1 // SPDX-License-Identifier: GPL-2.0
3 * Memory Migration functionality - linux/mm/migrate.c
5 * Copyright (C) 2006 Silicon Graphics, Inc., Christoph Lameter
7 * Page migration was first developed in the context of the memory hotplug
8 * project. The main authors of the migration code are:
10 * IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
11 * Hirokazu Takahashi <taka@valinux.co.jp>
12 * Dave Hansen <haveblue@us.ibm.com>
16 #include <linux/migrate.h>
17 #include <linux/export.h>
18 #include <linux/swap.h>
19 #include <linux/swapops.h>
20 #include <linux/pagemap.h>
21 #include <linux/buffer_head.h>
22 #include <linux/mm_inline.h>
23 #include <linux/nsproxy.h>
24 #include <linux/pagevec.h>
25 #include <linux/ksm.h>
26 #include <linux/rmap.h>
27 #include <linux/topology.h>
28 #include <linux/cpu.h>
29 #include <linux/cpuset.h>
30 #include <linux/writeback.h>
31 #include <linux/mempolicy.h>
32 #include <linux/vmalloc.h>
33 #include <linux/security.h>
34 #include <linux/backing-dev.h>
35 #include <linux/compaction.h>
36 #include <linux/syscalls.h>
37 #include <linux/hugetlb.h>
38 #include <linux/hugetlb_cgroup.h>
39 #include <linux/gfp.h>
40 #include <linux/pfn_t.h>
41 #include <linux/memremap.h>
42 #include <linux/userfaultfd_k.h>
43 #include <linux/balloon_compaction.h>
44 #include <linux/mmu_notifier.h>
45 #include <linux/page_idle.h>
46 #include <linux/page_owner.h>
47 #include <linux/sched/mm.h>
48 #include <linux/ptrace.h>
50 #include <asm/tlbflush.h>
52 #define CREATE_TRACE_POINTS
53 #include <trace/events/migrate.h>
58 * migrate_prep() needs to be called before we start compiling a list of pages
59 * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is
60 * undesirable, use migrate_prep_local()
62 int migrate_prep(void)
65 * Clear the LRU lists so pages can be isolated.
66 * Note that pages may be moved off the LRU after we have
67 * drained them. Those pages will fail to migrate like other
68 * pages that may be busy.
75 /* Do the necessary work of migrate_prep but not if it involves other CPUs */
76 int migrate_prep_local(void)
83 int isolate_movable_page(struct page
*page
, isolate_mode_t mode
)
85 struct address_space
*mapping
;
88 * Avoid burning cycles with pages that are yet under __free_pages(),
89 * or just got freed under us.
91 * In case we 'win' a race for a movable page being freed under us and
92 * raise its refcount preventing __free_pages() from doing its job
93 * the put_page() at the end of this block will take care of
94 * release this page, thus avoiding a nasty leakage.
96 if (unlikely(!get_page_unless_zero(page
)))
100 * Check PageMovable before holding a PG_lock because page's owner
101 * assumes anybody doesn't touch PG_lock of newly allocated page
102 * so unconditionally grapping the lock ruins page's owner side.
104 if (unlikely(!__PageMovable(page
)))
107 * As movable pages are not isolated from LRU lists, concurrent
108 * compaction threads can race against page migration functions
109 * as well as race against the releasing a page.
111 * In order to avoid having an already isolated movable page
112 * being (wrongly) re-isolated while it is under migration,
113 * or to avoid attempting to isolate pages being released,
114 * lets be sure we have the page lock
115 * before proceeding with the movable page isolation steps.
117 if (unlikely(!trylock_page(page
)))
120 if (!PageMovable(page
) || PageIsolated(page
))
121 goto out_no_isolated
;
123 mapping
= page_mapping(page
);
124 VM_BUG_ON_PAGE(!mapping
, page
);
126 if (!mapping
->a_ops
->isolate_page(page
, mode
))
127 goto out_no_isolated
;
129 /* Driver shouldn't use PG_isolated bit of page->flags */
130 WARN_ON_ONCE(PageIsolated(page
));
131 __SetPageIsolated(page
);
144 /* It should be called on page which is PG_movable */
145 void putback_movable_page(struct page
*page
)
147 struct address_space
*mapping
;
149 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
150 VM_BUG_ON_PAGE(!PageMovable(page
), page
);
151 VM_BUG_ON_PAGE(!PageIsolated(page
), page
);
153 mapping
= page_mapping(page
);
154 mapping
->a_ops
->putback_page(page
);
155 __ClearPageIsolated(page
);
159 * Put previously isolated pages back onto the appropriate lists
160 * from where they were once taken off for compaction/migration.
162 * This function shall be used whenever the isolated pageset has been
163 * built from lru, balloon, hugetlbfs page. See isolate_migratepages_range()
164 * and isolate_huge_page().
