE'
2733  * doesn't hit another vma.
2734  */
2735 static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
2736 {
2737 	address &= PAGE_MASK;
2738 	if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
2739 		struct vm_area_struct *prev = vma->vm_prev;
2740 
2741 		/*
2742 		 * Is there a mapping abutting this one below?
2743 		 *
2744 		 * That's only ok if it's the same stack mapping
2745 		 * that has gotten split..
2746 		 */
2747 		if (prev && prev->vm_end == address)
2748 			return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
2749 
2750 		return expand_downwards(vma, address - PAGE_SIZE);
2751 	}
2752 	if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
2753 		struct vm_area_struct *next = vma->vm_next;
2754 
2755 		/* As VM_GROWSDOWN but s/below/above/ */
2756 		if (next && next->vm_start == address + PAGE_SIZE)
2757 			return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
2758 
2759 		return expand_upwards(vma, address + PAGE_SIZE);
2760 	}
2761 	return 0;
2762 }
2763 
2764 /*
2765  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2766  * but allow concurrent faults), and pte mapped but not yet locked.
2767  * We return with mmap_sem still held, but pte unmapped and unlocked.
2768  */
2769 static int do_anonymous_page(struct vm_fault *vmf)
2770 {
2771 	struct vm_area_struct *vma = vmf->vma;
2772 	struct mem_cgroup *memcg;
2773 	struct page *page;
2774 	pte_t entry;
2775 
2776 	/* File mapping without ->vm_ops ? */
2777 	if (vma->vm_flags & VM_SHARED)
2778 		return VM_FAULT_SIGBUS;
2779 
2780 	/* Check if we need to add a guard page to the stack */
2781 	if (check_stack_guard_page(vma, vmf->address) < 0)
2782 		return VM_FAULT_SIGSEGV;
2783 
2784 	/*
2785 	 * Use pte_alloc() instead of pte_alloc_map().  We can't run
2786 	 * pte_offset_map() on pmds where a huge pmd might be created
2787 	 * from a different thread.
2788 	 *
2789 	 * pte_alloc_map() is safe to use under down_write(mmap_sem) or when
2790 	 * parallel threads are excluded by other means.
2791 	 *
2792 	 * Here we only have down_read(mmap_sem).
2793 	 */
2794 	if (pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))
2795 		return VM_FAULT_OOM;
2796 
2797 	/* See the comment in pte_alloc_one_map() */
2798 	if (unlikely(pmd_trans_unstable(vmf->pmd)))
2799 		return 0;
2800 
2801 	/* Use the zero-page for reads */
2802 	if (!(vmf->flags & FAULT_FLAG_WRITE) &&
2803 			!mm_forbids_zeropage(vma->vm_mm)) {
2804 		entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
2805 						vma->vm_page_prot));
2806 		vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2807 				vmf->address, &vmf->ptl);
2808 		if (!pte_none(*vmf->pte))
2809 			goto unlock;
2810 		/* Deliver the page fault to userland, check inside PT lock */
2811 		if (userfaultfd_missing(vma)) {
2812 			pte_unmap_unlock(vmf->pte, vmf->ptl);
2813 			return handle_userfault(vmf, VM_UFFD_MISSING);
2814 		}
2815 		goto setpte;
2816 	}
2817 
2818 	/* Allocate our own private page. */
2819 	if (unlikely(anon_vma_prepare(vma)))
2820 		goto oom;
2821 	page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
2822 	if (!page)
2823 		goto oom;
2824 
2825 	if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, &memcg, false))
2826 		goto oom_free_page;
2827 
2828 	/*
2829 	 * The memory barrier inside __SetPageUptodate makes sure that
2830 	 * preceeding stores to the page contents become visible before
2831 	 * the set_pte_at() write.
2832 	 */
2833 	__SetPageUptodate(page);
2834 
2835 	entry = mk_pte(page, vma->vm_page_prot);
2836 	if (vma->vm_flags & VM_WRITE)
2837 		entry = pte_mkwrite(pte_mkdirty(entry));
2838 
2839 	vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
2840 			&vmf->ptl);
2841 	if (!pte_none(*vmf->pte))
2842 		goto release;
2843 
2844 	/* Deliver the page fault to userland, check inside PT lock */
2845 	if (userfaultfd_missing(vma)) {
2846 		pte_unmap_unlock(vmf->pte, vmf->ptl);
2847 		mem_cgroup_cancel_charge(page, memcg, false);
2848 		put_page(page);
2849 		return handle_userfault(vmf, VM_UFFD_MISSING);
2850 	}
2851 
2852 	inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
2853 	page_add_new_anon_rmap(page, vma, vmf->address, false);
2854 	mem_cgroup_commit_charge(page, memcg, false, false);
2855 	lru_cache_add_active_or_unevictable(page, vma);
2856 setpte:
2857 	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
2858 
2859 	/* No need to invalidate - it was non-present before */
2860 	update_mmu_cache(vma, vmf->address, vmf->pte);
2861 unlock:
2862 	pte_unmap_unlock(vmf->pte, vmf->ptl);
2863 	return 0;
2864 release:
2865 	mem_cgroup_cancel_charge(page, memcg, false);
2866 	put_page(page);
2867 	goto unlock;
2868 oom_free_page:
2869 	put_page(page);
2870 oom:
2871 	return VM_FAULT_OOM;
2872 }
2873 
2874 /*
2875  * The mmap_sem must have been held on entry, and may have been
2876  * released depending on flags and vma->vm_ops->fault() return value.
2877  * See filemap_fault() and __lock_page_retry().
2878  */
2879 static int __do_fault(struct vm_fault *vmf)
2880 {
2881 	struct vm_area_struct *vma = vmf->vma;
2882 	int ret;
2883 
2884 	ret = vma->vm_ops->fault(vmf);
2885 	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
2886 			    VM_FAULT_DONE_COW)))
2887 		return ret;
2888 
2889 	if (unlikely(PageHWPoison(vmf->page))) {
2890 		if (ret & VM_FAULT_LOCKED)
2891 			unlock_page(vmf->page);
2892 		put_page(vmf->page);
2893 		vmf->page = NULL;
2894 		return VM_FAULT_HWPOISON;
2895 	}
2896 
2897 	if (unlikely(!(ret & VM_FAULT_LOCKED)))
2898 		lock_page(vmf->page);
2899 	else
2900 		VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page);
2901 
2902 	return ret;
2903 }
2904 
2905 static int pte_alloc_one_map(struct vm_fault *vmf)
2906 {
2907 	struct vm_area_struct *vma = vmf->vma;
2908 
2909 	if (!pmd_none(*vmf->pmd))
2910 		goto map_pte;
2911 	if (vmf->prealloc_pte) {
2912 		vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
2913 		if (unlikely(!pmd_none(*vmf->pmd))) {
2914 			spin_unlock(vmf->ptl);
2915 			goto map_pte;
2916 		}
2917 
2918 		atomic_long_inc(&vma->vm_mm->nr_ptes);
2919 		pmd_populate(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
2920 		spin_unlock(vmf->ptl);
2921 		vmf->prealloc_pte = NULL;
2922 	} else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))) {
2923 		return VM_FAULT_OOM;
2924 	}
2925 map_pte:
2926 	/*
2927 	 * If a huge pmd materialized under us just retry later.  Use
2928 	 * pmd_trans_unstable() instead of pmd_trans_huge() to ensure the pmd
2929 	 * didn't become pmd_trans_huge under us and then back to pmd_none, as
2930 	 * a result of MADV_DONTNEED running immediately after a huge pmd fault
2931 	 * in a different thread of this mm, in turn leading to a misleading
2932 	 * pmd_trans_huge() retval.  All we have to ensure is that it is a
2933 	 * regular pmd that we can walk with pte_offset_map() and we can do that
2934 	 * through an atomic read in C, which is what pmd_trans_unstable()
2935 	 * provides.
