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CommitLineData
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>
b20a3503 38
0d1836c3
MN
39#include <asm/tlbflush.h>
40
b20a3503
CL
41#include "internal.h"
42
b20a3503 43/*
742755a1 44 * migrate_prep() needs to be called before we start compiling a list of pages
748446bb
MG
45 * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is
46 * undesirable, use migrate_prep_local()
b20a3503
CL
47 */
48int migrate_prep(void)
49{
b20a3503
CL
50 /*
51 * Clear the LRU lists so pages can be isolated.
52 * Note that pages may be moved off the LRU after we have
53 * drained them. Those pages will fail to migrate like other
54 * pages that may be busy.
55 */
56 lru_add_drain_all();
57
58 return 0;
59}
60
748446bb
MG
61/* Do the necessary work of migrate_prep but not if it involves other CPUs */
62int migrate_prep_local(void)
63{
64 lru_add_drain();
65
66 return 0;
67}
68
b20a3503 69/*
894bc310
LS
70 * Add isolated pages on the list back to the LRU under page lock
71 * to avoid leaking evictable pages back onto unevictable list.
b20a3503 72 */
e13861d8 73void putback_lru_pages(struct list_head *l)
b20a3503
CL
74{
75 struct page *page;
76 struct page *page2;
b20a3503
CL
77
78 list_for_each_entry_safe(page, page2, l, lru) {
e24f0b8f 79 list_del(&page->lru);
a731286d 80 dec_zone_page_state(page, NR_ISOLATED_ANON +
6c0b1351 81 page_is_file_cache(page));
894bc310 82 putback_lru_page(page);
b20a3503 83 }
b20a3503
CL
84}
85
0697212a
CL
86/*
87 * Restore a potential migration pte to a working pte entry
88 */
e9995ef9
HD
89static int remove_migration_pte(struct page *new, struct vm_area_struct *vma,
90 unsigned long addr, void *old)
0697212a
CL
91{
92 struct mm_struct *mm = vma->vm_mm;
93 swp_entry_t entry;
94 pgd_t *pgd;
95 pud_t *pud;
96 pmd_t *pmd;
97 pte_t *ptep, pte;
98 spinlock_t *ptl;
99
290408d4
NH
100 if (unlikely(PageHuge(new))) {
101 ptep = huge_pte_offset(mm, addr);
102 if (!ptep)
103 goto out;
104 ptl = &mm->page_table_lock;
105 } else {
106 pgd = pgd_offset(mm, addr);
107 if (!pgd_present(*pgd))
108 goto out;
0697212a 109
290408d4
NH
110 pud = pud_offset(pgd, addr);
111 if (!pud_present(*pud))
112 goto out;
0697212a 113
290408d4 114 pmd = pmd_offset(pud, addr);
500d65d4
AA
115 if (pmd_trans_huge(*pmd))
116 goto out;
290408d4
NH
117 if (!pmd_present(*pmd))
118 goto out;
0697212a 119
290408d4 120 ptep = pte_offset_map(pmd, addr);
0697212a 121
486cf46f
HD
122 /*
123 * Peek to check is_swap_pte() before taking ptlock? No, we
124 * can race mremap's move_ptes(), which skips anon_vma lock.
125 */
290408d4
NH
126
127 ptl = pte_lockptr(mm, pmd);
128 }
0697212a 129
0697212a
CL
130 spin_lock(ptl);
131 pte = *ptep;
132 if (!is_swap_pte(pte))
e9995ef9 133 goto unlock;
0697212a
CL
134
135 entry = pte_to_swp_entry(pte);
136
e9995ef9
HD
137 if (!is_migration_entry(entry) ||
138 migration_entry_to_page(entry) != old)
139 goto unlock;
0697212a 140
0697212a
CL
141 get_page(new);
142 pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
143 if (is_write_migration_entry(entry))
144 pte = pte_mkwrite(pte);
3ef8fd7f 145#ifdef CONFIG_HUGETLB_PAGE
290408d4
NH
146 if (PageHuge(new))
147 pte = pte_mkhuge(pte);
3ef8fd7f 148#endif
97ee0524 149 flush_cache_page(vma, addr, pte_pfn(pte));
0697212a 150 set_pte_at(mm, addr, ptep, pte);
04e62a29 151
290408d4
NH
152 if (PageHuge(new)) {
153 if (PageAnon(new))
154 hugepage_add_anon_rmap(new, vma, addr);
155 else
156 page_dup_rmap(new);
157 } else if (PageAnon(new))
04e62a29
CL
158 page_add_anon_rmap(new, vma, addr);
159 else
160 page_add_file_rmap(new);
161
162 /* No need to invalidate - it was non-present before */
4b3073e1 163 update_mmu_cache(vma, addr, ptep);
e9995ef9 164unlock:
0697212a 165 pte_unmap_unlock(ptep, ptl);
e9995ef9
HD
166out:
167 return SWAP_AGAIN;
0697212a
CL
168}
169
04e62a29
CL
170/*
171 * Get rid of all migration entries and replace them by
172 * references to the indicated page.
173 */
174static void remove_migration_ptes(struct page *old, struct page *new)
175{
e9995ef9 176 rmap_walk(new, remove_migration_pte, old);
04e62a29
CL
177}
178
0697212a
CL
179/*
180 * Something used the pte of a page under migration. We need to
181 * get to the page and wait until migration is finished.
182 * When we return from this function the fault will be retried.
0697212a
CL
183 */
184void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
185 unsigned long address)
186{
187 pte_t *ptep, pte;
188 spinlock_t *ptl;
189 swp_entry_t entry;
190 struct page *page;
191
192 ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
193 pte = *ptep;
194 if (!is_swap_pte(pte))
195 goto out;
196
197 entry = pte_to_swp_entry(pte);
198 if (!is_migration_entry(entry))
199 goto out;
200
201 page = migration_entry_to_page(entry);
202
e286781d
NP
203 /*
204 * Once radix-tree replacement of page migration started, page_count
205 * *must* be zero. And, we don't want to call wait_on_page_locked()
206 * against a page without get_page().
207 * So, we use get_page_unless_zero(), here. Even failed, page fault
208 * will occur again.