166 void putback_movable_pages(struct list_head
*l
)
171 list_for_each_entry_safe(page
, page2
, l
, lru
) {
172 if (unlikely(PageHuge(page
))) {
173 putback_active_hugepage(page
);
176 list_del(&page
->lru
);
178 * We isolated non-lru movable page so here we can use
179 * __PageMovable because LRU page's mapping cannot have
180 * PAGE_MAPPING_MOVABLE.
182 if (unlikely(__PageMovable(page
))) {
183 VM_BUG_ON_PAGE(!PageIsolated(page
), page
);
185 if (PageMovable(page
))
186 putback_movable_page(page
);
188 __ClearPageIsolated(page
);
192 mod_node_page_state(page_pgdat(page
), NR_ISOLATED_ANON
+
193 page_is_file_cache(page
), -hpage_nr_pages(page
));
194 putback_lru_page(page
);
200 * Restore a potential migration pte to a working pte entry
202 static bool remove_migration_pte(struct page
*page
, struct vm_area_struct
*vma
,
203 unsigned long addr
, void *old
)
205 struct page_vma_mapped_walk pvmw
= {
209 .flags
= PVMW_SYNC
| PVMW_MIGRATION
,
215 VM_BUG_ON_PAGE(PageTail(page
), page
);
216 while (page_vma_mapped_walk(&pvmw
)) {
220 new = page
- pvmw
.page
->index
+
221 linear_page_index(vma
, pvmw
.address
);
223 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
224 /* PMD-mapped THP migration entry */
226 VM_BUG_ON_PAGE(PageHuge(page
) || !PageTransCompound(page
), page
);
227 remove_migration_pmd(&pvmw
, new);
233 pte
= pte_mkold(mk_pte(new, READ_ONCE(vma
->vm_page_prot
)));
234 if (pte_swp_soft_dirty(*pvmw
.pte
))
235 pte
= pte_mksoft_dirty(pte
);
238 * Recheck VMA as permissions can change since migration started
240 entry
= pte_to_swp_entry(*pvmw
.pte
);
241 if (is_write_migration_entry(entry
))
242 pte
= maybe_mkwrite(pte
, vma
);
244 if (unlikely(is_zone_device_page(new))) {
245 if (is_device_private_page(new)) {
246 entry
= make_device_private_entry(new, pte_write(pte
));
247 pte
= swp_entry_to_pte(entry
);
248 } else if (is_device_public_page(new)) {
249 pte
= pte_mkdevmap(pte
);
250 flush_dcache_page(new);
253 flush_dcache_page(new);
255 #ifdef CONFIG_HUGETLB_PAGE
257 pte
= pte_mkhuge(pte
);
258 pte
= arch_make_huge_pte(pte
, vma
, new, 0);
259 set_huge_pte_at(vma
->vm_mm
, pvmw
.address
, pvmw
.pte
, pte
);
261 hugepage_add_anon_rmap(new, vma
, pvmw
.address
);
263 page_dup_rmap(new, true);
267 set_pte_at(vma
->vm_mm
, pvmw
.address
, pvmw
.pte
, pte
);
270 page_add_anon_rmap(new, vma
, pvmw
.address
, false);
272 page_add_file_rmap(new, false);
274 if (vma
->vm_flags
& VM_LOCKED
&& !PageTransCompound(new))
277 if (PageTransHuge(page
) && PageMlocked(page
))
278 clear_page_mlock(page
);
280 /* No need to invalidate - it was non-present before */
281 update_mmu_cache(vma
, pvmw
.address
, pvmw
.pte
);
288 * Get rid of all migration entries and replace them by
289 * references to the indicated page.
291 void remove_migration_ptes(struct page
*old
, struct page
*new, bool locked
)
293 struct rmap_walk_control rwc
= {
294 .rmap_one
= remove_migration_pte
,
299 rmap_walk_locked(new, &rwc
);
301 rmap_walk(new, &rwc
);
305 * Something used the pte of a page under migration. We need to
306 * get to the page and wait until migration is finished.
307 * When we return from this function the fault will be retried.
309 void __migration_entry_wait(struct mm_struct
*mm
, pte_t
*ptep
,
318 if (!is_swap_pte(pte
))
321 entry
= pte_to_swp_entry(pte
);
322 if (!is_migration_entry(entry
))
325 page
= migration_entry_to_page(entry
);
328 * Once radix-tree replacement of page migration started, page_count
329 * *must* be zero. And, we don't want to call wait_on_page_locked()
330 * against a page without get_page().
