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b20a3503
CL
1/*
2 * Memory Migration functionality - linux/mm/migration.c
3 *
4 * Copyright (C) 2006 Silicon Graphics, Inc., Christoph Lameter
5 *
6 * Page migration was first developed in the context of the memory hotplug
7 * project. The main authors of the migration code are:
8 *
9 * IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
10 * Hirokazu Takahashi <taka@valinux.co.jp>
11 * Dave Hansen <haveblue@us.ibm.com>
cde53535 12 * Christoph Lameter
b20a3503
CL
13 */
14
15#include <linux/migrate.h>
b95f1b31 16#include <linux/export.h>
b20a3503 17#include <linux/swap.h>
0697212a 18#include <linux/swapops.h>
b20a3503 19#include <linux/pagemap.h>
e23ca00b 20#include <linux/buffer_head.h>
b20a3503 21#include <linux/mm_inline.h>
b488893a 22#include <linux/nsproxy.h>
b20a3503 23#include <linux/pagevec.h>
e9995ef9 24#include <linux/ksm.h>
b20a3503
CL
25#include <linux/rmap.h>
26#include <linux/topology.h>
27#include <linux/cpu.h>
28#include <linux/cpuset.h>
04e62a29 29#include <linux/writeback.h>
742755a1
CL
30#include <linux/mempolicy.h>
31#include <linux/vmalloc.h>
86c3a764 32#include <linux/security.h>
8a9f3ccd 33#include <linux/memcontrol.h>
4f5ca265 34#include <linux/syscalls.h>
290408d4 35#include <linux/hugetlb.h>
8e6ac7fa 36#include <linux/hugetlb_cgroup.h>
5a0e3ad6 37#include <linux/gfp.h>
bf6bddf1 38#include <linux/balloon_compaction.h>
f714f4f2 39#include <linux/mmu_notifier.h>
b20a3503 40
0d1836c3
MN
41#include <asm/tlbflush.h>
42
7b2a2d4a
MG
43#define CREATE_TRACE_POINTS
44#include <trace/events/migrate.h>
45
b20a3503
CL
46#include "internal.h"
47
b20a3503 48/*
742755a1 49 * migrate_prep() needs to be called before we start compiling a list of pages
748446bb
MG
50 * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is
51 * undesirable, use migrate_prep_local()
b20a3503
CL
52 */
53int migrate_prep(void)
54{
b20a3503
CL
55 /*
56 * Clear the LRU lists so pages can be isolated.
57 * Note that pages may be moved off the LRU after we have
58 * drained them. Those pages will fail to migrate like other
59 * pages that may be busy.
60 */
61 lru_add_drain_all();
62
63 return 0;
64}
65
748446bb
MG
66/* Do the necessary work of migrate_prep but not if it involves other CPUs */
67int migrate_prep_local(void)
68{
69 lru_add_drain();
70
71 return 0;
72}
73
5733c7d1
RA
74/*
75 * Put previously isolated pages back onto the appropriate lists
76 * from where they were once taken off for compaction/migration.
77 *
59c82b70
JK
78 * This function shall be used whenever the isolated pageset has been
79 * built from lru, balloon, hugetlbfs page. See isolate_migratepages_range()
80 * and isolate_huge_page().
5733c7d1
RA
81 */
82void putback_movable_pages(struct list_head *l)
83{
84 struct page *page;
85 struct page *page2;
86
b20a3503 87 list_for_each_entry_safe(page, page2, l, lru) {
31caf665
NH
88 if (unlikely(PageHuge(page))) {
89 putback_active_hugepage(page);
90 continue;
91 }
e24f0b8f 92 list_del(&page->lru);
a731286d 93 dec_zone_page_state(page, NR_ISOLATED_ANON +
6c0b1351 94 page_is_file_cache(page));
117aad1e 95 if (unlikely(isolated_balloon_page(page)))
bf6bddf1
RA
96 balloon_page_putback(page);
97 else
98 putback_lru_page(page);
b20a3503 99 }
b20a3503
CL
100}
101
0697212a
CL
102/*
103 * Restore a potential migration pte to a working pte entry
104 */
e9995ef9
HD
105static int remove_migration_pte(struct page *new, struct vm_area_struct *vma,
106 unsigned long addr, void *old)
0697212a
CL
107{
108 struct mm_struct *mm = vma->vm_mm;
109 swp_entry_t entry;
0697212a
CL
110 pmd_t *pmd;
111 pte_t *ptep, pte;
112 spinlock_t *ptl;
113
290408d4
NH
114 if (unlikely(PageHuge(new))) {
115 ptep = huge_pte_offset(mm, addr);
116 if (!ptep)
117 goto out;
cb900f41 118 ptl = huge_pte_lockptr(hstate_vma(vma), mm, ptep);
290408d4 119 } else {
6219049a
BL
120 pmd = mm_find_pmd(mm, addr);
121 if (!pmd)
290408d4 122 goto out;
0697212a 123
290408d4 124 ptep = pte_offset_map(pmd, addr);
0697212a 125
486cf46f
HD
126 /*
127 * Peek to check is_swap_pte() before taking ptlock? No, we
128 * can race mremap's move_ptes(), which skips anon_vma lock.
129 */
290408d4
NH
130
131 ptl = pte_lockptr(mm, pmd);
132 }
0697212a 133
0697212a
CL
134 spin_lock(ptl);
135 pte = *ptep;
136 if (!is_swap_pte(pte))
e9995ef9 137 goto unlock;
0697212a
CL
138
139 entry = pte_to_swp_entry(pte);
140
e9995ef9
HD
141 if (!is_migration_entry(entry) ||
142 migration_entry_to_page(entry) != old)
143 goto unlock;
0697212a 144
0697212a
CL
145 get_page(new);
146 pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
c3d16e16
CG
147 if (pte_swp_soft_dirty(*ptep))
148 pte = pte_mksoft_dirty(pte);
d3cb8bf6
MG
149
150 /* Recheck VMA as permissions can change since migration started */
0697212a 151 if (is_write_migration_entry(entry))
d3cb8bf6
MG
152 pte = maybe_mkwrite(pte, vma);
153
3ef8fd7f 154#ifdef CONFIG_HUGETLB_PAGE
be7517d6 155 if (PageHuge(new)) {
290408d4 156 pte = pte_mkhuge(pte);
be7517d6
TL
157 pte = arch_make_huge_pte(pte, vma, new, 0);
158 }
3ef8fd7f 159#endif
c2cc499c 160 flush_dcache_page(new);
0697212a 161 set_pte_at(mm, addr, ptep, pte);
04e62a29 162
290408d4
NH
163 if (PageHuge(new)) {
164 if (PageAnon(new))
165 hugepage_add_anon_rmap(new, vma, addr);
166 else
167 page_dup_rmap(new);
168 } else if (PageAnon(new))
04e62a29
CL
169 page_add_anon_rmap(new, vma, addr);
170 else
171 page_add_file_rmap(new);
172
173 /* No need to invalidate - it was non-present before */
4b3073e1 174 update_mmu_cache(vma, addr, ptep);
e9995ef9 175unlock:
0697212a 176 pte_unmap_unlock(ptep, ptl);
e9995ef9
HD
177out:
178 return SWAP_AGAIN;
0697212a
CL
179}
180
04e62a29
CL
181/*
182 * Get rid of all migration entries and replace them by
183 * references to the indicated page.
184 */
185static void remove_migration_ptes(struct page *old, struct page *new)
186{
051ac83a
JK
187 struct rmap_walk_control rwc = {
188 .rmap_one = remove_migration_pte,
189 .arg = old,
190 };
191
192 rmap_walk(new, &rwc);
04e62a29
CL
193}
194
0697212a
CL
195/*
196 * Something used the pte of a page under migration. We need to
197 * get to the page and wait until migration is finished.
198 * When we return from this function the fault will be retried.
0697212a 199 */
e66f17ff 200void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
30dad309 201 spinlock_t *ptl)
0697212a 202{
30dad309 203 pte_t pte;
0697212a
CL
204 swp_entry_t entry;
205 struct page *page;
206
30dad309 207 spin_lock(ptl);
0697212a
CL
208 pte = *ptep;
209 if (!is_swap_pte(pte))
210 goto out;
211
212 entry = pte_to_swp_entry(pte);
213 if (!is_migration_entry(entry))
214 goto out;
215
216 page = migration_entry_to_page(entry);
217
e286781d
NP
218 /*
219 * Once radix-tree replacement of page migration started, page_count
220 * *must* be zero. And, we don't want to call wait_on_page_locked()
221 * against a page without get_page().
222 * So, we use get_page_unless_zero(), here. Even failed, page fault
223 * will occur again.