2936 	 */
2937 	if (pmd_trans_unstable(vmf->pmd) || pmd_devmap(*vmf->pmd))
2938 		return VM_FAULT_NOPAGE;
2939 
2940 	vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
2941 			&vmf->ptl);
2942 	return 0;
2943 }
2944 
2945 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
2946 
2947 #define HPAGE_CACHE_INDEX_MASK (HPAGE_PMD_NR - 1)
2948 static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
2949 		unsigned long haddr)
2950 {
2951 	if (((vma->vm_start >> PAGE_SHIFT) & HPAGE_CACHE_INDEX_MASK) !=
2952 			(vma->vm_pgoff & HPAGE_CACHE_INDEX_MASK))
2953 		return false;
2954 	if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
2955 		return false;
2956 	return true;
2957 }
2958 
2959 static void deposit_prealloc_pte(struct vm_fault *vmf)
2960 {
2961 	struct vm_area_struct *vma = vmf->vma;
2962 
2963 	pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
2964 	/*
2965 	 * We are going to consume the prealloc table,
2966 	 * count that as nr_ptes.
2967 	 */
2968 	atomic_long_inc(&vma->vm_mm->nr_ptes);
2969 	vmf->prealloc_pte = NULL;
2970 }
2971 
2972 static int do_set_pmd(struct vm_fault *vmf, struct page *page)
2973 {
2974 	struct vm_area_struct *vma = vmf->vma;
2975 	bool write = vmf->flags & FAULT_FLAG_WRITE;
2976 	unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
2977 	pmd_t entry;
2978 	int i, ret;
2979 
2980 	if (!transhuge_vma_suitable(vma, haddr))
2981 		return VM_FAULT_FALLBACK;
2982 
2983 	ret = VM_FAULT_FALLBACK;
2984 	page = compound_head(page);
2985 
2986 	/*
2987 	 * Archs like ppc64 need additonal space to store information
2988 	 * related to pte entry. Use the preallocated table for that.
2989 	 */
2990 	if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
2991 		vmf->prealloc_pte = pte_alloc_one(vma->vm_mm, vmf->address);
2992 		if (!vmf->prealloc_pte)
2993 			return VM_FAULT_OOM;
2994 		smp_wmb(); /* See comment in __pte_alloc() */
2995 	}
2996 
2997 	vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
2998 	if (unlikely(!pmd_none(*vmf->pmd)))
2999 		goto out;
3000 
3001 	for (i = 0; i < HPAGE_PMD_NR; i++)
3002 		flush_icache_page(vma, page + i);
3003 
3004 	entry = mk_huge_pmd(page, vma->vm_page_prot);
3005 	if (write)
3006 		entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
3007 
3008 	add_mm_counter(vma->vm_mm, MM_FILEPAGES, HPAGE_PMD_NR);
3009 	page_add_file_rmap(page, true);
3010 	/*
3011 	 * deposit and withdraw with pmd lock held
3012 	 */
3013 	if (arch_needs_pgtable_deposit())
3014 		deposit_prealloc_pte(vmf);
3015 
3016 	set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
3017 
3018 	update_mmu_cache_pmd(vma, haddr, vmf->pmd);
3019 
3020 	/* fault is handled */
3021 	ret = 0;
3022 	count_vm_event(THP_FILE_MAPPED);
3023 out:
3024 	spin_unlock(vmf->ptl);
3025 	return ret;
3026 }
3027 #else
3028 static int do_set_pmd(struct vm_fault *vmf, struct page *page)
3029 {
3030 	BUILD_BUG();
3031 	return 0;
3032 }
3033 #endif
3034 
3035 /**
3036  * alloc_set_pte - setup new PTE entry for given page and add reverse page
3037  * mapping. If needed, the fucntion allocates page table or use pre-allocated.
3038  *
3039  * @vmf: fault environment
3040  * @memcg: memcg to charge page (only for private mappings)
3041  * @page: page to map
3042  *
3043  * Caller must take care of unlocking vmf->ptl, if vmf->pte is non-NULL on
3044  * return.
3045  *
3046  * Target users are page handler itself and implementations of
3047  * vm_ops->map_pages.
3048  */
3049 int alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,
3050 		struct page *page)
3051 {
3052 	struct vm_area_struct *vma = vmf->vma;
3053 	bool write = vmf->flags & FAULT_FLAG_WRITE;
3054 	pte_t entry;
3055 	int ret;
3056 
3057 	if (pmd_none(*vmf->pmd) && PageTransCompound(page) &&
3058 			IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
3059 		/* THP on COW? */
3060 		VM_BUG_ON_PAGE(memcg, page);
3061 
3062 		ret = do_set_pmd(vmf, page);
3063 		if (ret != VM_FAULT_FALLBACK)
3064 			return ret;
3065 	}
3066 
3067 	if (!vmf->pte) {
3068 		ret = pte_alloc_one_map(vmf);
3069 		if (ret)
3070 			return ret;
3071 	}
3072 
3073 	/* Re-check under ptl */
3074 	if (unlikely(!pte_none(*vmf->pte)))
3075 		return VM_FAULT_NOPAGE;
3076 
3077 	flush_icache_page(vma, page);
3078 	entry = mk_pte(page, vma->vm_page_prot);
3079 	if (write)
3080 		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3081 	/* copy-on-write page */
3082 	if (write && !(vma->vm_flags & VM_SHARED)) {
3083 		inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3084 		page_add_new_anon_rmap(page, vma, vmf->address, false);
3085 		mem_cgroup_commit_charge(page, memcg, false, false);
3086 		lru_cache_add_active_or_unevictable(page, vma);
3087 	} else {
3088 		inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
3089 		page_add_file_rmap(page, false);
3090 	}
3091 	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3092 
3093 	/* no need to invalidate: a not-present page won't be cached */
3094 	update_mmu_cache(vma, vmf->address, vmf->pte);
3095 
3096 	return 0;
3097 }
3098 
3099 
3100 /**
3101  * finish_fault - finish page fault once we have prepared the page to fault
3102  *
3103  * @vmf: structure describing the fault
3104  *
3105  * This function handles all that is needed to finish a page fault once the
3106  * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
3107  * given page, adds reverse page mapping, handles memcg charges and LRU
3108  * addition. The function returns 0 on success, VM_FAULT_ code in case of
3109  * error.
