FS-Cache: Release page->private after failed readahead
[linux-2.6-block.git] / mm / migrate.c
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>
16#include <linux/module.h>
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
CL
23#include <linux/pagevec.h>
24#include <linux/rmap.h>
25#include <linux/topology.h>
26#include <linux/cpu.h>
27#include <linux/cpuset.h>
04e62a29 28#include <linux/writeback.h>
742755a1
CL
29#include <linux/mempolicy.h>
30#include <linux/vmalloc.h>
86c3a764 31#include <linux/security.h>
8a9f3ccd 32#include <linux/memcontrol.h>
4f5ca265 33#include <linux/syscalls.h>
b20a3503
CL
34
35#include "internal.h"
36
b20a3503
CL
37#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
38
b20a3503 39/*
742755a1
CL
40 * migrate_prep() needs to be called before we start compiling a list of pages
41 * to be migrated using isolate_lru_page().
b20a3503
CL
42 */
43int migrate_prep(void)
44{
b20a3503
CL
45 /*
46 * Clear the LRU lists so pages can be isolated.
47 * Note that pages may be moved off the LRU after we have
48 * drained them. Those pages will fail to migrate like other
49 * pages that may be busy.
50 */
51 lru_add_drain_all();
52
53 return 0;
54}
55
b20a3503 56/*
894bc310
LS
57 * Add isolated pages on the list back to the LRU under page lock
58 * to avoid leaking evictable pages back onto unevictable list.
b20a3503
CL
59 *
60 * returns the number of pages put back.
61 */
62int putback_lru_pages(struct list_head *l)
63{
64 struct page *page;
65 struct page *page2;
66 int count = 0;
67
68 list_for_each_entry_safe(page, page2, l, lru) {
e24f0b8f 69 list_del(&page->lru);
894bc310 70 putback_lru_page(page);
b20a3503
CL
71 count++;
72 }
73 return count;
74}
75
0697212a
CL
76/*
77 * Restore a potential migration pte to a working pte entry
78 */
04e62a29 79static void remove_migration_pte(struct vm_area_struct *vma,
0697212a
CL
80 struct page *old, struct page *new)
81{
82 struct mm_struct *mm = vma->vm_mm;
83 swp_entry_t entry;
84 pgd_t *pgd;
85 pud_t *pud;
86 pmd_t *pmd;
87 pte_t *ptep, pte;
88 spinlock_t *ptl;
04e62a29
CL
89 unsigned long addr = page_address_in_vma(new, vma);
90
91 if (addr == -EFAULT)
92 return;
0697212a
CL
93
94 pgd = pgd_offset(mm, addr);
95 if (!pgd_present(*pgd))
96 return;
97
98 pud = pud_offset(pgd, addr);
99 if (!pud_present(*pud))
100 return;
101
102 pmd = pmd_offset(pud, addr);
103 if (!pmd_present(*pmd))
104 return;
105
106 ptep = pte_offset_map(pmd, addr);
107
108 if (!is_swap_pte(*ptep)) {
109 pte_unmap(ptep);
110 return;
111 }
112
113 ptl = pte_lockptr(mm, pmd);
114 spin_lock(ptl);
115 pte = *ptep;
116 if (!is_swap_pte(pte))
117 goto out;
118
119 entry = pte_to_swp_entry(pte);
120
121 if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old)
122 goto out;
123
0697212a
CL
124 get_page(new);
125 pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
126 if (is_write_migration_entry(entry))
127 pte = pte_mkwrite(pte);
97ee0524 128 flush_cache_page(vma, addr, pte_pfn(pte));
0697212a 129 set_pte_at(mm, addr, ptep, pte);
04e62a29
CL
130
131 if (PageAnon(new))
132 page_add_anon_rmap(new, vma, addr);
133 else
134 page_add_file_rmap(new);
135
136 /* No need to invalidate - it was non-present before */
137 update_mmu_cache(vma, addr, pte);
04e62a29 138
0697212a
CL
139out:
140 pte_unmap_unlock(ptep, ptl);
141}
142
143/*
04e62a29
CL
144 * Note that remove_file_migration_ptes will only work on regular mappings,
145 * Nonlinear mappings do not use migration entries.
146 */
147static void remove_file_migration_ptes(struct page *old, struct page *new)
148{
149 struct vm_area_struct *vma;
150 struct address_space *mapping = page_mapping(new);
151 struct prio_tree_iter iter;
152 pgoff_t pgoff = new->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
153
154 if (!mapping)
155 return;
156
157 spin_lock(&mapping->i_mmap_lock);
158
159 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff)
160 remove_migration_pte(vma, old, new);
161
162 spin_unlock(&mapping->i_mmap_lock);
163}
164
165/*
0697212a
CL
166 * Must hold mmap_sem lock on at least one of the vmas containing
167 * the page so that the anon_vma cannot vanish.
