2 * Memory Migration functionality - linux/mm/migration.c
4 * Copyright (C) 2006 Silicon Graphics, Inc., Christoph Lameter
6 * Page migration was first developed in the context of the memory hotplug
7 * project. The main authors of the migration code are:
9 * IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
10 * Hirokazu Takahashi <taka@valinux.co.jp>
11 * Dave Hansen <haveblue@us.ibm.com>
15 #include <linux/migrate.h>
16 #include <linux/module.h>
17 #include <linux/swap.h>
18 #include <linux/swapops.h>
19 #include <linux/pagemap.h>
20 #include <linux/buffer_head.h>
21 #include <linux/mm_inline.h>
22 #include <linux/nsproxy.h>
23 #include <linux/pagevec.h>
24 #include <linux/ksm.h>
25 #include <linux/rmap.h>
26 #include <linux/topology.h>
27 #include <linux/cpu.h>
28 #include <linux/cpuset.h>
29 #include <linux/writeback.h>
30 #include <linux/mempolicy.h>
31 #include <linux/vmalloc.h>
32 #include <linux/security.h>
33 #include <linux/memcontrol.h>
34 #include <linux/syscalls.h>
35 #include <linux/hugetlb.h>
36 #include <linux/gfp.h>
40 #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
43 * migrate_prep() needs to be called before we start compiling a list of pages
44 * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is
45 * undesirable, use migrate_prep_local()
47 int migrate_prep(void)
50 * Clear the LRU lists so pages can be isolated.
51 * Note that pages may be moved off the LRU after we have
52 * drained them. Those pages will fail to migrate like other
53 * pages that may be busy.
60 /* Do the necessary work of migrate_prep but not if it involves other CPUs */
61 int migrate_prep_local(void)
69 * Add isolated pages on the list back to the LRU under page lock
70 * to avoid leaking evictable pages back onto unevictable list.
72 void putback_lru_pages(struct list_head
*l
)
77 list_for_each_entry_safe(page
, page2
, l
, lru
) {
79 dec_zone_page_state(page
, NR_ISOLATED_ANON
+
80 page_is_file_cache(page
));
81 putback_lru_page(page
);
86 * Restore a potential migration pte to a working pte entry
88 static int remove_migration_pte(struct page
*new, struct vm_area_struct
*vma
,
89 unsigned long addr
, void *old
)
91 struct mm_struct
*mm
= vma
->vm_mm
;
99 if (unlikely(PageHuge(new))) {
100 ptep
= huge_pte_offset(mm
, addr
);
103 ptl
= &mm
->page_table_lock
;
105 pgd
= pgd_offset(mm
, addr
);
106 if (!pgd_present(*pgd
))
109 pud
= pud_offset(pgd
, addr
);
110 if (!pud_present(*pud
))
113 pmd
= pmd_offset(pud
, addr
);
114 if (!pmd_present(*pmd
))
117 ptep
= pte_offset_map(pmd
, addr
);
119 if (!is_swap_pte(*ptep
)) {
124 ptl
= pte_lockptr(mm
, pmd
);
129 if (!is_swap_pte(pte
))
132 entry
= pte_to_swp_entry(pte
);
134 if (!is_migration_entry(entry
) ||
135 migration_entry_to_page(entry
) != old
)
139 pte
= pte_mkold(mk_pte(new, vma
->vm_page_prot
));
140 if (is_write_migration_entry(entry
))
141 pte
= pte_mkwrite(pte
);
143 pte
= pte_mkhuge(pte
);
144 flush_cache_page(vma
, addr
, pte_pfn(pte
));
145 set_pte_at(mm
, addr
, ptep
, pte
);
149 hugepage_add_anon_rmap(new, vma
, addr
);
152 } else if (PageAnon(new))
153 page_add_anon_rmap(new, vma
, addr
);
155 page_add_file_rmap(new);
157 /* No need to invalidate - it was non-present before */
158 update_mmu_cache(vma
, addr
, ptep
);
160 pte_unmap_unlock(ptep
, ptl
);
166 * Get rid of all migration entries and replace them by
167 * references to the indicated page.