224 */
225 if (!get_page_unless_zero(page))
226 goto out;
0697212a
CL
227 pte_unmap_unlock(ptep, ptl);
228 wait_on_page_locked(page);
229 put_page(page);
230 return;
231out:
232 pte_unmap_unlock(ptep, ptl);
233}
234
30dad309
NH
235void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
236 unsigned long address)
237{
238 spinlock_t *ptl = pte_lockptr(mm, pmd);
239 pte_t *ptep = pte_offset_map(pmd, address);
240 __migration_entry_wait(mm, ptep, ptl);
241}
242
cb900f41
KS
243void migration_entry_wait_huge(struct vm_area_struct *vma,
244 struct mm_struct *mm, pte_t *pte)
30dad309 245{
cb900f41 246 spinlock_t *ptl = huge_pte_lockptr(hstate_vma(vma), mm, pte);
30dad309
NH
247 __migration_entry_wait(mm, pte, ptl);
248}
249
b969c4ab
MG
250#ifdef CONFIG_BLOCK
251/* Returns true if all buffers are successfully locked */
a6bc32b8
MG
252static bool buffer_migrate_lock_buffers(struct buffer_head *head,
253 enum migrate_mode mode)
b969c4ab
MG
254{
255 struct buffer_head *bh = head;
256
257 /* Simple case, sync compaction */
a6bc32b8 258 if (mode != MIGRATE_ASYNC) {
b969c4ab
MG
259 do {
260 get_bh(bh);
261 lock_buffer(bh);
262 bh = bh->b_this_page;
263
264 } while (bh != head);
265
266 return true;
267 }
268
269 /* async case, we cannot block on lock_buffer so use trylock_buffer */
270 do {
271 get_bh(bh);
272 if (!trylock_buffer(bh)) {
273 /*
274 * We failed to lock the buffer and cannot stall in
275 * async migration. Release the taken locks
276 */
277 struct buffer_head *failed_bh = bh;
278 put_bh(failed_bh);
279 bh = head;
280 while (bh != failed_bh) {
281 unlock_buffer(bh);
282 put_bh(bh);
283 bh = bh->b_this_page;
284 }
285 return false;
286 }
287
288 bh = bh->b_this_page;
289 } while (bh != head);
290 return true;
291}
292#else
293static inline bool buffer_migrate_lock_buffers(struct buffer_head *head,
a6bc32b8 294 enum migrate_mode mode)
b969c4ab
MG
295{
296 return true;
297}
298#endif /* CONFIG_BLOCK */
299
b20a3503 300/*
c3fcf8a5 301 * Replace the page in the mapping.
5b5c7120
CL
302 *
303 * The number of remaining references must be:
304 * 1 for anonymous pages without a mapping
305 * 2 for pages with a mapping
266cf658 306 * 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
b20a3503 307 */
36bc08cc 308int migrate_page_move_mapping(struct address_space *mapping,
b969c4ab 309 struct page *newpage, struct page *page,
8e321fef
BL
310 struct buffer_head *head, enum migrate_mode mode,
311 int extra_count)
b20a3503 312{
8e321fef 313 int expected_count = 1 + extra_count;
7cf9c2c7 314 void **pslot;
b20a3503 315
6c5240ae 316 if (!mapping) {
0e8c7d0f 317 /* Anonymous page without mapping */
8e321fef 318 if (page_count(page) != expected_count)
6c5240ae 319 return -EAGAIN;
78bd5209 320 return MIGRATEPAGE_SUCCESS;
6c5240ae
CL
321 }
322
19fd6231 323 spin_lock_irq(&mapping->tree_lock);
b20a3503 324
7cf9c2c7
NP
325 pslot = radix_tree_lookup_slot(&mapping->page_tree,
326 page_index(page));
b20a3503 327
8e321fef 328 expected_count += 1 + page_has_private(page);
e286781d 329 if (page_count(page) != expected_count ||
29c1f677 330 radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) {
19fd6231 331 spin_unlock_irq(&mapping->tree_lock);
e23ca00b 332 return -EAGAIN;
b20a3503
CL
333 }
334
e286781d 335 if (!page_freeze_refs(page, expected_count)) {
19fd6231 336 spin_unlock_irq(&mapping->tree_lock);
e286781d
NP
337 return -EAGAIN;
338 }
339
b969c4ab
MG
340 /*
341 * In the async migration case of moving a page with buffers, lock the
342 * buffers using trylock before the mapping is moved. If the mapping
343 * was moved, we later failed to lock the buffers and could not move
344 * the mapping back due to an elevated page count, we would have to
345 * block waiting on other references to be dropped.
346 */
a6bc32b8
MG
347 if (mode == MIGRATE_ASYNC && head &&
348 !buffer_migrate_lock_buffers(head, mode)) {
b969c4ab
MG
349 page_unfreeze_refs(page, expected_count);
350 spin_unlock_irq(&mapping->tree_lock);
351 return -EAGAIN;
352 }
353
b20a3503
CL
354 /*
355 * Now we know that no one else is looking at the page.
b20a3503 356 */
7cf9c2c7 357 get_page(newpage); /* add cache reference */
b20a3503
CL
358 if (PageSwapCache(page)) {
359 SetPageSwapCache(newpage);
360 set_page_private(newpage, page_private(page));
361 }
362
7cf9c2c7
NP
363 radix_tree_replace_slot(pslot, newpage);
364
365 /*
937a94c9
JG
366 * Drop cache reference from old page by unfreezing
367 * to one less reference.
7cf9c2c7
NP
368 * We know this isn't the last reference.
369 */
937a94c9 370 page_unfreeze_refs(page, expected_count - 1);
7cf9c2c7 371
0e8c7d0f
CL
372 /*
373 * If moved to a different zone then also account
374 * the page for that zone. Other VM counters will be
375 * taken care of when we establish references to the
376 * new page and drop references to the old page.
377 *
378 * Note that anonymous pages are accounted for
379 * via NR_FILE_PAGES and NR_ANON_PAGES if they
380 * are mapped to swap space.
381 */
382 __dec_zone_page_state(page, NR_FILE_PAGES);
383 __inc_zone_page_state(newpage, NR_FILE_PAGES);
99a15e21 384 if (!PageSwapCache(page) && PageSwapBacked(page)) {
4b02108a
KM
385 __dec_zone_page_state(page, NR_SHMEM);
386 __inc_zone_page_state(newpage, NR_SHMEM);
387 }
19fd6231 388 spin_unlock_irq(&mapping->tree_lock);
b20a3503 389
78bd5209 390 return MIGRATEPAGE_SUCCESS;
b20a3503 391}
b20a3503 392
290408d4
NH
393/*
394 * The expected number of remaining references is the same as that
395 * of migrate_page_move_mapping().
396 */
397int migrate_huge_page_move_mapping(struct address_space *mapping,
398 struct page *newpage, struct page *page)
399{
400 int expected_count;
401 void **pslot;
402
403 if (!mapping) {
404 if (page_count(page) != 1)
405 return -EAGAIN;
78bd5209 406 return MIGRATEPAGE_SUCCESS;
290408d4
NH
407 }
408
409 spin_lock_irq(&mapping->tree_lock);
410
411 pslot = radix_tree_lookup_slot(&mapping->page_tree,
412 page_index(page));
413
414 expected_count = 2 + page_has_private(page);
415 if (page_count(page) != expected_count ||
29c1f677 416 radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) {
290408d4
NH
417 spin_unlock_irq(&mapping->tree_lock);
418 return -EAGAIN;
419 }
420
421 if (!page_freeze_refs(page, expected_count)) {
422 spin_unlock_irq(&mapping->tree_lock);
423 return -EAGAIN;
424 }
425
426 get_page(newpage);
427
428 radix_tree_replace_slot(pslot, newpage);
429
937a94c9 430 page_unfreeze_refs(page, expected_count - 1);
290408d4
NH
431
432 spin_unlock_irq(&mapping->tree_lock);
78bd5209 433 return MIGRATEPAGE_SUCCESS;
290408d4
NH
434}
435
30b0a105
DH
436/*
437 * Gigantic pages are so large that we do not guarantee that page++ pointer
438 * arithmetic will work across the entire page. We need something more
439 * specialized.
440 */
441static void __copy_gigantic_page(struct page *dst, struct page *src,
442 int nr_pages)
443{
444 int i;
445 struct page *dst_base = dst;
446 struct page *src_base = src;
447
448 for (i = 0; i < nr_pages; ) {
449 cond_resched();
450 copy_highpage(dst, src);
451
452 i++;
453 dst = mem_map_next(dst, dst_base, i);
454 src = mem_map_next(src, src_base, i);
455 }
456}
457
458static void copy_huge_page(struct page *dst, struct page *src)
459{
460 int i;
461 int nr_pages;
462
463 if (PageHuge(src)) {
464 /* hugetlbfs page */
465 struct hstate *h = page_hstate(src);
466 nr_pages = pages_per_huge_page(h);
467
468 if (unlikely(nr_pages > MAX_ORDER_NR_PAGES)) {
469 __copy_gigantic_page(dst, src, nr_pages);
470 return;
471 }
472 } else {
473 /* thp page */
474 BUG_ON(!PageTransHuge(src));
475 nr_pages = hpage_nr_pages(src);
476 }
477
478 for (i = 0; i < nr_pages; i++) {
479 cond_resched();
480 copy_highpage(dst + i, src + i);
481 }
482}
483
b20a3503
CL
484/*
485 * Copy the page to its new location
486 */
290408d4 487void migrate_page_copy(struct page *newpage, struct page *page)
b20a3503 488{
7851a45c
RR
489 int cpupid;
490
b32967ff 491 if (PageHuge(page) || PageTransHuge(page))
290408d4
NH
492 copy_huge_page(newpage, page);
493 else
494 copy_highpage(newpage, page);
b20a3503
CL
495
496 if (PageError(page))
497 SetPageError(newpage);
498 if (PageReferenced(page))
499 SetPageReferenced(newpage);
500 if (PageUptodate(page))
501 SetPageUptodate(newpage);
894bc310 502 if (TestClearPageActive(page)) {
309381fe 503 VM_BUG_ON_PAGE(PageUnevictable(page), page);
b20a3503 504 SetPageActive(newpage);
418b27ef
LS
505 } else if (TestClearPageUnevictable(page))
506 SetPageUnevictable(newpage);
b20a3503
CL
507 if (PageChecked(page))
508 SetPageChecked(newpage);
509 if (PageMappedToDisk(page))
510 SetPageMappedToDisk(newpage);
511
512 if (PageDirty(page)) {
513 clear_page_dirty_for_io(page);
3a902c5f
NP
514 /*
515 * Want to mark the page and the radix tree as dirty, and
516 * redo the accounting that clear_page_dirty_for_io undid,
517 * but we can't use set_page_dirty because that function
518 * is actually a signal that all of the page has become dirty.