331 * So, we use get_page_unless_zero(), here. Even failed, page fault
334 if (!get_page_unless_zero(page
))
336 pte_unmap_unlock(ptep
, ptl
);
337 wait_on_page_locked(page
);
341 pte_unmap_unlock(ptep
, ptl
);
344 void migration_entry_wait(struct mm_struct
*mm
, pmd_t
*pmd
,
345 unsigned long address
)
347 spinlock_t
*ptl
= pte_lockptr(mm
, pmd
);
348 pte_t
*ptep
= pte_offset_map(pmd
, address
);
349 __migration_entry_wait(mm
, ptep
, ptl
);
352 void migration_entry_wait_huge(struct vm_area_struct
*vma
,
353 struct mm_struct
*mm
, pte_t
*pte
)
355 spinlock_t
*ptl
= huge_pte_lockptr(hstate_vma(vma
), mm
, pte
);
356 __migration_entry_wait(mm
, pte
, ptl
);
359 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
360 void pmd_migration_entry_wait(struct mm_struct
*mm
, pmd_t
*pmd
)
365 ptl
= pmd_lock(mm
, pmd
);
366 if (!is_pmd_migration_entry(*pmd
))
368 page
= migration_entry_to_page(pmd_to_swp_entry(*pmd
));
369 if (!get_page_unless_zero(page
))
372 wait_on_page_locked(page
);
381 /* Returns true if all buffers are successfully locked */
382 static bool buffer_migrate_lock_buffers(struct buffer_head
*head
,
383 enum migrate_mode mode
)
385 struct buffer_head
*bh
= head
;
387 /* Simple case, sync compaction */
388 if (mode
!= MIGRATE_ASYNC
) {
392 bh
= bh
->b_this_page
;
394 } while (bh
!= head
);
399 /* async case, we cannot block on lock_buffer so use trylock_buffer */
402 if (!trylock_buffer(bh
)) {
404 * We failed to lock the buffer and cannot stall in
405 * async migration. Release the taken locks
407 struct buffer_head
*failed_bh
= bh
;
410 while (bh
!= failed_bh
) {
413 bh
= bh
->b_this_page
;
418 bh
= bh
->b_this_page
;
419 } while (bh
!= head
);
423 static inline bool buffer_migrate_lock_buffers(struct buffer_head
*head
,
424 enum migrate_mode mode
)
428 #endif /* CONFIG_BLOCK */
431 * Replace the page in the mapping.
433 * The number of remaining references must be:
434 * 1 for anonymous pages without a mapping
435 * 2 for pages with a mapping
436 * 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
438 int migrate_page_move_mapping(struct address_space
*mapping
,
439 struct page
*newpage
, struct page
*page
,
440 struct buffer_head
*head
, enum migrate_mode mode
,
443 struct zone
*oldzone
, *newzone
;
445 int expected_count
= 1 + extra_count
;
449 * Device public or private pages have an extra refcount as they are
452 expected_count
+= is_device_private_page(page
);
453 expected_count
+= is_device_public_page(page
);
456 /* Anonymous page without mapping */
457 if (page_count(page
) != expected_count
)
460 /* No turning back from here */
461 newpage
->index
= page
->index
;
462 newpage
->mapping
= page
->mapping
;
463 if (PageSwapBacked(page
))
464 __SetPageSwapBacked(newpage
);
466 return MIGRATEPAGE_SUCCESS
;
469 oldzone
= page_zone(page
);
470 newzone
= page_zone(newpage
);
472 spin_lock_irq(&mapping
->tree_lock
);
474 pslot
= radix_tree_lookup_slot(&mapping
->page_tree
,
477 expected_count
+= 1 + page_has_private(page
);
478 if (page_count(page
) != expected_count
||
479 radix_tree_deref_slot_protected(pslot
, &mapping
->tree_lock
) != page
) {
480 spin_unlock_irq(&mapping
->tree_lock
);
484 if (!page_ref_freeze(page
, expected_count
)) {
485 spin_unlock_irq(&mapping
->tree_lock
);
490 * In the async migration case of moving a page with buffers, lock the
491 * buffers using trylock before the mapping is moved. If the mapping
492 * was moved, we later failed to lock the buffers and could not move
493 * the mapping back due to an elevated page count, we would have to
494 * block waiting on other references to be dropped.
496 if (mode
== MIGRATE_ASYNC
&& head
&&
497 !buffer_migrate_lock_buffers(head
, mode
)) {
498 page_ref_unfreeze(page
, expected_count
);
499 spin_unlock_irq(&mapping
->tree_lock
);
504 * Now we know that no one else is looking at the page:
505 * no turning back from here.