168 */
04e62a29 169static void remove_anon_migration_ptes(struct page *old, struct page *new)
0697212a
CL
170{
171 struct anon_vma *anon_vma;
172 struct vm_area_struct *vma;
173 unsigned long mapping;
174
175 mapping = (unsigned long)new->mapping;
176
177 if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0)
178 return;
179
180 /*
181 * We hold the mmap_sem lock. So no need to call page_lock_anon_vma.
182 */
183 anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON);
184 spin_lock(&anon_vma->lock);
185
186 list_for_each_entry(vma, &anon_vma->head, anon_vma_node)
04e62a29 187 remove_migration_pte(vma, old, new);
0697212a
CL
188
189 spin_unlock(&anon_vma->lock);
190}
191
04e62a29
CL
192/*
193 * Get rid of all migration entries and replace them by
194 * references to the indicated page.
195 */
196static void remove_migration_ptes(struct page *old, struct page *new)
197{
198 if (PageAnon(new))
199 remove_anon_migration_ptes(old, new);
200 else
201 remove_file_migration_ptes(old, new);
202}
203
0697212a
CL
204/*
205 * Something used the pte of a page under migration. We need to
206 * get to the page and wait until migration is finished.
207 * When we return from this function the fault will be retried.
208 *
209 * This function is called from do_swap_page().
210 */
211void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
212 unsigned long address)
213{
214 pte_t *ptep, pte;
215 spinlock_t *ptl;
216 swp_entry_t entry;
217 struct page *page;
218
219 ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
220 pte = *ptep;
221 if (!is_swap_pte(pte))
222 goto out;
223
224 entry = pte_to_swp_entry(pte);
225 if (!is_migration_entry(entry))
226 goto out;
227
228 page = migration_entry_to_page(entry);
229
e286781d
NP
230 /*
231 * Once radix-tree replacement of page migration started, page_count
232 * *must* be zero. And, we don't want to call wait_on_page_locked()
233 * against a page without get_page().
234 * So, we use get_page_unless_zero(), here. Even failed, page fault
235 * will occur again.
236 */
237 if (!get_page_unless_zero(page))
238 goto out;
0697212a
CL
239 pte_unmap_unlock(ptep, ptl);
240 wait_on_page_locked(page);
241 put_page(page);
242 return;
243out:
244 pte_unmap_unlock(ptep, ptl);
245}
246
b20a3503 247/*
c3fcf8a5 248 * Replace the page in the mapping.
5b5c7120
CL
249 *
250 * The number of remaining references must be:
251 * 1 for anonymous pages without a mapping
252 * 2 for pages with a mapping
253 * 3 for pages with a mapping and PagePrivate set.
b20a3503 254 */
2d1db3b1
CL
255static int migrate_page_move_mapping(struct address_space *mapping,
256 struct page *newpage, struct page *page)
b20a3503 257{
e286781d 258 int expected_count;
7cf9c2c7 259 void **pslot;
b20a3503 260
6c5240ae 261 if (!mapping) {
0e8c7d0f 262 /* Anonymous page without mapping */
6c5240ae
CL
263 if (page_count(page) != 1)
264 return -EAGAIN;
265 return 0;
266 }
267
19fd6231 268 spin_lock_irq(&mapping->tree_lock);
b20a3503 269
7cf9c2c7
NP
270 pslot = radix_tree_lookup_slot(&mapping->page_tree,
271 page_index(page));
b20a3503 272
e286781d
NP
273 expected_count = 2 + !!PagePrivate(page);
274 if (page_count(page) != expected_count ||
7cf9c2c7 275 (struct page *)radix_tree_deref_slot(pslot) != page) {
19fd6231 276 spin_unlock_irq(&mapping->tree_lock);
e23ca00b 277 return -EAGAIN;
b20a3503
CL
278 }
279
e286781d 280 if (!page_freeze_refs(page, expected_count)) {
19fd6231 281 spin_unlock_irq(&mapping->tree_lock);
e286781d
NP
282 return -EAGAIN;
283 }
284
b20a3503
CL
285 /*
286 * Now we know that no one else is looking at the page.
b20a3503 287 */
7cf9c2c7 288 get_page(newpage); /* add cache reference */
b20a3503
CL
289 if (PageSwapCache(page)) {
290 SetPageSwapCache(newpage);
291 set_page_private(newpage, page_private(page));
292 }
293
7cf9c2c7
NP
294 radix_tree_replace_slot(pslot, newpage);
295
e286781d 296 page_unfreeze_refs(page, expected_count);
7cf9c2c7
NP
297 /*
298 * Drop cache reference from old page.
299 * We know this isn't the last reference.
300 */
b20a3503 301 __put_page(page);
7cf9c2c7 302
0e8c7d0f
CL
303 /*
304 * If moved to a different zone then also account
305 * the page for that zone. Other VM counters will be
306 * taken care of when we establish references to the
307 * new page and drop references to the old page.
