2 * Memory Migration functionality - linux/mm/migrate.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/export.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/backing-dev.h>
34 #include <linux/compaction.h>
35 #include <linux/syscalls.h>
36 #include <linux/hugetlb.h>
37 #include <linux/hugetlb_cgroup.h>
38 #include <linux/gfp.h>
39 #include <linux/balloon_compaction.h>
40 #include <linux/mmu_notifier.h>
41 #include <linux/page_idle.h>
42 #include <linux/page_owner.h>
44 #include <asm/tlbflush.h>
46 #define CREATE_TRACE_POINTS
47 #include <trace/events/migrate.h>
52 * migrate_prep() needs to be called before we start compiling a list of pages
53 * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is
54 * undesirable, use migrate_prep_local()
56 int migrate_prep(void)
59 * Clear the LRU lists so pages can be isolated.
60 * Note that pages may be moved off the LRU after we have
61 * drained them. Those pages will fail to migrate like other
62 * pages that may be busy.
69 /* Do the necessary work of migrate_prep but not if it involves other CPUs */
70 int migrate_prep_local(void)
77 bool isolate_movable_page(struct page *page, isolate_mode_t mode)
79 struct address_space *mapping;
82 * Avoid burning cycles with pages that are yet under __free_pages(),
83 * or just got freed under us.
85 * In case we 'win' a race for a movable page being freed under us and
86 * raise its refcount preventing __free_pages() from doing its job
87 * the put_page() at the end of this block will take care of
88 * release this page, thus avoiding a nasty leakage.
90 if (unlikely(!get_page_unless_zero(page)))
94 * Check PageMovable before holding a PG_lock because page's owner
95 * assumes anybody doesn't touch PG_lock of newly allocated page
96 * so unconditionally grapping the lock ruins page's owner side.
98 if (unlikely(!__PageMovable(page)))
101 * As movable pages are not isolated from LRU lists, concurrent
102 * compaction threads can race against page migration functions
103 * as well as race against the releasing a page.
105 * In order to avoid having an already isolated movable page
106 * being (wrongly) re-isolated while it is under migration,
107 * or to avoid attempting to isolate pages being released,
108 * lets be sure we have the page lock
109 * before proceeding with the movable page isolation steps.
111 if (unlikely(!trylock_page(page)))
114 if (!PageMovable(page) || PageIsolated(page))
115 goto out_no_isolated;
117 mapping = page_mapping(page);
118 VM_BUG_ON_PAGE(!mapping, page);
120 if (!mapping->a_ops->isolate_page(page, mode))
121 goto out_no_isolated;
123 /* Driver shouldn't use PG_isolated bit of page->flags */
124 WARN_ON_ONCE(PageIsolated(page));
125 __SetPageIsolated(page);
138 /* It should be called on page which is PG_movable */
139 void putback_movable_page(struct page *page)
141 struct address_space *mapping;
143 VM_BUG_ON_PAGE(!PageLocked(page), page);
144 VM_BUG_ON_PAGE(!PageMovable(page), page);
145 VM_BUG_ON_PAGE(!PageIsolated(page), page);
147 mapping = page_mapping(page);
148 mapping->a_ops->putback_page(page);
149 __ClearPageIsolated(page);
153 * Put previously isolated pages back onto the appropriate lists
154 * from where they were once taken off for compaction/migration.
156 * This function shall be used whenever the isolated pageset has been
157 * built from lru, balloon, hugetlbfs page. See isolate_migratepages_range()
158 * and isolate_huge_page().
160 void putback_movable_pages(struct list_head *l)
165 list_for_each_entry_safe(page, page2, l, lru) {
166 if (unlikely(PageHuge(page))) {
167 putback_active_hugepage(page);
170 list_del(&page->lru);
172 * We isolated non-lru movable page so here we can use
173 * __PageMovable because LRU page's mapping cannot have
174 * PAGE_MAPPING_MOVABLE.
176 if (unlikely(__PageMovable(page))) {
177 VM_BUG_ON_PAGE(!PageIsolated(page), page);
179 if (PageMovable(page))
180 putback_movable_page(page);
182 __ClearPageIsolated(page);
186 putback_lru_page(page);
187 dec_node_page_state(page, NR_ISOLATED_ANON +
188 page_is_file_cache(page));
194 * Restore a potential migration pte to a working pte entry
196 static int remove_migration_pte(struct page *new, struct vm_area_struct *vma,
197 unsigned long addr, void *old)
199 struct mm_struct *mm = vma->vm_mm;
205 if (unlikely(PageHuge(new))) {
206 ptep = huge_pte_offset(mm, addr);
209 ptl = huge_pte_lockptr(hstate_vma(vma), mm, ptep);
211 pmd = mm_find_pmd(mm, addr);
215 ptep = pte_offset_map(pmd, addr);
218 * Peek to check is_swap_pte() before taking ptlock? No, we
219 * can race mremap's move_ptes(), which skips anon_vma lock.
222 ptl = pte_lockptr(mm, pmd);
227 if (!is_swap_pte(pte))
230 entry = pte_to_swp_entry(pte);
232 if (!is_migration_entry(entry) ||
233 migration_entry_to_page(entry) != old)
237 pte = pte_mkold(mk_pte(new, READ_ONCE(vma->vm_page_prot)));
238 if (pte_swp_soft_dirty(*ptep))
239 pte = pte_mksoft_dirty(pte);
241 /* Recheck VMA as permissions can change since migration started */
242 if (is_write_migration_entry(entry))
243 pte = maybe_mkwrite(pte, vma);
245 #ifdef CONFIG_HUGETLB_PAGE
247 pte = pte_mkhuge(pte);
248 pte = arch_make_huge_pte(pte, vma, new, 0);
251 flush_dcache_page(new);
252 set_pte_at(mm, addr, ptep, pte);
256 hugepage_add_anon_rmap(new, vma, addr);
258 page_dup_rmap(new, true);
259 } else if (PageAnon(new))
260 page_add_anon_rmap(new, vma, addr, false);
262 page_add_file_rmap(new, false);
264 if (vma->vm_flags & VM_LOCKED && !PageTransCompound(new))
267 /* No need to invalidate - it was non-present before */
268 update_mmu_cache(vma, addr, ptep);
270 pte_unmap_unlock(ptep, ptl);
276 * Get rid of all migration entries and replace them by
277 * references to the indicated page.
279 void remove_migration_ptes(struct page *old, struct page *new, bool locked)
281 struct rmap_walk_control rwc = {
282 .rmap_one = remove_migration_pte,
287 rmap_walk_locked(new, &rwc);
289 rmap_walk(new, &rwc);
293 * Something used the pte of a page under migration. We need to
294 * get to the page and wait until migration is finished.