507 newpage
->index
= page
->index
;
508 newpage
->mapping
= page
->mapping
;
509 get_page(newpage
); /* add cache reference */
510 if (PageSwapBacked(page
)) {
511 __SetPageSwapBacked(newpage
);
512 if (PageSwapCache(page
)) {
513 SetPageSwapCache(newpage
);
514 set_page_private(newpage
, page_private(page
));
517 VM_BUG_ON_PAGE(PageSwapCache(page
), page
);
520 /* Move dirty while page refs frozen and newpage not yet exposed */
521 dirty
= PageDirty(page
);
523 ClearPageDirty(page
);
524 SetPageDirty(newpage
);
527 radix_tree_replace_slot(&mapping
->page_tree
, pslot
, newpage
);
530 * Drop cache reference from old page by unfreezing
531 * to one less reference.
532 * We know this isn't the last reference.
534 page_ref_unfreeze(page
, expected_count
- 1);
536 spin_unlock(&mapping
->tree_lock
);
537 /* Leave irq disabled to prevent preemption while updating stats */
540 * If moved to a different zone then also account
541 * the page for that zone. Other VM counters will be
542 * taken care of when we establish references to the
543 * new page and drop references to the old page.
545 * Note that anonymous pages are accounted for
546 * via NR_FILE_PAGES and NR_ANON_MAPPED if they
547 * are mapped to swap space.
549 if (newzone
!= oldzone
) {
550 __dec_node_state(oldzone
->zone_pgdat
, NR_FILE_PAGES
);
551 __inc_node_state(newzone
->zone_pgdat
, NR_FILE_PAGES
);
552 if (PageSwapBacked(page
) && !PageSwapCache(page
)) {
553 __dec_node_state(oldzone
->zone_pgdat
, NR_SHMEM
);
554 __inc_node_state(newzone
->zone_pgdat
, NR_SHMEM
);
556 if (dirty
&& mapping_cap_account_dirty(mapping
)) {
557 __dec_node_state(oldzone
->zone_pgdat
, NR_FILE_DIRTY
);
558 __dec_zone_state(oldzone
, NR_ZONE_WRITE_PENDING
);
559 __inc_node_state(newzone
->zone_pgdat
, NR_FILE_DIRTY
);
560 __inc_zone_state(newzone
, NR_ZONE_WRITE_PENDING
);
565 return MIGRATEPAGE_SUCCESS
;
567 EXPORT_SYMBOL(migrate_page_move_mapping
);
570 * The expected number of remaining references is the same as that
571 * of migrate_page_move_mapping().
573 int migrate_huge_page_move_mapping(struct address_space
*mapping
,
574 struct page
*newpage
, struct page
*page
)
579 spin_lock_irq(&mapping
->tree_lock
);
581 pslot
= radix_tree_lookup_slot(&mapping
->page_tree
,
584 expected_count
= 2 + page_has_private(page
);
585 if (page_count(page
) != expected_count
||
586 radix_tree_deref_slot_protected(pslot
, &mapping
->tree_lock
) != page
) {
587 spin_unlock_irq(&mapping
->tree_lock
);
591 if (!page_ref_freeze(page
, expected_count
)) {
592 spin_unlock_irq(&mapping
->tree_lock
);
596 newpage
->index
= page
->index
;
597 newpage
->mapping
= page
->mapping
;
601 radix_tree_replace_slot(&mapping
->page_tree
, pslot
, newpage
);
603 page_ref_unfreeze(page
, expected_count
- 1);
605 spin_unlock_irq(&mapping
->tree_lock
);
607 return MIGRATEPAGE_SUCCESS
;
611 * Gigantic pages are so large that we do not guarantee that page++ pointer
612 * arithmetic will work across the entire page. We need something more
615 static void __copy_gigantic_page(struct page
*dst
, struct page
*src
,
619 struct page
*dst_base
= dst
;
620 struct page
*src_base
= src
;
622 for (i
= 0; i
< nr_pages
; ) {
624 copy_highpage(dst
, src
);
627 dst
= mem_map_next(dst
, dst_base
, i
);
628 src
= mem_map_next(src
, src_base
, i
);
632 static void copy_huge_page(struct page
*dst
, struct page
*src
)
639 struct hstate
*h
= page_hstate(src
);
640 nr_pages
= pages_per_huge_page(h
);
642 if (unlikely(nr_pages
> MAX_ORDER_NR_PAGES
)) {
643 __copy_gigantic_page(dst
, src
, nr_pages
);
648 BUG_ON(!PageTransHuge(src
));
649 nr_pages
= hpage_nr_pages(src
);
652 for (i
= 0; i
< nr_pages
; i
++) {
654 copy_highpage(dst
+ i
, src
+ i
);
659 * Copy the page to its new location
661 void migrate_page_states(struct page
*newpage
, struct page
*page
)
666 SetPageError(newpage
);
667 if (PageReferenced(page
))
668 SetPageReferenced(newpage
);
669 if (PageUptodate(page
))
670 SetPageUptodate(newpage
);
671 if (TestClearPageActive(page
)) {
672 VM_BUG_ON_PAGE(PageUnevictable(page
), page
);
673 SetPageActive(newpage
);
674 } else if (TestClearPageUnevictable(page
))
675 SetPageUnevictable(newpage
);
676 if (PageChecked(page
))
677 SetPageChecked(newpage
);
678 if (PageMappedToDisk(page
))
679 SetPageMappedToDisk(newpage
);
681 /* Move dirty on pages not done by migrate_page_move_mapping() */
683 SetPageDirty(newpage
);
685 if (page_is_young(page
))
686 set_page_young(newpage
);
687 if (page_is_idle(page
))
688 set_page_idle(newpage
);
691 * Copy NUMA information to the new page, to prevent over-eager
692 * future migrations of this same page.
