xref: /openbmc/linux/mm/memory_hotplug.c (revision 4f3db074)
1 /*
2  *  linux/mm/memory_hotplug.c
3  *
4  *  Copyright (C)
5  */
6 
7 #include <linux/stddef.h>
8 #include <linux/mm.h>
9 #include <linux/swap.h>
10 #include <linux/interrupt.h>
11 #include <linux/pagemap.h>
12 #include <linux/compiler.h>
13 #include <linux/export.h>
14 #include <linux/pagevec.h>
15 #include <linux/writeback.h>
16 #include <linux/slab.h>
17 #include <linux/sysctl.h>
18 #include <linux/cpu.h>
19 #include <linux/memory.h>
20 #include <linux/memory_hotplug.h>
21 #include <linux/highmem.h>
22 #include <linux/vmalloc.h>
23 #include <linux/ioport.h>
24 #include <linux/delay.h>
25 #include <linux/migrate.h>
26 #include <linux/page-isolation.h>
27 #include <linux/pfn.h>
28 #include <linux/suspend.h>
29 #include <linux/mm_inline.h>
30 #include <linux/firmware-map.h>
31 #include <linux/stop_machine.h>
32 #include <linux/hugetlb.h>
33 #include <linux/memblock.h>
34 #include <linux/bootmem.h>
35 
36 #include <asm/tlbflush.h>
37 
38 #include "internal.h"
39 
40 /*
41  * online_page_callback contains pointer to current page onlining function.
42  * Initially it is generic_online_page(). If it is required it could be
43  * changed by calling set_online_page_callback() for callback registration
44  * and restore_online_page_callback() for generic callback restore.
45  */
46 
47 static void generic_online_page(struct page *page);
48 
49 static online_page_callback_t online_page_callback = generic_online_page;
50 static DEFINE_MUTEX(online_page_callback_lock);
51 
52 /* The same as the cpu_hotplug lock, but for memory hotplug. */
53 static struct {
54 	struct task_struct *active_writer;
55 	struct mutex lock; /* Synchronizes accesses to refcount, */
56 	/*
57 	 * Also blocks the new readers during
58 	 * an ongoing mem hotplug operation.
59 	 */
60 	int refcount;
61 
62 #ifdef CONFIG_DEBUG_LOCK_ALLOC
63 	struct lockdep_map dep_map;
64 #endif
65 } mem_hotplug = {
66 	.active_writer = NULL,
67 	.lock = __MUTEX_INITIALIZER(mem_hotplug.lock),
68 	.refcount = 0,
69 #ifdef CONFIG_DEBUG_LOCK_ALLOC
70 	.dep_map = {.name = "mem_hotplug.lock" },
71 #endif
72 };
73 
74 /* Lockdep annotations for get/put_online_mems() and mem_hotplug_begin/end() */
75 #define memhp_lock_acquire_read() lock_map_acquire_read(&mem_hotplug.dep_map)
76 #define memhp_lock_acquire()      lock_map_acquire(&mem_hotplug.dep_map)
77 #define memhp_lock_release()      lock_map_release(&mem_hotplug.dep_map)
78 
79 void get_online_mems(void)
80 {
81 	might_sleep();
82 	if (mem_hotplug.active_writer == current)
83 		return;
84 	memhp_lock_acquire_read();
85 	mutex_lock(&mem_hotplug.lock);
86 	mem_hotplug.refcount++;
87 	mutex_unlock(&mem_hotplug.lock);
88 
89 }
90 
91 void put_online_mems(void)
92 {
93 	if (mem_hotplug.active_writer == current)
94 		return;
95 	mutex_lock(&mem_hotplug.lock);
96 
97 	if (WARN_ON(!mem_hotplug.refcount))
98 		mem_hotplug.refcount++; /* try to fix things up */
99 
100 	if (!--mem_hotplug.refcount && unlikely(mem_hotplug.active_writer))
101 		wake_up_process(mem_hotplug.active_writer);
102 	mutex_unlock(&mem_hotplug.lock);
103 	memhp_lock_release();
104 
105 }
106 
107 void mem_hotplug_begin(void)
108 {
109 	mem_hotplug.active_writer = current;
110 
111 	memhp_lock_acquire();
112 	for (;;) {
113 		mutex_lock(&mem_hotplug.lock);
114 		if (likely(!mem_hotplug.refcount))
115 			break;
116 		__set_current_state(TASK_UNINTERRUPTIBLE);
117 		mutex_unlock(&mem_hotplug.lock);
118 		schedule();
119 	}
120 }
121 
122 void mem_hotplug_done(void)
123 {
124 	mem_hotplug.active_writer = NULL;
125 	mutex_unlock(&mem_hotplug.lock);
126 	memhp_lock_release();
127 }
128 
129 /* add this memory to iomem resource */
130 static struct resource *register_memory_resource(u64 start, u64 size)
131 {
132 	struct resource *res;
133 	res = kzalloc(sizeof(struct resource), GFP_KERNEL);
134 	BUG_ON(!res);
135 
136 	res->name = "System RAM";
137 	res->start = start;
138 	res->end = start + size - 1;
139 	res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
140 	if (request_resource(&iomem_resource, res) < 0) {
141 		pr_debug("System RAM resource %pR cannot be added\n", res);
142 		kfree(res);
143 		res = NULL;
144 	}
145 	return res;
146 }
147 
148 static void release_memory_resource(struct resource *res)
149 {
150 	if (!res)
151 		return;
152 	release_resource(res);
153 	kfree(res);
154 	return;
155 }
156 
157 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
158 void get_page_bootmem(unsigned long info,  struct page *page,
159 		      unsigned long type)
160 {
161 	page->lru.next = (struct list_head *) type;
162 	SetPagePrivate(page);
163 	set_page_private(page, info);
164 	atomic_inc(&page->_count);
165 }
166 
167 void put_page_bootmem(struct page *page)
168 {
169 	unsigned long type;
170 
171 	type = (unsigned long) page->lru.next;
172 	BUG_ON(type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE ||
173 	       type > MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE);
174 
175 	if (atomic_dec_return(&page->_count) == 1) {
176 		ClearPagePrivate(page);
177 		set_page_private(page, 0);
178 		INIT_LIST_HEAD(&page->lru);
179 		free_reserved_page(page);
180 	}
181 }
182 
183 #ifdef CONFIG_HAVE_BOOTMEM_INFO_NODE
184 #ifndef CONFIG_SPARSEMEM_VMEMMAP
185 static void register_page_bootmem_info_section(unsigned long start_pfn)
186 {
187 	unsigned long *usemap, mapsize, section_nr, i;
188 	struct mem_section *ms;
189 	struct page *page, *memmap;
190 
191 	section_nr = pfn_to_section_nr(start_pfn);
192 	ms = __nr_to_section(section_nr);
193 
194 	/* Get section's memmap address */
195 	memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
196 
197 	/*
198 	 * Get page for the memmap's phys address
199 	 * XXX: need more consideration for sparse_vmemmap...
200 	 */
201 	page = virt_to_page(memmap);
202 	mapsize = sizeof(struct page) * PAGES_PER_SECTION;
203 	mapsize = PAGE_ALIGN(mapsize) >> PAGE_SHIFT;
204 
205 	/* remember memmap's page */
206 	for (i = 0; i < mapsize; i++, page++)
207 		get_page_bootmem(section_nr, page, SECTION_INFO);
208 
209 	usemap = __nr_to_section(section_nr)->pageblock_flags;
210 	page = virt_to_page(usemap);
211 
212 	mapsize = PAGE_ALIGN(usemap_size()) >> PAGE_SHIFT;
213 
214 	for (i = 0; i < mapsize; i++, page++)
215 		get_page_bootmem(section_nr, page, MIX_SECTION_INFO);
216 
217 }
218 #else /* CONFIG_SPARSEMEM_VMEMMAP */
219 static void register_page_bootmem_info_section(unsigned long start_pfn)
220 {
221 	unsigned long *usemap, mapsize, section_nr, i;
222 	struct mem_section *ms;
223 	struct page *page, *memmap;
224 
225 	if (!pfn_valid(start_pfn))
226 		return;
227 
228 	section_nr = pfn_to_section_nr(start_pfn);
229 	ms = __nr_to_section(section_nr);
230 
231 	memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
232 
233 	register_page_bootmem_memmap(section_nr, memmap, PAGES_PER_SECTION);
234 
235 	usemap = __nr_to_section(section_nr)->pageblock_flags;
236 	page = virt_to_page(usemap);
237 
238 	mapsize = PAGE_ALIGN(usemap_size()) >> PAGE_SHIFT;
239 
240 	for (i = 0; i < mapsize; i++, page++)
241 		get_page_bootmem(section_nr, page, MIX_SECTION_INFO);
242 }
243 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
244 
245 void register_page_bootmem_info_node(struct pglist_data *pgdat)
246 {
247 	unsigned long i, pfn, end_pfn, nr_pages;
248 	int node = pgdat->node_id;
249 	struct page *page;
250 	struct zone *zone;
251 
252 	nr_pages = PAGE_ALIGN(sizeof(struct pglist_data)) >> PAGE_SHIFT;
253 	page = virt_to_page(pgdat);
254 
255 	for (i = 0; i < nr_pages; i++, page++)
256 		get_page_bootmem(node, page, NODE_INFO);
257 
258 	zone = &pgdat->node_zones[0];
259 	for (; zone < pgdat->node_zones + MAX_NR_ZONES - 1; zone++) {
260 		if (zone_is_initialized(zone)) {
261 			nr_pages = zone->wait_table_hash_nr_entries
262 				* sizeof(wait_queue_head_t);
263 			nr_pages = PAGE_ALIGN(nr_pages) >> PAGE_SHIFT;
264 			page = virt_to_page(zone->wait_table);
265 
266 			for (i = 0; i < nr_pages; i++, page++)
267 				get_page_bootmem(node, page, NODE_INFO);
268 		}
269 	}
270 
271 	pfn = pgdat->node_start_pfn;
272 	end_pfn = pgdat_end_pfn(pgdat);
273 
274 	/* register section info */
275 	for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
276 		/*
277 		 * Some platforms can assign the same pfn to multiple nodes - on
278 		 * node0 as well as nodeN.  To avoid registering a pfn against
279 		 * multiple nodes we check that this pfn does not already
280 		 * reside in some other nodes.