209 */
210 if (!get_page_unless_zero(page))
211 goto out;
0697212a
CL
212 pte_unmap_unlock(ptep, ptl);
213 wait_on_page_locked(page);
214 put_page(page);
215 return;
216out:
217 pte_unmap_unlock(ptep, ptl);
218}
219
b969c4ab
MG
220#ifdef CONFIG_BLOCK
221/* Returns true if all buffers are successfully locked */
a6bc32b8
MG
222static bool buffer_migrate_lock_buffers(struct buffer_head *head,
223 enum migrate_mode mode)
b969c4ab
MG
224{
225 struct buffer_head *bh = head;
226
227 /* Simple case, sync compaction */
a6bc32b8 228 if (mode != MIGRATE_ASYNC) {
b969c4ab
MG
229 do {
230 get_bh(bh);
231 lock_buffer(bh);
232 bh = bh->b_this_page;
233
234 } while (bh != head);
235
236 return true;
237 }
238
239 /* async case, we cannot block on lock_buffer so use trylock_buffer */
240 do {
241 get_bh(bh);
242 if (!trylock_buffer(bh)) {
243 /*
244 * We failed to lock the buffer and cannot stall in
245 * async migration. Release the taken locks
246 */
247 struct buffer_head *failed_bh = bh;
248 put_bh(failed_bh);
249 bh = head;
250 while (bh != failed_bh) {
251 unlock_buffer(bh);
252 put_bh(bh);
253 bh = bh->b_this_page;
254 }
255 return false;
256 }
257
258 bh = bh->b_this_page;
259 } while (bh != head);
260 return true;
261}
262#else
263static inline bool buffer_migrate_lock_buffers(struct buffer_head *head,
a6bc32b8 264 enum migrate_mode mode)
b969c4ab
MG
265{
266 return true;
267}
268#endif /* CONFIG_BLOCK */
269
b20a3503 270/*
c3fcf8a5 271 * Replace the page in the mapping.
5b5c7120
CL
272 *
273 * The number of remaining references must be:
274 * 1 for anonymous pages without a mapping
275 * 2 for pages with a mapping
266cf658 276 * 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
b20a3503 277 */
2d1db3b1 278static int migrate_page_move_mapping(struct address_space *mapping,
b969c4ab 279 struct page *newpage, struct page *page,
a6bc32b8 280 struct buffer_head *head, enum migrate_mode mode)
b20a3503 281{
e286781d 282 int expected_count;
7cf9c2c7 283 void **pslot;
b20a3503 284
6c5240ae 285 if (!mapping) {
0e8c7d0f 286 /* Anonymous page without mapping */
6c5240ae
CL
287 if (page_count(page) != 1)
288 return -EAGAIN;
289 return 0;
290 }
291
19fd6231 292 spin_lock_irq(&mapping->tree_lock);
b20a3503 293
7cf9c2c7
NP
294 pslot = radix_tree_lookup_slot(&mapping->page_tree,
295 page_index(page));
b20a3503 296
edcf4748 297 expected_count = 2 + page_has_private(page);
e286781d 298 if (page_count(page) != expected_count ||
29c1f677 299 radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) {
19fd6231 300 spin_unlock_irq(&mapping->tree_lock);
e23ca00b 301 return -EAGAIN;
b20a3503
CL
302 }
303
e286781d 304 if (!page_freeze_refs(page, expected_count)) {
19fd6231 305 spin_unlock_irq(&mapping->tree_lock);
e286781d
NP
306 return -EAGAIN;
307 }
308
b969c4ab
MG
309 /*
310 * In the async migration case of moving a page with buffers, lock the
311 * buffers using trylock before the mapping is moved. If the mapping
312 * was moved, we later failed to lock the buffers and could not move
313 * the mapping back due to an elevated page count, we would have to
314 * block waiting on other references to be dropped.
315 */
a6bc32b8
MG
316 if (mode == MIGRATE_ASYNC && head &&
317 !buffer_migrate_lock_buffers(head, mode)) {
b969c4ab
MG
318 page_unfreeze_refs(page, expected_count);
319 spin_unlock_irq(&mapping->tree_lock);
320 return -EAGAIN;
321 }
322
b20a3503
CL
323 /*
324 * Now we know that no one else is looking at the page.
b20a3503 325 */
7cf9c2c7 326 get_page(newpage); /* add cache reference */
b20a3503
CL
327 if (PageSwapCache(page)) {
328 SetPageSwapCache(newpage);
329 set_page_private(newpage, page_private(page));
330 }
331
7cf9c2c7
NP
332 radix_tree_replace_slot(pslot, newpage);
333
334 /*
937a94c9
JG
335 * Drop cache reference from old page by unfreezing
336 * to one less reference.
7cf9c2c7
NP
337 * We know this isn't the last reference.
338 */
937a94c9 339 page_unfreeze_refs(page, expected_count - 1);
7cf9c2c7 340
0e8c7d0f
CL
341 /*
342 * If moved to a different zone then also account
343 * the page for that zone. Other VM counters will be
344 * taken care of when we establish references to the
345 * new page and drop references to the old page.
346 *
347 * Note that anonymous pages are accounted for
348 * via NR_FILE_PAGES and NR_ANON_PAGES if they
349 * are mapped to swap space.
350 */
351 __dec_zone_page_state(page, NR_FILE_PAGES);
352 __inc_zone_page_state(newpage, NR_FILE_PAGES);
99a15e21 353 if (!PageSwapCache(page) && PageSwapBacked(page)) {
4b02108a
KM
354 __dec_zone_page_state(page, NR_SHMEM);
355 __inc_zone_page_state(newpage, NR_SHMEM);
356 }
19fd6231 357 spin_unlock_irq(&mapping->tree_lock);
b20a3503
CL
358
359 return 0;
360}
b20a3503 361
290408d4
NH
362/*
363 * The expected number of remaining references is the same as that
364 * of migrate_page_move_mapping().