3110  *
3111  * The function expects the page to be locked and on success it consumes a
3112  * reference of a page being mapped (for the PTE which maps it).
3113  */
3114 int finish_fault(struct vm_fault *vmf)
3115 {
3116 	struct page *page;
3117 	int ret;
3118 
3119 	/* Did we COW the page? */
3120 	if ((vmf->flags & FAULT_FLAG_WRITE) &&
3121 	    !(vmf->vma->vm_flags & VM_SHARED))
3122 		page = vmf->cow_page;
3123 	else
3124 		page = vmf->page;
3125 	ret = alloc_set_pte(vmf, vmf->memcg, page);
3126 	if (vmf->pte)
3127 		pte_unmap_unlock(vmf->pte, vmf->ptl);
3128 	return ret;
3129 }
3130 
3131 static unsigned long fault_around_bytes __read_mostly =
3132 	rounddown_pow_of_two(65536);
3133 
3134 #ifdef CONFIG_DEBUG_FS
3135 static int fault_around_bytes_get(void *data, u64 *val)
3136 {
3137 	*val = fault_around_bytes;
3138 	return 0;
3139 }
3140 
3141 /*
3142  * fault_around_pages() and fault_around_mask() expects fault_around_bytes
3143  * rounded down to nearest page order. It's what do_fault_around() expects to
3144  * see.
3145  */
3146 static int fault_around_bytes_set(void *data, u64 val)
3147 {
3148 	if (val / PAGE_SIZE > PTRS_PER_PTE)
3149 		return -EINVAL;
3150 	if (val > PAGE_SIZE)
3151 		fault_around_bytes = rounddown_pow_of_two(val);
3152 	else
3153 		fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
3154 	return 0;
3155 }
3156 DEFINE_SIMPLE_ATTRIBUTE(fault_around_bytes_fops,
3157 		fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
3158 
3159 static int __init fault_around_debugfs(void)
3160 {
3161 	void *ret;
3162 
3163 	ret = debugfs_create_file("fault_around_bytes", 0644, NULL, NULL,
3164 			&fault_around_bytes_fops);
3165 	if (!ret)
3166 		pr_warn("Failed to create fault_around_bytes in debugfs");
3167 	return 0;
3168 }
3169 late_initcall(fault_around_debugfs);
3170 #endif
3171 
3172 /*
3173  * do_fault_around() tries to map few pages around the fault address. The hope
3174  * is that the pages will be needed soon and this will lower the number of
3175  * faults to handle.
3176  *
3177  * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
3178  * not ready to be mapped: not up-to-date, locked, etc.
3179  *
3180  * This function is called with the page table lock taken. In the split ptlock
3181  * case the page table lock only protects only those entries which belong to
3182  * the page table corresponding to the fault address.
3183  *
3184  * This function doesn't cross the VMA boundaries, in order to call map_pages()
3185  * only once.
3186  *
3187  * fault_around_pages() defines how many pages we'll try to map.
3188  * do_fault_around() expects it to return a power of two less than or equal to
3189  * PTRS_PER_PTE.
3190  *
3191  * The virtual address of the area that we map is naturally aligned to the
3192  * fault_around_pages() value (and therefore to page order).  This way it's
3193  * easier to guarantee that we don't cross page table boundaries.
3194  */
3195 static int do_fault_around(struct vm_fault *vmf)
3196 {
3197 	unsigned long address = vmf->address, nr_pages, mask;
3198 	pgoff_t start_pgoff = vmf->pgoff;
3199 	pgoff_t end_pgoff;
3200 	int off, ret = 0;
3201 
3202 	nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
3203 	mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
3204 
3205 	vmf->address = max(address & mask, vmf->vma->vm_start);
3206 	off = ((address - vmf->address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
3207 	start_pgoff -= off;
3208 
3209 	/*
3210 	 *  end_pgoff is either end of page table or end of vma
3211 	 *  or fault_around_pages() from start_pgoff, depending what is nearest.
3212 	 */
3213 	end_pgoff = start_pgoff -
3214 		((vmf->address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
3215 		PTRS_PER_PTE - 1;
3216 	end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1,
3217 			start_pgoff + nr_pages - 1);
3218 
3219 	if (pmd_none(*vmf->pmd)) {
3220 		vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm,
3221 						  vmf->address);
3222 		if (!vmf->prealloc_pte)
3223 			goto out;
3224 		smp_wmb(); /* See comment in __pte_alloc() */
3225 	}
3226 
3227 	vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff);
3228 
3229 	/* Huge page is mapped? Page fault is solved */
3230 	if (pmd_trans_huge(*vmf->pmd)) {
3231 		ret = VM_FAULT_NOPAGE;
3232 		goto out;
3233 	}
3234 
3235 	/* ->map_pages() haven't done anything useful. Cold page cache? */
3236 	if (!vmf->pte)
3237 		goto out;
3238 
3239 	/* check if the page fault is solved */
3240 	vmf->pte -= (vmf->address >> PAGE_SHIFT) - (address >> PAGE_SHIFT);
3241 	if (!pte_none(*vmf->pte))
3242 		ret = VM_FAULT_NOPAGE;
3243 	pte_unmap_unlock(vmf->pte, vmf->ptl);
3244 out:
3245 	vmf->address = address;
3246 	vmf->pte = NULL;
3247 	return ret;
3248 }
3249 
3250 static int do_read_fault(struct vm_fault *vmf)
3251 {
3252 	struct vm_area_struct *vma = vmf->vma;
3253 	int ret = 0;
3254 
3255 	/*
3256 	 * Let's call ->map_pages() first and use ->fault() as fallback
3257 	 * if page by the offset is not ready to be mapped (cold cache or
3258 	 * something).