281 		 */
282 		if (pfn_valid(pfn) && (pfn_to_nid(pfn) == node))
283 			register_page_bootmem_info_section(pfn);
284 	}
285 }
286 #endif /* CONFIG_HAVE_BOOTMEM_INFO_NODE */
287 
288 static void __meminit grow_zone_span(struct zone *zone, unsigned long start_pfn,
289 				     unsigned long end_pfn)
290 {
291 	unsigned long old_zone_end_pfn;
292 
293 	zone_span_writelock(zone);
294 
295 	old_zone_end_pfn = zone_end_pfn(zone);
296 	if (zone_is_empty(zone) || start_pfn < zone->zone_start_pfn)
297 		zone->zone_start_pfn = start_pfn;
298 
299 	zone->spanned_pages = max(old_zone_end_pfn, end_pfn) -
300 				zone->zone_start_pfn;
301 
302 	zone_span_writeunlock(zone);
303 }
304 
305 static void resize_zone(struct zone *zone, unsigned long start_pfn,
306 		unsigned long end_pfn)
307 {
308 	zone_span_writelock(zone);
309 
310 	if (end_pfn - start_pfn) {
311 		zone->zone_start_pfn = start_pfn;
312 		zone->spanned_pages = end_pfn - start_pfn;
313 	} else {
314 		/*
315 		 * make it consist as free_area_init_core(),
316 		 * if spanned_pages = 0, then keep start_pfn = 0
317 		 */
318 		zone->zone_start_pfn = 0;
319 		zone->spanned_pages = 0;
320 	}
321 
322 	zone_span_writeunlock(zone);
323 }
324 
325 static void fix_zone_id(struct zone *zone, unsigned long start_pfn,
326 		unsigned long end_pfn)
327 {
328 	enum zone_type zid = zone_idx(zone);
329 	int nid = zone->zone_pgdat->node_id;
330 	unsigned long pfn;
331 
332 	for (pfn = start_pfn; pfn < end_pfn; pfn++)
333 		set_page_links(pfn_to_page(pfn), zid, nid, pfn);
334 }
335 
336 /* Can fail with -ENOMEM from allocating a wait table with vmalloc() or
337  * alloc_bootmem_node_nopanic()/memblock_virt_alloc_node_nopanic() */
338 static int __ref ensure_zone_is_initialized(struct zone *zone,
339 			unsigned long start_pfn, unsigned long num_pages)
340 {
341 	if (!zone_is_initialized(zone))
342 		return init_currently_empty_zone(zone, start_pfn, num_pages,
343 						 MEMMAP_HOTPLUG);
344 	return 0;
345 }
346 
347 static int __meminit move_pfn_range_left(struct zone *z1, struct zone *z2,
348 		unsigned long start_pfn, unsigned long end_pfn)
349 {
350 	int ret;
351 	unsigned long flags;
352 	unsigned long z1_start_pfn;
353 
354 	ret = ensure_zone_is_initialized(z1, start_pfn, end_pfn - start_pfn);
355 	if (ret)
356 		return ret;
357 
358 	pgdat_resize_lock(z1->zone_pgdat, &flags);
359 
360 	/* can't move pfns which are higher than @z2 */
361 	if (end_pfn > zone_end_pfn(z2))
362 		goto out_fail;
363 	/* the move out part must be at the left most of @z2 */
364 	if (start_pfn > z2->zone_start_pfn)
365 		goto out_fail;
366 	/* must included/overlap */
367 	if (end_pfn <= z2->zone_start_pfn)
368 		goto out_fail;
369 
370 	/* use start_pfn for z1's start_pfn if z1 is empty */
371 	if (!zone_is_empty(z1))
372 		z1_start_pfn = z1->zone_start_pfn;
373 	else
374 		z1_start_pfn = start_pfn;
375 
376 	resize_zone(z1, z1_start_pfn, end_pfn);
377 	resize_zone(z2, end_pfn, zone_end_pfn(z2));
378 
379 	pgdat_resize_unlock(z1->zone_pgdat, &flags);
380 
381 	fix_zone_id(z1, start_pfn, end_pfn);
382 
383 	return 0;
384 out_fail:
385 	pgdat_resize_unlock(z1->zone_pgdat, &flags);
386 	return -1;
387 }
388 
389 static int __meminit move_pfn_range_right(struct zone *z1, struct zone *z2,
390 		unsigned long start_pfn, unsigned long end_pfn)
391 {
392 	int ret;
393 	unsigned long flags;
394 	unsigned long z2_end_pfn;
395 
396 	ret = ensure_zone_is_initialized(z2, start_pfn, end_pfn - start_pfn);
397 	if (ret)
398 		return ret;
399 
400 	pgdat_resize_lock(z1->zone_pgdat, &flags);
401 
402 	/* can't move pfns which are lower than @z1 */
403 	if (z1->zone_start_pfn > start_pfn)
404 		goto out_fail;
405 	/* the move out part mast at the right most of @z1 */
406 	if (zone_end_pfn(z1) >  end_pfn)
407 		goto out_fail;
408 	/* must included/overlap */
409 	if (start_pfn >= zone_end_pfn(z1))
410 		goto out_fail;
411 
412 	/* use end_pfn for z2's end_pfn if z2 is empty */
413 	if (!zone_is_empty(z2))
414 		z2_end_pfn = zone_end_pfn(z2);
415 	else
416 		z2_end_pfn = end_pfn;
417 
418 	resize_zone(z1, z1->zone_start_pfn, start_pfn);
419 	resize_zone(z2, start_pfn, z2_end_pfn);
420 
421 	pgdat_resize_unlock(z1->zone_pgdat, &flags);
422 
423 	fix_zone_id(z2, start_pfn, end_pfn);
424 
425 	return 0;
426 out_fail:
427 	pgdat_resize_unlock(z1->zone_pgdat, &flags);
428 	return -1;
429 }
430 
431 static void __meminit grow_pgdat_span(struct pglist_data *pgdat, unsigned long start_pfn,
432 				      unsigned long end_pfn)
433 {
434 	unsigned long old_pgdat_end_pfn = pgdat_end_pfn(pgdat);
435 
436 	if (!pgdat->node_spanned_pages || start_pfn < pgdat->node_start_pfn)
437 		pgdat->node_start_pfn = start_pfn;
438 
439 	pgdat->node_spanned_pages = max(old_pgdat_end_pfn, end_pfn) -
440 					pgdat->node_start_pfn;
441 }
442 
443 static int __meminit __add_zone(struct zone *zone, unsigned long phys_start_pfn)
444 {
445 	struct pglist_data *pgdat = zone->zone_pgdat;
446 	int nr_pages = PAGES_PER_SECTION;
447 	int nid = pgdat->node_id;
448 	int zone_type;
449 	unsigned long flags;
450 	int ret;
451 
452 	zone_type = zone - pgdat->node_zones;
453 	ret = ensure_zone_is_initialized(zone, phys_start_pfn, nr_pages);
454 	if (ret)
455 		return ret;
456 
457 	pgdat_resize_lock(zone->zone_pgdat, &flags);
458 	grow_zone_span(zone, phys_start_pfn, phys_start_pfn + nr_pages);
459 	grow_pgdat_span(zone->zone_pgdat, phys_start_pfn,
460 			phys_start_pfn + nr_pages);
461 	pgdat_resize_unlock(zone->zone_pgdat, &flags);
462 	memmap_init_zone(nr_pages, nid, zone_type,
463 			 phys_start_pfn, MEMMAP_HOTPLUG);
464 	return 0;
465 }
466 
467 static int __meminit __add_section(int nid, struct zone *zone,
468 					unsigned long phys_start_pfn)
469 {
470 	int ret;
471 
472 	if (pfn_valid(phys_start_pfn))
473 		return -EEXIST;
474 
475 	ret = sparse_add_one_section(zone, phys_start_pfn);
476 
477 	if (ret < 0)
478 		return ret;
479 
480 	ret = __add_zone(zone, phys_start_pfn);
481 
482 	if (ret < 0)
483 		return ret;
484 
485 	return register_new_memory(nid, __pfn_to_section(phys_start_pfn));
486 }
487 
488 /*
489  * Reasonably generic function for adding memory.  It is
490  * expected that archs that support memory hotplug will
491  * call this function after deciding the zone to which to
492  * add the new pages.