25985edc 519 * Whereas only part of our page may be dirty.
3a902c5f 520 */
752dc185
HD
521 if (PageSwapBacked(page))
522 SetPageDirty(newpage);
523 else
524 __set_page_dirty_nobuffers(newpage);
b20a3503
CL
525 }
526
7851a45c
RR
527 /*
528 * Copy NUMA information to the new page, to prevent over-eager
529 * future migrations of this same page.
530 */
531 cpupid = page_cpupid_xchg_last(page, -1);
532 page_cpupid_xchg_last(newpage, cpupid);
533
b291f000 534 mlock_migrate_page(newpage, page);
e9995ef9 535 ksm_migrate_page(newpage, page);
c8d6553b
HD
536 /*
537 * Please do not reorder this without considering how mm/ksm.c's
538 * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache().
539 */
b3b3a99c
NH
540 if (PageSwapCache(page))
541 ClearPageSwapCache(page);
b20a3503
CL
542 ClearPagePrivate(page);
543 set_page_private(page, 0);
b20a3503
CL
544
545 /*
546 * If any waiters have accumulated on the new page then
547 * wake them up.
548 */
549 if (PageWriteback(newpage))
550 end_page_writeback(newpage);
551}
b20a3503 552
1d8b85cc
CL
553/************************************************************
554 * Migration functions
555 ***********************************************************/
556
b20a3503
CL
557/*
558 * Common logic to directly migrate a single page suitable for
266cf658 559 * pages that do not use PagePrivate/PagePrivate2.
b20a3503
CL
560 *
561 * Pages are locked upon entry and exit.
562 */
2d1db3b1 563int migrate_page(struct address_space *mapping,
a6bc32b8
MG
564 struct page *newpage, struct page *page,
565 enum migrate_mode mode)
b20a3503
CL
566{
567 int rc;
568
569 BUG_ON(PageWriteback(page)); /* Writeback must be complete */
570
8e321fef 571 rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0);
b20a3503 572
78bd5209 573 if (rc != MIGRATEPAGE_SUCCESS)
b20a3503
CL
574 return rc;
575
576 migrate_page_copy(newpage, page);
78bd5209 577 return MIGRATEPAGE_SUCCESS;
b20a3503
CL
578}
579EXPORT_SYMBOL(migrate_page);
580
9361401e 581#ifdef CONFIG_BLOCK
1d8b85cc
CL
582/*
583 * Migration function for pages with buffers. This function can only be used
584 * if the underlying filesystem guarantees that no other references to "page"
585 * exist.
586 */
2d1db3b1 587int buffer_migrate_page(struct address_space *mapping,
a6bc32b8 588 struct page *newpage, struct page *page, enum migrate_mode mode)
1d8b85cc 589{
1d8b85cc
CL
590 struct buffer_head *bh, *head;
591 int rc;
592
1d8b85cc 593 if (!page_has_buffers(page))
a6bc32b8 594 return migrate_page(mapping, newpage, page, mode);
1d8b85cc
CL
595
596 head = page_buffers(page);
597
8e321fef 598 rc = migrate_page_move_mapping(mapping, newpage, page, head, mode, 0);
1d8b85cc 599
78bd5209 600 if (rc != MIGRATEPAGE_SUCCESS)
1d8b85cc
CL
601 return rc;
602
b969c4ab
MG
603 /*
604 * In the async case, migrate_page_move_mapping locked the buffers
605 * with an IRQ-safe spinlock held. In the sync case, the buffers
606 * need to be locked now
607 */
a6bc32b8
MG
608 if (mode != MIGRATE_ASYNC)
609 BUG_ON(!buffer_migrate_lock_buffers(head, mode));
1d8b85cc
CL
610
611 ClearPagePrivate(page);
612 set_page_private(newpage, page_private(page));
613 set_page_private(page, 0);
614 put_page(page);
615 get_page(newpage);
616
617 bh = head;
618 do {
619 set_bh_page(bh, newpage, bh_offset(bh));
620 bh = bh->b_this_page;
621
622 } while (bh != head);
623
624 SetPagePrivate(newpage);
625
626 migrate_page_copy(newpage, page);
627
628 bh = head;
629 do {
630 unlock_buffer(bh);
631 put_bh(bh);
632 bh = bh->b_this_page;
633
634 } while (bh != head);
635
78bd5209 636 return MIGRATEPAGE_SUCCESS;
1d8b85cc
CL
637}
638EXPORT_SYMBOL(buffer_migrate_page);
9361401e 639#endif
1d8b85cc 640
04e62a29
CL
641/*
642 * Writeback a page to clean the dirty state
643 */
644static int writeout(struct address_space *mapping, struct page *page)
8351a6e4 645{
04e62a29
CL
646 struct writeback_control wbc = {
647 .sync_mode = WB_SYNC_NONE,
648 .nr_to_write = 1,
649 .range_start = 0,
650 .range_end = LLONG_MAX,
04e62a29
CL
651 .for_reclaim = 1
652 };
653 int rc;
654
655 if (!mapping->a_ops->writepage)
656 /* No write method for the address space */
657 return -EINVAL;
658
659 if (!clear_page_dirty_for_io(page))
660 /* Someone else already triggered a write */
661 return -EAGAIN;
662
8351a6e4 663 /*
04e62a29
CL
664 * A dirty page may imply that the underlying filesystem has
665 * the page on some queue. So the page must be clean for
666 * migration. Writeout may mean we loose the lock and the
667 * page state is no longer what we checked for earlier.
668 * At this point we know that the migration attempt cannot
669 * be successful.
8351a6e4 670 */
04e62a29 671 remove_migration_ptes(page, page);
8351a6e4 672
04e62a29 673 rc = mapping->a_ops->writepage(page, &wbc);
8351a6e4 674
04e62a29
CL
675 if (rc != AOP_WRITEPAGE_ACTIVATE)
676 /* unlocked. Relock */
677 lock_page(page);
678
bda8550d 679 return (rc < 0) ? -EIO : -EAGAIN;
04e62a29
CL
680}
681
682/*
683 * Default handling if a filesystem does not provide a migration function.
684 */
685static int fallback_migrate_page(struct address_space *mapping,
a6bc32b8 686 struct page *newpage, struct page *page, enum migrate_mode mode)
04e62a29 687{
b969c4ab 688 if (PageDirty(page)) {
a6bc32b8
MG
689 /* Only writeback pages in full synchronous migration */
690 if (mode != MIGRATE_SYNC)
b969c4ab 691 return -EBUSY;
04e62a29 692 return writeout(mapping, page);
b969c4ab 693 }
8351a6e4
CL
694
695 /*
696 * Buffers may be managed in a filesystem specific way.
697 * We must have no buffers or drop them.
698 */
266cf658 699 if (page_has_private(page) &&
8351a6e4
CL
700 !try_to_release_page(page, GFP_KERNEL))
701 return -EAGAIN;
702
a6bc32b8 703 return migrate_page(mapping, newpage, page, mode);
8351a6e4
CL
704}
705
e24f0b8f
CL
706/*
707 * Move a page to a newly allocated page
708 * The page is locked and all ptes have been successfully removed.
709 *
710 * The new page will have replaced the old page if this function
711 * is successful.
894bc310
LS
712 *
713 * Return value:
714 * < 0 - error code
78bd5209 715 * MIGRATEPAGE_SUCCESS - success
e24f0b8f 716 */
3fe2011f 717static int move_to_new_page(struct page *newpage, struct page *page,
2ebba6b7 718 int page_was_mapped, enum migrate_mode mode)
e24f0b8f
CL
719{
720 struct address_space *mapping;
721 int rc;
722
723 /*
724 * Block others from accessing the page when we get around to
725 * establishing additional references. We are the only one
726 * holding a reference to the new page at this point.