3259 	 */
3260 	if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
3261 		ret = do_fault_around(vmf);
3262 		if (ret)
3263 			return ret;
3264 	}
3265 
3266 	ret = __do_fault(vmf);
3267 	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3268 		return ret;
3269 
3270 	ret |= finish_fault(vmf);
3271 	unlock_page(vmf->page);
3272 	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3273 		put_page(vmf->page);
3274 	return ret;
3275 }
3276 
3277 static int do_cow_fault(struct vm_fault *vmf)
3278 {
3279 	struct vm_area_struct *vma = vmf->vma;
3280 	int ret;
3281 
3282 	if (unlikely(anon_vma_prepare(vma)))
3283 		return VM_FAULT_OOM;
3284 
3285 	vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
3286 	if (!vmf->cow_page)
3287 		return VM_FAULT_OOM;
3288 
3289 	if (mem_cgroup_try_charge(vmf->cow_page, vma->vm_mm, GFP_KERNEL,
3290 				&vmf->memcg, false)) {
3291 		put_page(vmf->cow_page);
3292 		return VM_FAULT_OOM;
3293 	}
3294 
3295 	ret = __do_fault(vmf);
3296 	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3297 		goto uncharge_out;
3298 	if (ret & VM_FAULT_DONE_COW)
3299 		return ret;
3300 
3301 	copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
3302 	__SetPageUptodate(vmf->cow_page);
3303 
3304 	ret |= finish_fault(vmf);
3305 	unlock_page(vmf->page);
3306 	put_page(vmf->page);
3307 	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3308 		goto uncharge_out;
3309 	return ret;
3310 uncharge_out:
3311 	mem_cgroup_cancel_charge(vmf->cow_page, vmf->memcg, false);
3312 	put_page(vmf->cow_page);
3313 	return ret;
3314 }
3315 
3316 static int do_shared_fault(struct vm_fault *vmf)
3317 {
3318 	struct vm_area_struct *vma = vmf->vma;
3319 	int ret, tmp;
3320 
3321 	ret = __do_fault(vmf);
3322 	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3323 		return ret;
3324 
3325 	/*
3326 	 * Check if the backing address space wants to know that the page is
3327 	 * about to become writable
3328 	 */
3329 	if (vma->vm_ops->page_mkwrite) {
3330 		unlock_page(vmf->page);
3331 		tmp = do_page_mkwrite(vmf);
3332 		if (unlikely(!tmp ||
3333 				(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3334 			put_page(vmf->page);
3335 			return tmp;
3336 		}
3337 	}
3338 
3339 	ret |= finish_fault(vmf);
3340 	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3341 					VM_FAULT_RETRY))) {
3342 		unlock_page(vmf->page);
3343 		put_page(vmf->page);
3344 		return ret;
3345 	}
3346 
3347 	fault_dirty_shared_page(vma, vmf->page);
3348 	return ret;
3349 }
3350 
3351 /*
3352  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3353  * but allow concurrent faults).
3354  * The mmap_sem may have been released depending on flags and our
3355  * return value.  See filemap_fault() and __lock_page_or_retry().
3356  */
3357 static int do_fault(struct vm_fault *vmf)
3358 {
3359 	struct vm_area_struct *vma = vmf->vma;
3360 	int ret;
3361 
3362 	/* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */
3363 	if (!vma->vm_ops->fault)
3364 		ret = VM_FAULT_SIGBUS;
3365 	else if (!(vmf->flags & FAULT_FLAG_WRITE))
3366 		ret = do_read_fault(vmf);
3367 	else if (!(vma->vm_flags & VM_SHARED))
3368 		ret = do_cow_fault(vmf);
3369 	else
3370 		ret = do_shared_fault(vmf);
3371 
3372 	/* preallocated pagetable is unused: free it */
3373 	if (vmf->prealloc_pte) {
3374 		pte_free(vma->vm_mm, vmf->prealloc_pte);
3375 		vmf->prealloc_pte = NULL;
3376 	}
3377 	return ret;
3378 }
3379 
3380 static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3381 				unsigned long addr, int page_nid,
3382 				int *flags)
3383 {
3384 	get_page(page);
3385 
3386 	count_vm_numa_event(NUMA_HINT_FAULTS);
3387 	if (page_nid == numa_node_id()) {
3388 		count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3389 		*flags |= TNF_FAULT_LOCAL;
3390 	}
3391 
3392 	return mpol_misplaced(page, vma, addr);
3393 }
3394 
3395 static int do_numa_page(struct vm_fault *vmf)
3396 {
3397 	struct vm_area_struct *vma = vmf->vma;
3398 	struct page *page = NULL;
3399 	int page_nid = -1;
3400 	int last_cpupid;
3401 	int target_nid;
3402 	bool migrated = false;
3403 	pte_t pte;
3404 	bool was_writable = pte_savedwrite(vmf->orig_pte);
3405 	int flags = 0;
3406 
3407 	/*
3408 	 * The "pte" at this point cannot be used safely without
3409 	 * validation through pte_unmap_same(). It's of NUMA type but
3410 	 * the pfn may be screwed if the read is non atomic.
3411 	 */
3412 	vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd);
3413 	spin_lock(vmf->ptl);
3414 	if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
3415 		pte_unmap_unlock(vmf->pte, vmf->ptl);
3416 		goto out;
3417 	}
3418 
3419 	/*
3420 	 * Make it present again, Depending on how arch implementes non
3421 	 * accessible ptes, some can allow access by kernel mode.
3422 	 */
3423 	pte = ptep_modify_prot_start(vma->vm_mm, vmf->address, vmf->pte);
3424 	pte = pte_modify(pte, vma->vm_page_prot);
3425 	pte = pte_mkyoung(pte);
3426 	if (was_writable)
3427 		pte = pte_mkwrite(pte);
3428 	ptep_modify_prot_commit(vma->vm_mm, vmf->address, vmf->pte, pte);
3429 	update_mmu_cache(vma, vmf->address, vmf->pte);
3430 
3431 	page = vm_normal_page(vma, vmf->address, pte);
3432 	if (!page) {
3433 		pte_unmap_unlock(vmf->pte, vmf->ptl);
3434 		return 0;
3435 	}
3436 
3437 	/* TODO: handle PTE-mapped THP */
3438 	if (PageCompound(page)) {
3439 		pte_unmap_unlock(vmf->pte, vmf->ptl);
3440 		return 0;
3441 	}
3442 
3443 	/*
3444 	 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
3445 	 * much anyway since they can be in shared cache state. This misses
3446 	 * the case where a mapping is writable but the process never writes
3447 	 * to it but pte_write gets cleared during protection updates and
3448 	 * pte_dirty has unpredictable behaviour between PTE scan updates,
3449 	 * background writeback, dirty balancing and application behaviour.