169 static void remove_migration_ptes(struct page
*old
, struct page
*new)
171 rmap_walk(new, remove_migration_pte
, old
);
175 * Something used the pte of a page under migration. We need to
176 * get to the page and wait until migration is finished.
177 * When we return from this function the fault will be retried.
179 * This function is called from do_swap_page().
181 void migration_entry_wait(struct mm_struct
*mm
, pmd_t
*pmd
,
182 unsigned long address
)
189 ptep
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
191 if (!is_swap_pte(pte
))
194 entry
= pte_to_swp_entry(pte
);
195 if (!is_migration_entry(entry
))
198 page
= migration_entry_to_page(entry
);
201 * Once radix-tree replacement of page migration started, page_count
202 * *must* be zero. And, we don't want to call wait_on_page_locked()
203 * against a page without get_page().
204 * So, we use get_page_unless_zero(), here. Even failed, page fault
207 if (!get_page_unless_zero(page
))
209 pte_unmap_unlock(ptep
, ptl
);
210 wait_on_page_locked(page
);
214 pte_unmap_unlock(ptep
, ptl
);
218 * Replace the page in the mapping.
220 * The number of remaining references must be:
221 * 1 for anonymous pages without a mapping
222 * 2 for pages with a mapping
223 * 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
225 static int migrate_page_move_mapping(struct address_space
*mapping
,
226 struct page
*newpage
, struct page
*page
)
232 /* Anonymous page without mapping */
233 if (page_count(page
) != 1)
238 spin_lock_irq(&mapping
->tree_lock
);
240 pslot
= radix_tree_lookup_slot(&mapping
->page_tree
,
243 expected_count
= 2 + page_has_private(page
);
244 if (page_count(page
) != expected_count
||
245 (struct page
*)radix_tree_deref_slot(pslot
) != page
) {
246 spin_unlock_irq(&mapping
->tree_lock
);
250 if (!page_freeze_refs(page
, expected_count
)) {
251 spin_unlock_irq(&mapping
->tree_lock
);
256 * Now we know that no one else is looking at the page.
258 get_page(newpage
); /* add cache reference */
259 if (PageSwapCache(page
)) {
260 SetPageSwapCache(newpage
);
261 set_page_private(newpage
, page_private(page
));
264 radix_tree_replace_slot(pslot
, newpage
);
266 page_unfreeze_refs(page
, expected_count
);
268 * Drop cache reference from old page.
269 * We know this isn't the last reference.
274 * If moved to a different zone then also account
275 * the page for that zone. Other VM counters will be
276 * taken care of when we establish references to the
277 * new page and drop references to the old page.
279 * Note that anonymous pages are accounted for
280 * via NR_FILE_PAGES and NR_ANON_PAGES if they
281 * are mapped to swap space.
283 __dec_zone_page_state(page
, NR_FILE_PAGES
);
284 __inc_zone_page_state(newpage
, NR_FILE_PAGES
);
285 if (PageSwapBacked(page
)) {
286 __dec_zone_page_state(page
, NR_SHMEM
);
287 __inc_zone_page_state(newpage
, NR_SHMEM
);
289 spin_unlock_irq(&mapping
->tree_lock
);
295 * The expected number of remaining references is the same as that
296 * of migrate_page_move_mapping().