365 */
366int migrate_huge_page_move_mapping(struct address_space *mapping,
367 struct page *newpage, struct page *page)
368{
369 int expected_count;
370 void **pslot;
371
372 if (!mapping) {
373 if (page_count(page) != 1)
374 return -EAGAIN;
375 return 0;
376 }
377
378 spin_lock_irq(&mapping->tree_lock);
379
380 pslot = radix_tree_lookup_slot(&mapping->page_tree,
381 page_index(page));
382
383 expected_count = 2 + page_has_private(page);
384 if (page_count(page) != expected_count ||
29c1f677 385 radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) {
290408d4
NH
386 spin_unlock_irq(&mapping->tree_lock);
387 return -EAGAIN;
388 }
389
390 if (!page_freeze_refs(page, expected_count)) {
391 spin_unlock_irq(&mapping->tree_lock);
392 return -EAGAIN;
393 }
394
395 get_page(newpage);
396
397 radix_tree_replace_slot(pslot, newpage);
398
937a94c9 399 page_unfreeze_refs(page, expected_count - 1);
290408d4
NH
400
401 spin_unlock_irq(&mapping->tree_lock);
402 return 0;
403}
404
b20a3503
CL
405/*
406 * Copy the page to its new location
407 */
290408d4 408void migrate_page_copy(struct page *newpage, struct page *page)
b20a3503 409{
290408d4
NH
410 if (PageHuge(page))
411 copy_huge_page(newpage, page);
412 else
413 copy_highpage(newpage, page);
b20a3503
CL
414
415 if (PageError(page))
416 SetPageError(newpage);
417 if (PageReferenced(page))
418 SetPageReferenced(newpage);
419 if (PageUptodate(page))
420 SetPageUptodate(newpage);
894bc310
LS
421 if (TestClearPageActive(page)) {
422 VM_BUG_ON(PageUnevictable(page));
b20a3503 423 SetPageActive(newpage);
418b27ef
LS
424 } else if (TestClearPageUnevictable(page))
425 SetPageUnevictable(newpage);
b20a3503
CL
426 if (PageChecked(page))
427 SetPageChecked(newpage);
428 if (PageMappedToDisk(page))
429 SetPageMappedToDisk(newpage);
430
431 if (PageDirty(page)) {
432 clear_page_dirty_for_io(page);
3a902c5f
NP
433 /*
434 * Want to mark the page and the radix tree as dirty, and
435 * redo the accounting that clear_page_dirty_for_io undid,
436 * but we can't use set_page_dirty because that function
437 * is actually a signal that all of the page has become dirty.
25985edc 438 * Whereas only part of our page may be dirty.
3a902c5f 439 */
752dc185
HD
440 if (PageSwapBacked(page))
441 SetPageDirty(newpage);
442 else
443 __set_page_dirty_nobuffers(newpage);
b20a3503
CL
444 }
445
b291f000 446 mlock_migrate_page(newpage, page);
e9995ef9 447 ksm_migrate_page(newpage, page);
b291f000 448
b20a3503 449 ClearPageSwapCache(page);
b20a3503
CL
450 ClearPagePrivate(page);
451 set_page_private(page, 0);
b20a3503
CL
452
453 /*
454 * If any waiters have accumulated on the new page then
455 * wake them up.
456 */
457 if (PageWriteback(newpage))
458 end_page_writeback(newpage);
459}
b20a3503 460
1d8b85cc
CL
461/************************************************************
462 * Migration functions
463 ***********************************************************/
464
465/* Always fail migration. Used for mappings that are not movable */
2d1db3b1
CL
466int fail_migrate_page(struct address_space *mapping,
467 struct page *newpage, struct page *page)
1d8b85cc
CL
468{
469 return -EIO;
470}
471EXPORT_SYMBOL(fail_migrate_page);
472
b20a3503
CL
473/*
474 * Common logic to directly migrate a single page suitable for
266cf658 475 * pages that do not use PagePrivate/PagePrivate2.
b20a3503
CL
476 *
477 * Pages are locked upon entry and exit.
478 */
2d1db3b1 479int migrate_page(struct address_space *mapping,
a6bc32b8
MG
480 struct page *newpage, struct page *page,
481 enum migrate_mode mode)
b20a3503
CL
482{
483 int rc;
484
485 BUG_ON(PageWriteback(page)); /* Writeback must be complete */
486
a6bc32b8 487 rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode);
b20a3503
CL
488
489 if (rc)
490 return rc;
491
492 migrate_page_copy(newpage, page);
b20a3503
CL
493 return 0;
494}
495EXPORT_SYMBOL(migrate_page);
496
9361401e 497#ifdef CONFIG_BLOCK
1d8b85cc
CL
498/*
499 * Migration function for pages with buffers. This function can only be used
500 * if the underlying filesystem guarantees that no other references to "page"
501 * exist.
502 */
2d1db3b1 503int buffer_migrate_page(struct address_space *mapping,
a6bc32b8 504 struct page *newpage, struct page *page, enum migrate_mode mode)
1d8b85cc 505{
1d8b85cc
CL
506 struct buffer_head *bh, *head;
507 int rc;
508
1d8b85cc 509 if (!page_has_buffers(page))
a6bc32b8 510 return migrate_page(mapping, newpage, page, mode);
1d8b85cc
CL
511
512 head = page_buffers(page);
513
a6bc32b8 514 rc = migrate_page_move_mapping(mapping, newpage, page, head, mode);
1d8b85cc
CL
515
516 if (rc)
517 return rc;
518
b969c4ab
MG
519 /*
520 * In the async case, migrate_page_move_mapping locked the buffers
521 * with an IRQ-safe spinlock held. In the sync case, the buffers
522 * need to be locked now
523 */
a6bc32b8
MG
524 if (mode != MIGRATE_ASYNC)
525 BUG_ON(!buffer_migrate_lock_buffers(head, mode));
1d8b85cc
CL
526
527 ClearPagePrivate(page);
528 set_page_private(newpage, page_private(page));
529 set_page_private(page, 0);
530 put_page(page);
531 get_page(newpage);
532
533 bh = head;
534 do {
535 set_bh_page(bh, newpage, bh_offset(bh));
536 bh = bh->b_this_page;
537
538 } while (bh != head);
539
540 SetPagePrivate(newpage);
541
542 migrate_page_copy(newpage, page);
543
544 bh = head;
545 do {
546 unlock_buffer(bh);
547 put_bh(bh);
548 bh = bh->b_this_page;
549
550 } while (bh != head);
551
552 return 0;
553}
554EXPORT_SYMBOL(buffer_migrate_page);
9361401e 555#endif
1d8b85cc 556
04e62a29
CL
557/*
558 * Writeback a page to clean the dirty state
559 */
560static int writeout(struct address_space *mapping, struct page *page)
8351a6e4 561{
04e62a29
CL
562 struct writeback_control wbc = {
563 .sync_mode = WB_SYNC_NONE,
564 .nr_to_write = 1,
565 .range_start = 0,
566 .range_end = LLONG_MAX,
04e62a29
CL
567 .for_reclaim = 1
568 };
569 int rc;
570
571 if (!mapping->a_ops->writepage)
572 /* No write method for the address space */
573 return -EINVAL;
574
575 if (!clear_page_dirty_for_io(page))
576 /* Someone else already triggered a write */
577 return -EAGAIN;
578
8351a6e4 579 /*
04e62a29
CL
580 * A dirty page may imply that the underlying filesystem has
581 * the page on some queue. So the page must be clean for
582 * migration. Writeout may mean we loose the lock and the
583 * page state is no longer what we checked for earlier.