493  */
494 int __ref __add_pages(int nid, struct zone *zone, unsigned long phys_start_pfn,
495 			unsigned long nr_pages)
496 {
497 	unsigned long i;
498 	int err = 0;
499 	int start_sec, end_sec;
500 	/* during initialize mem_map, align hot-added range to section */
501 	start_sec = pfn_to_section_nr(phys_start_pfn);
502 	end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
503 
504 	for (i = start_sec; i <= end_sec; i++) {
505 		err = __add_section(nid, zone, section_nr_to_pfn(i));
506 
507 		/*
508 		 * EEXIST is finally dealt with by ioresource collision
509 		 * check. see add_memory() => register_memory_resource()
510 		 * Warning will be printed if there is collision.
511 		 */
512 		if (err && (err != -EEXIST))
513 			break;
514 		err = 0;
515 	}
516 
517 	return err;
518 }
519 EXPORT_SYMBOL_GPL(__add_pages);
520 
521 #ifdef CONFIG_MEMORY_HOTREMOVE
522 /* find the smallest valid pfn in the range [start_pfn, end_pfn) */
523 static int find_smallest_section_pfn(int nid, struct zone *zone,
524 				     unsigned long start_pfn,
525 				     unsigned long end_pfn)
526 {
527 	struct mem_section *ms;
528 
529 	for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SECTION) {
530 		ms = __pfn_to_section(start_pfn);
531 
532 		if (unlikely(!valid_section(ms)))
533 			continue;
534 
535 		if (unlikely(pfn_to_nid(start_pfn) != nid))
536 			continue;
537 
538 		if (zone && zone != page_zone(pfn_to_page(start_pfn)))
539 			continue;
540 
541 		return start_pfn;
542 	}
543 
544 	return 0;
545 }
546 
547 /* find the biggest valid pfn in the range [start_pfn, end_pfn). */
548 static int find_biggest_section_pfn(int nid, struct zone *zone,
549 				    unsigned long start_pfn,
550 				    unsigned long end_pfn)
551 {
552 	struct mem_section *ms;
553 	unsigned long pfn;
554 
555 	/* pfn is the end pfn of a memory section. */
556 	pfn = end_pfn - 1;
557 	for (; pfn >= start_pfn; pfn -= PAGES_PER_SECTION) {
558 		ms = __pfn_to_section(pfn);
559 
560 		if (unlikely(!valid_section(ms)))
561 			continue;
562 
563 		if (unlikely(pfn_to_nid(pfn) != nid))
564 			continue;
565 
566 		if (zone && zone != page_zone(pfn_to_page(pfn)))
567 			continue;
568 
569 		return pfn;
570 	}
571 
572 	return 0;
573 }
574 
575 static void shrink_zone_span(struct zone *zone, unsigned long start_pfn,
576 			     unsigned long end_pfn)
577 {
578 	unsigned long zone_start_pfn = zone->zone_start_pfn;
579 	unsigned long z = zone_end_pfn(zone); /* zone_end_pfn namespace clash */
580 	unsigned long zone_end_pfn = z;
581 	unsigned long pfn;
582 	struct mem_section *ms;
583 	int nid = zone_to_nid(zone);
584 
585 	zone_span_writelock(zone);
586 	if (zone_start_pfn == start_pfn) {
587 		/*
588 		 * If the section is smallest section in the zone, it need
589 		 * shrink zone->zone_start_pfn and zone->zone_spanned_pages.
590 		 * In this case, we find second smallest valid mem_section
591 		 * for shrinking zone.
592 		 */
593 		pfn = find_smallest_section_pfn(nid, zone, end_pfn,
594 						zone_end_pfn);
595 		if (pfn) {
596 			zone->zone_start_pfn = pfn;
597 			zone->spanned_pages = zone_end_pfn - pfn;
598 		}
599 	} else if (zone_end_pfn == end_pfn) {
600 		/*
601 		 * If the section is biggest section in the zone, it need
602 		 * shrink zone->spanned_pages.
603 		 * In this case, we find second biggest valid mem_section for
604 		 * shrinking zone.
605 		 */
606 		pfn = find_biggest_section_pfn(nid, zone, zone_start_pfn,
607 					       start_pfn);
608 		if (pfn)
609 			zone->spanned_pages = pfn - zone_start_pfn + 1;
610 	}
611 
612 	/*
613 	 * The section is not biggest or smallest mem_section in the zone, it
614 	 * only creates a hole in the zone. So in this case, we need not
615 	 * change the zone. But perhaps, the zone has only hole data. Thus
616 	 * it check the zone has only hole or not.
617 	 */
618 	pfn = zone_start_pfn;
619 	for (; pfn < zone_end_pfn; pfn += PAGES_PER_SECTION) {
620 		ms = __pfn_to_section(pfn);
621 
622 		if (unlikely(!valid_section(ms)))
623 			continue;
624 
625 		if (page_zone(pfn_to_page(pfn)) != zone)
626 			continue;
627 
628 		 /* If the section is current section, it continues the loop */
629 		if (start_pfn == pfn)
630 			continue;
631 
632 		/* If we find valid section, we have nothing to do */
633 		zone_span_writeunlock(zone);
634 		return;
635 	}
636 
637 	/* The zone has no valid section */
638 	zone->zone_start_pfn = 0;
639 	zone->spanned_pages = 0;
640 	zone_span_writeunlock(zone);
641 }
642 
643 static void shrink_pgdat_span(struct pglist_data *pgdat,
644 			      unsigned long start_pfn, unsigned long end_pfn)
645 {
646 	unsigned long pgdat_start_pfn = pgdat->node_start_pfn;
647 	unsigned long p = pgdat_end_pfn(pgdat); /* pgdat_end_pfn namespace clash */
648 	unsigned long pgdat_end_pfn = p;
649 	unsigned long pfn;
650 	struct mem_section *ms;
651 	int nid = pgdat->node_id;
652 
653 	if (pgdat_start_pfn == start_pfn) {
654 		/*
655 		 * If the section is smallest section in the pgdat, it need
656 		 * shrink pgdat->node_start_pfn and pgdat->node_spanned_pages.
657 		 * In this case, we find second smallest valid mem_section
658 		 * for shrinking zone.
659 		 */
660 		pfn = find_smallest_section_pfn(nid, NULL, end_pfn,
661 						pgdat_end_pfn);
662 		if (pfn) {
663 			pgdat->node_start_pfn = pfn;
664 			pgdat->node_spanned_pages = pgdat_end_pfn - pfn;
665 		}
666 	} else if (pgdat_end_pfn == end_pfn) {
667 		/*
668 		 * If the section is biggest section in the pgdat, it need
669 		 * shrink pgdat->node_spanned_pages.
670 		 * In this case, we find second biggest valid mem_section for
671 		 * shrinking zone.
672 		 */
673 		pfn = find_biggest_section_pfn(nid, NULL, pgdat_start_pfn,
674 					       start_pfn);
675 		if (pfn)
676 			pgdat->node_spanned_pages = pfn - pgdat_start_pfn + 1;
677 	}
678 
679 	/*
680 	 * If the section is not biggest or smallest mem_section in the pgdat,
681 	 * it only creates a hole in the pgdat. So in this case, we need not
682 	 * change the pgdat.
683 	 * But perhaps, the pgdat has only hole data. Thus it check the pgdat
684 	 * has only hole or not.
685 	 */
686 	pfn = pgdat_start_pfn;
687 	for (; pfn < pgdat_end_pfn; pfn += PAGES_PER_SECTION) {
688 		ms = __pfn_to_section(pfn);
689 
690 		if (unlikely(!valid_section(ms)))
691 			continue;
692 
693 		if (pfn_to_nid(pfn) != nid)
694 			continue;
695 
696 		 /* If the section is current section, it continues the loop */
697 		if (start_pfn == pfn)
698 			continue;
699 
700 		/* If we find valid section, we have nothing to do */
701 		return;
702 	}
703 
704 	/* The pgdat has no valid section */
705 	pgdat->node_start_pfn = 0;
706 	pgdat->node_spanned_pages = 0;
707 }
708 
709 static void __remove_zone(struct zone *zone, unsigned long start_pfn)
710 {
711 	struct pglist_data *pgdat = zone->zone_pgdat;
712 	int nr_pages = PAGES_PER_SECTION;
713 	int zone_type;
714 	unsigned long flags;
715 
716 	zone_type = zone - pgdat->node_zones;
717 
718 	pgdat_resize_lock(zone->zone_pgdat, &flags);
719 	shrink_zone_span(zone, start_pfn, start_pfn + nr_pages);
720 	shrink_pgdat_span(pgdat, start_pfn, start_pfn + nr_pages);
721 	pgdat_resize_unlock(zone->zone_pgdat, &flags);
722 }
723 
724 static int __remove_section(struct zone *zone, struct mem_section *ms)
725 {
726 	unsigned long start_pfn;
727 	int scn_nr;
728 	int ret = -EINVAL;
729 
730 	if (!valid_section(ms))
731 		return ret;
732 
733 	ret = unregister_memory_section(ms);
734 	if (ret)
735 		return ret;
736 
737 	scn_nr = __section_nr(ms);
738 	start_pfn = section_nr_to_pfn(scn_nr);
739 	__remove_zone(zone, start_pfn);
740 
741 	sparse_remove_one_section(zone, ms);
742 	return 0;
743 }
744 
745 /**
746  * __remove_pages() - remove sections of pages from a zone
747  * @zone: zone from which pages need to be removed
748  * @phys_start_pfn: starting pageframe (must be aligned to start of a section)
749  * @nr_pages: number of pages to remove (must be multiple of section size)
750  *
751  * Generic helper function to remove section mappings and sysfs entries
752  * for the section of the memory we are removing. Caller needs to make
753  * sure that pages are marked reserved and zones are adjust properly by
754  * calling offline_pages().