727 */
529ae9aa 728 if (!trylock_page(newpage))
e24f0b8f
CL
729 BUG();
730
731 /* Prepare mapping for the new page.*/
732 newpage->index = page->index;
733 newpage->mapping = page->mapping;
b2e18538
RR
734 if (PageSwapBacked(page))
735 SetPageSwapBacked(newpage);
e24f0b8f
CL
736
737 mapping = page_mapping(page);
738 if (!mapping)
a6bc32b8 739 rc = migrate_page(mapping, newpage, page, mode);
b969c4ab 740 else if (mapping->a_ops->migratepage)
e24f0b8f 741 /*
b969c4ab
MG
742 * Most pages have a mapping and most filesystems provide a
743 * migratepage callback. Anonymous pages are part of swap
744 * space which also has its own migratepage callback. This
745 * is the most common path for page migration.
e24f0b8f 746 */
b969c4ab 747 rc = mapping->a_ops->migratepage(mapping,
a6bc32b8 748 newpage, page, mode);
b969c4ab 749 else
a6bc32b8 750 rc = fallback_migrate_page(mapping, newpage, page, mode);
e24f0b8f 751
78bd5209 752 if (rc != MIGRATEPAGE_SUCCESS) {
e24f0b8f 753 newpage->mapping = NULL;
3fe2011f 754 } else {
0a31bc97 755 mem_cgroup_migrate(page, newpage, false);
2ebba6b7 756 if (page_was_mapped)
3fe2011f 757 remove_migration_ptes(page, newpage);
35512eca 758 page->mapping = NULL;
3fe2011f 759 }
e24f0b8f
CL
760
761 unlock_page(newpage);
762
763 return rc;
764}
765
0dabec93 766static int __unmap_and_move(struct page *page, struct page *newpage,
9c620e2b 767 int force, enum migrate_mode mode)
e24f0b8f 768{
0dabec93 769 int rc = -EAGAIN;
2ebba6b7 770 int page_was_mapped = 0;
3f6c8272 771 struct anon_vma *anon_vma = NULL;
95a402c3 772
529ae9aa 773 if (!trylock_page(page)) {
a6bc32b8 774 if (!force || mode == MIGRATE_ASYNC)
0dabec93 775 goto out;
3e7d3449
MG
776
777 /*
778 * It's not safe for direct compaction to call lock_page.
779 * For example, during page readahead pages are added locked
780 * to the LRU. Later, when the IO completes the pages are
781 * marked uptodate and unlocked. However, the queueing
782 * could be merging multiple pages for one bio (e.g.
783 * mpage_readpages). If an allocation happens for the
784 * second or third page, the process can end up locking
785 * the same page twice and deadlocking. Rather than
786 * trying to be clever about what pages can be locked,
787 * avoid the use of lock_page for direct compaction
788 * altogether.
789 */
790 if (current->flags & PF_MEMALLOC)
0dabec93 791 goto out;
3e7d3449 792
e24f0b8f
CL
793 lock_page(page);
794 }
795
796 if (PageWriteback(page)) {
11bc82d6 797 /*
fed5b64a 798 * Only in the case of a full synchronous migration is it
a6bc32b8
MG
799 * necessary to wait for PageWriteback. In the async case,
800 * the retry loop is too short and in the sync-light case,
801 * the overhead of stalling is too much
11bc82d6 802 */
a6bc32b8 803 if (mode != MIGRATE_SYNC) {
11bc82d6 804 rc = -EBUSY;
0a31bc97 805 goto out_unlock;
11bc82d6
AA
806 }
807 if (!force)
0a31bc97 808 goto out_unlock;
e24f0b8f
CL
809 wait_on_page_writeback(page);
810 }
e24f0b8f 811 /*
dc386d4d
KH
812 * By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
813 * we cannot notice that anon_vma is freed while we migrates a page.
1ce82b69 814 * This get_anon_vma() delays freeing anon_vma pointer until the end
dc386d4d 815 * of migration. File cache pages are no problem because of page_lock()
989f89c5
KH
816 * File Caches may use write_page() or lock_page() in migration, then,
817 * just care Anon page here.
dc386d4d 818 */
b79bc0a0 819 if (PageAnon(page) && !PageKsm(page)) {
1ce82b69 820 /*
4fc3f1d6 821 * Only page_lock_anon_vma_read() understands the subtleties of
1ce82b69
HD
822 * getting a hold on an anon_vma from outside one of its mms.
823 */
746b18d4 824 anon_vma = page_get_anon_vma(page);
1ce82b69
HD
825 if (anon_vma) {
826 /*
746b18d4 827 * Anon page
1ce82b69 828 */
1ce82b69 829 } else if (PageSwapCache(page)) {
3fe2011f
MG
830 /*
831 * We cannot be sure that the anon_vma of an unmapped
832 * swapcache page is safe to use because we don't
833 * know in advance if the VMA that this page belonged
834 * to still exists. If the VMA and others sharing the
835 * data have been freed, then the anon_vma could
836 * already be invalid.
837 *
838 * To avoid this possibility, swapcache pages get
839 * migrated but are not remapped when migration
840 * completes
841 */
3fe2011f 842 } else {
0a31bc97 843 goto out_unlock;
3fe2011f 844 }
989f89c5 845 }
62e1c553 846
d6d86c0a 847 if (unlikely(isolated_balloon_page(page))) {
bf6bddf1
RA
848 /*
849 * A ballooned page does not need any special attention from
850 * physical to virtual reverse mapping procedures.
851 * Skip any attempt to unmap PTEs or to remap swap cache,
852 * in order to avoid burning cycles at rmap level, and perform
853 * the page migration right away (proteced by page lock).
854 */
855 rc = balloon_page_migrate(newpage, page, mode);
0a31bc97 856 goto out_unlock;
bf6bddf1
RA
857 }
858
dc386d4d 859 /*
62e1c553
SL
860 * Corner case handling:
861 * 1. When a new swap-cache page is read into, it is added to the LRU
862 * and treated as swapcache but it has no rmap yet.
863 * Calling try_to_unmap() against a page->mapping==NULL page will
864 * trigger a BUG. So handle it here.
865 * 2. An orphaned page (see truncate_complete_page) might have
866 * fs-private metadata. The page can be picked up due to memory
867 * offlining. Everywhere else except page reclaim, the page is
868 * invisible to the vm, so the page can not be migrated. So try to
869 * free the metadata, so the page can be freed.
e24f0b8f 870 */
62e1c553 871 if (!page->mapping) {
309381fe 872 VM_BUG_ON_PAGE(PageAnon(page), page);
1ce82b69 873 if (page_has_private(page)) {
62e1c553 874 try_to_free_buffers(page);
0a31bc97 875 goto out_unlock;
62e1c553 876 }
abfc3488 877 goto skip_unmap;
62e1c553
SL
878 }
879
dc386d4d 880 /* Establish migration ptes or remove ptes */
2ebba6b7
HD
881 if (page_mapped(page)) {
882 try_to_unmap(page,
883 TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS);
884 page_was_mapped = 1;
885 }
dc386d4d 886
abfc3488 887skip_unmap:
e6a1530d 888 if (!page_mapped(page))
2ebba6b7 889 rc = move_to_new_page(newpage, page, page_was_mapped, mode);
e24f0b8f 890
2ebba6b7 891 if (rc && page_was_mapped)
e24f0b8f 892 remove_migration_ptes(page, page);
3f6c8272
MG
893
894 /* Drop an anon_vma reference if we took one */
76545066 895 if (anon_vma)
9e60109f 896 put_anon_vma(anon_vma);
3f6c8272 897
0a31bc97 898out_unlock:
e24f0b8f 899 unlock_page(page);
0dabec93
MK
900out:
901 return rc;
902}
95a402c3 903
ef2a5153
GU
904/*
905 * gcc 4.7 and 4.8 on arm get an ICEs when inlining unmap_and_move(). Work
906 * around it.
907 */
908#if (GCC_VERSION >= 40700 && GCC_VERSION < 40900) && defined(CONFIG_ARM)
909#define ICE_noinline noinline
910#else
911#define ICE_noinline
912#endif
913
0dabec93
MK
914/*
915 * Obtain the lock on page, remove all ptes and migrate the page
916 * to the newly allocated page in newpage.
917 */
ef2a5153
GU
918static ICE_noinline int unmap_and_move(new_page_t get_new_page,
919 free_page_t put_new_page,
920 unsigned long private, struct page *page,
add05cec
NH
921 int force, enum migrate_mode mode,
922 enum migrate_reason reason)
0dabec93
MK
923{
924 int rc = 0;
925 int *result = NULL;
926 struct page *newpage = get_new_page(page, private, &result);
927
928 if (!newpage)
929 return -ENOMEM;
930
931 if (page_count(page) == 1) {
932 /* page was freed from under us. So we are done. */
933 goto out;
934 }
935
936 if (unlikely(PageTransHuge(page)))
937 if (unlikely(split_huge_page(page)))
938 goto out;
939
9c620e2b 940 rc = __unmap_and_move(page, newpage, force, mode);
bf6bddf1 941
0dabec93 942out:
e24f0b8f 943 if (rc != -EAGAIN) {
0dabec93
MK
944 /*
945 * A page that has been migrated has all references
946 * removed and will be freed. A page that has not been
947 * migrated will have kepts its references and be
948 * restored.
949 */
950 list_del(&page->lru);
a731286d 951 dec_zone_page_state(page, NR_ISOLATED_ANON +
6c0b1351 952 page_is_file_cache(page));
add05cec
NH
953 if (reason != MR_MEMORY_FAILURE)
954 putback_lru_page(page);
e24f0b8f 955 }
68711a74 956
95a402c3 957 /*
68711a74
DR
958 * If migration was not successful and there's a freeing callback, use
959 * it. Otherwise, putback_lru_page() will drop the reference grabbed
960 * during isolation.