3450 	 */
3451 	if (!pte_write(pte))
3452 		flags |= TNF_NO_GROUP;
3453 
3454 	/*
3455 	 * Flag if the page is shared between multiple address spaces. This
3456 	 * is later used when determining whether to group tasks together
3457 	 */
3458 	if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
3459 		flags |= TNF_SHARED;
3460 
3461 	last_cpupid = page_cpupid_last(page);
3462 	page_nid = page_to_nid(page);
3463 	target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid,
3464 			&flags);
3465 	pte_unmap_unlock(vmf->pte, vmf->ptl);
3466 	if (target_nid == -1) {
3467 		put_page(page);
3468 		goto out;
3469 	}
3470 
3471 	/* Migrate to the requested node */
3472 	migrated = migrate_misplaced_page(page, vma, target_nid);
3473 	if (migrated) {
3474 		page_nid = target_nid;
3475 		flags |= TNF_MIGRATED;
3476 	} else
3477 		flags |= TNF_MIGRATE_FAIL;
3478 
3479 out:
3480 	if (page_nid != -1)
3481 		task_numa_fault(last_cpupid, page_nid, 1, flags);
3482 	return 0;
3483 }
3484 
3485 static int create_huge_pmd(struct vm_fault *vmf)
3486 {
3487 	if (vma_is_anonymous(vmf->vma))
3488 		return do_huge_pmd_anonymous_page(vmf);
3489 	if (vmf->vma->vm_ops->huge_fault)
3490 		return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
3491 	return VM_FAULT_FALLBACK;
3492 }
3493 
3494 static int wp_huge_pmd(struct vm_fault *vmf, pmd_t orig_pmd)
3495 {
3496 	if (vma_is_anonymous(vmf->vma))
3497 		return do_huge_pmd_wp_page(vmf, orig_pmd);
3498 	if (vmf->vma->vm_ops->huge_fault)
3499 		return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
3500 
3501 	/* COW handled on pte level: split pmd */
3502 	VM_BUG_ON_VMA(vmf->vma->vm_flags & VM_SHARED, vmf->vma);
3503 	__split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL);
3504 
3505 	return VM_FAULT_FALLBACK;
3506 }
3507 
3508 static inline bool vma_is_accessible(struct vm_area_struct *vma)
3509 {
3510 	return vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE);
3511 }
3512 
3513 static int create_huge_pud(struct vm_fault *vmf)
3514 {
3515 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3516 	/* No support for anonymous transparent PUD pages yet */
3517 	if (vma_is_anonymous(vmf->vma))
3518 		return VM_FAULT_FALLBACK;
3519 	if (vmf->vma->vm_ops->huge_fault)
3520 		return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
3521 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
3522 	return VM_FAULT_FALLBACK;
3523 }
3524 
3525 static int wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
3526 {
3527 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3528 	/* No support for anonymous transparent PUD pages yet */
3529 	if (vma_is_anonymous(vmf->vma))
3530 		return VM_FAULT_FALLBACK;
3531 	if (vmf->vma->vm_ops->huge_fault)
3532 		return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
3533 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
3534 	return VM_FAULT_FALLBACK;
3535 }
3536 
3537 /*
3538  * These routines also need to handle stuff like marking pages dirty
3539  * and/or accessed for architectures that don't do it in hardware (most
3540  * RISC architectures).  The early dirtying is also good on the i386.
3541  *
3542  * There is also a hook called "update_mmu_cache()" that architectures
3543  * with external mmu caches can use to update those (ie the Sparc or
3544  * PowerPC hashed page tables that act as extended TLBs).
3545  *
3546  * We enter with non-exclusive mmap_sem (to exclude vma changes, but allow
3547  * concurrent faults).
3548  *
3549  * The mmap_sem may have been released depending on flags and our return value.
3550  * See filemap_fault() and __lock_page_or_retry().
3551  */
3552 static int handle_pte_fault(struct vm_fault *vmf)
3553 {
3554 	pte_t entry;
3555 
3556 	if (unlikely(pmd_none(*vmf->pmd))) {
3557 		/*
3558 		 * Leave __pte_alloc() until later: because vm_ops->fault may
3559 		 * want to allocate huge page, and if we expose page table
3560 		 * for an instant, it will be difficult to retract from
3561 		 * concurrent faults and from rmap lookups.
3562 		 */
3563 		vmf->pte = NULL;
3564 	} else {
3565 		/* See comment in pte_alloc_one_map() */
3566 		if (pmd_trans_unstable(vmf->pmd) || pmd_devmap(*vmf->pmd))
3567 			return 0;
3568 		/*
3569 		 * A regular pmd is established and it can't morph into a huge
3570 		 * pmd from under us anymore at this point because we hold the
3571 		 * mmap_sem read mode and khugepaged takes it in write mode.
3572 		 * So now it's safe to run pte_offset_map().
3573 		 */
3574 		vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
3575 		vmf->orig_pte = *vmf->pte;
3576 
3577 		/*
3578 		 * some architectures can have larger ptes than wordsize,
3579 		 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and
3580 		 * CONFIG_32BIT=y, so READ_ONCE or ACCESS_ONCE cannot guarantee
3581 		 * atomic accesses.  The code below just needs a consistent
3582 		 * view for the ifs and we later double check anyway with the
3583 		 * ptl lock held. So here a barrier will do.
3584 		 */
3585 		barrier();
3586 		if (pte_none(vmf->orig_pte)) {
3587 			pte_unmap(vmf->pte);
3588 			vmf->pte = NULL;
3589 		}
3590 	}
3591 
3592 	if (!vmf->pte) {
3593 		if (vma_is_anonymous(vmf->vma))
3594 			return do_anonymous_page(vmf);
3595 		else
3596 			return do_fault(vmf);
3597 	}
3598 
3599 	if (!pte_present(vmf->orig_pte))
3600 		return do_swap_page(vmf);
3601 
3602 	if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
3603 		return do_numa_page(vmf);
3604 
3605 	vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
3606 	spin_lock(vmf->ptl);
3607 	entry = vmf->orig_pte;
3608 	if (unlikely(!pte_same(*vmf->pte, entry)))
3609 		goto unlock;
3610 	if (vmf->flags & FAULT_FLAG_WRITE) {
3611 		if (!pte_write(entry))
3612 			return do_wp_page(vmf);
3613 		entry = pte_mkdirty(entry);
3614 	}
3615 	entry = pte_mkyoung(entry);
3616 	if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry,
3617 				vmf->flags & FAULT_FLAG_WRITE)) {
3618 		update_mmu_cache(vmf->vma, vmf->address, vmf->pte);
3619 	} else {
3620 		/*
3621 		 * This is needed only for protection faults but the arch code
3622 		 * is not yet telling us if this is a protection fault or not.
3623 		 * This still avoids useless tlb flushes for .text page faults
3624 		 * with threads.
3625 		 */
3626 		if (vmf->flags & FAULT_FLAG_WRITE)
3627 			flush_tlb_fix_spurious_fault(vmf->vma, vmf->address);
3628 	}
3629 unlock:
3630 	pte_unmap_unlock(vmf->pte, vmf->ptl);
3631 	return 0;
3632 }
3633 
3634 /*
3635  * By the time we get here, we already hold the mm semaphore
3636  *
3637  * The mmap_sem may have been released depending on flags and our
3638  * return value.  See filemap_fault() and __lock_page_or_retry().