298 int migrate_huge_page_move_mapping(struct address_space
*mapping
,
299 struct page
*newpage
, struct page
*page
)
305 if (page_count(page
) != 1)
310 spin_lock_irq(&mapping
->tree_lock
);
312 pslot
= radix_tree_lookup_slot(&mapping
->page_tree
,
315 expected_count
= 2 + page_has_private(page
);
316 if (page_count(page
) != expected_count
||
317 (struct page
*)radix_tree_deref_slot(pslot
) != page
) {
318 spin_unlock_irq(&mapping
->tree_lock
);
322 if (!page_freeze_refs(page
, expected_count
)) {
323 spin_unlock_irq(&mapping
->tree_lock
);
329 radix_tree_replace_slot(pslot
, newpage
);
331 page_unfreeze_refs(page
, expected_count
);
335 spin_unlock_irq(&mapping
->tree_lock
);
340 * Copy the page to its new location
342 void migrate_page_copy(struct page
*newpage
, struct page
*page
)
345 copy_huge_page(newpage
, page
);
347 copy_highpage(newpage
, page
);
350 SetPageError(newpage
);
351 if (PageReferenced(page
))
352 SetPageReferenced(newpage
);
353 if (PageUptodate(page
))
354 SetPageUptodate(newpage
);
355 if (TestClearPageActive(page
)) {
356 VM_BUG_ON(PageUnevictable(page
));
357 SetPageActive(newpage
);
358 } else if (TestClearPageUnevictable(page
))
359 SetPageUnevictable(newpage
);
360 if (PageChecked(page
))
361 SetPageChecked(newpage
);
362 if (PageMappedToDisk(page
))
363 SetPageMappedToDisk(newpage
);
365 if (PageDirty(page
)) {
366 clear_page_dirty_for_io(page
);
368 * Want to mark the page and the radix tree as dirty, and
369 * redo the accounting that clear_page_dirty_for_io undid,
370 * but we can't use set_page_dirty because that function
371 * is actually a signal that all of the page has become dirty.
372 * Wheras only part of our page may be dirty.
374 __set_page_dirty_nobuffers(newpage
);
377 mlock_migrate_page(newpage
, page
);
378 ksm_migrate_page(newpage
, page
);
380 ClearPageSwapCache(page
);
381 ClearPagePrivate(page
);
382 set_page_private(page
, 0);
383 page
->mapping
= NULL
;
386 * If any waiters have accumulated on the new page then
389 if (PageWriteback(newpage
))
390 end_page_writeback(newpage
);
393 /************************************************************
394 * Migration functions
395 ***********************************************************/
397 /* Always fail migration. Used for mappings that are not movable */
398 int fail_migrate_page(struct address_space
*mapping
,
399 struct page
*newpage
, struct page
*page
)
403 EXPORT_SYMBOL(fail_migrate_page
);
406 * Common logic to directly migrate a single page suitable for
407 * pages that do not use PagePrivate/PagePrivate2.
409 * Pages are locked upon entry and exit.
411 int migrate_page(struct address_space
*mapping
,
412 struct page
*newpage
, struct page
*page
)
416 BUG_ON(PageWriteback(page
)); /* Writeback must be complete */
418 rc
= migrate_page_move_mapping(mapping
, newpage
, page
);
423 migrate_page_copy(newpage
, page
);
426 EXPORT_SYMBOL(migrate_page
);
430 * Migration function for pages with buffers. This function can only be used
431 * if the underlying filesystem guarantees that no other references to "page"
434 int buffer_migrate_page(struct address_space
*mapping
,
435 struct page
*newpage
, struct page
*page
)
437 struct buffer_head
*bh
, *head
;
440 if (!page_has_buffers(page
))
441 return migrate_page(mapping
, newpage
, page
);
443 head
= page_buffers(page
);
445 rc
= migrate_page_move_mapping(mapping
, newpage
, page
);
454 bh
= bh
->b_this_page
;
456 } while (bh
!= head
);
458 ClearPagePrivate(page
);
459 set_page_private(newpage
, page_private(page
));
460 set_page_private(page
, 0);
466 set_bh_page(bh
, newpage
, bh_offset(bh
));
467 bh
= bh
->b_this_page
;
469 } while (bh
!= head
);
471 SetPagePrivate(newpage
);
473 migrate_page_copy(newpage
, page
);
479 bh
= bh
->b_this_page
;
481 } while (bh
!= head
);
485 EXPORT_SYMBOL(buffer_migrate_page
);
489 * Writeback a page to clean the dirty state
491 static int writeout(struct address_space
*mapping
, struct page
*page
)
493 struct writeback_control wbc
= {
494 .sync_mode
= WB_SYNC_NONE
,
497 .range_end
= LLONG_MAX
,
503 if (!mapping
->a_ops
->writepage
)
504 /* No write method for the address space */
507 if (!clear_page_dirty_for_io(page
))
508 /* Someone else already triggered a write */
512 * A dirty page may imply that the underlying filesystem has
513 * the page on some queue. So the page must be clean for
514 * migration. Writeout may mean we loose the lock and the
515 * page state is no longer what we checked for earlier.