295 * When we return from this function the fault will be retried.
297 void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
306 if (!is_swap_pte(pte))
309 entry = pte_to_swp_entry(pte);
310 if (!is_migration_entry(entry))
313 page = migration_entry_to_page(entry);
316 * Once radix-tree replacement of page migration started, page_count
317 * *must* be zero. And, we don't want to call wait_on_page_locked()
318 * against a page without get_page().
319 * So, we use get_page_unless_zero(), here. Even failed, page fault
322 if (!get_page_unless_zero(page))
324 pte_unmap_unlock(ptep, ptl);
325 wait_on_page_locked(page);
329 pte_unmap_unlock(ptep, ptl);
332 void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
333 unsigned long address)
335 spinlock_t *ptl = pte_lockptr(mm, pmd);
336 pte_t *ptep = pte_offset_map(pmd, address);
337 __migration_entry_wait(mm, ptep, ptl);
340 void migration_entry_wait_huge(struct vm_area_struct *vma,
341 struct mm_struct *mm, pte_t *pte)
343 spinlock_t *ptl = huge_pte_lockptr(hstate_vma(vma), mm, pte);
344 __migration_entry_wait(mm, pte, ptl);
348 /* Returns true if all buffers are successfully locked */
349 static bool buffer_migrate_lock_buffers(struct buffer_head *head,
350 enum migrate_mode mode)
352 struct buffer_head *bh = head;
354 /* Simple case, sync compaction */
355 if (mode != MIGRATE_ASYNC) {
359 bh = bh->b_this_page;
361 } while (bh != head);
366 /* async case, we cannot block on lock_buffer so use trylock_buffer */
369 if (!trylock_buffer(bh)) {
371 * We failed to lock the buffer and cannot stall in
372 * async migration. Release the taken locks
374 struct buffer_head *failed_bh = bh;
377 while (bh != failed_bh) {
380 bh = bh->b_this_page;
385 bh = bh->b_this_page;
386 } while (bh != head);
390 static inline bool buffer_migrate_lock_buffers(struct buffer_head *head,
391 enum migrate_mode mode)
395 #endif /* CONFIG_BLOCK */
398 * Replace the page in the mapping.
400 * The number of remaining references must be:
401 * 1 for anonymous pages without a mapping
402 * 2 for pages with a mapping
403 * 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
405 int migrate_page_move_mapping(struct address_space *mapping,
406 struct page *newpage, struct page *page,
407 struct buffer_head *head, enum migrate_mode mode,
410 struct zone *oldzone, *newzone;
412 int expected_count = 1 + extra_count;
416 /* Anonymous page without mapping */
417 if (page_count(page) != expected_count)
420 /* No turning back from here */
421 newpage->index = page->index;
422 newpage->mapping = page->mapping;
423 if (PageSwapBacked(page))
424 __SetPageSwapBacked(newpage);
426 return MIGRATEPAGE_SUCCESS;
429 oldzone = page_zone(page);
430 newzone = page_zone(newpage);
432 spin_lock_irq(&mapping->tree_lock);
434 pslot = radix_tree_lookup_slot(&mapping->page_tree,
437 expected_count += 1 + page_has_private(page);
438 if (page_count(page) != expected_count ||
439 radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) {
440 spin_unlock_irq(&mapping->tree_lock);
444 if (!page_ref_freeze(page, expected_count)) {
445 spin_unlock_irq(&mapping->tree_lock);
450 * In the async migration case of moving a page with buffers, lock the
451 * buffers using trylock before the mapping is moved. If the mapping
452 * was moved, we later failed to lock the buffers and could not move
453 * the mapping back due to an elevated page count, we would have to
454 * block waiting on other references to be dropped.
456 if (mode == MIGRATE_ASYNC && head &&
457 !buffer_migrate_lock_buffers(head, mode)) {
458 page_ref_unfreeze(page, expected_count);
459 spin_unlock_irq(&mapping->tree_lock);
464 * Now we know that no one else is looking at the page:
465 * no turning back from here.
467 newpage->index = page->index;
468 newpage->mapping = page->mapping;
469 get_page(newpage); /* add cache reference */
470 if (PageSwapBacked(page)) {
471 __SetPageSwapBacked(newpage);
472 if (PageSwapCache(page)) {
473 SetPageSwapCache(newpage);
474 set_page_private(newpage, page_private(page));
477 VM_BUG_ON_PAGE(PageSwapCache(page), page);
480 /* Move dirty while page refs frozen and newpage not yet exposed */
481 dirty = PageDirty(page);
483 ClearPageDirty(page);
484 SetPageDirty(newpage);
487 radix_tree_replace_slot(&mapping->page_tree, pslot, newpage);
490 * Drop cache reference from old page by unfreezing
491 * to one less reference.
492 * We know this isn't the last reference.
494 page_ref_unfreeze(page, expected_count - 1);
496 spin_unlock(&mapping->tree_lock);
497 /* Leave irq disabled to prevent preemption while updating stats */
500 * If moved to a different zone then also account
501 * the page for that zone. Other VM counters will be
502 * taken care of when we establish references to the
503 * new page and drop references to the old page.
505 * Note that anonymous pages are accounted for
506 * via NR_FILE_PAGES and NR_ANON_MAPPED if they
507 * are mapped to swap space.
509 if (newzone != oldzone) {
510 __dec_node_state(oldzone->zone_pgdat, NR_FILE_PAGES);
511 __inc_node_state(newzone->zone_pgdat, NR_FILE_PAGES);
512 if (PageSwapBacked(page) && !PageSwapCache(page)) {
513 __dec_node_state(oldzone->zone_pgdat, NR_SHMEM);
514 __inc_node_state(newzone->zone_pgdat, NR_SHMEM);
516 if (dirty && mapping_cap_account_dirty(mapping)) {
517 __dec_node_state(oldzone->zone_pgdat, NR_FILE_DIRTY);
518 __dec_zone_state(oldzone, NR_ZONE_WRITE_PENDING);
519 __inc_node_state(newzone->zone_pgdat, NR_FILE_DIRTY);
520 __inc_zone_state(newzone, NR_ZONE_WRITE_PENDING);
525 return MIGRATEPAGE_SUCCESS;
527 EXPORT_SYMBOL(migrate_page_move_mapping);
530 * The expected number of remaining references is the same as that
531 * of migrate_page_move_mapping().