755  */
756 int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
757 		 unsigned long nr_pages)
758 {
759 	unsigned long i;
760 	int sections_to_remove;
761 	resource_size_t start, size;
762 	int ret = 0;
763 
764 	/*
765 	 * We can only remove entire sections
766 	 */
767 	BUG_ON(phys_start_pfn & ~PAGE_SECTION_MASK);
768 	BUG_ON(nr_pages % PAGES_PER_SECTION);
769 
770 	start = phys_start_pfn << PAGE_SHIFT;
771 	size = nr_pages * PAGE_SIZE;
772 	ret = release_mem_region_adjustable(&iomem_resource, start, size);
773 	if (ret) {
774 		resource_size_t endres = start + size - 1;
775 
776 		pr_warn("Unable to release resource <%pa-%pa> (%d)\n",
777 				&start, &endres, ret);
778 	}
779 
780 	sections_to_remove = nr_pages / PAGES_PER_SECTION;
781 	for (i = 0; i < sections_to_remove; i++) {
782 		unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION;
783 		ret = __remove_section(zone, __pfn_to_section(pfn));
784 		if (ret)
785 			break;
786 	}
787 	return ret;
788 }
789 EXPORT_SYMBOL_GPL(__remove_pages);
790 #endif /* CONFIG_MEMORY_HOTREMOVE */
791 
792 int set_online_page_callback(online_page_callback_t callback)
793 {
794 	int rc = -EINVAL;
795 
796 	get_online_mems();
797 	mutex_lock(&online_page_callback_lock);
798 
799 	if (online_page_callback == generic_online_page) {
800 		online_page_callback = callback;
801 		rc = 0;
802 	}
803 
804 	mutex_unlock(&online_page_callback_lock);
805 	put_online_mems();
806 
807 	return rc;
808 }
809 EXPORT_SYMBOL_GPL(set_online_page_callback);
810 
811 int restore_online_page_callback(online_page_callback_t callback)
812 {
813 	int rc = -EINVAL;
814 
815 	get_online_mems();
816 	mutex_lock(&online_page_callback_lock);
817 
818 	if (online_page_callback == callback) {
819 		online_page_callback = generic_online_page;
820 		rc = 0;
821 	}
822 
823 	mutex_unlock(&online_page_callback_lock);
824 	put_online_mems();
825 
826 	return rc;
827 }
828 EXPORT_SYMBOL_GPL(restore_online_page_callback);
829 
830 void __online_page_set_limits(struct page *page)
831 {
832 }
833 EXPORT_SYMBOL_GPL(__online_page_set_limits);
834 
835 void __online_page_increment_counters(struct page *page)
836 {
837 	adjust_managed_page_count(page, 1);
838 }
839 EXPORT_SYMBOL_GPL(__online_page_increment_counters);
840 
841 void __online_page_free(struct page *page)
842 {
843 	__free_reserved_page(page);
844 }
845 EXPORT_SYMBOL_GPL(__online_page_free);
846 
847 static void generic_online_page(struct page *page)
848 {
849 	__online_page_set_limits(page);
850 	__online_page_increment_counters(page);
851 	__online_page_free(page);
852 }
853 
854 static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
855 			void *arg)
856 {
857 	unsigned long i;
858 	unsigned long onlined_pages = *(unsigned long *)arg;
859 	struct page *page;
860 	if (PageReserved(pfn_to_page(start_pfn)))
861 		for (i = 0; i < nr_pages; i++) {
862 			page = pfn_to_page(start_pfn + i);
863 			(*online_page_callback)(page);
864 			onlined_pages++;
865 		}
866 	*(unsigned long *)arg = onlined_pages;
867 	return 0;
868 }
869 
870 #ifdef CONFIG_MOVABLE_NODE
871 /*
872  * When CONFIG_MOVABLE_NODE, we permit onlining of a node which doesn't have
873  * normal memory.
874  */
875 static bool can_online_high_movable(struct zone *zone)
876 {
877 	return true;
878 }
879 #else /* CONFIG_MOVABLE_NODE */
880 /* ensure every online node has NORMAL memory */
881 static bool can_online_high_movable(struct zone *zone)
882 {
883 	return node_state(zone_to_nid(zone), N_NORMAL_MEMORY);
884 }
885 #endif /* CONFIG_MOVABLE_NODE */
886 
887 /* check which state of node_states will be changed when online memory */
888 static void node_states_check_changes_online(unsigned long nr_pages,
889 	struct zone *zone, struct memory_notify *arg)
890 {
891 	int nid = zone_to_nid(zone);
892 	enum zone_type zone_last = ZONE_NORMAL;
893 
894 	/*
895 	 * If we have HIGHMEM or movable node, node_states[N_NORMAL_MEMORY]
896 	 * contains nodes which have zones of 0...ZONE_NORMAL,
897 	 * set zone_last to ZONE_NORMAL.
898 	 *
899 	 * If we don't have HIGHMEM nor movable node,
900 	 * node_states[N_NORMAL_MEMORY] contains nodes which have zones of
901 	 * 0...ZONE_MOVABLE, set zone_last to ZONE_MOVABLE.
902 	 */
903 	if (N_MEMORY == N_NORMAL_MEMORY)
904 		zone_last = ZONE_MOVABLE;
905 
906 	/*
907 	 * if the memory to be online is in a zone of 0...zone_last, and
908 	 * the zones of 0...zone_last don't have memory before online, we will
909 	 * need to set the node to node_states[N_NORMAL_MEMORY] after
910 	 * the memory is online.
911 	 */
912 	if (zone_idx(zone) <= zone_last && !node_state(nid, N_NORMAL_MEMORY))
913 		arg->status_change_nid_normal = nid;
914 	else
915 		arg->status_change_nid_normal = -1;
916 
917 #ifdef CONFIG_HIGHMEM
918 	/*
919 	 * If we have movable node, node_states[N_HIGH_MEMORY]
920 	 * contains nodes which have zones of 0...ZONE_HIGHMEM,
921 	 * set zone_last to ZONE_HIGHMEM.
922 	 *
923 	 * If we don't have movable node, node_states[N_NORMAL_MEMORY]
924 	 * contains nodes which have zones of 0...ZONE_MOVABLE,
925 	 * set zone_last to ZONE_MOVABLE.
926 	 */
927 	zone_last = ZONE_HIGHMEM;
928 	if (N_MEMORY == N_HIGH_MEMORY)
929 		zone_last = ZONE_MOVABLE;
930 
931 	if (zone_idx(zone) <= zone_last && !node_state(nid, N_HIGH_MEMORY))
932 		arg->status_change_nid_high = nid;
933 	else
934 		arg->status_change_nid_high = -1;
935 #else
936 	arg->status_change_nid_high = arg->status_change_nid_normal;
937 #endif
938 
939 	/*
940 	 * if the node don't have memory befor online, we will need to
941 	 * set the node to node_states[N_MEMORY] after the memory
942 	 * is online.
943 	 */
944 	if (!node_state(nid, N_MEMORY))
945 		arg->status_change_nid = nid;
946 	else
947 		arg->status_change_nid = -1;
948 }
949 
950 static void node_states_set_node(int node, struct memory_notify *arg)
951 {
952 	if (arg->status_change_nid_normal >= 0)
953 		node_set_state(node, N_NORMAL_MEMORY);
954 
955 	if (arg->status_change_nid_high >= 0)
956 		node_set_state(node, N_HIGH_MEMORY);
957 
958 	node_set_state(node, N_MEMORY);
959 }
960 
961 
962 /* Must be protected by mem_hotplug_begin() */
963 int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_type)
964 {
965 	unsigned long flags;
966 	unsigned long onlined_pages = 0;
967 	struct zone *zone;
968 	int need_zonelists_rebuild = 0;
969 	int nid;
970 	int ret;
971 	struct memory_notify arg;
972 
973 	/*
974 	 * This doesn't need a lock to do pfn_to_page().
975 	 * The section can't be removed here because of the
976 	 * memory_block->state_mutex.
977 	 */
978 	zone = page_zone(pfn_to_page(pfn));
979 
980 	if ((zone_idx(zone) > ZONE_NORMAL ||
981 	    online_type == MMOP_ONLINE_MOVABLE) &&
982 	    !can_online_high_movable(zone))
983 		return -EINVAL;
984 
985 	if (online_type == MMOP_ONLINE_KERNEL &&
986 	    zone_idx(zone) == ZONE_MOVABLE) {
987 		if (move_pfn_range_left(zone - 1, zone, pfn, pfn + nr_pages))
988 			return -EINVAL;
989 	}
990 	if (online_type == MMOP_ONLINE_MOVABLE &&
991 	    zone_idx(zone) == ZONE_MOVABLE - 1) {
992 		if (move_pfn_range_right(zone, zone + 1, pfn, pfn + nr_pages))
993 			return -EINVAL;
994 	}
995 
996 	/* Previous code may changed the zone of the pfn range */
997 	zone = page_zone(pfn_to_page(pfn));
998 
999 	arg.start_pfn = pfn;
1000 	arg.nr_pages = nr_pages;
1001 	node_states_check_changes_online(nr_pages, zone, &arg);
1002 
1003 	nid = pfn_to_nid(pfn);
1004 
1005 	ret = memory_notify(MEM_GOING_ONLINE, &arg);
1006 	ret = notifier_to_errno(ret);
1007 	if (ret) {
1008 		memory_notify(MEM_CANCEL_ONLINE, &arg);
1009 		return ret;
1010 	}
1011 	/*
1012 	 * If this zone is not populated, then it is not in zonelist.