516 * At this point we know that the migration attempt cannot
519 remove_migration_ptes(page
, page
);
521 rc
= mapping
->a_ops
->writepage(page
, &wbc
);
523 if (rc
!= AOP_WRITEPAGE_ACTIVATE
)
524 /* unlocked. Relock */
527 return (rc
< 0) ? -EIO
: -EAGAIN
;
531 * Default handling if a filesystem does not provide a migration function.
533 static int fallback_migrate_page(struct address_space
*mapping
,
534 struct page
*newpage
, struct page
*page
)
537 return writeout(mapping
, page
);
540 * Buffers may be managed in a filesystem specific way.
541 * We must have no buffers or drop them.
543 if (page_has_private(page
) &&
544 !try_to_release_page(page
, GFP_KERNEL
))
547 return migrate_page(mapping
, newpage
, page
);
551 * Move a page to a newly allocated page
552 * The page is locked and all ptes have been successfully removed.
554 * The new page will have replaced the old page if this function
561 static int move_to_new_page(struct page
*newpage
, struct page
*page
,
564 struct address_space
*mapping
;
568 * Block others from accessing the page when we get around to
569 * establishing additional references. We are the only one
570 * holding a reference to the new page at this point.
572 if (!trylock_page(newpage
))
575 /* Prepare mapping for the new page.*/
576 newpage
->index
= page
->index
;
577 newpage
->mapping
= page
->mapping
;
578 if (PageSwapBacked(page
))
579 SetPageSwapBacked(newpage
);
581 mapping
= page_mapping(page
);
583 rc
= migrate_page(mapping
, newpage
, page
);
584 else if (mapping
->a_ops
->migratepage
)
586 * Most pages have a mapping and most filesystems
587 * should provide a migration function. Anonymous
588 * pages are part of swap space which also has its
589 * own migration function. This is the most common
590 * path for page migration.
592 rc
= mapping
->a_ops
->migratepage(mapping
,
595 rc
= fallback_migrate_page(mapping
, newpage
, page
);
598 newpage
->mapping
= NULL
;
601 remove_migration_ptes(page
, newpage
);
604 unlock_page(newpage
);
610 * Obtain the lock on page, remove all ptes and migrate the page
611 * to the newly allocated page in newpage.
613 static int unmap_and_move(new_page_t get_new_page
, unsigned long private,
614 struct page
*page
, int force
, int offlining
)
618 struct page
*newpage
= get_new_page(page
, private, &result
);
619 int remap_swapcache
= 1;
622 struct mem_cgroup
*mem
= NULL
;
623 struct anon_vma
*anon_vma
= NULL
;
628 if (page_count(page
) == 1) {
629 /* page was freed from under us. So we are done. */
633 /* prepare cgroup just returns 0 or -ENOMEM */
636 if (!trylock_page(page
)) {
643 * Only memory hotplug's offline_pages() caller has locked out KSM,
644 * and can safely migrate a KSM page. The other cases have skipped
645 * PageKsm along with PageReserved - but it is only now when we have
646 * the page lock that we can be certain it will not go KSM beneath us
647 * (KSM will not upgrade a page from PageAnon to PageKsm when it sees
648 * its pagecount raised, but only here do we take the page lock which
651 if (PageKsm(page
) && !offlining
) {
656 /* charge against new page */
657 charge
= mem_cgroup_prepare_migration(page
, newpage
, &mem
);
658 if (charge
== -ENOMEM
) {
664 if (PageWriteback(page
)) {
667 wait_on_page_writeback(page
);
670 * By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
671 * we cannot notice that anon_vma is freed while we migrates a page.