533 int migrate_huge_page_move_mapping(struct address_space *mapping,
534 struct page *newpage, struct page *page)
539 spin_lock_irq(&mapping->tree_lock);
541 pslot = radix_tree_lookup_slot(&mapping->page_tree,
544 expected_count = 2 + page_has_private(page);
545 if (page_count(page) != expected_count ||
546 radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) {
547 spin_unlock_irq(&mapping->tree_lock);
551 if (!page_ref_freeze(page, expected_count)) {
552 spin_unlock_irq(&mapping->tree_lock);
556 newpage->index = page->index;
557 newpage->mapping = page->mapping;
561 radix_tree_replace_slot(&mapping->page_tree, pslot, newpage);
563 page_ref_unfreeze(page, expected_count - 1);
565 spin_unlock_irq(&mapping->tree_lock);
567 return MIGRATEPAGE_SUCCESS;
571 * Gigantic pages are so large that we do not guarantee that page++ pointer
572 * arithmetic will work across the entire page. We need something more
575 static void __copy_gigantic_page(struct page *dst, struct page *src,
579 struct page *dst_base = dst;
580 struct page *src_base = src;
582 for (i = 0; i < nr_pages; ) {
584 copy_highpage(dst, src);
587 dst = mem_map_next(dst, dst_base, i);
588 src = mem_map_next(src, src_base, i);
592 static void copy_huge_page(struct page *dst, struct page *src)
599 struct hstate *h = page_hstate(src);
600 nr_pages = pages_per_huge_page(h);
602 if (unlikely(nr_pages > MAX_ORDER_NR_PAGES)) {
603 __copy_gigantic_page(dst, src, nr_pages);
608 BUG_ON(!PageTransHuge(src));
609 nr_pages = hpage_nr_pages(src);
612 for (i = 0; i < nr_pages; i++) {
614 copy_highpage(dst + i, src + i);
619 * Copy the page to its new location
621 void migrate_page_copy(struct page *newpage, struct page *page)
625 if (PageHuge(page) || PageTransHuge(page))
626 copy_huge_page(newpage, page);
628 copy_highpage(newpage, page);
631 SetPageError(newpage);
632 if (PageReferenced(page))
633 SetPageReferenced(newpage);
634 if (PageUptodate(page))
635 SetPageUptodate(newpage);
636 if (TestClearPageActive(page)) {
637 VM_BUG_ON_PAGE(PageUnevictable(page), page);
638 SetPageActive(newpage);
639 } else if (TestClearPageUnevictable(page))
640 SetPageUnevictable(newpage);
641 if (PageChecked(page))
642 SetPageChecked(newpage);
643 if (PageMappedToDisk(page))
644 SetPageMappedToDisk(newpage);
646 /* Move dirty on pages not done by migrate_page_move_mapping() */
648 SetPageDirty(newpage);
650 if (page_is_young(page))
651 set_page_young(newpage);
652 if (page_is_idle(page))
653 set_page_idle(newpage);
656 * Copy NUMA information to the new page, to prevent over-eager
657 * future migrations of this same page.
659 cpupid = page_cpupid_xchg_last(page, -1);
660 page_cpupid_xchg_last(newpage, cpupid);
662 ksm_migrate_page(newpage, page);
664 * Please do not reorder this without considering how mm/ksm.c's
665 * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache().
667 if (PageSwapCache(page))
668 ClearPageSwapCache(page);
669 ClearPagePrivate(page);
670 set_page_private(page, 0);
673 * If any waiters have accumulated on the new page then
676 if (PageWriteback(newpage))
677 end_page_writeback(newpage);
679 copy_page_owner(page, newpage);
681 mem_cgroup_migrate(page, newpage);
683 EXPORT_SYMBOL(migrate_page_copy);
685 /************************************************************
686 * Migration functions
687 ***********************************************************/
690 * Common logic to directly migrate a single LRU page suitable for
691 * pages that do not use PagePrivate/PagePrivate2.
693 * Pages are locked upon entry and exit.
695 int migrate_page(struct address_space *mapping,
696 struct page *newpage, struct page *page,
697 enum migrate_mode mode)
701 BUG_ON(PageWriteback(page)); /* Writeback must be complete */
703 rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0);
705 if (rc != MIGRATEPAGE_SUCCESS)
708 migrate_page_copy(newpage, page);
709 return MIGRATEPAGE_SUCCESS;
711 EXPORT_SYMBOL(migrate_page);
715 * Migration function for pages with buffers. This function can only be used
716 * if the underlying filesystem guarantees that no other references to "page"
719 int buffer_migrate_page(struct address_space *mapping,
720 struct page *newpage, struct page *page, enum migrate_mode mode)
722 struct buffer_head *bh, *head;
725 if (!page_has_buffers(page))
726 return migrate_page(mapping, newpage, page, mode);
728 head = page_buffers(page);
730 rc = migrate_page_move_mapping(mapping, newpage, page, head, mode, 0);
732 if (rc != MIGRATEPAGE_SUCCESS)
736 * In the async case, migrate_page_move_mapping locked the buffers
737 * with an IRQ-safe spinlock held. In the sync case, the buffers
738 * need to be locked now
740 if (mode != MIGRATE_ASYNC)
741 BUG_ON(!buffer_migrate_lock_buffers(head, mode));
743 ClearPagePrivate(page);
744 set_page_private(newpage, page_private(page));
745 set_page_private(page, 0);
751 set_bh_page(bh, newpage, bh_offset(bh));
752 bh = bh->b_this_page;
754 } while (bh != head);
756 SetPagePrivate(newpage);
758 migrate_page_copy(newpage, page);
764 bh = bh->b_this_page;
766 } while (bh != head);
768 return MIGRATEPAGE_SUCCESS;
770 EXPORT_SYMBOL(buffer_migrate_page);
774 * Writeback a page to clean the dirty state
776 static int writeout(struct address_space *mapping, struct page *page)
778 struct writeback_control wbc = {
779 .sync_mode = WB_SYNC_NONE,
782 .range_end = LLONG_MAX,
787 if (!mapping->a_ops->writepage)
788 /* No write method for the address space */
791 if (!clear_page_dirty_for_io(page))
792 /* Someone else already triggered a write */
796 * A dirty page may imply that the underlying filesystem has
797 * the page on some queue. So the page must be clean for
798 * migration. Writeout may mean we loose the lock and the
799 * page state is no longer what we checked for earlier.