1013 	 * This means the page allocator ignores this zone.
1014 	 * So, zonelist must be updated after online.
1015 	 */
1016 	mutex_lock(&zonelists_mutex);
1017 	if (!populated_zone(zone)) {
1018 		need_zonelists_rebuild = 1;
1019 		build_all_zonelists(NULL, zone);
1020 	}
1021 
1022 	ret = walk_system_ram_range(pfn, nr_pages, &onlined_pages,
1023 		online_pages_range);
1024 	if (ret) {
1025 		if (need_zonelists_rebuild)
1026 			zone_pcp_reset(zone);
1027 		mutex_unlock(&zonelists_mutex);
1028 		printk(KERN_DEBUG "online_pages [mem %#010llx-%#010llx] failed\n",
1029 		       (unsigned long long) pfn << PAGE_SHIFT,
1030 		       (((unsigned long long) pfn + nr_pages)
1031 			    << PAGE_SHIFT) - 1);
1032 		memory_notify(MEM_CANCEL_ONLINE, &arg);
1033 		return ret;
1034 	}
1035 
1036 	zone->present_pages += onlined_pages;
1037 
1038 	pgdat_resize_lock(zone->zone_pgdat, &flags);
1039 	zone->zone_pgdat->node_present_pages += onlined_pages;
1040 	pgdat_resize_unlock(zone->zone_pgdat, &flags);
1041 
1042 	if (onlined_pages) {
1043 		node_states_set_node(zone_to_nid(zone), &arg);
1044 		if (need_zonelists_rebuild)
1045 			build_all_zonelists(NULL, NULL);
1046 		else
1047 			zone_pcp_update(zone);
1048 	}
1049 
1050 	mutex_unlock(&zonelists_mutex);
1051 
1052 	init_per_zone_wmark_min();
1053 
1054 	if (onlined_pages)
1055 		kswapd_run(zone_to_nid(zone));
1056 
1057 	vm_total_pages = nr_free_pagecache_pages();
1058 
1059 	writeback_set_ratelimit();
1060 
1061 	if (onlined_pages)
1062 		memory_notify(MEM_ONLINE, &arg);
1063 	return 0;
1064 }
1065 #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
1066 
1067 static void reset_node_present_pages(pg_data_t *pgdat)
1068 {
1069 	struct zone *z;
1070 
1071 	for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++)
1072 		z->present_pages = 0;
1073 
1074 	pgdat->node_present_pages = 0;
1075 }
1076 
1077 /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
1078 static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
1079 {
1080 	struct pglist_data *pgdat;
1081 	unsigned long zones_size[MAX_NR_ZONES] = {0};
1082 	unsigned long zholes_size[MAX_NR_ZONES] = {0};
1083 	unsigned long start_pfn = PFN_DOWN(start);
1084 
1085 	pgdat = NODE_DATA(nid);
1086 	if (!pgdat) {
1087 		pgdat = arch_alloc_nodedata(nid);
1088 		if (!pgdat)
1089 			return NULL;
1090 
1091 		arch_refresh_nodedata(nid, pgdat);
1092 	} else {
1093 		/* Reset the nr_zones and classzone_idx to 0 before reuse */
1094 		pgdat->nr_zones = 0;
1095 		pgdat->classzone_idx = 0;
1096 	}
1097 
1098 	/* we can use NODE_DATA(nid) from here */
1099 
1100 	/* init node's zones as empty zones, we don't have any present pages.*/
1101 	free_area_init_node(nid, zones_size, start_pfn, zholes_size);
1102 
1103 	/*
1104 	 * The node we allocated has no zone fallback lists. For avoiding
1105 	 * to access not-initialized zonelist, build here.
1106 	 */
1107 	mutex_lock(&zonelists_mutex);
1108 	build_all_zonelists(pgdat, NULL);
1109 	mutex_unlock(&zonelists_mutex);
1110 
1111 	/*
1112 	 * zone->managed_pages is set to an approximate value in
1113 	 * free_area_init_core(), which will cause
1114 	 * /sys/device/system/node/nodeX/meminfo has wrong data.
1115 	 * So reset it to 0 before any memory is onlined.
1116 	 */
1117 	reset_node_managed_pages(pgdat);
1118 
1119 	/*
1120 	 * When memory is hot-added, all the memory is in offline state. So
1121 	 * clear all zones' present_pages because they will be updated in
1122 	 * online_pages() and offline_pages().
1123 	 */
1124 	reset_node_present_pages(pgdat);
1125 
1126 	return pgdat;
1127 }
1128 
1129 static void rollback_node_hotadd(int nid, pg_data_t *pgdat)
1130 {
1131 	arch_refresh_nodedata(nid, NULL);
1132 	arch_free_nodedata(pgdat);
1133 	return;
1134 }
1135 
1136 
1137 /**
1138  * try_online_node - online a node if offlined
1139  *
1140  * called by cpu_up() to online a node without onlined memory.
1141  */
1142 int try_online_node(int nid)
1143 {
1144 	pg_data_t	*pgdat;
1145 	int	ret;
1146 
1147 	if (node_online(nid))
1148 		return 0;
1149 
1150 	mem_hotplug_begin();
1151 	pgdat = hotadd_new_pgdat(nid, 0);
1152 	if (!pgdat) {
1153 		pr_err("Cannot online node %d due to NULL pgdat\n", nid);
1154 		ret = -ENOMEM;
1155 		goto out;
1156 	}
1157 	node_set_online(nid);
1158 	ret = register_one_node(nid);
1159 	BUG_ON(ret);
1160 
1161 	if (pgdat->node_zonelists->_zonerefs->zone == NULL) {
1162 		mutex_lock(&zonelists_mutex);
1163 		build_all_zonelists(NULL, NULL);
1164 		mutex_unlock(&zonelists_mutex);
1165 	}
1166 
1167 out:
1168 	mem_hotplug_done();
1169 	return ret;
1170 }
1171 
1172 static int check_hotplug_memory_range(u64 start, u64 size)
1173 {
1174 	u64 start_pfn = PFN_DOWN(start);
1175 	u64 nr_pages = size >> PAGE_SHIFT;
1176 
1177 	/* Memory range must be aligned with section */
1178 	if ((start_pfn & ~PAGE_SECTION_MASK) ||
1179 	    (nr_pages % PAGES_PER_SECTION) || (!nr_pages)) {
1180 		pr_err("Section-unaligned hotplug range: start 0x%llx, size 0x%llx\n",
1181 				(unsigned long long)start,
1182 				(unsigned long long)size);
1183 		return -EINVAL;
1184 	}
1185 
1186 	return 0;
1187 }
1188 
1189 /*
1190  * If movable zone has already been setup, newly added memory should be check.
1191  * If its address is higher than movable zone, it should be added as movable.
1192  * Without this check, movable zone may overlap with other zone.
1193  */
1194 static int should_add_memory_movable(int nid, u64 start, u64 size)
1195 {
1196 	unsigned long start_pfn = start >> PAGE_SHIFT;
1197 	pg_data_t *pgdat = NODE_DATA(nid);
1198 	struct zone *movable_zone = pgdat->node_zones + ZONE_MOVABLE;
1199 
1200 	if (zone_is_empty(movable_zone))
1201 		return 0;
1202 
1203 	if (movable_zone->zone_start_pfn <= start_pfn)
1204 		return 1;
1205 
1206 	return 0;
1207 }
1208 
1209 int zone_for_memory(int nid, u64 start, u64 size, int zone_default)
1210 {
1211 	if (should_add_memory_movable(nid, start, size))
1212 		return ZONE_MOVABLE;
1213 
1214 	return zone_default;
1215 }
1216 
1217 /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
1218 int __ref add_memory(int nid, u64 start, u64 size)
1219 {
1220 	pg_data_t *pgdat = NULL;
1221 	bool new_pgdat;
1222 	bool new_node;
1223 	struct resource *res;
1224 	int ret;
1225 
1226 	ret = check_hotplug_memory_range(start, size);
1227 	if (ret)
1228 		return ret;
1229 
1230 	res = register_memory_resource(start, size);
1231 	ret = -EEXIST;
1232 	if (!res)
1233 		return ret;
1234 
1235 	{	/* Stupid hack to suppress address-never-null warning */
1236 		void *p = NODE_DATA(nid);
1237 		new_pgdat = !p;
1238 	}
1239 
1240 	mem_hotplug_begin();
1241 
1242 	new_node = !node_online(nid);
1243 	if (new_node) {
1244 		pgdat = hotadd_new_pgdat(nid, start);
1245 		ret = -ENOMEM;
1246 		if (!pgdat)
1247 			goto error;
1248 	}
1249 
1250 	/* call arch's memory hotadd */
1251 	ret = arch_add_memory(nid, start, size);
1252 
1253 	if (ret < 0)
1254 		goto error;
1255 
1256 	/* we online node here. we can't roll back from here. */
1257 	node_set_online(nid);
1258 
1259 	if (new_node) {
1260 		ret = register_one_node(nid);
1261 		/*
1262 		 * If sysfs file of new node can't create, cpu on the node
1263 		 * can't be hot-added. There is no rollback way now.