694 cpupid
= page_cpupid_xchg_last(page
, -1);
695 page_cpupid_xchg_last(newpage
, cpupid
);
697 ksm_migrate_page(newpage
, page
);
699 * Please do not reorder this without considering how mm/ksm.c's
700 * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache().
702 if (PageSwapCache(page
))
703 ClearPageSwapCache(page
);
704 ClearPagePrivate(page
);
705 set_page_private(page
, 0);
708 * If any waiters have accumulated on the new page then
711 if (PageWriteback(newpage
))
712 end_page_writeback(newpage
);
714 copy_page_owner(page
, newpage
);
716 mem_cgroup_migrate(page
, newpage
);
718 EXPORT_SYMBOL(migrate_page_states
);
720 void migrate_page_copy(struct page
*newpage
, struct page
*page
)
722 if (PageHuge(page
) || PageTransHuge(page
))
723 copy_huge_page(newpage
, page
);
725 copy_highpage(newpage
, page
);
727 migrate_page_states(newpage
, page
);
729 EXPORT_SYMBOL(migrate_page_copy
);
731 /************************************************************
732 * Migration functions
733 ***********************************************************/
736 * Common logic to directly migrate a single LRU page suitable for
737 * pages that do not use PagePrivate/PagePrivate2.
739 * Pages are locked upon entry and exit.
741 int migrate_page(struct address_space
*mapping
,
742 struct page
*newpage
, struct page
*page
,
743 enum migrate_mode mode
)
747 BUG_ON(PageWriteback(page
)); /* Writeback must be complete */
749 rc
= migrate_page_move_mapping(mapping
, newpage
, page
, NULL
, mode
, 0);
751 if (rc
!= MIGRATEPAGE_SUCCESS
)
754 if (mode
!= MIGRATE_SYNC_NO_COPY
)
755 migrate_page_copy(newpage
, page
);
757 migrate_page_states(newpage
, page
);
758 return MIGRATEPAGE_SUCCESS
;
760 EXPORT_SYMBOL(migrate_page
);
764 * Migration function for pages with buffers. This function can only be used
765 * if the underlying filesystem guarantees that no other references to "page"
768 int buffer_migrate_page(struct address_space
*mapping
,
769 struct page
*newpage
, struct page
*page
, enum migrate_mode mode
)
771 struct buffer_head
*bh
, *head
;
774 if (!page_has_buffers(page
))
775 return migrate_page(mapping
, newpage
, page
, mode
);
777 head
= page_buffers(page
);
779 rc
= migrate_page_move_mapping(mapping
, newpage
, page
, head
, mode
, 0);
781 if (rc
!= MIGRATEPAGE_SUCCESS
)
785 * In the async case, migrate_page_move_mapping locked the buffers
786 * with an IRQ-safe spinlock held. In the sync case, the buffers
787 * need to be locked now
789 if (mode
!= MIGRATE_ASYNC
)
790 BUG_ON(!buffer_migrate_lock_buffers(head
, mode
));
792 ClearPagePrivate(page
);
793 set_page_private(newpage
, page_private(page
));
794 set_page_private(page
, 0);
800 set_bh_page(bh
, newpage
, bh_offset(bh
));
801 bh
= bh
->b_this_page
;
803 } while (bh
!= head
);
805 SetPagePrivate(newpage
);
807 if (mode
!= MIGRATE_SYNC_NO_COPY
)
808 migrate_page_copy(newpage
, page
);
810 migrate_page_states(newpage
, page
);
816 bh
= bh
->b_this_page
;
818 } while (bh
!= head
);
820 return MIGRATEPAGE_SUCCESS
;
822 EXPORT_SYMBOL(buffer_migrate_page
);
826 * Writeback a page to clean the dirty state
828 static int writeout(struct address_space
*mapping
, struct page
*page
)
830 struct writeback_control wbc
= {
831 .sync_mode
= WB_SYNC_NONE
,
834 .range_end
= LLONG_MAX
,
839 if (!mapping
->a_ops
->writepage
)
840 /* No write method for the address space */
843 if (!clear_page_dirty_for_io(page
))
844 /* Someone else already triggered a write */
848 * A dirty page may imply that the underlying filesystem has
849 * the page on some queue. So the page must be clean for
850 * migration. Writeout may mean we loose the lock and the
851 * page state is no longer what we checked for earlier.