800 * At this point we know that the migration attempt cannot
803 remove_migration_ptes(page, page, false);
805 rc = mapping->a_ops->writepage(page, &wbc);
807 if (rc != AOP_WRITEPAGE_ACTIVATE)
808 /* unlocked. Relock */
811 return (rc < 0) ? -EIO : -EAGAIN;
815 * Default handling if a filesystem does not provide a migration function.
817 static int fallback_migrate_page(struct address_space *mapping,
818 struct page *newpage, struct page *page, enum migrate_mode mode)
820 if (PageDirty(page)) {
821 /* Only writeback pages in full synchronous migration */
822 if (mode != MIGRATE_SYNC)
824 return writeout(mapping, page);
828 * Buffers may be managed in a filesystem specific way.
829 * We must have no buffers or drop them.
831 if (page_has_private(page) &&
832 !try_to_release_page(page, GFP_KERNEL))
835 return migrate_page(mapping, newpage, page, mode);
839 * Move a page to a newly allocated page
840 * The page is locked and all ptes have been successfully removed.
842 * The new page will have replaced the old page if this function
847 * MIGRATEPAGE_SUCCESS - success
849 static int move_to_new_page(struct page *newpage, struct page *page,
850 enum migrate_mode mode)
852 struct address_space *mapping;
854 bool is_lru = !__PageMovable(page);
856 VM_BUG_ON_PAGE(!PageLocked(page), page);
857 VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
859 mapping = page_mapping(page);
861 if (likely(is_lru)) {
863 rc = migrate_page(mapping, newpage, page, mode);
864 else if (mapping->a_ops->migratepage)
866 * Most pages have a mapping and most filesystems
867 * provide a migratepage callback. Anonymous pages
868 * are part of swap space which also has its own
869 * migratepage callback. This is the most common path
870 * for page migration.
872 rc = mapping->a_ops->migratepage(mapping, newpage,
875 rc = fallback_migrate_page(mapping, newpage,
879 * In case of non-lru page, it could be released after
880 * isolation step. In that case, we shouldn't try migration.
882 VM_BUG_ON_PAGE(!PageIsolated(page), page);
883 if (!PageMovable(page)) {
884 rc = MIGRATEPAGE_SUCCESS;
885 __ClearPageIsolated(page);
889 rc = mapping->a_ops->migratepage(mapping, newpage,
891 WARN_ON_ONCE(rc == MIGRATEPAGE_SUCCESS &&
892 !PageIsolated(page));
896 * When successful, old pagecache page->mapping must be cleared before
897 * page is freed; but stats require that PageAnon be left as PageAnon.
899 if (rc == MIGRATEPAGE_SUCCESS) {
900 if (__PageMovable(page)) {
901 VM_BUG_ON_PAGE(!PageIsolated(page), page);
904 * We clear PG_movable under page_lock so any compactor
905 * cannot try to migrate this page.
907 __ClearPageIsolated(page);
911 * Anonymous and movable page->mapping will be cleard by
912 * free_pages_prepare so don't reset it here for keeping
913 * the type to work PageAnon, for example.
915 if (!PageMappingFlags(page))
916 page->mapping = NULL;
922 static int __unmap_and_move(struct page *page, struct page *newpage,
923 int force, enum migrate_mode mode)
926 int page_was_mapped = 0;
927 struct anon_vma *anon_vma = NULL;
928 bool is_lru = !__PageMovable(page);
930 if (!trylock_page(page)) {
931 if (!force || mode == MIGRATE_ASYNC)
935 * It's not safe for direct compaction to call lock_page.
936 * For example, during page readahead pages are added locked
937 * to the LRU. Later, when the IO completes the pages are
938 * marked uptodate and unlocked. However, the queueing
939 * could be merging multiple pages for one bio (e.g.
940 * mpage_readpages). If an allocation happens for the
941 * second or third page, the process can end up locking
942 * the same page twice and deadlocking. Rather than
943 * trying to be clever about what pages can be locked,
944 * avoid the use of lock_page for direct compaction
947 if (current->flags & PF_MEMALLOC)
953 if (PageWriteback(page)) {
955 * Only in the case of a full synchronous migration is it
956 * necessary to wait for PageWriteback. In the async case,
957 * the retry loop is too short and in the sync-light case,
958 * the overhead of stalling is too much
960 if (mode != MIGRATE_SYNC) {
966 wait_on_page_writeback(page);
970 * By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
971 * we cannot notice that anon_vma is freed while we migrates a page.
972 * This get_anon_vma() delays freeing anon_vma pointer until the end
973 * of migration. File cache pages are no problem because of page_lock()
974 * File Caches may use write_page() or lock_page() in migration, then,
975 * just care Anon page here.
977 * Only page_get_anon_vma() understands the subtleties of
978 * getting a hold on an anon_vma from outside one of its mms.
979 * But if we cannot get anon_vma, then we won't need it anyway,
980 * because that implies that the anon page is no longer mapped
981 * (and cannot be remapped so long as we hold the page lock).
983 if (PageAnon(page) && !PageKsm(page))
984 anon_vma = page_get_anon_vma(page);
987 * Block others from accessing the new page when we get around to
988 * establishing additional references. We are usually the only one
989 * holding a reference to newpage at this point. We used to have a BUG
990 * here if trylock_page(newpage) fails, but would like to allow for
991 * cases where there might be a race with the previous use of newpage.
992 * This is much like races on refcount of oldpage: just don't BUG().
994 if (unlikely(!trylock_page(newpage)))
997 if (unlikely(!is_lru)) {
998 rc = move_to_new_page(newpage, page, mode);
999 goto out_unlock_both;
1003 * Corner case handling:
1004 * 1. When a new swap-cache page is read into, it is added to the LRU
1005 * and treated as swapcache but it has no rmap yet.
1006 * Calling try_to_unmap() against a page->mapping==NULL page will
1007 * trigger a BUG. So handle it here.
1008 * 2. An orphaned page (see truncate_complete_page) might have
1009 * fs-private metadata. The page can be picked up due to memory
1010 * offlining. Everywhere else except page reclaim, the page is
1011 * invisible to the vm, so the page can not be migrated. So try to
1012 * free the metadata, so the page can be freed.