1264 		 * So, check by BUG_ON() to catch it reluctantly..
1265 		 */
1266 		BUG_ON(ret);
1267 	}
1268 
1269 	/* create new memmap entry */
1270 	firmware_map_add_hotplug(start, start + size, "System RAM");
1271 
1272 	goto out;
1273 
1274 error:
1275 	/* rollback pgdat allocation and others */
1276 	if (new_pgdat)
1277 		rollback_node_hotadd(nid, pgdat);
1278 	release_memory_resource(res);
1279 
1280 out:
1281 	mem_hotplug_done();
1282 	return ret;
1283 }
1284 EXPORT_SYMBOL_GPL(add_memory);
1285 
1286 #ifdef CONFIG_MEMORY_HOTREMOVE
1287 /*
1288  * A free page on the buddy free lists (not the per-cpu lists) has PageBuddy
1289  * set and the size of the free page is given by page_order(). Using this,
1290  * the function determines if the pageblock contains only free pages.
1291  * Due to buddy contraints, a free page at least the size of a pageblock will
1292  * be located at the start of the pageblock
1293  */
1294 static inline int pageblock_free(struct page *page)
1295 {
1296 	return PageBuddy(page) && page_order(page) >= pageblock_order;
1297 }
1298 
1299 /* Return the start of the next active pageblock after a given page */
1300 static struct page *next_active_pageblock(struct page *page)
1301 {
1302 	/* Ensure the starting page is pageblock-aligned */
1303 	BUG_ON(page_to_pfn(page) & (pageblock_nr_pages - 1));
1304 
1305 	/* If the entire pageblock is free, move to the end of free page */
1306 	if (pageblock_free(page)) {
1307 		int order;
1308 		/* be careful. we don't have locks, page_order can be changed.*/
1309 		order = page_order(page);
1310 		if ((order < MAX_ORDER) && (order >= pageblock_order))
1311 			return page + (1 << order);
1312 	}
1313 
1314 	return page + pageblock_nr_pages;
1315 }
1316 
1317 /* Checks if this range of memory is likely to be hot-removable. */
1318 int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
1319 {
1320 	struct page *page = pfn_to_page(start_pfn);
1321 	struct page *end_page = page + nr_pages;
1322 
1323 	/* Check the starting page of each pageblock within the range */
1324 	for (; page < end_page; page = next_active_pageblock(page)) {
1325 		if (!is_pageblock_removable_nolock(page))
1326 			return 0;
1327 		cond_resched();
1328 	}
1329 
1330 	/* All pageblocks in the memory block are likely to be hot-removable */
1331 	return 1;
1332 }
1333 
1334 /*
1335  * Confirm all pages in a range [start, end) is belongs to the same zone.
1336  */
1337 int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
1338 {
1339 	unsigned long pfn;
1340 	struct zone *zone = NULL;
1341 	struct page *page;
1342 	int i;
1343 	for (pfn = start_pfn;
1344 	     pfn < end_pfn;
1345 	     pfn += MAX_ORDER_NR_PAGES) {
1346 		i = 0;
1347 		/* This is just a CONFIG_HOLES_IN_ZONE check.*/
1348 		while ((i < MAX_ORDER_NR_PAGES) && !pfn_valid_within(pfn + i))
1349 			i++;
1350 		if (i == MAX_ORDER_NR_PAGES)
1351 			continue;
1352 		page = pfn_to_page(pfn + i);
1353 		if (zone && page_zone(page) != zone)
1354 			return 0;
1355 		zone = page_zone(page);
1356 	}
1357 	return 1;
1358 }
1359 
1360 /*
1361  * Scan pfn range [start,end) to find movable/migratable pages (LRU pages
1362  * and hugepages). We scan pfn because it's much easier than scanning over
1363  * linked list. This function returns the pfn of the first found movable
1364  * page if it's found, otherwise 0.
1365  */
1366 static unsigned long scan_movable_pages(unsigned long start, unsigned long end)
1367 {
1368 	unsigned long pfn;
1369 	struct page *page;
1370 	for (pfn = start; pfn < end; pfn++) {
1371 		if (pfn_valid(pfn)) {
1372 			page = pfn_to_page(pfn);
1373 			if (PageLRU(page))
1374 				return pfn;
1375 			if (PageHuge(page)) {
1376 				if (page_huge_active(page))
1377 					return pfn;
1378 				else
1379 					pfn = round_up(pfn + 1,
1380 						1 << compound_order(page)) - 1;
1381 			}
1382 		}
1383 	}
1384 	return 0;
1385 }
1386 
1387 #define NR_OFFLINE_AT_ONCE_PAGES	(256)
1388 static int
1389 do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
1390 {
1391 	unsigned long pfn;
1392 	struct page *page;
1393 	int move_pages = NR_OFFLINE_AT_ONCE_PAGES;
1394 	int not_managed = 0;
1395 	int ret = 0;
1396 	LIST_HEAD(source);
1397 
1398 	for (pfn = start_pfn; pfn < end_pfn && move_pages > 0; pfn++) {
1399 		if (!pfn_valid(pfn))
1400 			continue;
1401 		page = pfn_to_page(pfn);
1402 
1403 		if (PageHuge(page)) {
1404 			struct page *head = compound_head(page);
1405 			pfn = page_to_pfn(head) + (1<<compound_order(head)) - 1;
1406 			if (compound_order(head) > PFN_SECTION_SHIFT) {
1407 				ret = -EBUSY;
1408 				break;
1409 			}
1410 			if (isolate_huge_page(page, &source))
1411 				move_pages -= 1 << compound_order(head);
1412 			continue;
1413 		}
1414 
1415 		if (!get_page_unless_zero(page))
1416 			continue;
1417 		/*
1418 		 * We can skip free pages. And we can only deal with pages on
1419 		 * LRU.
1420 		 */
1421 		ret = isolate_lru_page(page);
1422 		if (!ret) { /* Success */
1423 			put_page(page);
1424 			list_add_tail(&page->lru, &source);
1425 			move_pages--;
1426 			inc_zone_page_state(page, NR_ISOLATED_ANON +
1427 					    page_is_file_cache(page));
1428 
1429 		} else {
1430 #ifdef CONFIG_DEBUG_VM
1431 			printk(KERN_ALERT "removing pfn %lx from LRU failed\n",
1432 			       pfn);
1433 			dump_page(page, "failed to remove from LRU");
1434 #endif
1435 			put_page(page);
1436 			/* Because we don't have big zone->lock. we should
1437 			   check this again here. */
1438 			if (page_count(page)) {
1439 				not_managed++;
1440 				ret = -EBUSY;
1441 				break;
1442 			}
1443 		}
1444 	}
1445 	if (!list_empty(&source)) {
1446 		if (not_managed) {
1447 			putback_movable_pages(&source);
1448 			goto out;
1449 		}
1450 
1451 		/*
1452 		 * alloc_migrate_target should be improooooved!!
1453 		 * migrate_pages returns # of failed pages.
1454 		 */
1455 		ret = migrate_pages(&source, alloc_migrate_target, NULL, 0,
1456 					MIGRATE_SYNC, MR_MEMORY_HOTPLUG);
1457 		if (ret)
1458 			putback_movable_pages(&source);
1459 	}
1460 out:
1461 	return ret;
1462 }
1463 
1464 /*
1465  * remove from free_area[] and mark all as Reserved.
1466  */
1467 static int
1468 offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages,
1469 			void *data)
1470 {
1471 	__offline_isolated_pages(start, start + nr_pages);
1472 	return 0;
1473 }
1474 
1475 static void
1476 offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
1477 {
1478 	walk_system_ram_range(start_pfn, end_pfn - start_pfn, NULL,
1479 				offline_isolated_pages_cb);
1480 }
1481 
1482 /*
1483  * Check all pages in range, recoreded as memory resource, are isolated.
1484  */
1485 static int
1486 check_pages_isolated_cb(unsigned long start_pfn, unsigned long nr_pages,
1487 			void *data)
1488 {
1489 	int ret;
1490 	long offlined = *(long *)data;
1491 	ret = test_pages_isolated(start_pfn, start_pfn + nr_pages, true);
1492 	offlined = nr_pages;
1493 	if (!ret)
1494 		*(long *)data += offlined;
1495 	return ret;
1496 }
1497 
1498 static long
1499 check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
1500 {
1501 	long offlined = 0;
1502 	int ret;
1503 
1504 	ret = walk_system_ram_range(start_pfn, end_pfn - start_pfn, &offlined,
1505 			check_pages_isolated_cb);
1506 	if (ret < 0)
1507 		offlined = (long)ret;
1508 	return offlined;
1509 }
1510 
1511 #ifdef CONFIG_MOVABLE_NODE
1512 /*
1513  * When CONFIG_MOVABLE_NODE, we permit offlining of a node which doesn't have
1514  * normal memory.
1515  */
1516 static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
1517 {
1518 	return true;
1519 }
1520 #else /* CONFIG_MOVABLE_NODE */
1521 /* ensure the node has NORMAL memory if it is still online */
1522 static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
1523 {
1524 	struct pglist_data *pgdat = zone->zone_pgdat;
1525 	unsigned long present_pages = 0;
1526 	enum zone_type zt;
1527 
1528 	for (zt = 0; zt <= ZONE_NORMAL; zt++)
1529 		present_pages += pgdat->node_zones[zt].present_pages;
1530 
1531 	if (present_pages > nr_pages)
1532 		return true;
1533 
1534 	present_pages = 0;
1535 	for (; zt <= ZONE_MOVABLE; zt++)
1536 		present_pages += pgdat->node_zones[zt].present_pages;
1537 
1538 	/*
1539 	 * we can't offline the last normal memory until all
1540 	 * higher memory is offlined.