672 * This rcu_read_lock() delays freeing anon_vma pointer until the end
673 * of migration. File cache pages are no problem because of page_lock()
674 * File Caches may use write_page() or lock_page() in migration, then,
675 * just care Anon page here.
677 if (PageAnon(page
)) {
681 /* Determine how to safely use anon_vma */
682 if (!page_mapped(page
)) {
683 if (!PageSwapCache(page
))
687 * We cannot be sure that the anon_vma of an unmapped
688 * swapcache page is safe to use because we don't
689 * know in advance if the VMA that this page belonged
690 * to still exists. If the VMA and others sharing the
691 * data have been freed, then the anon_vma could
692 * already be invalid.
694 * To avoid this possibility, swapcache pages get
695 * migrated but are not remapped when migration
701 * Take a reference count on the anon_vma if the
702 * page is mapped so that it is guaranteed to
703 * exist when the page is remapped later
705 anon_vma
= page_anon_vma(page
);
706 get_anon_vma(anon_vma
);
711 * Corner case handling:
712 * 1. When a new swap-cache page is read into, it is added to the LRU
713 * and treated as swapcache but it has no rmap yet.
714 * Calling try_to_unmap() against a page->mapping==NULL page will
715 * trigger a BUG. So handle it here.
716 * 2. An orphaned page (see truncate_complete_page) might have
717 * fs-private metadata. The page can be picked up due to memory
718 * offlining. Everywhere else except page reclaim, the page is
719 * invisible to the vm, so the page can not be migrated. So try to
720 * free the metadata, so the page can be freed.
722 if (!page
->mapping
) {
723 if (!PageAnon(page
) && page_has_private(page
)) {
725 * Go direct to try_to_free_buffers() here because
726 * a) that's what try_to_release_page() would do anyway
727 * b) we may be under rcu_read_lock() here, so we can't
728 * use GFP_KERNEL which is what try_to_release_page()
729 * needs to be effective.
731 try_to_free_buffers(page
);
737 /* Establish migration ptes or remove ptes */
738 try_to_unmap(page
, TTU_MIGRATION
|TTU_IGNORE_MLOCK
|TTU_IGNORE_ACCESS
);
741 if (!page_mapped(page
))
742 rc
= move_to_new_page(newpage
, page
, remap_swapcache
);
744 if (rc
&& remap_swapcache
)
745 remove_migration_ptes(page
, page
);
748 /* Drop an anon_vma reference if we took one */
750 drop_anon_vma(anon_vma
);
756 mem_cgroup_end_migration(mem
, page
, newpage
);
762 * A page that has been migrated has all references
763 * removed and will be freed. A page that has not been
764 * migrated will have kepts its references and be
767 list_del(&page
->lru
);
768 dec_zone_page_state(page
, NR_ISOLATED_ANON
+
769 page_is_file_cache(page
));
770 putback_lru_page(page
);
776 * Move the new page to the LRU. If migration was not successful
777 * then this will free the page.
779 putback_lru_page(newpage
);
785 *result
= page_to_nid(newpage
);
791 * Counterpart of unmap_and_move_page() for hugepage migration.
793 * This function doesn't wait the completion of hugepage I/O
794 * because there is no race between I/O and migration for hugepage.
795 * Note that currently hugepage I/O occurs only in direct I/O
796 * where no lock is held and PG_writeback is irrelevant,
797 * and writeback status of all subpages are counted in the reference
798 * count of the head page (i.e. if all subpages of a 2MB hugepage are
799 * under direct I/O, the reference of the head page is 512 and a bit more.)
800 * This means that when we try to migrate hugepage whose subpages are
801 * doing direct I/O, some references remain after try_to_unmap() and
802 * hugepage migration fails without data corruption.
804 * There is also no race when direct I/O is issued on the page under migration,
805 * because then pte is replaced with migration swap entry and direct I/O code
806 * will wait in the page fault for migration to complete.