584 * At this point we know that the migration attempt cannot
585 * be successful.
8351a6e4 586 */
04e62a29 587 remove_migration_ptes(page, page);
8351a6e4 588
04e62a29 589 rc = mapping->a_ops->writepage(page, &wbc);
8351a6e4 590
04e62a29
CL
591 if (rc != AOP_WRITEPAGE_ACTIVATE)
592 /* unlocked. Relock */
593 lock_page(page);
594
bda8550d 595 return (rc < 0) ? -EIO : -EAGAIN;
04e62a29
CL
596}
597
598/*
599 * Default handling if a filesystem does not provide a migration function.
600 */
601static int fallback_migrate_page(struct address_space *mapping,
a6bc32b8 602 struct page *newpage, struct page *page, enum migrate_mode mode)
04e62a29 603{
b969c4ab 604 if (PageDirty(page)) {
a6bc32b8
MG
605 /* Only writeback pages in full synchronous migration */
606 if (mode != MIGRATE_SYNC)
b969c4ab 607 return -EBUSY;
04e62a29 608 return writeout(mapping, page);
b969c4ab 609 }
8351a6e4
CL
610
611 /*
612 * Buffers may be managed in a filesystem specific way.
613 * We must have no buffers or drop them.
614 */
266cf658 615 if (page_has_private(page) &&
8351a6e4
CL
616 !try_to_release_page(page, GFP_KERNEL))
617 return -EAGAIN;
618
a6bc32b8 619 return migrate_page(mapping, newpage, page, mode);
8351a6e4
CL
620}
621
e24f0b8f
CL
622/*
623 * Move a page to a newly allocated page
624 * The page is locked and all ptes have been successfully removed.
625 *
626 * The new page will have replaced the old page if this function
627 * is successful.
894bc310
LS
628 *
629 * Return value:
630 * < 0 - error code
631 * == 0 - success
e24f0b8f 632 */
3fe2011f 633static int move_to_new_page(struct page *newpage, struct page *page,
a6bc32b8 634 int remap_swapcache, enum migrate_mode mode)
e24f0b8f
CL
635{
636 struct address_space *mapping;
637 int rc;
638
639 /*
640 * Block others from accessing the page when we get around to
641 * establishing additional references. We are the only one
642 * holding a reference to the new page at this point.
643 */
529ae9aa 644 if (!trylock_page(newpage))
e24f0b8f
CL
645 BUG();
646
647 /* Prepare mapping for the new page.*/
648 newpage->index = page->index;
649 newpage->mapping = page->mapping;
b2e18538
RR
650 if (PageSwapBacked(page))
651 SetPageSwapBacked(newpage);
e24f0b8f
CL
652
653 mapping = page_mapping(page);
654 if (!mapping)
a6bc32b8 655 rc = migrate_page(mapping, newpage, page, mode);
b969c4ab 656 else if (mapping->a_ops->migratepage)
e24f0b8f 657 /*
b969c4ab
MG
658 * Most pages have a mapping and most filesystems provide a
659 * migratepage callback. Anonymous pages are part of swap
660 * space which also has its own migratepage callback. This
661 * is the most common path for page migration.
e24f0b8f 662 */
b969c4ab 663 rc = mapping->a_ops->migratepage(mapping,
a6bc32b8 664 newpage, page, mode);
b969c4ab 665 else
a6bc32b8 666 rc = fallback_migrate_page(mapping, newpage, page, mode);
e24f0b8f 667
3fe2011f 668 if (rc) {
e24f0b8f 669 newpage->mapping = NULL;
3fe2011f
MG
670 } else {
671 if (remap_swapcache)
672 remove_migration_ptes(page, newpage);
35512eca 673 page->mapping = NULL;
3fe2011f 674 }
e24f0b8f
CL
675
676 unlock_page(newpage);
677
678 return rc;
679}
680
0dabec93 681static int __unmap_and_move(struct page *page, struct page *newpage,
a6bc32b8 682 int force, bool offlining, enum migrate_mode mode)
e24f0b8f 683{
0dabec93 684 int rc = -EAGAIN;
3fe2011f 685 int remap_swapcache = 1;
56039efa 686 struct mem_cgroup *mem;
3f6c8272 687 struct anon_vma *anon_vma = NULL;
95a402c3 688
529ae9aa 689 if (!trylock_page(page)) {
a6bc32b8 690 if (!force || mode == MIGRATE_ASYNC)
0dabec93 691 goto out;
3e7d3449
MG
692
693 /*
694 * It's not safe for direct compaction to call lock_page.
695 * For example, during page readahead pages are added locked
696 * to the LRU. Later, when the IO completes the pages are
697 * marked uptodate and unlocked. However, the queueing
698 * could be merging multiple pages for one bio (e.g.
699 * mpage_readpages). If an allocation happens for the
700 * second or third page, the process can end up locking
701 * the same page twice and deadlocking. Rather than
702 * trying to be clever about what pages can be locked,
703 * avoid the use of lock_page for direct compaction
704 * altogether.
705 */
706 if (current->flags & PF_MEMALLOC)
0dabec93 707 goto out;
3e7d3449 708
e24f0b8f
CL
709 lock_page(page);
710 }
711
62b61f61
HD
712 /*
713 * Only memory hotplug's offline_pages() caller has locked out KSM,
714 * and can safely migrate a KSM page. The other cases have skipped
715 * PageKsm along with PageReserved - but it is only now when we have
716 * the page lock that we can be certain it will not go KSM beneath us
717 * (KSM will not upgrade a page from PageAnon to PageKsm when it sees
718 * its pagecount raised, but only here do we take the page lock which
719 * serializes that).