308 *
309 * Note that anonymous pages are accounted for
310 * via NR_FILE_PAGES and NR_ANON_PAGES if they
311 * are mapped to swap space.
312 */
313 __dec_zone_page_state(page, NR_FILE_PAGES);
314 __inc_zone_page_state(newpage, NR_FILE_PAGES);
315
19fd6231 316 spin_unlock_irq(&mapping->tree_lock);
b20a3503
CL
317
318 return 0;
319}
b20a3503
CL
320
321/*
322 * Copy the page to its new location
323 */
e7340f73 324static void migrate_page_copy(struct page *newpage, struct page *page)
b20a3503 325{
b7abea96
KH
326 int anon;
327
b20a3503
CL
328 copy_highpage(newpage, page);
329
330 if (PageError(page))
331 SetPageError(newpage);
332 if (PageReferenced(page))
333 SetPageReferenced(newpage);
334 if (PageUptodate(page))
335 SetPageUptodate(newpage);
894bc310
LS
336 if (TestClearPageActive(page)) {
337 VM_BUG_ON(PageUnevictable(page));
b20a3503 338 SetPageActive(newpage);
894bc310
LS
339 } else
340 unevictable_migrate_page(newpage, page);
b20a3503
CL
341 if (PageChecked(page))
342 SetPageChecked(newpage);
343 if (PageMappedToDisk(page))
344 SetPageMappedToDisk(newpage);
345
346 if (PageDirty(page)) {
347 clear_page_dirty_for_io(page);
3a902c5f
NP
348 /*
349 * Want to mark the page and the radix tree as dirty, and
350 * redo the accounting that clear_page_dirty_for_io undid,
351 * but we can't use set_page_dirty because that function
352 * is actually a signal that all of the page has become dirty.
353 * Wheras only part of our page may be dirty.
354 */
355 __set_page_dirty_nobuffers(newpage);
b20a3503
CL
356 }
357
b291f000
NP
358 mlock_migrate_page(newpage, page);
359
b20a3503 360 ClearPageSwapCache(page);
b20a3503
CL
361 ClearPagePrivate(page);
362 set_page_private(page, 0);
b7abea96
KH
363 /* page->mapping contains a flag for PageAnon() */
364 anon = PageAnon(page);
b20a3503
CL
365 page->mapping = NULL;
366
367 /*
368 * If any waiters have accumulated on the new page then
369 * wake them up.
370 */
371 if (PageWriteback(newpage))
372 end_page_writeback(newpage);
373}
b20a3503 374
1d8b85cc
CL
375/************************************************************
376 * Migration functions
377 ***********************************************************/
378
379/* Always fail migration. Used for mappings that are not movable */
2d1db3b1
CL
380int fail_migrate_page(struct address_space *mapping,
381 struct page *newpage, struct page *page)
1d8b85cc
CL
382{
383 return -EIO;
384}
385EXPORT_SYMBOL(fail_migrate_page);
386
b20a3503
CL
387/*
388 * Common logic to directly migrate a single page suitable for
389 * pages that do not use PagePrivate.
390 *
391 * Pages are locked upon entry and exit.
392 */
2d1db3b1
CL
393int migrate_page(struct address_space *mapping,
394 struct page *newpage, struct page *page)
b20a3503
CL
395{
396 int rc;
397
398 BUG_ON(PageWriteback(page)); /* Writeback must be complete */
399
2d1db3b1 400 rc = migrate_page_move_mapping(mapping, newpage, page);
b20a3503
CL
401
402 if (rc)
403 return rc;
404
405 migrate_page_copy(newpage, page);
b20a3503
CL
406 return 0;
407}
408EXPORT_SYMBOL(migrate_page);
409
9361401e 410#ifdef CONFIG_BLOCK
1d8b85cc
CL
411/*
412 * Migration function for pages with buffers. This function can only be used
413 * if the underlying filesystem guarantees that no other references to "page"
414 * exist.