852 * At this point we know that the migration attempt cannot
855 remove_migration_ptes(page
, page
, false);
857 rc
= mapping
->a_ops
->writepage(page
, &wbc
);
859 if (rc
!= AOP_WRITEPAGE_ACTIVATE
)
860 /* unlocked. Relock */
863 return (rc
< 0) ? -EIO
: -EAGAIN
;
867 * Default handling if a filesystem does not provide a migration function.
869 static int fallback_migrate_page(struct address_space
*mapping
,
870 struct page
*newpage
, struct page
*page
, enum migrate_mode mode
)
872 if (PageDirty(page
)) {
873 /* Only writeback pages in full synchronous migration */
876 case MIGRATE_SYNC_NO_COPY
:
881 return writeout(mapping
, page
);
885 * Buffers may be managed in a filesystem specific way.
886 * We must have no buffers or drop them.
888 if (page_has_private(page
) &&
889 !try_to_release_page(page
, GFP_KERNEL
))
892 return migrate_page(mapping
, newpage
, page
, mode
);
896 * Move a page to a newly allocated page
897 * The page is locked and all ptes have been successfully removed.
899 * The new page will have replaced the old page if this function
904 * MIGRATEPAGE_SUCCESS - success
906 static int move_to_new_page(struct page
*newpage
, struct page
*page
,
907 enum migrate_mode mode
)
909 struct address_space
*mapping
;
911 bool is_lru
= !__PageMovable(page
);
913 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
914 VM_BUG_ON_PAGE(!PageLocked(newpage
), newpage
);
916 mapping
= page_mapping(page
);
918 if (likely(is_lru
)) {
920 rc
= migrate_page(mapping
, newpage
, page
, mode
);
921 else if (mapping
->a_ops
->migratepage
)
923 * Most pages have a mapping and most filesystems
924 * provide a migratepage callback. Anonymous pages
925 * are part of swap space which also has its own
926 * migratepage callback. This is the most common path
927 * for page migration.
929 rc
= mapping
->a_ops
->migratepage(mapping
, newpage
,
932 rc
= fallback_migrate_page(mapping
, newpage
,
936 * In case of non-lru page, it could be released after
937 * isolation step. In that case, we shouldn't try migration.
939 VM_BUG_ON_PAGE(!PageIsolated(page
), page
);
940 if (!PageMovable(page
)) {
941 rc
= MIGRATEPAGE_SUCCESS
;
942 __ClearPageIsolated(page
);
946 rc
= mapping
->a_ops
->migratepage(mapping
, newpage
,
948 WARN_ON_ONCE(rc
== MIGRATEPAGE_SUCCESS
&&
949 !PageIsolated(page
));
953 * When successful, old pagecache page->mapping must be cleared before
954 * page is freed; but stats require that PageAnon be left as PageAnon.
956 if (rc
== MIGRATEPAGE_SUCCESS
) {
957 if (__PageMovable(page
)) {
958 VM_BUG_ON_PAGE(!PageIsolated(page
), page
);
961 * We clear PG_movable under page_lock so any compactor
962 * cannot try to migrate this page.
964 __ClearPageIsolated(page
);
968 * Anonymous and movable page->mapping will be cleard by
969 * free_pages_prepare so don't reset it here for keeping
970 * the type to work PageAnon, for example.
972 if (!PageMappingFlags(page
))
973 page
->mapping
= NULL
;
979 static int __unmap_and_move(struct page
*page
, struct page
*newpage
,
980 int force
, enum migrate_mode mode
)
983 int page_was_mapped
= 0;
984 struct anon_vma
*anon_vma
= NULL
;
985 bool is_lru
= !__PageMovable(page
);
987 if (!trylock_page(page
)) {
988 if (!force
|| mode
== MIGRATE_ASYNC
)
992 * It's not safe for direct compaction to call lock_page.
993 * For example, during page readahead pages are added locked
994 * to the LRU. Later, when the IO completes the pages are
995 * marked uptodate and unlocked. However, the queueing
996 * could be merging multiple pages for one bio (e.g.
997 * mpage_readpages). If an allocation happens for the
998 * second or third page, the process can end up locking
999 * the same page twice and deadlocking. Rather than
1000 * trying to be clever about what pages can be locked,
1001 * avoid the use of lock_page for direct compaction
1004 if (current
->flags
& PF_MEMALLOC
)
1010 if (PageWriteback(page
)) {
1012 * Only in the case of a full synchronous migration is it
1013 * necessary to wait for PageWriteback. In the async case,
1014 * the retry loop is too short and in the sync-light case,
1015 * the overhead of stalling is too much
1019 case MIGRATE_SYNC_NO_COPY
:
1027 wait_on_page_writeback(page
);
1031 * By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
1032 * we cannot notice that anon_vma is freed while we migrates a page.