95a402c3 961 */
8bdd6380
HD
962 if (rc != MIGRATEPAGE_SUCCESS && put_new_page) {
963 ClearPageSwapBacked(newpage);
68711a74 964 put_new_page(newpage, private);
d6d86c0a
KK
965 } else if (unlikely(__is_movable_balloon_page(newpage))) {
966 /* drop our reference, page already in the balloon */
967 put_page(newpage);
8bdd6380 968 } else
68711a74
DR
969 putback_lru_page(newpage);
970
742755a1
CL
971 if (result) {
972 if (rc)
973 *result = rc;
974 else
975 *result = page_to_nid(newpage);
976 }
e24f0b8f
CL
977 return rc;
978}
979
290408d4
NH
980/*
981 * Counterpart of unmap_and_move_page() for hugepage migration.
982 *
983 * This function doesn't wait the completion of hugepage I/O
984 * because there is no race between I/O and migration for hugepage.
985 * Note that currently hugepage I/O occurs only in direct I/O
986 * where no lock is held and PG_writeback is irrelevant,
987 * and writeback status of all subpages are counted in the reference
988 * count of the head page (i.e. if all subpages of a 2MB hugepage are
989 * under direct I/O, the reference of the head page is 512 and a bit more.)
990 * This means that when we try to migrate hugepage whose subpages are
991 * doing direct I/O, some references remain after try_to_unmap() and
992 * hugepage migration fails without data corruption.
993 *
994 * There is also no race when direct I/O is issued on the page under migration,
995 * because then pte is replaced with migration swap entry and direct I/O code
996 * will wait in the page fault for migration to complete.
997 */
998static int unmap_and_move_huge_page(new_page_t get_new_page,
68711a74
DR
999 free_page_t put_new_page, unsigned long private,
1000 struct page *hpage, int force,
1001 enum migrate_mode mode)
290408d4
NH
1002{
1003 int rc = 0;
1004 int *result = NULL;
2ebba6b7 1005 int page_was_mapped = 0;
32665f2b 1006 struct page *new_hpage;
290408d4
NH
1007 struct anon_vma *anon_vma = NULL;
1008
83467efb
NH
1009 /*
1010 * Movability of hugepages depends on architectures and hugepage size.
1011 * This check is necessary because some callers of hugepage migration
1012 * like soft offline and memory hotremove don't walk through page
1013 * tables or check whether the hugepage is pmd-based or not before
1014 * kicking migration.
1015 */
100873d7 1016 if (!hugepage_migration_supported(page_hstate(hpage))) {
32665f2b 1017 putback_active_hugepage(hpage);
83467efb 1018 return -ENOSYS;
32665f2b 1019 }
83467efb 1020
32665f2b 1021 new_hpage = get_new_page(hpage, private, &result);
290408d4
NH
1022 if (!new_hpage)
1023 return -ENOMEM;
1024
1025 rc = -EAGAIN;
1026
1027 if (!trylock_page(hpage)) {
a6bc32b8 1028 if (!force || mode != MIGRATE_SYNC)
290408d4
NH
1029 goto out;
1030 lock_page(hpage);
1031 }
1032
746b18d4
PZ
1033 if (PageAnon(hpage))
1034 anon_vma = page_get_anon_vma(hpage);
290408d4 1035
2ebba6b7
HD
1036 if (page_mapped(hpage)) {
1037 try_to_unmap(hpage,
1038 TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS);
1039 page_was_mapped = 1;
1040 }
290408d4
NH
1041
1042 if (!page_mapped(hpage))
2ebba6b7 1043 rc = move_to_new_page(new_hpage, hpage, page_was_mapped, mode);
290408d4 1044
2ebba6b7 1045 if (rc != MIGRATEPAGE_SUCCESS && page_was_mapped)
290408d4
NH
1046 remove_migration_ptes(hpage, hpage);
1047
fd4a4663 1048 if (anon_vma)
9e60109f 1049 put_anon_vma(anon_vma);
8e6ac7fa 1050
68711a74 1051 if (rc == MIGRATEPAGE_SUCCESS)
8e6ac7fa
AK
1052 hugetlb_cgroup_migrate(hpage, new_hpage);
1053
290408d4 1054 unlock_page(hpage);
09761333 1055out:
b8ec1cee
NH
1056 if (rc != -EAGAIN)
1057 putback_active_hugepage(hpage);
68711a74
DR
1058
1059 /*
1060 * If migration was not successful and there's a freeing callback, use
1061 * it. Otherwise, put_page() will drop the reference grabbed during
1062 * isolation.
1063 */
1064 if (rc != MIGRATEPAGE_SUCCESS && put_new_page)
1065 put_new_page(new_hpage, private);
1066 else
1067 put_page(new_hpage);
1068
290408d4
NH
1069 if (result) {
1070 if (rc)
1071 *result = rc;
1072 else
1073 *result = page_to_nid(new_hpage);
1074 }
1075 return rc;
1076}
1077
b20a3503 1078/*
c73e5c9c
SB
1079 * migrate_pages - migrate the pages specified in a list, to the free pages
1080 * supplied as the target for the page migration
b20a3503 1081 *
c73e5c9c
SB
1082 * @from: The list of pages to be migrated.
1083 * @get_new_page: The function used to allocate free pages to be used
1084 * as the target of the page migration.
68711a74
DR
1085 * @put_new_page: The function used to free target pages if migration
1086 * fails, or NULL if no special handling is necessary.
c73e5c9c
SB
1087 * @private: Private data to be passed on to get_new_page()
1088 * @mode: The migration mode that specifies the constraints for
1089 * page migration, if any.
1090 * @reason: The reason for page migration.
b20a3503 1091 *
c73e5c9c
SB
1092 * The function returns after 10 attempts or if no pages are movable any more
1093 * because the list has become empty or no retryable pages exist any more.
1094 * The caller should call putback_lru_pages() to return pages to the LRU
28bd6578 1095 * or free list only if ret != 0.
b20a3503 1096 *
c73e5c9c 1097 * Returns the number of pages that were not migrated, or an error code.
b20a3503 1098 */
9c620e2b 1099int migrate_pages(struct list_head *from, new_page_t get_new_page,
68711a74
DR
1100 free_page_t put_new_page, unsigned long private,
1101 enum migrate_mode mode, int reason)
b20a3503 1102{
e24f0b8f 1103 int retry = 1;
b20a3503 1104 int nr_failed = 0;
5647bc29 1105 int nr_succeeded = 0;
b20a3503
CL
1106 int pass = 0;
1107 struct page *page;
1108 struct page *page2;
1109 int swapwrite = current->flags & PF_SWAPWRITE;
1110 int rc;
1111
1112 if (!swapwrite)
1113 current->flags |= PF_SWAPWRITE;
1114
e24f0b8f
CL
1115 for(pass = 0; pass < 10 && retry; pass++) {
1116 retry = 0;
b20a3503 1117
e24f0b8f 1118 list_for_each_entry_safe(page, page2, from, lru) {
e24f0b8f 1119 cond_resched();
2d1db3b1 1120
31caf665
NH
1121 if (PageHuge(page))
1122 rc = unmap_and_move_huge_page(get_new_page,
68711a74
DR
1123 put_new_page, private, page,
1124 pass > 2, mode);
31caf665 1125 else
68711a74 1126 rc = unmap_and_move(get_new_page, put_new_page,
add05cec
NH
1127 private, page, pass > 2, mode,
1128 reason);
2d1db3b1 1129
e24f0b8f 1130 switch(rc) {
95a402c3
CL
1131 case -ENOMEM:
1132 goto out;
e24f0b8f 1133 case -EAGAIN:
2d1db3b1 1134 retry++;
e24f0b8f 1135 break;
78bd5209 1136 case MIGRATEPAGE_SUCCESS:
5647bc29 1137 nr_succeeded++;
e24f0b8f
CL
1138 break;
1139 default:
354a3363
NH
1140 /*
1141 * Permanent failure (-EBUSY, -ENOSYS, etc.):
1142 * unlike -EAGAIN case, the failed page is
1143 * removed from migration page list and not
1144 * retried in the next outer loop.
1145 */
2d1db3b1 1146 nr_failed++;
e24f0b8f 1147 break;
2d1db3b1 1148 }
b20a3503
CL
1149 }
1150 }
78bd5209 1151 rc = nr_failed + retry;
95a402c3 1152out:
5647bc29
MG
1153 if (nr_succeeded)
1154 count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded);
1155 if (nr_failed)
1156 count_vm_events(PGMIGRATE_FAIL, nr_failed);
7b2a2d4a
MG
1157 trace_mm_migrate_pages(nr_succeeded, nr_failed, mode, reason);
1158
b20a3503
CL
1159 if (!swapwrite)
1160 current->flags &= ~PF_SWAPWRITE;
1161
78bd5209 1162 return rc;
b20a3503 1163}
95a402c3 1164
742755a1
CL
1165#ifdef CONFIG_NUMA
1166/*
1167 * Move a list of individual pages
1168 */
1169struct page_to_node {
1170 unsigned long addr;
1171 struct page *page;
1172 int node;
1173 int status;
1174};
1175
1176static struct page *new_page_node(struct page *p, unsigned long private,
1177 int **result)
1178{
1179 struct page_to_node *pm = (struct page_to_node *)private;
1180
1181 while (pm->node != MAX_NUMNODES && pm->page != p)
1182 pm++;
1183
1184 if (pm->node == MAX_NUMNODES)
1185 return NULL;
1186
1187 *result = &pm->status;
1188
e632a938
NH
1189 if (PageHuge(p))
1190 return alloc_huge_page_node(page_hstate(compound_head(p)),
1191 pm->node);
1192 else
1193 return alloc_pages_exact_node(pm->node,
e97ca8e5 1194 GFP_HIGHUSER_MOVABLE | __GFP_THISNODE, 0);
742755a1
CL
1195}
1196
1197/*
1198 * Move a set of pages as indicated in the pm array. The addr
1199 * field must be set to the virtual address of the page to be moved
1200 * and the node number must contain a valid target node.