415 */
2d1db3b1
CL
416int buffer_migrate_page(struct address_space *mapping,
417 struct page *newpage, struct page *page)
1d8b85cc 418{
1d8b85cc
CL
419 struct buffer_head *bh, *head;
420 int rc;
421
1d8b85cc 422 if (!page_has_buffers(page))
2d1db3b1 423 return migrate_page(mapping, newpage, page);
1d8b85cc
CL
424
425 head = page_buffers(page);
426
2d1db3b1 427 rc = migrate_page_move_mapping(mapping, newpage, page);
1d8b85cc
CL
428
429 if (rc)
430 return rc;
431
432 bh = head;
433 do {
434 get_bh(bh);
435 lock_buffer(bh);
436 bh = bh->b_this_page;
437
438 } while (bh != head);
439
440 ClearPagePrivate(page);
441 set_page_private(newpage, page_private(page));
442 set_page_private(page, 0);
443 put_page(page);
444 get_page(newpage);
445
446 bh = head;
447 do {
448 set_bh_page(bh, newpage, bh_offset(bh));
449 bh = bh->b_this_page;
450
451 } while (bh != head);
452
453 SetPagePrivate(newpage);
454
455 migrate_page_copy(newpage, page);
456
457 bh = head;
458 do {
459 unlock_buffer(bh);
460 put_bh(bh);
461 bh = bh->b_this_page;
462
463 } while (bh != head);
464
465 return 0;
466}
467EXPORT_SYMBOL(buffer_migrate_page);
9361401e 468#endif
1d8b85cc 469
04e62a29
CL
470/*
471 * Writeback a page to clean the dirty state
472 */
473static int writeout(struct address_space *mapping, struct page *page)
8351a6e4 474{
04e62a29
CL
475 struct writeback_control wbc = {
476 .sync_mode = WB_SYNC_NONE,
477 .nr_to_write = 1,
478 .range_start = 0,
479 .range_end = LLONG_MAX,
480 .nonblocking = 1,
481 .for_reclaim = 1
482 };
483 int rc;
484
485 if (!mapping->a_ops->writepage)
486 /* No write method for the address space */
487 return -EINVAL;
488
489 if (!clear_page_dirty_for_io(page))
490 /* Someone else already triggered a write */
491 return -EAGAIN;
492
8351a6e4 493 /*
04e62a29
CL
494 * A dirty page may imply that the underlying filesystem has
495 * the page on some queue. So the page must be clean for
496 * migration. Writeout may mean we loose the lock and the
497 * page state is no longer what we checked for earlier.
498 * At this point we know that the migration attempt cannot
499 * be successful.
8351a6e4 500 */
04e62a29 501 remove_migration_ptes(page, page);
8351a6e4 502
04e62a29 503 rc = mapping->a_ops->writepage(page, &wbc);
8351a6e4 504
04e62a29
CL
505 if (rc != AOP_WRITEPAGE_ACTIVATE)
506 /* unlocked. Relock */
507 lock_page(page);
508
bda8550d 509 return (rc < 0) ? -EIO : -EAGAIN;
04e62a29
CL
510}
511
512/*
513 * Default handling if a filesystem does not provide a migration function.
514 */
515static int fallback_migrate_page(struct address_space *mapping,
516 struct page *newpage, struct page *page)
517{
518 if (PageDirty(page))
519 return writeout(mapping, page);
8351a6e4
CL
520
521 /*
522 * Buffers may be managed in a filesystem specific way.
523 * We must have no buffers or drop them.
524 */
b398f6bf 525 if (PagePrivate(page) &&
8351a6e4
CL
526 !try_to_release_page(page, GFP_KERNEL))
527 return -EAGAIN;
528
529 return migrate_page(mapping, newpage, page);
530}
531
e24f0b8f
CL
532/*
533 * Move a page to a newly allocated page
534 * The page is locked and all ptes have been successfully removed.
535 *
536 * The new page will have replaced the old page if this function
537 * is successful.
894bc310
LS
538 *
539 * Return value:
540 * < 0 - error code
541 * == 0 - success
e24f0b8f
CL
542 */
543static int move_to_new_page(struct page *newpage, struct page *page)
544{
545 struct address_space *mapping;
546 int rc;
547
548 /*
549 * Block others from accessing the page when we get around to
550 * establishing additional references. We are the only one
551 * holding a reference to the new page at this point.
552 */
529ae9aa 553 if (!trylock_page(newpage))
e24f0b8f
CL
554 BUG();
555
556 /* Prepare mapping for the new page.*/
557 newpage->index = page->index;
558 newpage->mapping = page->mapping;
b2e18538
RR
559 if (PageSwapBacked(page))
560 SetPageSwapBacked(newpage);
e24f0b8f
CL
561
562 mapping = page_mapping(page);
563 if (!mapping)
564 rc = migrate_page(mapping, newpage, page);
565 else if (mapping->a_ops->migratepage)
566 /*
567 * Most pages have a mapping and most filesystems
568 * should provide a migration function. Anonymous
569 * pages are part of swap space which also has its
570 * own migration function. This is the most common
571 * path for page migration.
572 */
573 rc = mapping->a_ops->migratepage(mapping,
574 newpage, page);
575 else
576 rc = fallback_migrate_page(mapping, newpage, page);
577
ae41be37 578 if (!rc) {
e24f0b8f 579 remove_migration_ptes(page, newpage);
ae41be37 580 } else
e24f0b8f
CL
581 newpage->mapping = NULL;
582
583 unlock_page(newpage);
584
585 return rc;
586}
587
588/*
589 * Obtain the lock on page, remove all ptes and migrate the page
590 * to the newly allocated page in newpage.