1033 * This get_anon_vma() delays freeing anon_vma pointer until the end
1034 * of migration. File cache pages are no problem because of page_lock()
1035 * File Caches may use write_page() or lock_page() in migration, then,
1036 * just care Anon page here.
1038 * Only page_get_anon_vma() understands the subtleties of
1039 * getting a hold on an anon_vma from outside one of its mms.
1040 * But if we cannot get anon_vma, then we won't need it anyway,
1041 * because that implies that the anon page is no longer mapped
1042 * (and cannot be remapped so long as we hold the page lock).
1044 if (PageAnon(page
) && !PageKsm(page
))
1045 anon_vma
= page_get_anon_vma(page
);
1048 * Block others from accessing the new page when we get around to
1049 * establishing additional references. We are usually the only one
1050 * holding a reference to newpage at this point. We used to have a BUG
1051 * here if trylock_page(newpage) fails, but would like to allow for
1052 * cases where there might be a race with the previous use of newpage.
1053 * This is much like races on refcount of oldpage: just don't BUG().
1055 if (unlikely(!trylock_page(newpage
)))
1058 if (unlikely(!is_lru
)) {
1059 rc
= move_to_new_page(newpage
, page
, mode
);
1060 goto out_unlock_both
;
1064 * Corner case handling:
1065 * 1. When a new swap-cache page is read into, it is added to the LRU
1066 * and treated as swapcache but it has no rmap yet.
1067 * Calling try_to_unmap() against a page->mapping==NULL page will
1068 * trigger a BUG. So handle it here.
1069 * 2. An orphaned page (see truncate_complete_page) might have
1070 * fs-private metadata. The page can be picked up due to memory
1071 * offlining. Everywhere else except page reclaim, the page is
1072 * invisible to the vm, so the page can not be migrated. So try to
1073 * free the metadata, so the page can be freed.
1075 if (!page
->mapping
) {
1076 VM_BUG_ON_PAGE(PageAnon(page
), page
);
1077 if (page_has_private(page
)) {
1078 try_to_free_buffers(page
);
1079 goto out_unlock_both
;
1081 } else if (page_mapped(page
)) {
1082 /* Establish migration ptes */
1083 VM_BUG_ON_PAGE(PageAnon(page
) && !PageKsm(page
) && !anon_vma
,
1086 TTU_MIGRATION
|TTU_IGNORE_MLOCK
|TTU_IGNORE_ACCESS
);
1087 page_was_mapped
= 1;
1090 if (!page_mapped(page
))
1091 rc
= move_to_new_page(newpage
, page
, mode
);
1093 if (page_was_mapped
)
1094 remove_migration_ptes(page
,
1095 rc
== MIGRATEPAGE_SUCCESS
? newpage
: page
, false);
1098 unlock_page(newpage
);
1100 /* Drop an anon_vma reference if we took one */
1102 put_anon_vma(anon_vma
);
1106 * If migration is successful, decrease refcount of the newpage
1107 * which will not free the page because new page owner increased
1108 * refcounter. As well, if it is LRU page, add the page to LRU
1109 * list in here. Use the old state of the isolated source page to
1110 * determine if we migrated a LRU page. newpage was already unlocked
1111 * and possibly modified by its owner - don't rely on the page
1114 if (rc
== MIGRATEPAGE_SUCCESS
) {
1115 if (unlikely(!is_lru
))
1118 putback_lru_page(newpage
);
1125 * gcc 4.7 and 4.8 on arm get an ICEs when inlining unmap_and_move(). Work
1128 #if (GCC_VERSION >= 40700 && GCC_VERSION < 40900) && defined(CONFIG_ARM)
1129 #define ICE_noinline noinline
1131 #define ICE_noinline
1135 * Obtain the lock on page, remove all ptes and migrate the page
1136 * to the newly allocated page in newpage.