5e9a0f02 1201 * The pm array ends with node = MAX_NUMNODES.
742755a1 1202 */
5e9a0f02
BG
1203static int do_move_page_to_node_array(struct mm_struct *mm,
1204 struct page_to_node *pm,
1205 int migrate_all)
742755a1
CL
1206{
1207 int err;
1208 struct page_to_node *pp;
1209 LIST_HEAD(pagelist);
1210
1211 down_read(&mm->mmap_sem);
1212
1213 /*
1214 * Build a list of pages to migrate
1215 */
742755a1
CL
1216 for (pp = pm; pp->node != MAX_NUMNODES; pp++) {
1217 struct vm_area_struct *vma;
1218 struct page *page;
1219
742755a1
CL
1220 err = -EFAULT;
1221 vma = find_vma(mm, pp->addr);
70384dc6 1222 if (!vma || pp->addr < vma->vm_start || !vma_migratable(vma))
742755a1
CL
1223 goto set_status;
1224
500d65d4 1225 page = follow_page(vma, pp->addr, FOLL_GET|FOLL_SPLIT);
89f5b7da
LT
1226
1227 err = PTR_ERR(page);
1228 if (IS_ERR(page))
1229 goto set_status;
1230
742755a1
CL
1231 err = -ENOENT;
1232 if (!page)
1233 goto set_status;
1234
62b61f61 1235 /* Use PageReserved to check for zero page */
b79bc0a0 1236 if (PageReserved(page))
742755a1
CL
1237 goto put_and_set;
1238
1239 pp->page = page;
1240 err = page_to_nid(page);
1241
1242 if (err == pp->node)
1243 /*
1244 * Node already in the right place
1245 */
1246 goto put_and_set;
1247
1248 err = -EACCES;
1249 if (page_mapcount(page) > 1 &&
1250 !migrate_all)
1251 goto put_and_set;
1252
e632a938 1253 if (PageHuge(page)) {
e66f17ff
NH
1254 if (PageHead(page))
1255 isolate_huge_page(page, &pagelist);
e632a938
NH
1256 goto put_and_set;
1257 }
1258
62695a84 1259 err = isolate_lru_page(page);
6d9c285a 1260 if (!err) {
62695a84 1261 list_add_tail(&page->lru, &pagelist);
6d9c285a
KM
1262 inc_zone_page_state(page, NR_ISOLATED_ANON +
1263 page_is_file_cache(page));
1264 }
742755a1
CL
1265put_and_set:
1266 /*
1267 * Either remove the duplicate refcount from
1268 * isolate_lru_page() or drop the page ref if it was
1269 * not isolated.
1270 */
1271 put_page(page);
1272set_status:
1273 pp->status = err;
1274 }
1275
e78bbfa8 1276 err = 0;
cf608ac1 1277 if (!list_empty(&pagelist)) {
68711a74 1278 err = migrate_pages(&pagelist, new_page_node, NULL,
9c620e2b 1279 (unsigned long)pm, MIGRATE_SYNC, MR_SYSCALL);
cf608ac1 1280 if (err)
e632a938 1281 putback_movable_pages(&pagelist);
cf608ac1 1282 }
742755a1
CL
1283
1284 up_read(&mm->mmap_sem);
1285 return err;
1286}
1287
5e9a0f02
BG
1288/*
1289 * Migrate an array of page address onto an array of nodes and fill
1290 * the corresponding array of status.
1291 */
3268c63e 1292static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
5e9a0f02
BG
1293 unsigned long nr_pages,
1294 const void __user * __user *pages,
1295 const int __user *nodes,
1296 int __user *status, int flags)
1297{
3140a227 1298 struct page_to_node *pm;
3140a227
BG
1299 unsigned long chunk_nr_pages;
1300 unsigned long chunk_start;
1301 int err;
5e9a0f02 1302
3140a227
BG
1303 err = -ENOMEM;
1304 pm = (struct page_to_node *)__get_free_page(GFP_KERNEL);
1305 if (!pm)
5e9a0f02 1306 goto out;
35282a2d
BG
1307
1308 migrate_prep();
1309
5e9a0f02 1310 /*
3140a227
BG
1311 * Store a chunk of page_to_node array in a page,
1312 * but keep the last one as a marker
5e9a0f02 1313 */
3140a227 1314 chunk_nr_pages = (PAGE_SIZE / sizeof(struct page_to_node)) - 1;
5e9a0f02 1315
3140a227
BG
1316 for (chunk_start = 0;
1317 chunk_start < nr_pages;
1318 chunk_start += chunk_nr_pages) {
1319 int j;
5e9a0f02 1320
3140a227
BG
1321 if (chunk_start + chunk_nr_pages > nr_pages)
1322 chunk_nr_pages = nr_pages - chunk_start;
1323
1324 /* fill the chunk pm with addrs and nodes from user-space */
1325 for (j = 0; j < chunk_nr_pages; j++) {
1326 const void __user *p;
5e9a0f02
BG
1327 int node;
1328
3140a227
BG
1329 err = -EFAULT;
1330 if (get_user(p, pages + j + chunk_start))
1331 goto out_pm;
1332 pm[j].addr = (unsigned long) p;
1333
1334 if (get_user(node, nodes + j + chunk_start))
5e9a0f02
BG
1335 goto out_pm;
1336
1337 err = -ENODEV;
6f5a55f1
LT
1338 if (node < 0 || node >= MAX_NUMNODES)
1339 goto out_pm;
1340
389162c2 1341 if (!node_state(node, N_MEMORY))
5e9a0f02
BG
1342 goto out_pm;
1343
1344 err = -EACCES;
1345 if (!node_isset(node, task_nodes))
1346 goto out_pm;
1347
3140a227
BG
1348 pm[j].node = node;
1349 }
1350
1351 /* End marker for this chunk */
1352 pm[chunk_nr_pages].node = MAX_NUMNODES;
1353
1354 /* Migrate this chunk */
1355 err = do_move_page_to_node_array(mm, pm,
1356 flags & MPOL_MF_MOVE_ALL);
1357 if (err < 0)
1358 goto out_pm;
5e9a0f02 1359
5e9a0f02 1360 /* Return status information */
3140a227
BG
1361 for (j = 0; j < chunk_nr_pages; j++)
1362 if (put_user(pm[j].status, status + j + chunk_start)) {
5e9a0f02 1363 err = -EFAULT;
3140a227
BG
1364 goto out_pm;
1365 }
1366 }
1367 err = 0;
5e9a0f02
BG
1368
1369out_pm:
3140a227 1370 free_page((unsigned long)pm);
5e9a0f02
BG
1371out:
1372 return err;
1373}
1374
742755a1 1375/*
2f007e74 1376 * Determine the nodes of an array of pages and store it in an array of status.
742755a1 1377 */
80bba129
BG
1378static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
1379 const void __user **pages, int *status)
742755a1 1380{
2f007e74 1381 unsigned long i;
2f007e74 1382
742755a1
CL
1383 down_read(&mm->mmap_sem);
1384
2f007e74 1385 for (i = 0; i < nr_pages; i++) {
80bba129 1386 unsigned long addr = (unsigned long)(*pages);
742755a1
CL
1387 struct vm_area_struct *vma;
1388 struct page *page;
c095adbc 1389 int err = -EFAULT;
2f007e74
BG
1390
1391 vma = find_vma(mm, addr);
70384dc6 1392 if (!vma || addr < vma->vm_start)
742755a1
CL
1393 goto set_status;
1394
2f007e74 1395 page = follow_page(vma, addr, 0);
89f5b7da
LT
1396
1397 err = PTR_ERR(page);
1398 if (IS_ERR(page))
1399 goto set_status;
1400
742755a1
CL
1401 err = -ENOENT;
1402 /* Use PageReserved to check for zero page */
b79bc0a0 1403 if (!page || PageReserved(page))
742755a1
CL
1404 goto set_status;
1405
1406 err = page_to_nid(page);
1407set_status:
80bba129
BG
1408 *status = err;
1409
1410 pages++;
1411 status++;
1412 }
1413
1414 up_read(&mm->mmap_sem);
1415}
1416
1417/*
1418 * Determine the nodes of a user array of pages and store it in
1419 * a user array of status.
1420 */
1421static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages,
1422 const void __user * __user *pages,
1423 int __user *status)
1424{
1425#define DO_PAGES_STAT_CHUNK_NR 16
1426 const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR];
1427 int chunk_status[DO_PAGES_STAT_CHUNK_NR];
80bba129 1428
87b8d1ad
PA
1429 while (nr_pages) {
1430 unsigned long chunk_nr;
80bba129 1431
87b8d1ad
PA
1432 chunk_nr = nr_pages;
1433 if (chunk_nr > DO_PAGES_STAT_CHUNK_NR)
1434 chunk_nr = DO_PAGES_STAT_CHUNK_NR;
1435
1436 if (copy_from_user(chunk_pages, pages, chunk_nr * sizeof(*chunk_pages)))
1437 break;
80bba129
BG
1438
1439 do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status);
1440
87b8d1ad
PA
1441 if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status)))
1442 break;
742755a1 1443
87b8d1ad
PA
1444 pages += chunk_nr;
1445 status += chunk_nr;
1446 nr_pages -= chunk_nr;
1447 }
1448 return nr_pages ? -EFAULT : 0;
742755a1
CL
1449}
1450
1451/*
1452 * Move a list of pages in the address space of the currently executing
1453 * process.