591 */
95a402c3
CL
592static int unmap_and_move(new_page_t get_new_page, unsigned long private,
593 struct page *page, int force)
e24f0b8f
CL
594{
595 int rc = 0;
742755a1
CL
596 int *result = NULL;
597 struct page *newpage = get_new_page(page, private, &result);
989f89c5 598 int rcu_locked = 0;
ae41be37 599 int charge = 0;
01b1ae63 600 struct mem_cgroup *mem;
95a402c3
CL
601
602 if (!newpage)
603 return -ENOMEM;
e24f0b8f 604
894bc310 605 if (page_count(page) == 1) {
e24f0b8f 606 /* page was freed from under us. So we are done. */
95a402c3 607 goto move_newpage;
894bc310 608 }
e24f0b8f 609
e8589cc1 610 /* prepare cgroup just returns 0 or -ENOMEM */
e24f0b8f 611 rc = -EAGAIN;
01b1ae63 612
529ae9aa 613 if (!trylock_page(page)) {
e24f0b8f 614 if (!force)
95a402c3 615 goto move_newpage;
e24f0b8f
CL
616 lock_page(page);
617 }
618
01b1ae63
KH
619 /* charge against new page */
620 charge = mem_cgroup_prepare_migration(page, &mem);
621 if (charge == -ENOMEM) {
622 rc = -ENOMEM;
623 goto unlock;
624 }
625 BUG_ON(charge);
626
e24f0b8f
CL
627 if (PageWriteback(page)) {
628 if (!force)
01b1ae63 629 goto uncharge;
e24f0b8f
CL
630 wait_on_page_writeback(page);
631 }
e24f0b8f 632 /*
dc386d4d
KH
633 * By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
634 * we cannot notice that anon_vma is freed while we migrates a page.
635 * This rcu_read_lock() delays freeing anon_vma pointer until the end
636 * of migration. File cache pages are no problem because of page_lock()
989f89c5
KH
637 * File Caches may use write_page() or lock_page() in migration, then,
638 * just care Anon page here.
dc386d4d 639 */
989f89c5
KH
640 if (PageAnon(page)) {
641 rcu_read_lock();
642 rcu_locked = 1;
643 }
62e1c553 644
dc386d4d 645 /*
62e1c553
SL
646 * Corner case handling:
647 * 1. When a new swap-cache page is read into, it is added to the LRU
648 * and treated as swapcache but it has no rmap yet.
649 * Calling try_to_unmap() against a page->mapping==NULL page will
650 * trigger a BUG. So handle it here.
651 * 2. An orphaned page (see truncate_complete_page) might have
652 * fs-private metadata. The page can be picked up due to memory
653 * offlining. Everywhere else except page reclaim, the page is
654 * invisible to the vm, so the page can not be migrated. So try to
655 * free the metadata, so the page can be freed.
e24f0b8f 656 */
62e1c553
SL
657 if (!page->mapping) {
658 if (!PageAnon(page) && PagePrivate(page)) {
659 /*
660 * Go direct to try_to_free_buffers() here because
661 * a) that's what try_to_release_page() would do anyway
662 * b) we may be under rcu_read_lock() here, so we can't
663 * use GFP_KERNEL which is what try_to_release_page()
664 * needs to be effective.
665 */
666 try_to_free_buffers(page);
667 }
dc386d4d 668 goto rcu_unlock;
62e1c553
SL
669 }
670
dc386d4d 671 /* Establish migration ptes or remove ptes */
e6a1530d 672 try_to_unmap(page, 1);
dc386d4d 673
e6a1530d
CL
674 if (!page_mapped(page))
675 rc = move_to_new_page(newpage, page);
e24f0b8f 676
e8589cc1 677 if (rc)
e24f0b8f 678 remove_migration_ptes(page, page);
dc386d4d 679rcu_unlock:
989f89c5
KH
680 if (rcu_locked)
681 rcu_read_unlock();
01b1ae63
KH
682uncharge:
683 if (!charge)
684 mem_cgroup_end_migration(mem, page, newpage);
e24f0b8f
CL
685unlock:
686 unlock_page(page);
95a402c3 687
e24f0b8f 688 if (rc != -EAGAIN) {
aaa994b3
CL
689 /*
690 * A page that has been migrated has all references
691 * removed and will be freed. A page that has not been
692 * migrated will have kepts its references and be
693 * restored.
694 */
695 list_del(&page->lru);
894bc310 696 putback_lru_page(page);
e24f0b8f 697 }
95a402c3
CL
698
699move_newpage:
894bc310 700
95a402c3
CL
701 /*
702 * Move the new page to the LRU. If migration was not successful
703 * then this will free the page.