1541 	 */
1542 	return present_pages == 0;
1543 }
1544 #endif /* CONFIG_MOVABLE_NODE */
1545 
1546 static int __init cmdline_parse_movable_node(char *p)
1547 {
1548 #ifdef CONFIG_MOVABLE_NODE
1549 	/*
1550 	 * Memory used by the kernel cannot be hot-removed because Linux
1551 	 * cannot migrate the kernel pages. When memory hotplug is
1552 	 * enabled, we should prevent memblock from allocating memory
1553 	 * for the kernel.
1554 	 *
1555 	 * ACPI SRAT records all hotpluggable memory ranges. But before
1556 	 * SRAT is parsed, we don't know about it.
1557 	 *
1558 	 * The kernel image is loaded into memory at very early time. We
1559 	 * cannot prevent this anyway. So on NUMA system, we set any
1560 	 * node the kernel resides in as un-hotpluggable.
1561 	 *
1562 	 * Since on modern servers, one node could have double-digit
1563 	 * gigabytes memory, we can assume the memory around the kernel
1564 	 * image is also un-hotpluggable. So before SRAT is parsed, just
1565 	 * allocate memory near the kernel image to try the best to keep
1566 	 * the kernel away from hotpluggable memory.
1567 	 */
1568 	memblock_set_bottom_up(true);
1569 	movable_node_enabled = true;
1570 #else
1571 	pr_warn("movable_node option not supported\n");
1572 #endif
1573 	return 0;
1574 }
1575 early_param("movable_node", cmdline_parse_movable_node);
1576 
1577 /* check which state of node_states will be changed when offline memory */
1578 static void node_states_check_changes_offline(unsigned long nr_pages,
1579 		struct zone *zone, struct memory_notify *arg)
1580 {
1581 	struct pglist_data *pgdat = zone->zone_pgdat;
1582 	unsigned long present_pages = 0;
1583 	enum zone_type zt, zone_last = ZONE_NORMAL;
1584 
1585 	/*
1586 	 * If we have HIGHMEM or movable node, node_states[N_NORMAL_MEMORY]
1587 	 * contains nodes which have zones of 0...ZONE_NORMAL,
1588 	 * set zone_last to ZONE_NORMAL.
1589 	 *
1590 	 * If we don't have HIGHMEM nor movable node,
1591 	 * node_states[N_NORMAL_MEMORY] contains nodes which have zones of
1592 	 * 0...ZONE_MOVABLE, set zone_last to ZONE_MOVABLE.
1593 	 */
1594 	if (N_MEMORY == N_NORMAL_MEMORY)
1595 		zone_last = ZONE_MOVABLE;
1596 
1597 	/*
1598 	 * check whether node_states[N_NORMAL_MEMORY] will be changed.
1599 	 * If the memory to be offline is in a zone of 0...zone_last,
1600 	 * and it is the last present memory, 0...zone_last will
1601 	 * become empty after offline , thus we can determind we will
1602 	 * need to clear the node from node_states[N_NORMAL_MEMORY].
1603 	 */
1604 	for (zt = 0; zt <= zone_last; zt++)
1605 		present_pages += pgdat->node_zones[zt].present_pages;
1606 	if (zone_idx(zone) <= zone_last && nr_pages >= present_pages)
1607 		arg->status_change_nid_normal = zone_to_nid(zone);
1608 	else
1609 		arg->status_change_nid_normal = -1;
1610 
1611 #ifdef CONFIG_HIGHMEM
1612 	/*
1613 	 * If we have movable node, node_states[N_HIGH_MEMORY]
1614 	 * contains nodes which have zones of 0...ZONE_HIGHMEM,
1615 	 * set zone_last to ZONE_HIGHMEM.
1616 	 *
1617 	 * If we don't have movable node, node_states[N_NORMAL_MEMORY]
1618 	 * contains nodes which have zones of 0...ZONE_MOVABLE,
1619 	 * set zone_last to ZONE_MOVABLE.
1620 	 */
1621 	zone_last = ZONE_HIGHMEM;
1622 	if (N_MEMORY == N_HIGH_MEMORY)
1623 		zone_last = ZONE_MOVABLE;
1624 
1625 	for (; zt <= zone_last; zt++)
1626 		present_pages += pgdat->node_zones[zt].present_pages;
1627 	if (zone_idx(zone) <= zone_last && nr_pages >= present_pages)
1628 		arg->status_change_nid_high = zone_to_nid(zone);
1629 	else
1630 		arg->status_change_nid_high = -1;
1631 #else
1632 	arg->status_change_nid_high = arg->status_change_nid_normal;
1633 #endif
1634 
1635 	/*
1636 	 * node_states[N_HIGH_MEMORY] contains nodes which have 0...ZONE_MOVABLE
1637 	 */
1638 	zone_last = ZONE_MOVABLE;
1639 
1640 	/*
1641 	 * check whether node_states[N_HIGH_MEMORY] will be changed
1642 	 * If we try to offline the last present @nr_pages from the node,
1643 	 * we can determind we will need to clear the node from
1644 	 * node_states[N_HIGH_MEMORY].
1645 	 */
1646 	for (; zt <= zone_last; zt++)
1647 		present_pages += pgdat->node_zones[zt].present_pages;
1648 	if (nr_pages >= present_pages)
1649 		arg->status_change_nid = zone_to_nid(zone);
1650 	else
1651 		arg->status_change_nid = -1;
1652 }
1653 
1654 static void node_states_clear_node(int node, struct memory_notify *arg)
1655 {
1656 	if (arg->status_change_nid_normal >= 0)
1657 		node_clear_state(node, N_NORMAL_MEMORY);
1658 
1659 	if ((N_MEMORY != N_NORMAL_MEMORY) &&
1660 	    (arg->status_change_nid_high >= 0))
1661 		node_clear_state(node, N_HIGH_MEMORY);
1662 
1663 	if ((N_MEMORY != N_HIGH_MEMORY) &&
1664 	    (arg->status_change_nid >= 0))
1665 		node_clear_state(node, N_MEMORY);
1666 }
1667 
1668 static int __ref __offline_pages(unsigned long start_pfn,
1669 		  unsigned long end_pfn, unsigned long timeout)
1670 {
1671 	unsigned long pfn, nr_pages, expire;
1672 	long offlined_pages;
1673 	int ret, drain, retry_max, node;
1674 	unsigned long flags;
1675 	struct zone *zone;
1676 	struct memory_notify arg;
1677 
1678 	/* at least, alignment against pageblock is necessary */
1679 	if (!IS_ALIGNED(start_pfn, pageblock_nr_pages))
1680 		return -EINVAL;
1681 	if (!IS_ALIGNED(end_pfn, pageblock_nr_pages))
1682 		return -EINVAL;
1683 	/* This makes hotplug much easier...and readable.
1684 	   we assume this for now. .*/
1685 	if (!test_pages_in_a_zone(start_pfn, end_pfn))
1686 		return -EINVAL;
1687 
1688 	zone = page_zone(pfn_to_page(start_pfn));
1689 	node = zone_to_nid(zone);
1690 	nr_pages = end_pfn - start_pfn;
1691 
1692 	if (zone_idx(zone) <= ZONE_NORMAL && !can_offline_normal(zone, nr_pages))
1693 		return -EINVAL;
1694 
1695 	/* set above range as isolated */
1696 	ret = start_isolate_page_range(start_pfn, end_pfn,
1697 				       MIGRATE_MOVABLE, true);
1698 	if (ret)
1699 		return ret;
1700 
1701 	arg.start_pfn = start_pfn;
1702 	arg.nr_pages = nr_pages;
1703 	node_states_check_changes_offline(nr_pages, zone, &arg);
1704 
1705 	ret = memory_notify(MEM_GOING_OFFLINE, &arg);
1706 	ret = notifier_to_errno(ret);
1707 	if (ret)
1708 		goto failed_removal;
1709 
1710 	pfn = start_pfn;
1711 	expire = jiffies + timeout;
1712 	drain = 0;
1713 	retry_max = 5;
1714 repeat:
1715 	/* start memory hot removal */
1716 	ret = -EAGAIN;
1717 	if (time_after(jiffies, expire))
1718 		goto failed_removal;
1719 	ret = -EINTR;
1720 	if (signal_pending(current))
1721 		goto failed_removal;
1722 	ret = 0;
1723 	if (drain) {
1724 		lru_add_drain_all();
1725 		cond_resched();
1726 		drain_all_pages(zone);
1727 	}
1728 
1729 	pfn = scan_movable_pages(start_pfn, end_pfn);
1730 	if (pfn) { /* We have movable pages */
1731 		ret = do_migrate_range(pfn, end_pfn);
1732 		if (!ret) {
1733 			drain = 1;
1734 			goto repeat;
1735 		} else {
1736 			if (ret < 0)
1737 				if (--retry_max == 0)
1738 					goto failed_removal;
1739 			yield();
1740 			drain = 1;
1741 			goto repeat;
1742 		}
1743 	}
1744 	/* drain all zone's lru pagevec, this is asynchronous... */
1745 	lru_add_drain_all();
1746 	yield();
1747 	/* drain pcp pages, this is synchronous. */
1748 	drain_all_pages(zone);
1749 	/*
1750 	 * dissolve free hugepages in the memory block before doing offlining
1751 	 * actually in order to make hugetlbfs's object counting consistent.