720 */
721 if (PageKsm(page) && !offlining) {
722 rc = -EBUSY;
723 goto unlock;
724 }
725
01b1ae63 726 /* charge against new page */
0030f535 727 mem_cgroup_prepare_migration(page, newpage, &mem);
01b1ae63 728
e24f0b8f 729 if (PageWriteback(page)) {
11bc82d6 730 /*
a6bc32b8
MG
731 * Only in the case of a full syncronous migration is it
732 * necessary to wait for PageWriteback. In the async case,
733 * the retry loop is too short and in the sync-light case,
734 * the overhead of stalling is too much
11bc82d6 735 */
a6bc32b8 736 if (mode != MIGRATE_SYNC) {
11bc82d6
AA
737 rc = -EBUSY;
738 goto uncharge;
739 }
740 if (!force)
01b1ae63 741 goto uncharge;
e24f0b8f
CL
742 wait_on_page_writeback(page);
743 }
e24f0b8f 744 /*
dc386d4d
KH
745 * By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
746 * we cannot notice that anon_vma is freed while we migrates a page.
1ce82b69 747 * This get_anon_vma() delays freeing anon_vma pointer until the end
dc386d4d 748 * of migration. File cache pages are no problem because of page_lock()
989f89c5
KH
749 * File Caches may use write_page() or lock_page() in migration, then,
750 * just care Anon page here.
dc386d4d 751 */
989f89c5 752 if (PageAnon(page)) {
1ce82b69
HD
753 /*
754 * Only page_lock_anon_vma() understands the subtleties of
755 * getting a hold on an anon_vma from outside one of its mms.
756 */
746b18d4 757 anon_vma = page_get_anon_vma(page);
1ce82b69
HD
758 if (anon_vma) {
759 /*
746b18d4 760 * Anon page
1ce82b69 761 */
1ce82b69 762 } else if (PageSwapCache(page)) {
3fe2011f
MG
763 /*
764 * We cannot be sure that the anon_vma of an unmapped
765 * swapcache page is safe to use because we don't
766 * know in advance if the VMA that this page belonged
767 * to still exists. If the VMA and others sharing the
768 * data have been freed, then the anon_vma could
769 * already be invalid.
770 *
771 * To avoid this possibility, swapcache pages get
772 * migrated but are not remapped when migration
773 * completes
774 */
775 remap_swapcache = 0;
776 } else {
1ce82b69 777 goto uncharge;
3fe2011f 778 }
989f89c5 779 }
62e1c553 780
dc386d4d 781 /*
62e1c553
SL
782 * Corner case handling:
783 * 1. When a new swap-cache page is read into, it is added to the LRU
784 * and treated as swapcache but it has no rmap yet.
785 * Calling try_to_unmap() against a page->mapping==NULL page will
786 * trigger a BUG. So handle it here.
787 * 2. An orphaned page (see truncate_complete_page) might have
788 * fs-private metadata. The page can be picked up due to memory
789 * offlining. Everywhere else except page reclaim, the page is
790 * invisible to the vm, so the page can not be migrated. So try to
791 * free the metadata, so the page can be freed.
e24f0b8f 792 */
62e1c553 793 if (!page->mapping) {
1ce82b69
HD
794 VM_BUG_ON(PageAnon(page));
795 if (page_has_private(page)) {
62e1c553 796 try_to_free_buffers(page);
1ce82b69 797 goto uncharge;
62e1c553 798 }
abfc3488 799 goto skip_unmap;
62e1c553
SL
800 }
801
dc386d4d 802 /* Establish migration ptes or remove ptes */
14fa31b8 803 try_to_unmap(page, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS);
dc386d4d 804
abfc3488 805skip_unmap:
e6a1530d 806 if (!page_mapped(page))
a6bc32b8 807 rc = move_to_new_page(newpage, page, remap_swapcache, mode);
e24f0b8f 808
3fe2011f 809 if (rc && remap_swapcache)
e24f0b8f 810 remove_migration_ptes(page, page);
3f6c8272
MG
811
812 /* Drop an anon_vma reference if we took one */
76545066 813 if (anon_vma)
9e60109f 814 put_anon_vma(anon_vma);
3f6c8272 815
01b1ae63 816uncharge:
0030f535 817 mem_cgroup_end_migration(mem, page, newpage, rc == 0);
e24f0b8f
CL
818unlock:
819 unlock_page(page);
0dabec93
MK
820out:
821 return rc;
822}
95a402c3 823
0dabec93
MK
824/*
825 * Obtain the lock on page, remove all ptes and migrate the page
826 * to the newly allocated page in newpage.
827 */
828static int unmap_and_move(new_page_t get_new_page, unsigned long private,
a6bc32b8
MG
829 struct page *page, int force, bool offlining,
830 enum migrate_mode mode)
0dabec93
MK
831{
832 int rc = 0;
833 int *result = NULL;
834 struct page *newpage = get_new_page(page, private, &result);
835
836 if (!newpage)
837 return -ENOMEM;
838
839 if (page_count(page) == 1) {
840 /* page was freed from under us. So we are done. */
841 goto out;
842 }
843
844 if (unlikely(PageTransHuge(page)))
845 if (unlikely(split_huge_page(page)))
846 goto out;
847
a6bc32b8 848 rc = __unmap_and_move(page, newpage, force, offlining, mode);
0dabec93 849out:
e24f0b8f 850 if (rc != -EAGAIN) {
0dabec93
MK
851 /*
852 * A page that has been migrated has all references
853 * removed and will be freed. A page that has not been
854 * migrated will have kepts its references and be
855 * restored.
856 */
857 list_del(&page->lru);
a731286d 858 dec_zone_page_state(page, NR_ISOLATED_ANON +
6c0b1351 859 page_is_file_cache(page));
894bc310 860 putback_lru_page(page);
e24f0b8f 861 }
95a402c3
CL
862 /*
863 * Move the new page to the LRU. If migration was not successful
864 * then this will free the page.
865 */
894bc310 866 putback_lru_page(newpage);
742755a1
CL
867 if (result) {
868 if (rc)
869 *result = rc;
870 else
871 *result = page_to_nid(newpage);
872 }
e24f0b8f
CL
873 return rc;
874}
875
290408d4
NH
876/*
877 * Counterpart of unmap_and_move_page() for hugepage migration.
878 *
879 * This function doesn't wait the completion of hugepage I/O
880 * because there is no race between I/O and migration for hugepage.
881 * Note that currently hugepage I/O occurs only in direct I/O
882 * where no lock is held and PG_writeback is irrelevant,
883 * and writeback status of all subpages are counted in the reference
884 * count of the head page (i.e. if all subpages of a 2MB hugepage are
885 * under direct I/O, the reference of the head page is 512 and a bit more.)