1014 if (!page->mapping) {
1015 VM_BUG_ON_PAGE(PageAnon(page), page);
1016 if (page_has_private(page)) {
1017 try_to_free_buffers(page);
1018 goto out_unlock_both;
1020 } else if (page_mapped(page)) {
1021 /* Establish migration ptes */
1022 VM_BUG_ON_PAGE(PageAnon(page) && !PageKsm(page) && !anon_vma,
1025 TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS);
1026 page_was_mapped = 1;
1029 if (!page_mapped(page))
1030 rc = move_to_new_page(newpage, page, mode);
1032 if (page_was_mapped)
1033 remove_migration_ptes(page,
1034 rc == MIGRATEPAGE_SUCCESS ? newpage : page, false);
1037 unlock_page(newpage);
1039 /* Drop an anon_vma reference if we took one */
1041 put_anon_vma(anon_vma);
1045 * If migration is successful, decrease refcount of the newpage
1046 * which will not free the page because new page owner increased
1047 * refcounter. As well, if it is LRU page, add the page to LRU
1050 if (rc == MIGRATEPAGE_SUCCESS) {
1051 if (unlikely(__PageMovable(newpage)))
1054 putback_lru_page(newpage);
1061 * gcc 4.7 and 4.8 on arm get an ICEs when inlining unmap_and_move(). Work
1064 #if (GCC_VERSION >= 40700 && GCC_VERSION < 40900) && defined(CONFIG_ARM)
1065 #define ICE_noinline noinline
1067 #define ICE_noinline
1071 * Obtain the lock on page, remove all ptes and migrate the page
1072 * to the newly allocated page in newpage.
1074 static ICE_noinline int unmap_and_move(new_page_t get_new_page,
1075 free_page_t put_new_page,
1076 unsigned long private, struct page *page,
1077 int force, enum migrate_mode mode,
1078 enum migrate_reason reason)
1080 int rc = MIGRATEPAGE_SUCCESS;
1082 struct page *newpage;
1084 newpage = get_new_page(page, private, &result);
1088 if (page_count(page) == 1) {
1089 /* page was freed from under us. So we are done. */
1090 ClearPageActive(page);
1091 ClearPageUnevictable(page);
1092 if (unlikely(__PageMovable(page))) {
1094 if (!PageMovable(page))
1095 __ClearPageIsolated(page);
1099 put_new_page(newpage, private);
1105 if (unlikely(PageTransHuge(page))) {
1107 rc = split_huge_page(page);
1113 rc = __unmap_and_move(page, newpage, force, mode);
1114 if (rc == MIGRATEPAGE_SUCCESS)
1115 set_page_owner_migrate_reason(newpage, reason);
1118 if (rc != -EAGAIN) {
1120 * A page that has been migrated has all references
1121 * removed and will be freed. A page that has not been
1122 * migrated will have kepts its references and be
1125 list_del(&page->lru);
1128 * Compaction can migrate also non-LRU pages which are
1129 * not accounted to NR_ISOLATED_*. They can be recognized
1132 if (likely(!__PageMovable(page)))
1133 dec_node_page_state(page, NR_ISOLATED_ANON +
1134 page_is_file_cache(page));
1138 * If migration is successful, releases reference grabbed during
1139 * isolation. Otherwise, restore the page to right list unless
1142 if (rc == MIGRATEPAGE_SUCCESS) {
1144 if (reason == MR_MEMORY_FAILURE) {
1146 * Set PG_HWPoison on just freed page
1147 * intentionally. Although it's rather weird,
1148 * it's how HWPoison flag works at the moment.
1150 if (!test_set_page_hwpoison(page))
1151 num_poisoned_pages_inc();
1154 if (rc != -EAGAIN) {
1155 if (likely(!__PageMovable(page))) {
1156 putback_lru_page(page);
1161 if (PageMovable(page))
1162 putback_movable_page(page);
1164 __ClearPageIsolated(page);
1170 put_new_page(newpage, private);
1179 *result = page_to_nid(newpage);
1185 * Counterpart of unmap_and_move_page() for hugepage migration.
1187 * This function doesn't wait the completion of hugepage I/O
1188 * because there is no race between I/O and migration for hugepage.
1189 * Note that currently hugepage I/O occurs only in direct I/O
1190 * where no lock is held and PG_writeback is irrelevant,
1191 * and writeback status of all subpages are counted in the reference
1192 * count of the head page (i.e. if all subpages of a 2MB hugepage are
1193 * under direct I/O, the reference of the head page is 512 and a bit more.)
1194 * This means that when we try to migrate hugepage whose subpages are
1195 * doing direct I/O, some references remain after try_to_unmap() and
1196 * hugepage migration fails without data corruption.
1198 * There is also no race when direct I/O is issued on the page under migration,
1199 * because then pte is replaced with migration swap entry and direct I/O code
1200 * will wait in the page fault for migration to complete.
1202 static int unmap_and_move_huge_page(new_page_t get_new_page,
1203 free_page_t put_new_page, unsigned long private,
1204 struct page *hpage, int force,
1205 enum migrate_mode mode, int reason)
1209 int page_was_mapped = 0;
1210 struct page *new_hpage;
1211 struct anon_vma *anon_vma = NULL;
1214 * Movability of hugepages depends on architectures and hugepage size.
1215 * This check is necessary because some callers of hugepage migration
1216 * like soft offline and memory hotremove don't walk through page
1217 * tables or check whether the hugepage is pmd-based or not before
1218 * kicking migration.
1220 if (!hugepage_migration_supported(page_hstate(hpage))) {
1221 putback_active_hugepage(hpage);
1225 new_hpage = get_new_page(hpage, private, &result);
1229 if (!trylock_page(hpage)) {
1230 if (!force || mode != MIGRATE_SYNC)
1235 if (PageAnon(hpage))
1236 anon_vma = page_get_anon_vma(hpage);
1238 if (unlikely(!trylock_page(new_hpage)))
1241 if (page_mapped(hpage)) {
1243 TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS);
1244 page_was_mapped = 1;
1247 if (!page_mapped(hpage))
1248 rc = move_to_new_page(new_hpage, hpage, mode);
1250 if (page_was_mapped)
1251 remove_migration_ptes(hpage,
1252 rc == MIGRATEPAGE_SUCCESS ? new_hpage : hpage, false);
1254 unlock_page(new_hpage);
1258 put_anon_vma(anon_vma);
1260 if (rc == MIGRATEPAGE_SUCCESS) {
1261 hugetlb_cgroup_migrate(hpage, new_hpage);
1262 put_new_page = NULL;
1263 set_page_owner_migrate_reason(new_hpage, reason);
1269 putback_active_hugepage(hpage);
1272 * If migration was not successful and there's a freeing callback, use
1273 * it. Otherwise, put_page() will drop the reference grabbed during
1277 put_new_page(new_hpage, private);
1279 putback_active_hugepage(new_hpage);
1285 *result = page_to_nid(new_hpage);
1291 * migrate_pages - migrate the pages specified in a list, to the free pages
1292 * supplied as the target for the page migration
1294 * @from: The list of pages to be migrated.