704 */
894bc310
LS
705 putback_lru_page(newpage);
706
742755a1
CL
707 if (result) {
708 if (rc)
709 *result = rc;
710 else
711 *result = page_to_nid(newpage);
712 }
e24f0b8f
CL
713 return rc;
714}
715
b20a3503
CL
716/*
717 * migrate_pages
718 *
95a402c3
CL
719 * The function takes one list of pages to migrate and a function
720 * that determines from the page to be migrated and the private data
721 * the target of the move and allocates the page.
b20a3503
CL
722 *
723 * The function returns after 10 attempts or if no pages
724 * are movable anymore because to has become empty
aaa994b3 725 * or no retryable pages exist anymore. All pages will be
e9534b3f 726 * returned to the LRU or freed.
b20a3503 727 *
95a402c3 728 * Return: Number of pages not migrated or error code.
b20a3503 729 */
95a402c3
CL
730int migrate_pages(struct list_head *from,
731 new_page_t get_new_page, unsigned long private)
b20a3503 732{
e24f0b8f 733 int retry = 1;
b20a3503
CL
734 int nr_failed = 0;
735 int pass = 0;
736 struct page *page;
737 struct page *page2;
738 int swapwrite = current->flags & PF_SWAPWRITE;
739 int rc;
740
741 if (!swapwrite)
742 current->flags |= PF_SWAPWRITE;
743
e24f0b8f
CL
744 for(pass = 0; pass < 10 && retry; pass++) {
745 retry = 0;
b20a3503 746
e24f0b8f 747 list_for_each_entry_safe(page, page2, from, lru) {
e24f0b8f 748 cond_resched();
2d1db3b1 749
95a402c3
CL
750 rc = unmap_and_move(get_new_page, private,
751 page, pass > 2);
2d1db3b1 752
e24f0b8f 753 switch(rc) {
95a402c3
CL
754 case -ENOMEM:
755 goto out;
e24f0b8f 756 case -EAGAIN:
2d1db3b1 757 retry++;
e24f0b8f
CL
758 break;
759 case 0:
e24f0b8f
CL
760 break;
761 default:
2d1db3b1 762 /* Permanent failure */
2d1db3b1 763 nr_failed++;
e24f0b8f 764 break;
2d1db3b1 765 }
b20a3503
CL
766 }
767 }
95a402c3
CL
768 rc = 0;
769out:
b20a3503
CL
770 if (!swapwrite)
771 current->flags &= ~PF_SWAPWRITE;
772
aaa994b3 773 putback_lru_pages(from);
b20a3503 774
95a402c3
CL
775 if (rc)
776 return rc;
b20a3503 777
95a402c3 778 return nr_failed + retry;
b20a3503 779}
95a402c3 780
742755a1
CL
781#ifdef CONFIG_NUMA
782/*
783 * Move a list of individual pages
784 */
785struct page_to_node {
786 unsigned long addr;
787 struct page *page;
788 int node;
789 int status;
790};
791
792static struct page *new_page_node(struct page *p, unsigned long private,
793 int **result)
794{
795 struct page_to_node *pm = (struct page_to_node *)private;
796
797 while (pm->node != MAX_NUMNODES && pm->page != p)
798 pm++;
799
800 if (pm->node == MAX_NUMNODES)
801 return NULL;
802
803 *result = &pm->status;
804
769848c0
MG
805 return alloc_pages_node(pm->node,
806 GFP_HIGHUSER_MOVABLE | GFP_THISNODE, 0);
742755a1
CL
807}
808
809/*
810 * Move a set of pages as indicated in the pm array. The addr
811 * field must be set to the virtual address of the page to be moved
812 * and the node number must contain a valid target node.
5e9a0f02 813 * The pm array ends with node = MAX_NUMNODES.
742755a1 814 */
5e9a0f02
BG
815static int do_move_page_to_node_array(struct mm_struct *mm,
816 struct page_to_node *pm,
817 int migrate_all)
742755a1
CL
818{
819 int err;
820 struct page_to_node *pp;
821 LIST_HEAD(pagelist);
822
0aedadf9 823 migrate_prep();
742755a1
CL
824 down_read(&mm->mmap_sem);
825
826 /*
827 * Build a list of pages to migrate
828 */
742755a1
CL
829 for (pp = pm; pp->node != MAX_NUMNODES; pp++) {
830 struct vm_area_struct *vma;
831 struct page *page;
832
742755a1
CL
833 err = -EFAULT;
834 vma = find_vma(mm, pp->addr);
0dc952dc 835 if (!vma || !vma_migratable(vma))
742755a1
CL
836 goto set_status;
837
838 page = follow_page(vma, pp->addr, FOLL_GET);
89f5b7da
LT
839
840 err = PTR_ERR(page);
841 if (IS_ERR(page))
842 goto set_status;
843
742755a1
CL
844 err = -ENOENT;
845 if (!page)
846 goto set_status;
847
848 if (PageReserved(page)) /* Check for zero page */
849 goto put_and_set;
850
851 pp->page = page;
852 err = page_to_nid(page);
853
854 if (err == pp->node)
855 /*
856 * Node already in the right place
857 */
858 goto put_and_set;
859
860 err = -EACCES;
861 if (page_mapcount(page) > 1 &&
862 !migrate_all)
863 goto put_and_set;
864
62695a84
NP
865 err = isolate_lru_page(page);
866 if (!err)
867 list_add_tail(&page->lru, &pagelist);
742755a1
CL
868put_and_set:
869 /*
870 * Either remove the duplicate refcount from
871 * isolate_lru_page() or drop the page ref if it was
872 * not isolated.