1454 */
938bb9f5
HC
1455SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,
1456 const void __user * __user *, pages,
1457 const int __user *, nodes,
1458 int __user *, status, int, flags)
742755a1 1459{
c69e8d9c 1460 const struct cred *cred = current_cred(), *tcred;
742755a1 1461 struct task_struct *task;
742755a1 1462 struct mm_struct *mm;
5e9a0f02 1463 int err;
3268c63e 1464 nodemask_t task_nodes;
742755a1
CL
1465
1466 /* Check flags */
1467 if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
1468 return -EINVAL;
1469
1470 if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
1471 return -EPERM;
1472
1473 /* Find the mm_struct */
a879bf58 1474 rcu_read_lock();
228ebcbe 1475 task = pid ? find_task_by_vpid(pid) : current;
742755a1 1476 if (!task) {
a879bf58 1477 rcu_read_unlock();
742755a1
CL
1478 return -ESRCH;
1479 }
3268c63e 1480 get_task_struct(task);
742755a1
CL
1481
1482 /*
1483 * Check if this process has the right to modify the specified
1484 * process. The right exists if the process has administrative
1485 * capabilities, superuser privileges or the same
1486 * userid as the target process.
1487 */
c69e8d9c 1488 tcred = __task_cred(task);
b38a86eb
EB
1489 if (!uid_eq(cred->euid, tcred->suid) && !uid_eq(cred->euid, tcred->uid) &&
1490 !uid_eq(cred->uid, tcred->suid) && !uid_eq(cred->uid, tcred->uid) &&
742755a1 1491 !capable(CAP_SYS_NICE)) {
c69e8d9c 1492 rcu_read_unlock();
742755a1 1493 err = -EPERM;
5e9a0f02 1494 goto out;
742755a1 1495 }
c69e8d9c 1496 rcu_read_unlock();
742755a1 1497
86c3a764
DQ
1498 err = security_task_movememory(task);
1499 if (err)
5e9a0f02 1500 goto out;
86c3a764 1501
3268c63e
CL
1502 task_nodes = cpuset_mems_allowed(task);
1503 mm = get_task_mm(task);
1504 put_task_struct(task);
1505
6e8b09ea
SL
1506 if (!mm)
1507 return -EINVAL;
1508
1509 if (nodes)
1510 err = do_pages_move(mm, task_nodes, nr_pages, pages,
1511 nodes, status, flags);
1512 else
1513 err = do_pages_stat(mm, nr_pages, pages, status);
742755a1 1514
742755a1
CL
1515 mmput(mm);
1516 return err;
3268c63e
CL
1517
1518out:
1519 put_task_struct(task);
1520 return err;
742755a1 1521}
742755a1 1522
7039e1db
PZ
1523#ifdef CONFIG_NUMA_BALANCING
1524/*
1525 * Returns true if this is a safe migration target node for misplaced NUMA
1526 * pages. Currently it only checks the watermarks which crude
1527 */
1528static bool migrate_balanced_pgdat(struct pglist_data *pgdat,
3abef4e6 1529 unsigned long nr_migrate_pages)
7039e1db
PZ
1530{
1531 int z;
1532 for (z = pgdat->nr_zones - 1; z >= 0; z--) {
1533 struct zone *zone = pgdat->node_zones + z;
1534
1535 if (!populated_zone(zone))
1536 continue;
1537
6e543d57 1538 if (!zone_reclaimable(zone))
7039e1db
PZ
1539 continue;
1540
1541 /* Avoid waking kswapd by allocating pages_to_migrate pages. */
1542 if (!zone_watermark_ok(zone, 0,
1543 high_wmark_pages(zone) +
1544 nr_migrate_pages,
1545 0, 0))
1546 continue;
1547 return true;
1548 }
1549 return false;
1550}
1551
1552static struct page *alloc_misplaced_dst_page(struct page *page,
1553 unsigned long data,
1554 int **result)
1555{
1556 int nid = (int) data;
1557 struct page *newpage;
1558
1559 newpage = alloc_pages_exact_node(nid,
e97ca8e5
JW
1560 (GFP_HIGHUSER_MOVABLE |
1561 __GFP_THISNODE | __GFP_NOMEMALLOC |
1562 __GFP_NORETRY | __GFP_NOWARN) &
7039e1db 1563 ~GFP_IOFS, 0);
bac0382c 1564
7039e1db
PZ
1565 return newpage;
1566}
1567
a8f60772
MG
1568/*
1569 * page migration rate limiting control.
1570 * Do not migrate more than @pages_to_migrate in a @migrate_interval_millisecs
1571 * window of time. Default here says do not migrate more than 1280M per second.
1572 */
1573static unsigned int migrate_interval_millisecs __read_mostly = 100;
1574static unsigned int ratelimit_pages __read_mostly = 128 << (20 - PAGE_SHIFT);
1575
b32967ff 1576/* Returns true if the node is migrate rate-limited after the update */
1c30e017
MG
1577static bool numamigrate_update_ratelimit(pg_data_t *pgdat,
1578 unsigned long nr_pages)
7039e1db 1579{
a8f60772
MG
1580 /*
1581 * Rate-limit the amount of data that is being migrated to a node.
1582 * Optimal placement is no good if the memory bus is saturated and
1583 * all the time is being spent migrating!
1584 */
a8f60772 1585 if (time_after(jiffies, pgdat->numabalancing_migrate_next_window)) {
1c5e9c27 1586 spin_lock(&pgdat->numabalancing_migrate_lock);
a8f60772
MG
1587 pgdat->numabalancing_migrate_nr_pages = 0;
1588 pgdat->numabalancing_migrate_next_window = jiffies +
1589 msecs_to_jiffies(migrate_interval_millisecs);
1c5e9c27 1590 spin_unlock(&pgdat->numabalancing_migrate_lock);
a8f60772 1591 }
af1839d7
MG
1592 if (pgdat->numabalancing_migrate_nr_pages > ratelimit_pages) {
1593 trace_mm_numa_migrate_ratelimit(current, pgdat->node_id,
1594 nr_pages);
1c5e9c27 1595 return true;
af1839d7 1596 }
1c5e9c27
MG
1597
1598 /*
1599 * This is an unlocked non-atomic update so errors are possible.
1600 * The consequences are failing to migrate when we potentiall should
1601 * have which is not severe enough to warrant locking. If it is ever
1602 * a problem, it can be converted to a per-cpu counter.
1603 */
1604 pgdat->numabalancing_migrate_nr_pages += nr_pages;
1605 return false;
b32967ff
MG
1606}
1607
1c30e017 1608static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
b32967ff 1609{
340ef390 1610 int page_lru;
a8f60772 1611
309381fe 1612 VM_BUG_ON_PAGE(compound_order(page) && !PageTransHuge(page), page);
3abef4e6 1613
7039e1db 1614 /* Avoid migrating to a node that is nearly full */
340ef390
HD
1615 if (!migrate_balanced_pgdat(pgdat, 1UL << compound_order(page)))
1616 return 0;
7039e1db 1617
340ef390
HD
1618 if (isolate_lru_page(page))
1619 return 0;
7039e1db 1620
340ef390
HD
1621 /*
1622 * migrate_misplaced_transhuge_page() skips page migration's usual
1623 * check on page_count(), so we must do it here, now that the page
1624 * has been isolated: a GUP pin, or any other pin, prevents migration.
1625 * The expected page count is 3: 1 for page's mapcount and 1 for the
1626 * caller's pin and 1 for the reference taken by isolate_lru_page().
1627 */
1628 if (PageTransHuge(page) && page_count(page) != 3) {
1629 putback_lru_page(page);
1630 return 0;
7039e1db
PZ
1631 }
1632
340ef390
HD
1633 page_lru = page_is_file_cache(page);
1634 mod_zone_page_state(page_zone(page), NR_ISOLATED_ANON + page_lru,
1635 hpage_nr_pages(page));
1636
149c33e1 1637 /*
340ef390
HD
1638 * Isolating the page has taken another reference, so the
1639 * caller's reference can be safely dropped without the page
1640 * disappearing underneath us during migration.
149c33e1
MG
1641 */
1642 put_page(page);
340ef390 1643 return 1;
b32967ff
MG
1644}
1645
de466bd6
MG
1646bool pmd_trans_migrating(pmd_t pmd)
1647{
1648 struct page *page = pmd_page(pmd);
1649 return PageLocked(page);
1650}
1651
b32967ff
MG
1652/*
1653 * Attempt to migrate a misplaced page to the specified destination
1654 * node. Caller is expected to have an elevated reference count on
1655 * the page that will be dropped by this function before returning.