808 static int unmap_and_move_huge_page(new_page_t get_new_page
,
809 unsigned long private, struct page
*hpage
,
810 int force
, int offlining
)
814 struct page
*new_hpage
= get_new_page(hpage
, private, &result
);
816 struct anon_vma
*anon_vma
= NULL
;
823 if (!trylock_page(hpage
)) {
829 if (PageAnon(hpage
)) {
833 if (page_mapped(hpage
)) {
834 anon_vma
= page_anon_vma(hpage
);
835 atomic_inc(&anon_vma
->external_refcount
);
839 try_to_unmap(hpage
, TTU_MIGRATION
|TTU_IGNORE_MLOCK
|TTU_IGNORE_ACCESS
);
841 if (!page_mapped(hpage
))
842 rc
= move_to_new_page(new_hpage
, hpage
, 1);
845 remove_migration_ptes(hpage
, hpage
);
847 if (anon_vma
&& atomic_dec_and_lock(&anon_vma
->external_refcount
,
849 int empty
= list_empty(&anon_vma
->head
);
850 spin_unlock(&anon_vma
->lock
);
852 anon_vma_free(anon_vma
);
861 list_del(&hpage
->lru
);
871 *result
= page_to_nid(new_hpage
);
879 * The function takes one list of pages to migrate and a function
880 * that determines from the page to be migrated and the private data
881 * the target of the move and allocates the page.
883 * The function returns after 10 attempts or if no pages
884 * are movable anymore because to has become empty
885 * or no retryable pages exist anymore. All pages will be
886 * returned to the LRU or freed.
888 * Return: Number of pages not migrated or error code.
890 int migrate_pages(struct list_head
*from
,
891 new_page_t get_new_page
, unsigned long private, int offlining
)
898 int swapwrite
= current
->flags
& PF_SWAPWRITE
;
902 current
->flags
|= PF_SWAPWRITE
;
904 for(pass
= 0; pass
< 10 && retry
; pass
++) {
907 list_for_each_entry_safe(page
, page2
, from
, lru
) {
910 rc
= unmap_and_move(get_new_page
, private,
911 page
, pass
> 2, offlining
);
922 /* Permanent failure */
931 current
->flags
&= ~PF_SWAPWRITE
;
933 putback_lru_pages(from
);
938 return nr_failed
+ retry
;
941 int migrate_huge_pages(struct list_head
*from
,
942 new_page_t get_new_page
, unsigned long private, int offlining
)
951 for (pass
= 0; pass
< 10 && retry
; pass
++) {
954 list_for_each_entry_safe(page
, page2
, from
, lru
) {
957 rc
= unmap_and_move_huge_page(get_new_page
,
958 private, page
, pass
> 2, offlining
);
969 /* Permanent failure */
978 list_for_each_entry_safe(page
, page2
, from
, lru
)
984 return nr_failed
+ retry
;
989 * Move a list of individual pages
991 struct page_to_node
{
998 static struct page
*new_page_node(struct page
*p
, unsigned long private,
1001 struct page_to_node
*pm
= (struct page_to_node
*)private;
1003 while (pm
->node
!= MAX_NUMNODES
&& pm
->page
!= p
)
1006 if (pm
->node
== MAX_NUMNODES
)
1009 *result
= &pm
->status
;
1011 return alloc_pages_exact_node(pm
->node
,
1012 GFP_HIGHUSER_MOVABLE
| GFP_THISNODE
, 0);
1016 * Move a set of pages as indicated in the pm array. The addr
1017 * field must be set to the virtual address of the page to be moved
1018 * and the node number must contain a valid target node.
1019 * The pm array ends with node = MAX_NUMNODES.