3639  */
3640 static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
3641 		unsigned int flags)
3642 {
3643 	struct vm_fault vmf = {
3644 		.vma = vma,
3645 		.address = address & PAGE_MASK,
3646 		.flags = flags,
3647 		.pgoff = linear_page_index(vma, address),
3648 		.gfp_mask = __get_fault_gfp_mask(vma),
3649 	};
3650 	struct mm_struct *mm = vma->vm_mm;
3651 	pgd_t *pgd;
3652 	int ret;
3653 
3654 	pgd = pgd_offset(mm, address);
3655 
3656 	vmf.pud = pud_alloc(mm, pgd, address);
3657 	if (!vmf.pud)
3658 		return VM_FAULT_OOM;
3659 	if (pud_none(*vmf.pud) && transparent_hugepage_enabled(vma)) {
3660 		ret = create_huge_pud(&vmf);
3661 		if (!(ret & VM_FAULT_FALLBACK))
3662 			return ret;
3663 	} else {
3664 		pud_t orig_pud = *vmf.pud;
3665 
3666 		barrier();
3667 		if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
3668 			unsigned int dirty = flags & FAULT_FLAG_WRITE;
3669 
3670 			/* NUMA case for anonymous PUDs would go here */
3671 
3672 			if (dirty && !pud_write(orig_pud)) {
3673 				ret = wp_huge_pud(&vmf, orig_pud);
3674 				if (!(ret & VM_FAULT_FALLBACK))
3675 					return ret;
3676 			} else {
3677 				huge_pud_set_accessed(&vmf, orig_pud);
3678 				return 0;
3679 			}
3680 		}
3681 	}
3682 
3683 	vmf.pmd = pmd_alloc(mm, vmf.pud, address);
3684 	if (!vmf.pmd)
3685 		return VM_FAULT_OOM;
3686 	if (pmd_none(*vmf.pmd) && transparent_hugepage_enabled(vma)) {
3687 		ret = create_huge_pmd(&vmf);
3688 		if (!(ret & VM_FAULT_FALLBACK))
3689 			return ret;
3690 	} else {
3691 		pmd_t orig_pmd = *vmf.pmd;
3692 
3693 		barrier();
3694 		if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
3695 			if (pmd_protnone(orig_pmd) && vma_is_accessible(vma))
3696 				return do_huge_pmd_numa_page(&vmf, orig_pmd);
3697 
3698 			if ((vmf.flags & FAULT_FLAG_WRITE) &&
3699 					!pmd_write(orig_pmd)) {
3700 				ret = wp_huge_pmd(&vmf, orig_pmd);
3701 				if (!(ret & VM_FAULT_FALLBACK))
3702 					return ret;
3703 			} else {
3704 				huge_pmd_set_accessed(&vmf, orig_pmd);
3705 				return 0;
3706 			}
3707 		}
3708 	}
3709 
3710 	return handle_pte_fault(&vmf);
3711 }
3712 
3713 /*
3714  * By the time we get here, we already hold the mm semaphore
3715  *
3716  * The mmap_sem may have been released depending on flags and our
3717  * return value.  See filemap_fault() and __lock_page_or_retry().
3718  */
3719 int handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
3720 		unsigned int flags)
3721 {
3722 	int ret;
3723 
3724 	__set_current_state(TASK_RUNNING);
3725 
3726 	count_vm_event(PGFAULT);
3727 	mem_cgroup_count_vm_event(vma->vm_mm, PGFAULT);
3728 
3729 	/* do counter updates before entering really critical section. */
3730 	check_sync_rss_stat(current);
3731 
3732 	/*
3733 	 * Enable the memcg OOM handling for faults triggered in user
3734 	 * space.  Kernel faults are handled more gracefully.
3735 	 */
3736 	if (flags & FAULT_FLAG_USER)
3737 		mem_cgroup_oom_enable();
3738 
3739 	if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
3740 					    flags & FAULT_FLAG_INSTRUCTION,
3741 					    flags & FAULT_FLAG_REMOTE))
3742 		return VM_FAULT_SIGSEGV;
3743 
3744 	if (unlikely(is_vm_hugetlb_page(vma)))
3745 		ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
3746 	else
3747 		ret = __handle_mm_fault(vma, address, flags);
3748 
3749 	if (flags & FAULT_FLAG_USER) {
3750 		mem_cgroup_oom_disable();
3751 		/*
3752 		 * The task may have entered a memcg OOM situation but
3753 		 * if the allocation error was handled gracefully (no
3754 		 * VM_FAULT_OOM), there is no need to kill anything.
3755 		 * Just clean up the OOM state peacefully.
3756 		 */
3757 		if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
3758 			mem_cgroup_oom_synchronize(false);
3759 	}
3760 
3761 	/*
3762 	 * This mm has been already reaped by the oom reaper and so the
3763 	 * refault cannot be trusted in general. Anonymous refaults would
3764 	 * lose data and give a zero page instead e.g. This is especially
3765 	 * problem for use_mm() because regular tasks will just die and
3766 	 * the corrupted data will not be visible anywhere while kthread
3767 	 * will outlive the oom victim and potentially propagate the date
3768 	 * further.
3769 	 */
3770 	if (unlikely((current->flags & PF_KTHREAD) && !(ret & VM_FAULT_ERROR)
3771 				&& test_bit(MMF_UNSTABLE, &vma->vm_mm->flags)))
3772 		ret = VM_FAULT_SIGBUS;
3773 
3774 	return ret;
3775 }
3776 EXPORT_SYMBOL_GPL(handle_mm_fault);
3777 
3778 #ifndef __PAGETABLE_PUD_FOLDED
3779 /*
3780  * Allocate page upper directory.
3781  * We've already handled the fast-path in-line.
3782  */
3783 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
3784 {
3785 	pud_t *new = pud_alloc_one(mm, address);
3786 	if (!new)
3787 		return -ENOMEM;
3788 
3789 	smp_wmb(); /* See comment in __pte_alloc */
3790 
3791 	spin_lock(&mm->page_table_lock);
3792 	if (pgd_present(*pgd))		/* Another has populated it */
3793 		pud_free(mm, new);
3794 	else
3795 		pgd_populate(mm, pgd, new);
3796 	spin_unlock(&mm->page_table_lock);
3797 	return 0;
3798 }
3799 #endif /* __PAGETABLE_PUD_FOLDED */
3800 
3801 #ifndef __PAGETABLE_PMD_FOLDED
3802 /*
3803  * Allocate page middle directory.
3804  * We've already handled the fast-path in-line.