1295 * @get_new_page: The function used to allocate free pages to be used
1296 * as the target of the page migration.
1297 * @put_new_page: The function used to free target pages if migration
1298 * fails, or NULL if no special handling is necessary.
1299 * @private: Private data to be passed on to get_new_page()
1300 * @mode: The migration mode that specifies the constraints for
1301 * page migration, if any.
1302 * @reason: The reason for page migration.
1304 * The function returns after 10 attempts or if no pages are movable any more
1305 * because the list has become empty or no retryable pages exist any more.
1306 * The caller should call putback_movable_pages() to return pages to the LRU
1307 * or free list only if ret != 0.
1309 * Returns the number of pages that were not migrated, or an error code.
1311 int migrate_pages(struct list_head *from, new_page_t get_new_page,
1312 free_page_t put_new_page, unsigned long private,
1313 enum migrate_mode mode, int reason)
1317 int nr_succeeded = 0;
1321 int swapwrite = current->flags & PF_SWAPWRITE;
1325 current->flags |= PF_SWAPWRITE;
1327 for(pass = 0; pass < 10 && retry; pass++) {
1330 list_for_each_entry_safe(page, page2, from, lru) {
1334 rc = unmap_and_move_huge_page(get_new_page,
1335 put_new_page, private, page,
1336 pass > 2, mode, reason);
1338 rc = unmap_and_move(get_new_page, put_new_page,
1339 private, page, pass > 2, mode,
1349 case MIGRATEPAGE_SUCCESS:
1354 * Permanent failure (-EBUSY, -ENOSYS, etc.):
1355 * unlike -EAGAIN case, the failed page is
1356 * removed from migration page list and not
1357 * retried in the next outer loop.
1368 count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded);
1370 count_vm_events(PGMIGRATE_FAIL, nr_failed);
1371 trace_mm_migrate_pages(nr_succeeded, nr_failed, mode, reason);
1374 current->flags &= ~PF_SWAPWRITE;
1381 * Move a list of individual pages
1383 struct page_to_node {
1390 static struct page *new_page_node(struct page *p, unsigned long private,
1393 struct page_to_node *pm = (struct page_to_node *)private;
1395 while (pm->node != MAX_NUMNODES && pm->page != p)
1398 if (pm->node == MAX_NUMNODES)
1401 *result = &pm->status;
1404 return alloc_huge_page_node(page_hstate(compound_head(p)),
1407 return __alloc_pages_node(pm->node,
1408 GFP_HIGHUSER_MOVABLE | __GFP_THISNODE, 0);
1412 * Move a set of pages as indicated in the pm array. The addr
1413 * field must be set to the virtual address of the page to be moved
1414 * and the node number must contain a valid target node.
1415 * The pm array ends with node = MAX_NUMNODES.
1417 static int do_move_page_to_node_array(struct mm_struct *mm,
1418 struct page_to_node *pm,
1422 struct page_to_node *pp;
1423 LIST_HEAD(pagelist);
1425 down_read(&mm->mmap_sem);
1428 * Build a list of pages to migrate
1430 for (pp = pm; pp->node != MAX_NUMNODES; pp++) {
1431 struct vm_area_struct *vma;
1435 vma = find_vma(mm, pp->addr);
1436 if (!vma || pp->addr < vma->vm_start || !vma_migratable(vma))
1439 /* FOLL_DUMP to ignore special (like zero) pages */
1440 page = follow_page(vma, pp->addr,
1441 FOLL_GET | FOLL_SPLIT | FOLL_DUMP);
1443 err = PTR_ERR(page);
1452 err = page_to_nid(page);
1454 if (err == pp->node)
1456 * Node already in the right place
1461 if (page_mapcount(page) > 1 &&
1465 if (PageHuge(page)) {
1467 isolate_huge_page(page, &pagelist);
1471 err = isolate_lru_page(page);
1473 list_add_tail(&page->lru, &pagelist);
1474 inc_node_page_state(page, NR_ISOLATED_ANON +
1475 page_is_file_cache(page));
1479 * Either remove the duplicate refcount from
1480 * isolate_lru_page() or drop the page ref if it was
1489 if (!list_empty(&pagelist)) {
1490 err = migrate_pages(&pagelist, new_page_node, NULL,
1491 (unsigned long)pm, MIGRATE_SYNC, MR_SYSCALL);
1493 putback_movable_pages(&pagelist);
1496 up_read(&mm->mmap_sem);
1501 * Migrate an array of page address onto an array of nodes and fill
1502 * the corresponding array of status.
1504 static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
1505 unsigned long nr_pages,
1506 const void __user * __user *pages,
1507 const int __user *nodes,
1508 int __user *status, int flags)
1510 struct page_to_node *pm;
1511 unsigned long chunk_nr_pages;
1512 unsigned long chunk_start;
1516 pm = (struct page_to_node *)__get_free_page(GFP_KERNEL);
1523 * Store a chunk of page_to_node array in a page,
1524 * but keep the last one as a marker
1526 chunk_nr_pages = (PAGE_SIZE / sizeof(struct page_to_node)) - 1;
1528 for (chunk_start = 0;
1529 chunk_start < nr_pages;
1530 chunk_start += chunk_nr_pages) {
1533 if (chunk_start + chunk_nr_pages > nr_pages)
1534 chunk_nr_pages = nr_pages - chunk_start;
1536 /* fill the chunk pm with addrs and nodes from user-space */
1537 for (j = 0; j < chunk_nr_pages; j++) {
1538 const void __user *p;
1542 if (get_user(p, pages + j + chunk_start))
1544 pm[j].addr = (unsigned long) p;
1546 if (get_user(node, nodes + j + chunk_start))
1550 if (node < 0 || node >= MAX_NUMNODES)
1553 if (!node_state(node, N_MEMORY))
1557 if (!node_isset(node, task_nodes))
1563 /* End marker for this chunk */
1564 pm[chunk_nr_pages].node = MAX_NUMNODES;
1566 /* Migrate this chunk */
1567 err = do_move_page_to_node_array(mm, pm,
1568 flags & MPOL_MF_MOVE_ALL);
1572 /* Return status information */
1573 for (j = 0; j < chunk_nr_pages; j++)
1574 if (put_user(pm[j].status, status + j + chunk_start)) {
1582 free_page((unsigned long)pm);
1588 * Determine the nodes of an array of pages and store it in an array of status.