1021 static int do_move_page_to_node_array(struct mm_struct
*mm
,
1022 struct page_to_node
*pm
,
1026 struct page_to_node
*pp
;
1027 LIST_HEAD(pagelist
);
1029 down_read(&mm
->mmap_sem
);
1032 * Build a list of pages to migrate
1034 for (pp
= pm
; pp
->node
!= MAX_NUMNODES
; pp
++) {
1035 struct vm_area_struct
*vma
;
1039 vma
= find_vma(mm
, pp
->addr
);
1040 if (!vma
|| !vma_migratable(vma
))
1043 page
= follow_page(vma
, pp
->addr
, FOLL_GET
);
1045 err
= PTR_ERR(page
);
1053 /* Use PageReserved to check for zero page */
1054 if (PageReserved(page
) || PageKsm(page
))
1058 err
= page_to_nid(page
);
1060 if (err
== pp
->node
)
1062 * Node already in the right place
1067 if (page_mapcount(page
) > 1 &&
1071 err
= isolate_lru_page(page
);
1073 list_add_tail(&page
->lru
, &pagelist
);
1074 inc_zone_page_state(page
, NR_ISOLATED_ANON
+
1075 page_is_file_cache(page
));
1079 * Either remove the duplicate refcount from
1080 * isolate_lru_page() or drop the page ref if it was
1089 if (!list_empty(&pagelist
))
1090 err
= migrate_pages(&pagelist
, new_page_node
,
1091 (unsigned long)pm
, 0);
1093 up_read(&mm
->mmap_sem
);
1098 * Migrate an array of page address onto an array of nodes and fill
1099 * the corresponding array of status.
1101 static int do_pages_move(struct mm_struct
*mm
, struct task_struct
*task
,
1102 unsigned long nr_pages
,
1103 const void __user
* __user
*pages
,
1104 const int __user
*nodes
,
1105 int __user
*status
, int flags
)
1107 struct page_to_node
*pm
;
1108 nodemask_t task_nodes
;
1109 unsigned long chunk_nr_pages
;
1110 unsigned long chunk_start
;
1113 task_nodes
= cpuset_mems_allowed(task
);
1116 pm
= (struct page_to_node
*)__get_free_page(GFP_KERNEL
);
1123 * Store a chunk of page_to_node array in a page,
1124 * but keep the last one as a marker
1126 chunk_nr_pages
= (PAGE_SIZE
/ sizeof(struct page_to_node
)) - 1;
1128 for (chunk_start
= 0;
1129 chunk_start
< nr_pages
;
1130 chunk_start
+= chunk_nr_pages
) {
1133 if (chunk_start
+ chunk_nr_pages
> nr_pages
)
1134 chunk_nr_pages
= nr_pages
- chunk_start
;
1136 /* fill the chunk pm with addrs and nodes from user-space */
1137 for (j
= 0; j
< chunk_nr_pages
; j
++) {
1138 const void __user
*p
;
1142 if (get_user(p
, pages
+ j
+ chunk_start
))
1144 pm
[j
].addr
= (unsigned long) p
;
1146 if (get_user(node
, nodes
+ j
+ chunk_start
))
1150 if (node
< 0 || node
>= MAX_NUMNODES
)
1153 if (!node_state(node
, N_HIGH_MEMORY
))
1157 if (!node_isset(node
, task_nodes
))
1163 /* End marker for this chunk */
1164 pm
[chunk_nr_pages
].node
= MAX_NUMNODES
;
1166 /* Migrate this chunk */
1167 err
= do_move_page_to_node_array(mm
, pm
,
1168 flags
& MPOL_MF_MOVE_ALL
);
1172 /* Return status information */
1173 for (j
= 0; j
< chunk_nr_pages
; j
++)
1174 if (put_user(pm
[j
].status
, status
+ j
+ chunk_start
)) {
1182 free_page((unsigned long)pm
);
1188 * Determine the nodes of an array of pages and store it in an array of status.