3805  */
3806 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
3807 {
3808 	spinlock_t *ptl;
3809 	pmd_t *new = pmd_alloc_one(mm, address);
3810 	if (!new)
3811 		return -ENOMEM;
3812 
3813 	smp_wmb(); /* See comment in __pte_alloc */
3814 
3815 	ptl = pud_lock(mm, pud);
3816 #ifndef __ARCH_HAS_4LEVEL_HACK
3817 	if (!pud_present(*pud)) {
3818 		mm_inc_nr_pmds(mm);
3819 		pud_populate(mm, pud, new);
3820 	} else	/* Another has populated it */
3821 		pmd_free(mm, new);
3822 #else
3823 	if (!pgd_present(*pud)) {
3824 		mm_inc_nr_pmds(mm);
3825 		pgd_populate(mm, pud, new);
3826 	} else /* Another has populated it */
3827 		pmd_free(mm, new);
3828 #endif /* __ARCH_HAS_4LEVEL_HACK */
3829 	spin_unlock(ptl);
3830 	return 0;
3831 }
3832 #endif /* __PAGETABLE_PMD_FOLDED */
3833 
3834 static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
3835 		pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
3836 {
3837 	pgd_t *pgd;
3838 	pud_t *pud;
3839 	pmd_t *pmd;
3840 	pte_t *ptep;
3841 
3842 	pgd = pgd_offset(mm, address);
3843 	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3844 		goto out;
3845 
3846 	pud = pud_offset(pgd, address);
3847 	if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3848 		goto out;
3849 
3850 	pmd = pmd_offset(pud, address);
3851 	VM_BUG_ON(pmd_trans_huge(*pmd));
3852 
3853 	if (pmd_huge(*pmd)) {
3854 		if (!pmdpp)
3855 			goto out;
3856 
3857 		*ptlp = pmd_lock(mm, pmd);
3858 		if (pmd_huge(*pmd)) {
3859 			*pmdpp = pmd;
3860 			return 0;
3861 		}
3862 		spin_unlock(*ptlp);
3863 	}
3864 
3865 	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3866 		goto out;
3867 
3868 	ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3869 	if (!ptep)
3870 		goto out;
3871 	if (!pte_present(*ptep))
3872 		goto unlock;
3873 	*ptepp = ptep;
3874 	return 0;
3875 unlock:
3876 	pte_unmap_unlock(ptep, *ptlp);
3877 out:
3878 	return -EINVAL;
3879 }
3880 
3881 static inline int follow_pte(struct mm_struct *mm, unsigned long address,
3882 			     pte_t **ptepp, spinlock_t **ptlp)
3883 {
3884 	int res;
3885 
3886 	/* (void) is needed to make gcc happy */
3887 	(void) __cond_lock(*ptlp,
3888 			   !(res = __follow_pte_pmd(mm, address, ptepp, NULL,
3889 					   ptlp)));
3890 	return res;
3891 }
3892 
3893 int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
3894 			     pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
3895 {
3896 	int res;
3897 
3898 	/* (void) is needed to make gcc happy */
3899 	(void) __cond_lock(*ptlp,
3900 			   !(res = __follow_pte_pmd(mm, address, ptepp, pmdpp,
3901 					   ptlp)));
3902 	return res;
3903 }
3904 EXPORT_SYMBOL(follow_pte_pmd);
3905 
3906 /**
3907  * follow_pfn - look up PFN at a user virtual address
3908  * @vma: memory mapping
3909  * @address: user virtual address
3910  * @pfn: location to store found PFN
3911  *
3912  * Only IO mappings and raw PFN mappings are allowed.
3913  *
3914  * Returns zero and the pfn at @pfn on success, -ve otherwise.
3915  */
3916 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
3917 	unsigned long *pfn)
3918 {
3919 	int ret = -EINVAL;
3920 	spinlock_t *ptl;
3921 	pte_t *ptep;
3922 
3923 	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3924 		return ret;
3925 
3926 	ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
3927 	if (ret)
3928 		return ret;
3929 	*pfn = pte_pfn(*ptep);
3930 	pte_unmap_unlock(ptep, ptl);
3931 	return 0;
3932 }
3933 EXPORT_SYMBOL(follow_pfn);
3934 
3935 #ifdef CONFIG_HAVE_IOREMAP_PROT
3936 int follow_phys(struct vm_area_struct *vma,
3937 		unsigned long address, unsigned int flags,
3938 		unsigned long *prot, resource_size_t *phys)
3939 {
3940 	int ret = -EINVAL;
3941 	pte_t *ptep, pte;
3942 	spinlock_t *ptl;
3943 
3944 	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3945 		goto out;
3946 
3947 	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3948 		goto out;
3949 	pte = *ptep;
3950 
3951 	if ((flags & FOLL_WRITE) && !pte_write(pte))
3952 		goto unlock;
3953 
3954 	*prot = pgprot_val(pte_pgprot(pte));
3955 	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3956 
3957 	ret = 0;
3958 unlock:
3959 	pte_unmap_unlock(ptep, ptl);
3960 out:
3961 	return ret;
3962 }
3963 
3964 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
3965 			void *buf, int len, int write)
3966 {
3967 	resource_size_t phys_addr;
3968 	unsigned long prot = 0;
3969 	void __iomem *maddr;
3970 	int offset = addr & (PAGE_SIZE-1);
3971 
3972 	if (follow_phys(vma, addr, write, &prot, &phys_addr))
3973 		return -EINVAL;
3974 
3975 	maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
3976 	if (write)
3977 		memcpy_toio(maddr + offset, buf, len);
3978 	else
3979 		memcpy_fromio(buf, maddr + offset, len);
3980 	iounmap(maddr);
3981 
3982 	return len;
3983 }
3984 EXPORT_SYMBOL_GPL(generic_access_phys);
3985 #endif
3986 
3987 /*
3988  * Access another process' address space as given in mm.  If non-NULL, use the
3989  * given task for page fault accounting.
3990  */
3991 int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
3992 		unsigned long addr, void *buf, int len, unsigned int gup_flags)
3993 {
3994 	struct vm_area_struct *vma;
3995 	void *old_buf = buf;
3996 	int write = gup_flags & FOLL_WRITE;
3997 
3998 	down_read(&mm->mmap_sem);
3999 	/* ignore errors, just check how much was successfully transferred */
4000 	while (len) {
4001 		int bytes, ret, offset;
4002 		void *maddr;
4003 		struct page *page = NULL;
4004 
4005 		ret = get_user_pages_remote(tsk, mm, addr, 1,
4006 				gup_flags, &page, &vma, NULL);
4007 		if (ret <= 0) {
4008 #ifndef CONFIG_HAVE_IOREMAP_PROT
4009 			break;
4010 #else
4011 			/*
4012 			 * Check if this is a VM_IO | VM_PFNMAP VMA, which
4013 			 * we can access using slightly different code.
4014 			 */
4015 			vma = find_vma(mm, addr);
4016 			if (!vma || vma->vm_start > addr)
4017 				break;
4018 			if (vma->vm_ops && vma->vm_ops->access)
4019 				ret = vma->vm_ops->access(vma, addr, buf,
4020 							  len, write);
4021 			if (ret <= 0)
4022 				break;
4023 			bytes = ret;
4024 #endif
4025 		} else {
4026 			bytes = len;
4027 			offset = addr & (PAGE_SIZE-1);
4028 			if (bytes > PAGE_SIZE-offset)
4029 				bytes = PAGE_SIZE-offset;
4030 
4031 			maddr = kmap(page);
4032 			if (write) {
4033 				copy_to_user_page(vma, page, addr,
4034 						  maddr + offset, buf, bytes);
4035 				set_page_dirty_lock(page);
4036 			} else {
4037 				copy_from_user_page(vma, page, addr,
4038 						    buf, maddr + offset, bytes);
4039 			}
4040 			kunmap(page);
4041 			put_page(page);
4042 		}
4043 		len -= bytes;
4044 		buf += bytes;
4045 		addr += bytes;
4046 	}
4047 	up_read(&mm->mmap_sem);
4048 
4049 	return buf - old_buf;
4050 }
4051 
4052 /**
4053  * access_remote_vm - access another process' address space
4054  * @mm:		the mm_struct of the target address space
4055  * @addr:	start address to access
4056  * @buf:	source or destination buffer
4057  * @len:	number of bytes to transfer
4058  * @gup_flags:	flags modifying lookup behaviour
4059  *
4060  * The caller must hold a reference on @mm.