1590 static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
1591 const void __user **pages, int *status)
1595 down_read(&mm->mmap_sem);
1597 for (i = 0; i < nr_pages; i++) {
1598 unsigned long addr = (unsigned long)(*pages);
1599 struct vm_area_struct *vma;
1603 vma = find_vma(mm, addr);
1604 if (!vma || addr < vma->vm_start)
1607 /* FOLL_DUMP to ignore special (like zero) pages */
1608 page = follow_page(vma, addr, FOLL_DUMP);
1610 err = PTR_ERR(page);
1614 err = page ? page_to_nid(page) : -ENOENT;
1622 up_read(&mm->mmap_sem);
1626 * Determine the nodes of a user array of pages and store it in
1627 * a user array of status.
1629 static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages,
1630 const void __user * __user *pages,
1633 #define DO_PAGES_STAT_CHUNK_NR 16
1634 const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR];
1635 int chunk_status[DO_PAGES_STAT_CHUNK_NR];
1638 unsigned long chunk_nr;
1640 chunk_nr = nr_pages;
1641 if (chunk_nr > DO_PAGES_STAT_CHUNK_NR)
1642 chunk_nr = DO_PAGES_STAT_CHUNK_NR;
1644 if (copy_from_user(chunk_pages, pages, chunk_nr * sizeof(*chunk_pages)))
1647 do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status);
1649 if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status)))
1654 nr_pages -= chunk_nr;
1656 return nr_pages ? -EFAULT : 0;
1660 * Move a list of pages in the address space of the currently executing
1663 SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,
1664 const void __user * __user *, pages,
1665 const int __user *, nodes,
1666 int __user *, status, int, flags)
1668 const struct cred *cred = current_cred(), *tcred;
1669 struct task_struct *task;
1670 struct mm_struct *mm;
1672 nodemask_t task_nodes;
1675 if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
1678 if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
1681 /* Find the mm_struct */
1683 task = pid ? find_task_by_vpid(pid) : current;
1688 get_task_struct(task);
1691 * Check if this process has the right to modify the specified
1692 * process. The right exists if the process has administrative
1693 * capabilities, superuser privileges or the same
1694 * userid as the target process.
1696 tcred = __task_cred(task);
1697 if (!uid_eq(cred->euid, tcred->suid) && !uid_eq(cred->euid, tcred->uid) &&
1698 !uid_eq(cred->uid, tcred->suid) && !uid_eq(cred->uid, tcred->uid) &&
1699 !capable(CAP_SYS_NICE)) {
1706 err = security_task_movememory(task);
1710 task_nodes = cpuset_mems_allowed(task);
1711 mm = get_task_mm(task);
1712 put_task_struct(task);
1718 err = do_pages_move(mm, task_nodes, nr_pages, pages,
1719 nodes, status, flags);
1721 err = do_pages_stat(mm, nr_pages, pages, status);
1727 put_task_struct(task);
1731 #ifdef CONFIG_NUMA_BALANCING
1733 * Returns true if this is a safe migration target node for misplaced NUMA
1734 * pages. Currently it only checks the watermarks which crude
1736 static bool migrate_balanced_pgdat(struct pglist_data *pgdat,
1737 unsigned long nr_migrate_pages)
1741 if (!pgdat_reclaimable(pgdat))
1744 for (z = pgdat->nr_zones - 1; z >= 0; z--) {
1745 struct zone *zone = pgdat->node_zones + z;
1747 if (!populated_zone(zone))
1750 /* Avoid waking kswapd by allocating pages_to_migrate pages. */
1751 if (!zone_watermark_ok(zone, 0,
1752 high_wmark_pages(zone) +
1761 static struct page *alloc_misplaced_dst_page(struct page *page,
1765 int nid = (int) data;
1766 struct page *newpage;
1768 newpage = __alloc_pages_node(nid,
1769 (GFP_HIGHUSER_MOVABLE |
1770 __GFP_THISNODE | __GFP_NOMEMALLOC |
1771 __GFP_NORETRY | __GFP_NOWARN) &
1778 * page migration rate limiting control.
1779 * Do not migrate more than @pages_to_migrate in a @migrate_interval_millisecs
1780 * window of time. Default here says do not migrate more than 1280M per second.
1782 static unsigned int migrate_interval_millisecs __read_mostly = 100;
1783 static unsigned int ratelimit_pages __read_mostly = 128 << (20 - PAGE_SHIFT);
1785 /* Returns true if the node is migrate rate-limited after the update */
1786 static bool numamigrate_update_ratelimit(pg_data_t *pgdat,
1787 unsigned long nr_pages)
1790 * Rate-limit the amount of data that is being migrated to a node.
1791 * Optimal placement is no good if the memory bus is saturated and
1792 * all the time is being spent migrating!
1794 if (time_after(jiffies, pgdat->numabalancing_migrate_next_window)) {
1795 spin_lock(&pgdat->numabalancing_migrate_lock);
1796 pgdat->numabalancing_migrate_nr_pages = 0;
1797 pgdat->numabalancing_migrate_next_window = jiffies +
1798 msecs_to_jiffies(migrate_interval_millisecs);
1799 spin_unlock(&pgdat->numabalancing_migrate_lock);
1801 if (pgdat->numabalancing_migrate_nr_pages > ratelimit_pages) {
1802 trace_mm_numa_migrate_ratelimit(current, pgdat->node_id,
1808 * This is an unlocked non-atomic update so errors are possible.
1809 * The consequences are failing to migrate when we potentiall should
1810 * have which is not severe enough to warrant locking. If it is ever
1811 * a problem, it can be converted to a per-cpu counter.
1813 pgdat->numabalancing_migrate_nr_pages += nr_pages;
1817 static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
1821 VM_BUG_ON_PAGE(compound_order(page) && !PageTransHuge(page), page);
1823 /* Avoid migrating to a node that is nearly full */
1824 if (!migrate_balanced_pgdat(pgdat, 1UL << compound_order(page)))
1827 if (isolate_lru_page(page))
1831 * migrate_misplaced_transhuge_page() skips page migration's usual
1832 * check on page_count(), so we must do it here, now that the page
1833 * has been isolated: a GUP pin, or any other pin, prevents migration.
1834 * The expected page count is 3: 1 for page's mapcount and 1 for the
1835 * caller's pin and 1 for the reference taken by isolate_lru_page().
1837 if (PageTransHuge(page) && page_count(page) != 3) {
1838 putback_lru_page(page);
1842 page_lru = page_is_file_cache(page);
1843 mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + page_lru,
1844 hpage_nr_pages(page));
1847 * Isolating the page has taken another reference, so the
1848 * caller's reference can be safely dropped without the page
1849 * disappearing underneath us during migration.