1656 */
1bc115d8
MG
1657int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
1658 int node)
b32967ff
MG
1659{
1660 pg_data_t *pgdat = NODE_DATA(node);
340ef390 1661 int isolated;
b32967ff
MG
1662 int nr_remaining;
1663 LIST_HEAD(migratepages);
1664
1665 /*
1bc115d8
MG
1666 * Don't migrate file pages that are mapped in multiple processes
1667 * with execute permissions as they are probably shared libraries.
b32967ff 1668 */
1bc115d8
MG
1669 if (page_mapcount(page) != 1 && page_is_file_cache(page) &&
1670 (vma->vm_flags & VM_EXEC))
b32967ff 1671 goto out;
b32967ff
MG
1672
1673 /*
1674 * Rate-limit the amount of data that is being migrated to a node.
1675 * Optimal placement is no good if the memory bus is saturated and
1676 * all the time is being spent migrating!
1677 */
340ef390 1678 if (numamigrate_update_ratelimit(pgdat, 1))
b32967ff 1679 goto out;
b32967ff
MG
1680
1681 isolated = numamigrate_isolate_page(pgdat, page);
1682 if (!isolated)
1683 goto out;
1684
1685 list_add(&page->lru, &migratepages);
9c620e2b 1686 nr_remaining = migrate_pages(&migratepages, alloc_misplaced_dst_page,
68711a74
DR
1687 NULL, node, MIGRATE_ASYNC,
1688 MR_NUMA_MISPLACED);
b32967ff 1689 if (nr_remaining) {
59c82b70
JK
1690 if (!list_empty(&migratepages)) {
1691 list_del(&page->lru);
1692 dec_zone_page_state(page, NR_ISOLATED_ANON +
1693 page_is_file_cache(page));
1694 putback_lru_page(page);
1695 }
b32967ff
MG
1696 isolated = 0;
1697 } else
1698 count_vm_numa_event(NUMA_PAGE_MIGRATE);
7039e1db 1699 BUG_ON(!list_empty(&migratepages));
7039e1db 1700 return isolated;
340ef390
HD
1701
1702out:
1703 put_page(page);
1704 return 0;
7039e1db 1705}
220018d3 1706#endif /* CONFIG_NUMA_BALANCING */
b32967ff 1707
220018d3 1708#if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
340ef390
HD
1709/*
1710 * Migrates a THP to a given target node. page must be locked and is unlocked
1711 * before returning.
1712 */
b32967ff
MG
1713int migrate_misplaced_transhuge_page(struct mm_struct *mm,
1714 struct vm_area_struct *vma,
1715 pmd_t *pmd, pmd_t entry,
1716 unsigned long address,
1717 struct page *page, int node)
1718{
c4088ebd 1719 spinlock_t *ptl;
b32967ff
MG
1720 pg_data_t *pgdat = NODE_DATA(node);
1721 int isolated = 0;
1722 struct page *new_page = NULL;
b32967ff 1723 int page_lru = page_is_file_cache(page);
f714f4f2
MG
1724 unsigned long mmun_start = address & HPAGE_PMD_MASK;
1725 unsigned long mmun_end = mmun_start + HPAGE_PMD_SIZE;
2b4847e7 1726 pmd_t orig_entry;
b32967ff 1727
b32967ff
MG
1728 /*
1729 * Rate-limit the amount of data that is being migrated to a node.
1730 * Optimal placement is no good if the memory bus is saturated and
1731 * all the time is being spent migrating!
1732 */
d28d4335 1733 if (numamigrate_update_ratelimit(pgdat, HPAGE_PMD_NR))
b32967ff
MG
1734 goto out_dropref;
1735
1736 new_page = alloc_pages_node(node,
e97ca8e5
JW
1737 (GFP_TRANSHUGE | __GFP_THISNODE) & ~__GFP_WAIT,
1738 HPAGE_PMD_ORDER);
340ef390
HD
1739 if (!new_page)
1740 goto out_fail;
1741
b32967ff 1742 isolated = numamigrate_isolate_page(pgdat, page);
340ef390 1743 if (!isolated) {
b32967ff 1744 put_page(new_page);
340ef390 1745 goto out_fail;
b32967ff
MG
1746 }
1747
b0943d61
MG
1748 if (mm_tlb_flush_pending(mm))
1749 flush_tlb_range(vma, mmun_start, mmun_end);
1750
b32967ff
MG
1751 /* Prepare a page as a migration target */
1752 __set_page_locked(new_page);
1753 SetPageSwapBacked(new_page);
1754
1755 /* anon mapping, we can simply copy page->mapping to the new page: */
1756 new_page->mapping = page->mapping;
1757 new_page->index = page->index;
1758 migrate_page_copy(new_page, page);
1759 WARN_ON(PageLRU(new_page));
1760
1761 /* Recheck the target PMD */
f714f4f2 1762 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
c4088ebd 1763 ptl = pmd_lock(mm, pmd);
2b4847e7
MG
1764 if (unlikely(!pmd_same(*pmd, entry) || page_count(page) != 2)) {
1765fail_putback:
c4088ebd 1766 spin_unlock(ptl);
f714f4f2 1767 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
b32967ff
MG
1768
1769 /* Reverse changes made by migrate_page_copy() */
1770 if (TestClearPageActive(new_page))
1771 SetPageActive(page);
1772 if (TestClearPageUnevictable(new_page))
1773 SetPageUnevictable(page);
1774 mlock_migrate_page(page, new_page);
1775
1776 unlock_page(new_page);
1777 put_page(new_page); /* Free it */
1778
a54a407f
MG
1779 /* Retake the callers reference and putback on LRU */
1780 get_page(page);
b32967ff 1781 putback_lru_page(page);
a54a407f
MG
1782 mod_zone_page_state(page_zone(page),
1783 NR_ISOLATED_ANON + page_lru, -HPAGE_PMD_NR);
eb4489f6
MG
1784
1785 goto out_unlock;
b32967ff
MG
1786 }
1787
2b4847e7 1788 orig_entry = *pmd;
b32967ff 1789 entry = mk_pmd(new_page, vma->vm_page_prot);
b32967ff 1790 entry = pmd_mkhuge(entry);
2b4847e7 1791 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
b32967ff 1792
2b4847e7
MG
1793 /*
1794 * Clear the old entry under pagetable lock and establish the new PTE.
1795 * Any parallel GUP will either observe the old page blocking on the
1796 * page lock, block on the page table lock or observe the new page.
1797 * The SetPageUptodate on the new page and page_add_new_anon_rmap
1798 * guarantee the copy is visible before the pagetable update.
1799 */
f714f4f2 1800 flush_cache_range(vma, mmun_start, mmun_end);
11de9927 1801 page_add_anon_rmap(new_page, vma, mmun_start);
8809aa2d 1802 pmdp_huge_clear_flush_notify(vma, mmun_start, pmd);
f714f4f2
MG
1803 set_pmd_at(mm, mmun_start, pmd, entry);
1804 flush_tlb_range(vma, mmun_start, mmun_end);
ce4a9cc5 1805 update_mmu_cache_pmd(vma, address, &entry);
2b4847e7
MG
1806
1807 if (page_count(page) != 2) {
f714f4f2
MG
1808 set_pmd_at(mm, mmun_start, pmd, orig_entry);
1809 flush_tlb_range(vma, mmun_start, mmun_end);
34ee645e 1810 mmu_notifier_invalidate_range(mm, mmun_start, mmun_end);
2b4847e7
MG
1811 update_mmu_cache_pmd(vma, address, &entry);
1812 page_remove_rmap(new_page);
1813 goto fail_putback;
1814 }
1815
0a31bc97
JW
1816 mem_cgroup_migrate(page, new_page, false);
1817
b32967ff 1818 page_remove_rmap(page);
2b4847e7 1819
c4088ebd 1820 spin_unlock(ptl);
f714f4f2 1821 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
b32967ff 1822
11de9927
MG
1823 /* Take an "isolate" reference and put new page on the LRU. */
1824 get_page(new_page);
1825 putback_lru_page(new_page);
1826
b32967ff
MG
1827 unlock_page(new_page);
1828 unlock_page(page);
1829 put_page(page); /* Drop the rmap reference */
1830 put_page(page); /* Drop the LRU isolation reference */
1831
1832 count_vm_events(PGMIGRATE_SUCCESS, HPAGE_PMD_NR);
1833 count_vm_numa_events(NUMA_PAGE_MIGRATE, HPAGE_PMD_NR);
1834
b32967ff
MG
1835 mod_zone_page_state(page_zone(page),
1836 NR_ISOLATED_ANON + page_lru,
1837 -HPAGE_PMD_NR);
1838 return isolated;
1839
340ef390
HD
1840out_fail:
1841 count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR);
b32967ff 1842out_dropref:
2b4847e7
MG
1843 ptl = pmd_lock(mm, pmd);
1844 if (pmd_same(*pmd, entry)) {
4d942466 1845 entry = pmd_modify(entry, vma->vm_page_prot);
f714f4f2 1846 set_pmd_at(mm, mmun_start, pmd, entry);
2b4847e7
MG
1847 update_mmu_cache_pmd(vma, address, &entry);
1848 }
1849 spin_unlock(ptl);
a54a407f 1850
eb4489f6 1851out_unlock:
340ef390 1852 unlock_page(page);
b32967ff 1853 put_page(page);
b32967ff
MG
1854 return 0;
1855}
7039e1db
PZ
1856#endif /* CONFIG_NUMA_BALANCING */
1857
1858#endif /* CONFIG_NUMA */