886 * This means that when we try to migrate hugepage whose subpages are
887 * doing direct I/O, some references remain after try_to_unmap() and
888 * hugepage migration fails without data corruption.
889 *
890 * There is also no race when direct I/O is issued on the page under migration,
891 * because then pte is replaced with migration swap entry and direct I/O code
892 * will wait in the page fault for migration to complete.
893 */
894static int unmap_and_move_huge_page(new_page_t get_new_page,
895 unsigned long private, struct page *hpage,
a6bc32b8
MG
896 int force, bool offlining,
897 enum migrate_mode mode)
290408d4
NH
898{
899 int rc = 0;
900 int *result = NULL;
901 struct page *new_hpage = get_new_page(hpage, private, &result);
290408d4
NH
902 struct anon_vma *anon_vma = NULL;
903
904 if (!new_hpage)
905 return -ENOMEM;
906
907 rc = -EAGAIN;
908
909 if (!trylock_page(hpage)) {
a6bc32b8 910 if (!force || mode != MIGRATE_SYNC)
290408d4
NH
911 goto out;
912 lock_page(hpage);
913 }
914
746b18d4
PZ
915 if (PageAnon(hpage))
916 anon_vma = page_get_anon_vma(hpage);
290408d4
NH
917
918 try_to_unmap(hpage, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS);
919
920 if (!page_mapped(hpage))
a6bc32b8 921 rc = move_to_new_page(new_hpage, hpage, 1, mode);
290408d4
NH
922
923 if (rc)
924 remove_migration_ptes(hpage, hpage);
925
fd4a4663 926 if (anon_vma)
9e60109f 927 put_anon_vma(anon_vma);
8e6ac7fa
AK
928
929 if (!rc)
930 hugetlb_cgroup_migrate(hpage, new_hpage);
931
290408d4 932 unlock_page(hpage);
09761333 933out:
290408d4 934 put_page(new_hpage);
290408d4
NH
935 if (result) {
936 if (rc)
937 *result = rc;
938 else
939 *result = page_to_nid(new_hpage);
940 }
941 return rc;
942}
943
b20a3503
CL
944/*
945 * migrate_pages
946 *
95a402c3
CL
947 * The function takes one list of pages to migrate and a function
948 * that determines from the page to be migrated and the private data
949 * the target of the move and allocates the page.
b20a3503
CL
950 *
951 * The function returns after 10 attempts or if no pages
952 * are movable anymore because to has become empty
cf608ac1
MK
953 * or no retryable pages exist anymore.
954 * Caller should call putback_lru_pages to return pages to the LRU
28bd6578 955 * or free list only if ret != 0.
b20a3503 956 *
95a402c3 957 * Return: Number of pages not migrated or error code.
b20a3503 958 */
95a402c3 959int migrate_pages(struct list_head *from,
7f0f2496 960 new_page_t get_new_page, unsigned long private, bool offlining,
a6bc32b8 961 enum migrate_mode mode)
b20a3503 962{
e24f0b8f 963 int retry = 1;
b20a3503
CL
964 int nr_failed = 0;
965 int pass = 0;
966 struct page *page;
967 struct page *page2;
968 int swapwrite = current->flags & PF_SWAPWRITE;
969 int rc;
970
971 if (!swapwrite)
972 current->flags |= PF_SWAPWRITE;
973
e24f0b8f
CL
974 for(pass = 0; pass < 10 && retry; pass++) {
975 retry = 0;
b20a3503 976
e24f0b8f 977 list_for_each_entry_safe(page, page2, from, lru) {
e24f0b8f 978 cond_resched();
2d1db3b1 979
95a402c3 980 rc = unmap_and_move(get_new_page, private,
77f1fe6b 981 page, pass > 2, offlining,
a6bc32b8 982 mode);
2d1db3b1 983
e24f0b8f 984 switch(rc) {
95a402c3
CL
985 case -ENOMEM:
986 goto out;
e24f0b8f 987 case -EAGAIN:
2d1db3b1 988 retry++;
e24f0b8f
CL
989 break;
990 case 0:
e24f0b8f
CL
991 break;
992 default:
2d1db3b1 993 /* Permanent failure */
2d1db3b1 994 nr_failed++;
e24f0b8f 995 break;
2d1db3b1 996 }
b20a3503
CL
997 }
998 }
95a402c3
CL
999 rc = 0;
1000out:
b20a3503
CL
1001 if (!swapwrite)
1002 current->flags &= ~PF_SWAPWRITE;
1003
95a402c3
CL
1004 if (rc)
1005 return rc;
b20a3503 1006
95a402c3 1007 return nr_failed + retry;
b20a3503 1008}
95a402c3 1009
189ebff2
AK
1010int migrate_huge_page(struct page *hpage, new_page_t get_new_page,
1011 unsigned long private, bool offlining,
1012 enum migrate_mode mode)
290408d4 1013{
189ebff2
AK
1014 int pass, rc;
1015
1016 for (pass = 0; pass < 10; pass++) {
1017 rc = unmap_and_move_huge_page(get_new_page,
1018 private, hpage, pass > 2, offlining,
1019 mode);
1020 switch (rc) {
1021 case -ENOMEM:
1022 goto out;
1023 case -EAGAIN:
1024 /* try again */
290408d4 1025 cond_resched();
189ebff2
AK
1026 break;
1027 case 0:
1028 goto out;
1029 default:
1030 rc = -EIO;
1031 goto out;
290408d4
NH
1032 }
1033 }
290408d4 1034out:
189ebff2 1035 return rc;
290408d4
NH
1036}
1037
742755a1
CL
1038#ifdef CONFIG_NUMA
1039/*
1040 * Move a list of individual pages
1041 */
1042struct page_to_node {
1043 unsigned long addr;
1044 struct page *page;
1045 int node;
1046 int status;
1047};
1048
1049static struct page *new_page_node(struct page *p, unsigned long private,
1050 int **result)
1051{
1052 struct page_to_node *pm = (struct page_to_node *)private;
1053
1054 while (pm->node != MAX_NUMNODES && pm->page != p)
1055 pm++;
1056
1057 if (pm->node == MAX_NUMNODES)
1058 return NULL;
1059
1060 *result = &pm->status;
1061
6484eb3e 1062 return alloc_pages_exact_node(pm->node,
769848c0 1063 GFP_HIGHUSER_MOVABLE | GFP_THISNODE, 0);
742755a1
CL
1064}
1065
1066/*
1067 * Move a set of pages as indicated in the pm array. The addr
1068 * field must be set to the virtual address of the page to be moved
1069 * and the node number must contain a valid target node.