1855 bool pmd_trans_migrating(pmd_t pmd)
1857 struct page *page = pmd_page(pmd);
1858 return PageLocked(page);
1862 * Attempt to migrate a misplaced page to the specified destination
1863 * node. Caller is expected to have an elevated reference count on
1864 * the page that will be dropped by this function before returning.
1866 int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
1869 pg_data_t *pgdat = NODE_DATA(node);
1872 LIST_HEAD(migratepages);
1875 * Don't migrate file pages that are mapped in multiple processes
1876 * with execute permissions as they are probably shared libraries.
1878 if (page_mapcount(page) != 1 && page_is_file_cache(page) &&
1879 (vma->vm_flags & VM_EXEC))
1883 * Rate-limit the amount of data that is being migrated to a node.
1884 * Optimal placement is no good if the memory bus is saturated and
1885 * all the time is being spent migrating!
1887 if (numamigrate_update_ratelimit(pgdat, 1))
1890 isolated = numamigrate_isolate_page(pgdat, page);
1894 list_add(&page->lru, &migratepages);
1895 nr_remaining = migrate_pages(&migratepages, alloc_misplaced_dst_page,
1896 NULL, node, MIGRATE_ASYNC,
1899 if (!list_empty(&migratepages)) {
1900 list_del(&page->lru);
1901 dec_node_page_state(page, NR_ISOLATED_ANON +
1902 page_is_file_cache(page));
1903 putback_lru_page(page);
1907 count_vm_numa_event(NUMA_PAGE_MIGRATE);
1908 BUG_ON(!list_empty(&migratepages));
1915 #endif /* CONFIG_NUMA_BALANCING */
1917 #if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
1919 * Migrates a THP to a given target node. page must be locked and is unlocked
1922 int migrate_misplaced_transhuge_page(struct mm_struct *mm,
1923 struct vm_area_struct *vma,
1924 pmd_t *pmd, pmd_t entry,
1925 unsigned long address,
1926 struct page *page, int node)
1929 pg_data_t *pgdat = NODE_DATA(node);
1931 struct page *new_page = NULL;
1932 int page_lru = page_is_file_cache(page);
1933 unsigned long mmun_start = address & HPAGE_PMD_MASK;
1934 unsigned long mmun_end = mmun_start + HPAGE_PMD_SIZE;
1938 * Rate-limit the amount of data that is being migrated to a node.
1939 * Optimal placement is no good if the memory bus is saturated and
1940 * all the time is being spent migrating!
1942 if (numamigrate_update_ratelimit(pgdat, HPAGE_PMD_NR))
1945 new_page = alloc_pages_node(node,
1946 (GFP_TRANSHUGE_LIGHT | __GFP_THISNODE),
1950 prep_transhuge_page(new_page);
1952 isolated = numamigrate_isolate_page(pgdat, page);
1958 * We are not sure a pending tlb flush here is for a huge page
1959 * mapping or not. Hence use the tlb range variant
1961 if (mm_tlb_flush_pending(mm))
1962 flush_tlb_range(vma, mmun_start, mmun_end);
1964 /* Prepare a page as a migration target */
1965 __SetPageLocked(new_page);
1966 __SetPageSwapBacked(new_page);
1968 /* anon mapping, we can simply copy page->mapping to the new page: */
1969 new_page->mapping = page->mapping;
1970 new_page->index = page->index;
1971 migrate_page_copy(new_page, page);
1972 WARN_ON(PageLRU(new_page));
1974 /* Recheck the target PMD */
1975 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1976 ptl = pmd_lock(mm, pmd);
1977 if (unlikely(!pmd_same(*pmd, entry) || page_count(page) != 2)) {
1980 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1982 /* Reverse changes made by migrate_page_copy() */
1983 if (TestClearPageActive(new_page))
1984 SetPageActive(page);
1985 if (TestClearPageUnevictable(new_page))
1986 SetPageUnevictable(page);
1988 unlock_page(new_page);
1989 put_page(new_page); /* Free it */
1991 /* Retake the callers reference and putback on LRU */
1993 putback_lru_page(page);
1994 mod_node_page_state(page_pgdat(page),
1995 NR_ISOLATED_ANON + page_lru, -HPAGE_PMD_NR);
2001 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
2002 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
2005 * Clear the old entry under pagetable lock and establish the new PTE.
2006 * Any parallel GUP will either observe the old page blocking on the
2007 * page lock, block on the page table lock or observe the new page.
2008 * The SetPageUptodate on the new page and page_add_new_anon_rmap
2009 * guarantee the copy is visible before the pagetable update.
2011 flush_cache_range(vma, mmun_start, mmun_end);
2012 page_add_anon_rmap(new_page, vma, mmun_start, true);
2013 pmdp_huge_clear_flush_notify(vma, mmun_start, pmd);
2014 set_pmd_at(mm, mmun_start, pmd, entry);
2015 update_mmu_cache_pmd(vma, address, &entry);
2017 if (page_count(page) != 2) {
2018 set_pmd_at(mm, mmun_start, pmd, orig_entry);
2019 flush_pmd_tlb_range(vma, mmun_start, mmun_end);
2020 mmu_notifier_invalidate_range(mm, mmun_start, mmun_end);
2021 update_mmu_cache_pmd(vma, address, &entry);
2022 page_remove_rmap(new_page, true);
2026 mlock_migrate_page(new_page, page);
2027 page_remove_rmap(page, true);
2028 set_page_owner_migrate_reason(new_page, MR_NUMA_MISPLACED);
2031 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2033 /* Take an "isolate" reference and put new page on the LRU. */
2035 putback_lru_page(new_page);
2037 unlock_page(new_page);
2039 put_page(page); /* Drop the rmap reference */
2040 put_page(page); /* Drop the LRU isolation reference */
2042 count_vm_events(PGMIGRATE_SUCCESS, HPAGE_PMD_NR);
2043 count_vm_numa_events(NUMA_PAGE_MIGRATE, HPAGE_PMD_NR);
2045 mod_node_page_state(page_pgdat(page),
2046 NR_ISOLATED_ANON + page_lru,
2051 count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR);
2053 ptl = pmd_lock(mm, pmd);
2054 if (pmd_same(*pmd, entry)) {
2055 entry = pmd_modify(entry, vma->vm_page_prot);
2056 set_pmd_at(mm, mmun_start, pmd, entry);
2057 update_mmu_cache_pmd(vma, address, &entry);
2066 #endif /* CONFIG_NUMA_BALANCING */
2068 #endif /* CONFIG_NUMA */