873 */
874 put_page(page);
875set_status:
876 pp->status = err;
877 }
878
e78bbfa8 879 err = 0;
742755a1
CL
880 if (!list_empty(&pagelist))
881 err = migrate_pages(&pagelist, new_page_node,
882 (unsigned long)pm);
742755a1
CL
883
884 up_read(&mm->mmap_sem);
885 return err;
886}
887
5e9a0f02
BG
888/*
889 * Migrate an array of page address onto an array of nodes and fill
890 * the corresponding array of status.
891 */
892static int do_pages_move(struct mm_struct *mm, struct task_struct *task,
893 unsigned long nr_pages,
894 const void __user * __user *pages,
895 const int __user *nodes,
896 int __user *status, int flags)
897{
3140a227 898 struct page_to_node *pm;
5e9a0f02 899 nodemask_t task_nodes;
3140a227
BG
900 unsigned long chunk_nr_pages;
901 unsigned long chunk_start;
902 int err;
5e9a0f02
BG
903
904 task_nodes = cpuset_mems_allowed(task);
905
3140a227
BG
906 err = -ENOMEM;
907 pm = (struct page_to_node *)__get_free_page(GFP_KERNEL);
908 if (!pm)
5e9a0f02 909 goto out;
5e9a0f02 910 /*
3140a227
BG
911 * Store a chunk of page_to_node array in a page,
912 * but keep the last one as a marker
5e9a0f02 913 */
3140a227 914 chunk_nr_pages = (PAGE_SIZE / sizeof(struct page_to_node)) - 1;
5e9a0f02 915
3140a227
BG
916 for (chunk_start = 0;
917 chunk_start < nr_pages;
918 chunk_start += chunk_nr_pages) {
919 int j;
5e9a0f02 920
3140a227
BG
921 if (chunk_start + chunk_nr_pages > nr_pages)
922 chunk_nr_pages = nr_pages - chunk_start;
923
924 /* fill the chunk pm with addrs and nodes from user-space */
925 for (j = 0; j < chunk_nr_pages; j++) {
926 const void __user *p;
5e9a0f02
BG
927 int node;
928
3140a227
BG
929 err = -EFAULT;
930 if (get_user(p, pages + j + chunk_start))
931 goto out_pm;
932 pm[j].addr = (unsigned long) p;
933
934 if (get_user(node, nodes + j + chunk_start))
5e9a0f02
BG
935 goto out_pm;
936
937 err = -ENODEV;
938 if (!node_state(node, N_HIGH_MEMORY))
939 goto out_pm;
940
941 err = -EACCES;
942 if (!node_isset(node, task_nodes))
943 goto out_pm;
944
3140a227
BG
945 pm[j].node = node;
946 }
947
948 /* End marker for this chunk */
949 pm[chunk_nr_pages].node = MAX_NUMNODES;
950
951 /* Migrate this chunk */
952 err = do_move_page_to_node_array(mm, pm,
953 flags & MPOL_MF_MOVE_ALL);
954 if (err < 0)
955 goto out_pm;
5e9a0f02 956
5e9a0f02 957 /* Return status information */
3140a227
BG
958 for (j = 0; j < chunk_nr_pages; j++)
959 if (put_user(pm[j].status, status + j + chunk_start)) {
5e9a0f02 960 err = -EFAULT;
3140a227
BG
961 goto out_pm;
962 }
963 }
964 err = 0;
5e9a0f02
BG
965
966out_pm:
3140a227 967 free_page((unsigned long)pm);
5e9a0f02
BG
968out:
969 return err;
970}
971
742755a1 972/*
2f007e74 973 * Determine the nodes of an array of pages and store it in an array of status.
742755a1 974 */
80bba129
BG
975static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
976 const void __user **pages, int *status)
742755a1 977{
2f007e74 978 unsigned long i;
2f007e74 979
742755a1
CL
980 down_read(&mm->mmap_sem);
981
2f007e74 982 for (i = 0; i < nr_pages; i++) {
80bba129 983 unsigned long addr = (unsigned long)(*pages);
742755a1
CL
984 struct vm_area_struct *vma;
985 struct page *page;
c095adbc 986 int err = -EFAULT;
2f007e74
BG
987
988 vma = find_vma(mm, addr);
742755a1
CL
989 if (!vma)
990 goto set_status;
991
2f007e74 992 page = follow_page(vma, addr, 0);
89f5b7da
LT
993
994 err = PTR_ERR(page);
995 if (IS_ERR(page))
996 goto set_status;
997
742755a1
CL
998 err = -ENOENT;
999 /* Use PageReserved to check for zero page */
1000 if (!page || PageReserved(page))
1001 goto set_status;
1002
1003 err = page_to_nid(page);
1004set_status:
80bba129
BG
1005 *status = err;
1006
1007 pages++;
1008 status++;
1009 }
1010
1011 up_read(&mm->mmap_sem);
1012}
1013
1014/*
1015 * Determine the nodes of a user array of pages and store it in
1016 * a user array of status.