1190 static void do_pages_stat_array(struct mm_struct
*mm
, unsigned long nr_pages
,
1191 const void __user
**pages
, int *status
)
1195 down_read(&mm
->mmap_sem
);
1197 for (i
= 0; i
< nr_pages
; i
++) {
1198 unsigned long addr
= (unsigned long)(*pages
);
1199 struct vm_area_struct
*vma
;
1203 vma
= find_vma(mm
, addr
);
1207 page
= follow_page(vma
, addr
, 0);
1209 err
= PTR_ERR(page
);
1214 /* Use PageReserved to check for zero page */
1215 if (!page
|| PageReserved(page
) || PageKsm(page
))
1218 err
= page_to_nid(page
);
1226 up_read(&mm
->mmap_sem
);
1230 * Determine the nodes of a user array of pages and store it in
1231 * a user array of status.
1233 static int do_pages_stat(struct mm_struct
*mm
, unsigned long nr_pages
,
1234 const void __user
* __user
*pages
,
1237 #define DO_PAGES_STAT_CHUNK_NR 16
1238 const void __user
*chunk_pages
[DO_PAGES_STAT_CHUNK_NR
];
1239 int chunk_status
[DO_PAGES_STAT_CHUNK_NR
];
1242 unsigned long chunk_nr
;
1244 chunk_nr
= nr_pages
;
1245 if (chunk_nr
> DO_PAGES_STAT_CHUNK_NR
)
1246 chunk_nr
= DO_PAGES_STAT_CHUNK_NR
;
1248 if (copy_from_user(chunk_pages
, pages
, chunk_nr
* sizeof(*chunk_pages
)))
1251 do_pages_stat_array(mm
, chunk_nr
, chunk_pages
, chunk_status
);
1253 if (copy_to_user(status
, chunk_status
, chunk_nr
* sizeof(*status
)))
1258 nr_pages
-= chunk_nr
;
1260 return nr_pages
? -EFAULT
: 0;
1264 * Move a list of pages in the address space of the currently executing
1267 SYSCALL_DEFINE6(move_pages
, pid_t
, pid
, unsigned long, nr_pages
,
1268 const void __user
* __user
*, pages
,
1269 const int __user
*, nodes
,
1270 int __user
*, status
, int, flags
)
1272 const struct cred
*cred
= current_cred(), *tcred
;
1273 struct task_struct
*task
;
1274 struct mm_struct
*mm
;
1278 if (flags
& ~(MPOL_MF_MOVE
|MPOL_MF_MOVE_ALL
))
1281 if ((flags
& MPOL_MF_MOVE_ALL
) && !capable(CAP_SYS_NICE
))
1284 /* Find the mm_struct */
1285 read_lock(&tasklist_lock
);
1286 task
= pid
? find_task_by_vpid(pid
) : current
;
1288 read_unlock(&tasklist_lock
);
1291 mm
= get_task_mm(task
);
1292 read_unlock(&tasklist_lock
);
1298 * Check if this process has the right to modify the specified
1299 * process. The right exists if the process has administrative
1300 * capabilities, superuser privileges or the same
1301 * userid as the target process.
1304 tcred
= __task_cred(task
);
1305 if (cred
->euid
!= tcred
->suid
&& cred
->euid
!= tcred
->uid
&&
1306 cred
->uid
!= tcred
->suid
&& cred
->uid
!= tcred
->uid
&&
1307 !capable(CAP_SYS_NICE
)) {
1314 err
= security_task_movememory(task
);
1319 err
= do_pages_move(mm
, task
, nr_pages
, pages
, nodes
, status
,
1322 err
= do_pages_stat(mm
, nr_pages
, pages
, status
);
1331 * Call migration functions in the vma_ops that may prepare
1332 * memory in a vm for migration. migration functions may perform
1333 * the migration for vmas that do not have an underlying page struct.
1335 int migrate_vmas(struct mm_struct
*mm
, const nodemask_t
*to
,
1336 const nodemask_t
*from
, unsigned long flags
)
1338 struct vm_area_struct
*vma
;
1341 for (vma
= mm
->mmap
; vma
&& !err
; vma
= vma
->vm_next
) {
1342 if (vma
->vm_ops
&& vma
->vm_ops
->migrate
) {
1343 err
= vma
->vm_ops
->migrate(vma
, to
, from
, flags
);
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