5e9a0f02 1070 * The pm array ends with node = MAX_NUMNODES.
742755a1 1071 */
5e9a0f02
BG
1072static int do_move_page_to_node_array(struct mm_struct *mm,
1073 struct page_to_node *pm,
1074 int migrate_all)
742755a1
CL
1075{
1076 int err;
1077 struct page_to_node *pp;
1078 LIST_HEAD(pagelist);
1079
1080 down_read(&mm->mmap_sem);
1081
1082 /*
1083 * Build a list of pages to migrate
1084 */
742755a1
CL
1085 for (pp = pm; pp->node != MAX_NUMNODES; pp++) {
1086 struct vm_area_struct *vma;
1087 struct page *page;
1088
742755a1
CL
1089 err = -EFAULT;
1090 vma = find_vma(mm, pp->addr);
70384dc6 1091 if (!vma || pp->addr < vma->vm_start || !vma_migratable(vma))
742755a1
CL
1092 goto set_status;
1093
500d65d4 1094 page = follow_page(vma, pp->addr, FOLL_GET|FOLL_SPLIT);
89f5b7da
LT
1095
1096 err = PTR_ERR(page);
1097 if (IS_ERR(page))
1098 goto set_status;
1099
742755a1
CL
1100 err = -ENOENT;
1101 if (!page)
1102 goto set_status;
1103
62b61f61
HD
1104 /* Use PageReserved to check for zero page */
1105 if (PageReserved(page) || PageKsm(page))
742755a1
CL
1106 goto put_and_set;
1107
1108 pp->page = page;
1109 err = page_to_nid(page);
1110
1111 if (err == pp->node)
1112 /*
1113 * Node already in the right place
1114 */
1115 goto put_and_set;
1116
1117 err = -EACCES;
1118 if (page_mapcount(page) > 1 &&
1119 !migrate_all)
1120 goto put_and_set;
1121
62695a84 1122 err = isolate_lru_page(page);
6d9c285a 1123 if (!err) {
62695a84 1124 list_add_tail(&page->lru, &pagelist);
6d9c285a
KM
1125 inc_zone_page_state(page, NR_ISOLATED_ANON +
1126 page_is_file_cache(page));
1127 }
742755a1
CL
1128put_and_set:
1129 /*
1130 * Either remove the duplicate refcount from
1131 * isolate_lru_page() or drop the page ref if it was
1132 * not isolated.
1133 */
1134 put_page(page);
1135set_status:
1136 pp->status = err;
1137 }
1138
e78bbfa8 1139 err = 0;
cf608ac1 1140 if (!list_empty(&pagelist)) {
742755a1 1141 err = migrate_pages(&pagelist, new_page_node,
a6bc32b8 1142 (unsigned long)pm, 0, MIGRATE_SYNC);
cf608ac1
MK
1143 if (err)
1144 putback_lru_pages(&pagelist);
1145 }
742755a1
CL
1146
1147 up_read(&mm->mmap_sem);
1148 return err;
1149}
1150
5e9a0f02
BG
1151/*
1152 * Migrate an array of page address onto an array of nodes and fill
1153 * the corresponding array of status.
1154 */
3268c63e 1155static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
5e9a0f02
BG
1156 unsigned long nr_pages,
1157 const void __user * __user *pages,
1158 const int __user *nodes,
1159 int __user *status, int flags)
1160{
3140a227 1161 struct page_to_node *pm;
3140a227
BG
1162 unsigned long chunk_nr_pages;
1163 unsigned long chunk_start;
1164 int err;
5e9a0f02 1165
3140a227
BG
1166 err = -ENOMEM;
1167 pm = (struct page_to_node *)__get_free_page(GFP_KERNEL);
1168 if (!pm)
5e9a0f02 1169 goto out;
35282a2d
BG
1170
1171 migrate_prep();
1172
5e9a0f02 1173 /*
3140a227
BG
1174 * Store a chunk of page_to_node array in a page,
1175 * but keep the last one as a marker
5e9a0f02 1176 */
3140a227 1177 chunk_nr_pages = (PAGE_SIZE / sizeof(struct page_to_node)) - 1;
5e9a0f02 1178
3140a227
BG
1179 for (chunk_start = 0;
1180 chunk_start < nr_pages;
1181 chunk_start += chunk_nr_pages) {
1182 int j;
5e9a0f02 1183
3140a227
BG
1184 if (chunk_start + chunk_nr_pages > nr_pages)
1185 chunk_nr_pages = nr_pages - chunk_start;
1186
1187 /* fill the chunk pm with addrs and nodes from user-space */
1188 for (j = 0; j < chunk_nr_pages; j++) {
1189 const void __user *p;
5e9a0f02
BG
1190 int node;
1191
3140a227
BG
1192 err = -EFAULT;
1193 if (get_user(p, pages + j + chunk_start))
1194 goto out_pm;
1195 pm[j].addr = (unsigned long) p;
1196
1197 if (get_user(node, nodes + j + chunk_start))
5e9a0f02
BG
1198 goto out_pm;
1199
1200 err = -ENODEV;
6f5a55f1
LT
1201 if (node < 0 || node >= MAX_NUMNODES)
1202 goto out_pm;
1203
5e9a0f02
BG
1204 if (!node_state(node, N_HIGH_MEMORY))
1205 goto out_pm;
1206
1207 err = -EACCES;
1208 if (!node_isset(node, task_nodes))
1209 goto out_pm;
1210
3140a227
BG
1211 pm[j].node = node;
1212 }
1213
1214 /* End marker for this chunk */
1215 pm[chunk_nr_pages].node = MAX_NUMNODES;
1216
1217 /* Migrate this chunk */
1218 err = do_move_page_to_node_array(mm, pm,
1219 flags & MPOL_MF_MOVE_ALL);
1220 if (err < 0)
1221 goto out_pm;
5e9a0f02 1222
5e9a0f02 1223 /* Return status information */
3140a227
BG
1224 for (j = 0; j < chunk_nr_pages; j++)
1225 if (put_user(pm[j].status, status + j + chunk_start)) {
5e9a0f02 1226 err = -EFAULT;
3140a227
BG
1227 goto out_pm;
1228 }
1229 }
1230 err = 0;
5e9a0f02
BG
1231
1232out_pm:
3140a227 1233 free_page((unsigned long)pm);
5e9a0f02
BG
1234out:
1235 return err;
1236}
1237
742755a1 1238/*
2f007e74 1239 * Determine the nodes of an array of pages and store it in an array of status.