1017 */
1018static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages,
1019 const void __user * __user *pages,
1020 int __user *status)
1021{
1022#define DO_PAGES_STAT_CHUNK_NR 16
1023 const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR];
1024 int chunk_status[DO_PAGES_STAT_CHUNK_NR];
1025 unsigned long i, chunk_nr = DO_PAGES_STAT_CHUNK_NR;
1026 int err;
1027
1028 for (i = 0; i < nr_pages; i += chunk_nr) {
1029 if (chunk_nr + i > nr_pages)
1030 chunk_nr = nr_pages - i;
1031
1032 err = copy_from_user(chunk_pages, &pages[i],
1033 chunk_nr * sizeof(*chunk_pages));
1034 if (err) {
1035 err = -EFAULT;
1036 goto out;
1037 }
1038
1039 do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status);
1040
1041 err = copy_to_user(&status[i], chunk_status,
1042 chunk_nr * sizeof(*chunk_status));
1043 if (err) {
1044 err = -EFAULT;
1045 goto out;
1046 }
742755a1 1047 }
2f007e74 1048 err = 0;
742755a1 1049
2f007e74 1050out:
2f007e74 1051 return err;
742755a1
CL
1052}
1053
1054/*
1055 * Move a list of pages in the address space of the currently executing
1056 * process.
1057 */
938bb9f5
HC
1058SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,
1059 const void __user * __user *, pages,
1060 const int __user *, nodes,
1061 int __user *, status, int, flags)
742755a1 1062{
c69e8d9c 1063 const struct cred *cred = current_cred(), *tcred;
742755a1 1064 struct task_struct *task;
742755a1 1065 struct mm_struct *mm;
5e9a0f02 1066 int err;
742755a1
CL
1067
1068 /* Check flags */
1069 if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
1070 return -EINVAL;
1071
1072 if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
1073 return -EPERM;
1074
1075 /* Find the mm_struct */
1076 read_lock(&tasklist_lock);
228ebcbe 1077 task = pid ? find_task_by_vpid(pid) : current;
742755a1
CL
1078 if (!task) {
1079 read_unlock(&tasklist_lock);
1080 return -ESRCH;
1081 }
1082 mm = get_task_mm(task);
1083 read_unlock(&tasklist_lock);
1084
1085 if (!mm)
1086 return -EINVAL;
1087
1088 /*
1089 * Check if this process has the right to modify the specified
1090 * process. The right exists if the process has administrative
1091 * capabilities, superuser privileges or the same
1092 * userid as the target process.
1093 */
c69e8d9c
DH
1094 rcu_read_lock();
1095 tcred = __task_cred(task);
b6dff3ec
DH
1096 if (cred->euid != tcred->suid && cred->euid != tcred->uid &&
1097 cred->uid != tcred->suid && cred->uid != tcred->uid &&
742755a1 1098 !capable(CAP_SYS_NICE)) {
c69e8d9c 1099 rcu_read_unlock();
742755a1 1100 err = -EPERM;
5e9a0f02 1101 goto out;
742755a1 1102 }
c69e8d9c 1103 rcu_read_unlock();
742755a1 1104
86c3a764
DQ
1105 err = security_task_movememory(task);
1106 if (err)
5e9a0f02 1107 goto out;
86c3a764 1108
5e9a0f02
BG
1109 if (nodes) {
1110 err = do_pages_move(mm, task, nr_pages, pages, nodes, status,
1111 flags);
1112 } else {
2f007e74 1113 err = do_pages_stat(mm, nr_pages, pages, status);
742755a1
CL
1114 }
1115
742755a1 1116out:
742755a1
CL
1117 mmput(mm);
1118 return err;
1119}
742755a1 1120
7b2259b3
CL
1121/*
1122 * Call migration functions in the vma_ops that may prepare
1123 * memory in a vm for migration. migration functions may perform
1124 * the migration for vmas that do not have an underlying page struct.
1125 */
1126int migrate_vmas(struct mm_struct *mm, const nodemask_t *to,
1127 const nodemask_t *from, unsigned long flags)
1128{
1129 struct vm_area_struct *vma;
1130 int err = 0;
1131
1001c9fb 1132 for (vma = mm->mmap; vma && !err; vma = vma->vm_next) {
7b2259b3
CL
1133 if (vma->vm_ops && vma->vm_ops->migrate) {
1134 err = vma->vm_ops->migrate(vma, to, from, flags);
1135 if (err)
1136 break;
1137 }
1138 }
1139 return err;
1140}
83d1674a 1141#endif