1752 	 */
1753 	dissolve_free_huge_pages(start_pfn, end_pfn);
1754 	/* check again */
1755 	offlined_pages = check_pages_isolated(start_pfn, end_pfn);
1756 	if (offlined_pages < 0) {
1757 		ret = -EBUSY;
1758 		goto failed_removal;
1759 	}
1760 	printk(KERN_INFO "Offlined Pages %ld\n", offlined_pages);
1761 	/* Ok, all of our target is isolated.
1762 	   We cannot do rollback at this point. */
1763 	offline_isolated_pages(start_pfn, end_pfn);
1764 	/* reset pagetype flags and makes migrate type to be MOVABLE */
1765 	undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
1766 	/* removal success */
1767 	adjust_managed_page_count(pfn_to_page(start_pfn), -offlined_pages);
1768 	zone->present_pages -= offlined_pages;
1769 
1770 	pgdat_resize_lock(zone->zone_pgdat, &flags);
1771 	zone->zone_pgdat->node_present_pages -= offlined_pages;
1772 	pgdat_resize_unlock(zone->zone_pgdat, &flags);
1773 
1774 	init_per_zone_wmark_min();
1775 
1776 	if (!populated_zone(zone)) {
1777 		zone_pcp_reset(zone);
1778 		mutex_lock(&zonelists_mutex);
1779 		build_all_zonelists(NULL, NULL);
1780 		mutex_unlock(&zonelists_mutex);
1781 	} else
1782 		zone_pcp_update(zone);
1783 
1784 	node_states_clear_node(node, &arg);
1785 	if (arg.status_change_nid >= 0)
1786 		kswapd_stop(node);
1787 
1788 	vm_total_pages = nr_free_pagecache_pages();
1789 	writeback_set_ratelimit();
1790 
1791 	memory_notify(MEM_OFFLINE, &arg);
1792 	return 0;
1793 
1794 failed_removal:
1795 	printk(KERN_INFO "memory offlining [mem %#010llx-%#010llx] failed\n",
1796 	       (unsigned long long) start_pfn << PAGE_SHIFT,
1797 	       ((unsigned long long) end_pfn << PAGE_SHIFT) - 1);
1798 	memory_notify(MEM_CANCEL_OFFLINE, &arg);
1799 	/* pushback to free area */
1800 	undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
1801 	return ret;
1802 }
1803 
1804 /* Must be protected by mem_hotplug_begin() */
1805 int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
1806 {
1807 	return __offline_pages(start_pfn, start_pfn + nr_pages, 120 * HZ);
1808 }
1809 #endif /* CONFIG_MEMORY_HOTREMOVE */
1810 
1811 /**
1812  * walk_memory_range - walks through all mem sections in [start_pfn, end_pfn)
1813  * @start_pfn: start pfn of the memory range
1814  * @end_pfn: end pfn of the memory range
1815  * @arg: argument passed to func
1816  * @func: callback for each memory section walked
1817  *
1818  * This function walks through all present mem sections in range
1819  * [start_pfn, end_pfn) and call func on each mem section.
1820  *
1821  * Returns the return value of func.
1822  */
1823 int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
1824 		void *arg, int (*func)(struct memory_block *, void *))
1825 {
1826 	struct memory_block *mem = NULL;
1827 	struct mem_section *section;
1828 	unsigned long pfn, section_nr;
1829 	int ret;
1830 
1831 	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
1832 		section_nr = pfn_to_section_nr(pfn);
1833 		if (!present_section_nr(section_nr))
1834 			continue;
1835 
1836 		section = __nr_to_section(section_nr);
1837 		/* same memblock? */
1838 		if (mem)
1839 			if ((section_nr >= mem->start_section_nr) &&
1840 			    (section_nr <= mem->end_section_nr))
1841 				continue;
1842 
1843 		mem = find_memory_block_hinted(section, mem);
1844 		if (!mem)
1845 			continue;
1846 
1847 		ret = func(mem, arg);
1848 		if (ret) {
1849 			kobject_put(&mem->dev.kobj);
1850 			return ret;
1851 		}
1852 	}
1853 
1854 	if (mem)
1855 		kobject_put(&mem->dev.kobj);
1856 
1857 	return 0;
1858 }
1859 
1860 #ifdef CONFIG_MEMORY_HOTREMOVE
1861 static int check_memblock_offlined_cb(struct memory_block *mem, void *arg)
1862 {
1863 	int ret = !is_memblock_offlined(mem);
1864 
1865 	if (unlikely(ret)) {
1866 		phys_addr_t beginpa, endpa;
1867 
1868 		beginpa = PFN_PHYS(section_nr_to_pfn(mem->start_section_nr));
1869 		endpa = PFN_PHYS(section_nr_to_pfn(mem->end_section_nr + 1))-1;
1870 		pr_warn("removing memory fails, because memory "
1871 			"[%pa-%pa] is onlined\n",
1872 			&beginpa, &endpa);
1873 	}
1874 
1875 	return ret;
1876 }
1877 
1878 static int check_cpu_on_node(pg_data_t *pgdat)
1879 {
1880 	int cpu;
1881 
1882 	for_each_present_cpu(cpu) {
1883 		if (cpu_to_node(cpu) == pgdat->node_id)
1884 			/*
1885 			 * the cpu on this node isn't removed, and we can't
1886 			 * offline this node.
1887 			 */
1888 			return -EBUSY;
1889 	}
1890 
1891 	return 0;
1892 }
1893 
1894 static void unmap_cpu_on_node(pg_data_t *pgdat)
1895 {
1896 #ifdef CONFIG_ACPI_NUMA
1897 	int cpu;
1898 
1899 	for_each_possible_cpu(cpu)
1900 		if (cpu_to_node(cpu) == pgdat->node_id)
1901 			numa_clear_node(cpu);
1902 #endif
1903 }
1904 
1905 static int check_and_unmap_cpu_on_node(pg_data_t *pgdat)
1906 {
1907 	int ret;
1908 
1909 	ret = check_cpu_on_node(pgdat);
1910 	if (ret)
1911 		return ret;
1912 
1913 	/*
1914 	 * the node will be offlined when we come here, so we can clear
1915 	 * the cpu_to_node() now.
1916 	 */
1917 
1918 	unmap_cpu_on_node(pgdat);
1919 	return 0;
1920 }
1921 
1922 /**
1923  * try_offline_node
1924  *
1925  * Offline a node if all memory sections and cpus of the node are removed.
1926  *
1927  * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
1928  * and online/offline operations before this call.
1929  */
1930 void try_offline_node(int nid)
1931 {
1932 	pg_data_t *pgdat = NODE_DATA(nid);
1933 	unsigned long start_pfn = pgdat->node_start_pfn;
1934 	unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
1935 	unsigned long pfn;
1936 	int i;
1937 
1938 	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
1939 		unsigned long section_nr = pfn_to_section_nr(pfn);
1940 
1941 		if (!present_section_nr(section_nr))
1942 			continue;
1943 
1944 		if (pfn_to_nid(pfn) != nid)
1945 			continue;
1946 
1947 		/*
1948 		 * some memory sections of this node are not removed, and we
1949 		 * can't offline node now.
1950 		 */
1951 		return;
1952 	}
1953 
1954 	if (check_and_unmap_cpu_on_node(pgdat))
1955 		return;
1956 
1957 	/*
1958 	 * all memory/cpu of this node are removed, we can offline this
1959 	 * node now.
1960 	 */
1961 	node_set_offline(nid);
1962 	unregister_one_node(nid);
1963 
1964 	/* free waittable in each zone */
1965 	for (i = 0; i < MAX_NR_ZONES; i++) {
1966 		struct zone *zone = pgdat->node_zones + i;
1967 
1968 		/*
1969 		 * wait_table may be allocated from boot memory,
1970 		 * here only free if it's allocated by vmalloc.
1971 		 */
1972 		if (is_vmalloc_addr(zone->wait_table))
1973 			vfree(zone->wait_table);
1974 	}
1975 }
1976 EXPORT_SYMBOL(try_offline_node);
1977 
1978 /**
1979  * remove_memory
1980  *
1981  * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
1982  * and online/offline operations before this call, as required by
1983  * try_offline_node().
1984  */
1985 void __ref remove_memory(int nid, u64 start, u64 size)
1986 {
1987 	int ret;
1988 
1989 	BUG_ON(check_hotplug_memory_range(start, size));
1990 
1991 	mem_hotplug_begin();
1992 
1993 	/*
1994 	 * All memory blocks must be offlined before removing memory.  Check
1995 	 * whether all memory blocks in question are offline and trigger a BUG()
1996 	 * if this is not the case.
1997 	 */
1998 	ret = walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1), NULL,
1999 				check_memblock_offlined_cb);
2000 	if (ret)
2001 		BUG();
2002 
2003 	/* remove memmap entry */
2004 	firmware_map_remove(start, start + size, "System RAM");
2005 
2006 	arch_remove_memory(start, size);
2007 
2008 	try_offline_node(nid);
2009 
2010 	mem_hotplug_done();
2011 }
2012 EXPORT_SYMBOL_GPL(remove_memory);
2013 #endif /* CONFIG_MEMORY_HOTREMOVE */
2014