742755a1 1240 */
80bba129
BG
1241static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
1242 const void __user **pages, int *status)
742755a1 1243{
2f007e74 1244 unsigned long i;
2f007e74 1245
742755a1
CL
1246 down_read(&mm->mmap_sem);
1247
2f007e74 1248 for (i = 0; i < nr_pages; i++) {
80bba129 1249 unsigned long addr = (unsigned long)(*pages);
742755a1
CL
1250 struct vm_area_struct *vma;
1251 struct page *page;
c095adbc 1252 int err = -EFAULT;
2f007e74
BG
1253
1254 vma = find_vma(mm, addr);
70384dc6 1255 if (!vma || addr < vma->vm_start)
742755a1
CL
1256 goto set_status;
1257
2f007e74 1258 page = follow_page(vma, addr, 0);
89f5b7da
LT
1259
1260 err = PTR_ERR(page);
1261 if (IS_ERR(page))
1262 goto set_status;
1263
742755a1
CL
1264 err = -ENOENT;
1265 /* Use PageReserved to check for zero page */
62b61f61 1266 if (!page || PageReserved(page) || PageKsm(page))
742755a1
CL
1267 goto set_status;
1268
1269 err = page_to_nid(page);
1270set_status:
80bba129
BG
1271 *status = err;
1272
1273 pages++;
1274 status++;
1275 }
1276
1277 up_read(&mm->mmap_sem);
1278}
1279
1280/*
1281 * Determine the nodes of a user array of pages and store it in
1282 * a user array of status.
1283 */
1284static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages,
1285 const void __user * __user *pages,
1286 int __user *status)
1287{
1288#define DO_PAGES_STAT_CHUNK_NR 16
1289 const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR];
1290 int chunk_status[DO_PAGES_STAT_CHUNK_NR];
80bba129 1291
87b8d1ad
PA
1292 while (nr_pages) {
1293 unsigned long chunk_nr;
80bba129 1294
87b8d1ad
PA
1295 chunk_nr = nr_pages;
1296 if (chunk_nr > DO_PAGES_STAT_CHUNK_NR)
1297 chunk_nr = DO_PAGES_STAT_CHUNK_NR;
1298
1299 if (copy_from_user(chunk_pages, pages, chunk_nr * sizeof(*chunk_pages)))
1300 break;
80bba129
BG
1301
1302 do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status);
1303
87b8d1ad
PA
1304 if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status)))
1305 break;
742755a1 1306
87b8d1ad
PA
1307 pages += chunk_nr;
1308 status += chunk_nr;
1309 nr_pages -= chunk_nr;
1310 }
1311 return nr_pages ? -EFAULT : 0;
742755a1
CL
1312}
1313
1314/*
1315 * Move a list of pages in the address space of the currently executing
1316 * process.
1317 */
938bb9f5
HC
1318SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,
1319 const void __user * __user *, pages,
1320 const int __user *, nodes,
1321 int __user *, status, int, flags)
742755a1 1322{
c69e8d9c 1323 const struct cred *cred = current_cred(), *tcred;
742755a1 1324 struct task_struct *task;
742755a1 1325 struct mm_struct *mm;
5e9a0f02 1326 int err;
3268c63e 1327 nodemask_t task_nodes;
742755a1
CL
1328
1329 /* Check flags */
1330 if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
1331 return -EINVAL;
1332
1333 if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
1334 return -EPERM;
1335
1336 /* Find the mm_struct */
a879bf58 1337 rcu_read_lock();
228ebcbe 1338 task = pid ? find_task_by_vpid(pid) : current;
742755a1 1339 if (!task) {
a879bf58 1340 rcu_read_unlock();
742755a1
CL
1341 return -ESRCH;
1342 }
3268c63e 1343 get_task_struct(task);
742755a1
CL
1344
1345 /*
1346 * Check if this process has the right to modify the specified
1347 * process. The right exists if the process has administrative
1348 * capabilities, superuser privileges or the same
1349 * userid as the target process.
1350 */
c69e8d9c 1351 tcred = __task_cred(task);
b38a86eb
EB
1352 if (!uid_eq(cred->euid, tcred->suid) && !uid_eq(cred->euid, tcred->uid) &&
1353 !uid_eq(cred->uid, tcred->suid) && !uid_eq(cred->uid, tcred->uid) &&
742755a1 1354 !capable(CAP_SYS_NICE)) {
c69e8d9c 1355 rcu_read_unlock();
742755a1 1356 err = -EPERM;
5e9a0f02 1357 goto out;
742755a1 1358 }
c69e8d9c 1359 rcu_read_unlock();
742755a1 1360
86c3a764
DQ
1361 err = security_task_movememory(task);
1362 if (err)
5e9a0f02 1363 goto out;
86c3a764 1364
3268c63e
CL
1365 task_nodes = cpuset_mems_allowed(task);
1366 mm = get_task_mm(task);
1367 put_task_struct(task);
1368
6e8b09ea
SL
1369 if (!mm)
1370 return -EINVAL;
1371
1372 if (nodes)
1373 err = do_pages_move(mm, task_nodes, nr_pages, pages,
1374 nodes, status, flags);
1375 else
1376 err = do_pages_stat(mm, nr_pages, pages, status);
742755a1 1377
742755a1
CL
1378 mmput(mm);
1379 return err;
3268c63e
CL
1380
1381out:
1382 put_task_struct(task);
1383 return err;
742755a1 1384}
742755a1 1385
7b2259b3
CL
1386/*
1387 * Call migration functions in the vma_ops that may prepare
1388 * memory in a vm for migration. migration functions may perform
1389 * the migration for vmas that do not have an underlying page struct.
1390 */
1391int migrate_vmas(struct mm_struct *mm, const nodemask_t *to,
1392 const nodemask_t *from, unsigned long flags)
1393{
1394 struct vm_area_struct *vma;
1395 int err = 0;
1396
1001c9fb 1397 for (vma = mm->mmap; vma && !err; vma = vma->vm_next) {
7b2259b3
CL
1398 if (vma->vm_ops && vma->vm_ops->migrate) {
1399 err = vma->vm_ops->migrate(vma, to, from, flags);
1400 if (err)
1401 break;
1402 }
1403 }
1404 return err;
1405}
83d1674a 1406#endif