4061  */
4062 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
4063 		void *buf, int len, unsigned int gup_flags)
4064 {
4065 	return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
4066 }
4067 
4068 /*
4069  * Access another process' address space.
4070  * Source/target buffer must be kernel space,
4071  * Do not walk the page table directly, use get_user_pages
4072  */
4073 int access_process_vm(struct task_struct *tsk, unsigned long addr,
4074 		void *buf, int len, unsigned int gup_flags)
4075 {
4076 	struct mm_struct *mm;
4077 	int ret;
4078 
4079 	mm = get_task_mm(tsk);
4080 	if (!mm)
4081 		return 0;
4082 
4083 	ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
4084 
4085 	mmput(mm);
4086 
4087 	return ret;
4088 }
4089 EXPORT_SYMBOL_GPL(access_process_vm);
4090 
4091 /*
4092  * Print the name of a VMA.
4093  */
4094 void print_vma_addr(char *prefix, unsigned long ip)
4095 {
4096 	struct mm_struct *mm = current->mm;
4097 	struct vm_area_struct *vma;
4098 
4099 	/*
4100 	 * Do not print if we are in atomic
4101 	 * contexts (in exception stacks, etc.):
4102 	 */
4103 	if (preempt_count())
4104 		return;
4105 
4106 	down_read(&mm->mmap_sem);
4107 	vma = find_vma(mm, ip);
4108 	if (vma && vma->vm_file) {
4109 		struct file *f = vma->vm_file;
4110 		char *buf = (char *)__get_free_page(GFP_KERNEL);
4111 		if (buf) {
4112 			char *p;
4113 
4114 			p = file_path(f, buf, PAGE_SIZE);
4115 			if (IS_ERR(p))
4116 				p = "?";
4117 			printk("%s%s[%lx+%lx]", prefix, kbasename(p),
4118 					vma->vm_start,
4119 					vma->vm_end - vma->vm_start);
4120 			free_page((unsigned long)buf);
4121 		}
4122 	}
4123 	up_read(&mm->mmap_sem);
4124 }
4125 
4126 #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4127 void __might_fault(const char *file, int line)
4128 {
4129 	/*
4130 	 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
4131 	 * holding the mmap_sem, this is safe because kernel memory doesn't
4132 	 * get paged out, therefore we'll never actually fault, and the
4133 	 * below annotations will generate false positives.
4134 	 */
4135 	if (segment_eq(get_fs(), KERNEL_DS))
4136 		return;
4137 	if (pagefault_disabled())
4138 		return;
4139 	__might_sleep(file, line, 0);
4140 #if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4141 	if (current->mm)
4142 		might_lock_read(&current->mm->mmap_sem);
4143 #endif
4144 }
4145 EXPORT_SYMBOL(__might_fault);
4146 #endif
4147 
4148 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
4149 static void clear_gigantic_page(struct page *page,
4150 				unsigned long addr,
4151 				unsigned int pages_per_huge_page)
4152 {
4153 	int i;
4154 	struct page *p = page;
4155 
4156 	might_sleep();
4157 	for (i = 0; i < pages_per_huge_page;
4158 	     i++, p = mem_map_next(p, page, i)) {
4159 		cond_resched();
4160 		clear_user_highpage(p, addr + i * PAGE_SIZE);
4161 	}
4162 }
4163 void clear_huge_page(struct page *page,
4164 		     unsigned long addr, unsigned int pages_per_huge_page)
4165 {
4166 	int i;
4167 
4168 	if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4169 		clear_gigantic_page(page, addr, pages_per_huge_page);
4170 		return;
4171 	}
4172 
4173 	might_sleep();
4174 	for (i = 0; i < pages_per_huge_page; i++) {
4175 		cond_resched();
4176 		clear_user_highpage(page + i, addr + i * PAGE_SIZE);
4177 	}
4178 }
4179 
4180 static void copy_user_gigantic_page(struct page *dst, struct page *src,
4181 				    unsigned long addr,
4182 				    struct vm_area_struct *vma,
4183 				    unsigned int pages_per_huge_page)
4184 {
4185 	int i;
4186 	struct page *dst_base = dst;
4187 	struct page *src_base = src;
4188 
4189 	for (i = 0; i < pages_per_huge_page; ) {
4190 		cond_resched();
4191 		copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
4192 
4193 		i++;
4194 		dst = mem_map_next(dst, dst_base, i);
4195 		src = mem_map_next(src, src_base, i);
4196 	}
4197 }
4198 
4199 void copy_user_huge_page(struct page *dst, struct page *src,
4200 			 unsigned long addr, struct vm_area_struct *vma,
4201 			 unsigned int pages_per_huge_page)
4202 {
4203 	int i;
4204 
4205 	if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4206 		copy_user_gigantic_page(dst, src, addr, vma,
4207 					pages_per_huge_page);
4208 		return;
4209 	}
4210 
4211 	might_sleep();
4212 	for (i = 0; i < pages_per_huge_page; i++) {
4213 		cond_resched();
4214 		copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
4215 	}
4216 }
4217 
4218 long copy_huge_page_from_user(struct page *dst_page,
4219 				const void __user *usr_src,
4220 				unsigned int pages_per_huge_page,
4221 				bool allow_pagefault)
4222 {
4223 	void *src = (void *)usr_src;
4224 	void *page_kaddr;
4225 	unsigned long i, rc = 0;
4226 	unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
4227 
4228 	for (i = 0; i < pages_per_huge_page; i++) {
4229 		if (allow_pagefault)
4230 			page_kaddr = kmap(dst_page + i);
4231 		else
4232 			page_kaddr = kmap_atomic(dst_page + i);
4233 		rc = copy_from_user(page_kaddr,
4234 				(const void __user *)(src + i * PAGE_SIZE),
4235 				PAGE_SIZE);
4236 		if (allow_pagefault)
4237 			kunmap(dst_page + i);
4238 		else
4239 			kunmap_atomic(page_kaddr);
4240 
4241 		ret_val -= (PAGE_SIZE - rc);
4242 		if (rc)
4243 			break;
4244 
4245 		cond_resched();
4246 	}
4247 	return ret_val;
4248 }
4249 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
4250 
4251 #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
4252 
4253 static struct kmem_cache *page_ptl_cachep;
4254 
4255 void __init ptlock_cache_init(void)
4256 {
4257 	page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
4258 			SLAB_PANIC, NULL);
4259 }
4260 
4261 bool ptlock_alloc(struct page *page)
4262 {
4263 	spinlock_t *ptl;
4264 
4265 	ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
4266 	if (!ptl)
4267 		return false;
4268 	page->ptl = ptl;
4269 	return true;
4270 }
4271 
4272 void ptlock_free(struct page *page)
4273 {
4274 	kmem_cache_free(page_ptl_cachep, page->ptl);
4275 }
4276 #endif
4277