1138 static ICE_noinline
int unmap_and_move(new_page_t get_new_page
,
1139 free_page_t put_new_page
,
1140 unsigned long private, struct page
*page
,
1141 int force
, enum migrate_mode mode
,
1142 enum migrate_reason reason
)
1144 int rc
= MIGRATEPAGE_SUCCESS
;
1146 struct page
*newpage
;
1148 newpage
= get_new_page(page
, private, &result
);
1152 if (page_count(page
) == 1) {
1153 /* page was freed from under us. So we are done. */
1154 ClearPageActive(page
);
1155 ClearPageUnevictable(page
);
1156 if (unlikely(__PageMovable(page
))) {
1158 if (!PageMovable(page
))
1159 __ClearPageIsolated(page
);
1163 put_new_page(newpage
, private);
1169 if (unlikely(PageTransHuge(page
) && !PageTransHuge(newpage
))) {
1171 rc
= split_huge_page(page
);
1177 rc
= __unmap_and_move(page
, newpage
, force
, mode
);
1178 if (rc
== MIGRATEPAGE_SUCCESS
)
1179 set_page_owner_migrate_reason(newpage
, reason
);
1182 if (rc
!= -EAGAIN
) {
1184 * A page that has been migrated has all references
1185 * removed and will be freed. A page that has not been
1186 * migrated will have kepts its references and be
1189 list_del(&page
->lru
);
1192 * Compaction can migrate also non-LRU pages which are
1193 * not accounted to NR_ISOLATED_*. They can be recognized
1196 if (likely(!__PageMovable(page
)))
1197 mod_node_page_state(page_pgdat(page
), NR_ISOLATED_ANON
+
1198 page_is_file_cache(page
), -hpage_nr_pages(page
));
1202 * If migration is successful, releases reference grabbed during
1203 * isolation. Otherwise, restore the page to right list unless
1206 if (rc
== MIGRATEPAGE_SUCCESS
) {
1208 if (reason
== MR_MEMORY_FAILURE
) {
1210 * Set PG_HWPoison on just freed page
1211 * intentionally. Although it's rather weird,
1212 * it's how HWPoison flag works at the moment.
1214 if (!test_set_page_hwpoison(page
))
1215 num_poisoned_pages_inc();
1218 if (rc
!= -EAGAIN
) {
1219 if (likely(!__PageMovable(page
))) {
1220 putback_lru_page(page
);
1225 if (PageMovable(page
))
1226 putback_movable_page(page
);
1228 __ClearPageIsolated(page
);
1234 put_new_page(newpage
, private);
1243 *result
= page_to_nid(newpage
);
1249 * Counterpart of unmap_and_move_page() for hugepage migration.
1251 * This function doesn't wait the completion of hugepage I/O
1252 * because there is no race between I/O and migration for hugepage.
1253 * Note that currently hugepage I/O occurs only in direct I/O
1254 * where no lock is held and PG_writeback is irrelevant,
1255 * and writeback status of all subpages are counted in the reference
1256 * count of the head page (i.e. if all subpages of a 2MB hugepage are
1257 * under direct I/O, the reference of the head page is 512 and a bit more.)
1258 * This means that when we try to migrate hugepage whose subpages are
1259 * doing direct I/O, some references remain after try_to_unmap() and
1260 * hugepage migration fails without data corruption.
1262 * There is also no race when direct I/O is issued on the page under migration,
1263 * because then pte is replaced with migration swap entry and direct I/O code
1264 * will wait in the page fault for migration to complete.
1266 static int unmap_and_move_huge_page(new_page_t get_new_page
,
1267 free_page_t put_new_page
, unsigned long private,
1268 struct page
*hpage
, int force
,
1269 enum migrate_mode mode
, int reason
)
1273 int page_was_mapped
= 0;
1274 struct page
*new_hpage
;
1275 struct anon_vma
*anon_vma
= NULL
;
1278 * Movability of hugepages depends on architectures and hugepage size.
1279 * This check is necessary because some callers of hugepage migration
1280 * like soft offline and memory hotremove don't walk through page
1281 * tables or check whether the hugepage is pmd-based or not before
1282 * kicking migration.
1284 if (!hugepage_migration_supported(page_hstate(hpage
))) {
1285 putback_active_hugepage(hpage
);
1289 new_hpage
= get_new_page(hpage
, private, &result
);
1293 if (!trylock_page(hpage
)) {
1298 case MIGRATE_SYNC_NO_COPY
:
1307 * Check for pages which are in the process of being freed. Without
1308 * page_mapping() set, hugetlbfs specific move page routine will not
1309 * be called and we could leak usage counts for subpools.
1311 if (page_private(hpage
) && !page_mapping(hpage
)) {
1316 if (PageAnon(hpage
))
1317 anon_vma
= page_get_anon_vma(hpage
);
1319 if (unlikely(!trylock_page(new_hpage
)))
1322 if (page_mapped(hpage
)) {
1324 TTU_MIGRATION
|TTU_IGNORE_MLOCK
|TTU_IGNORE_ACCESS
);
1325 page_was_mapped
= 1;
1328 if (!page_mapped(hpage
))
1329 rc
= move_to_new_page(new_hpage
, hpage
, mode
);
1331 if (page_was_mapped
)
1332 remove_migration_ptes(hpage
,
1333 rc
== MIGRATEPAGE_SUCCESS
? new_hpage
: hpage
, false);
1335 unlock_page(new_hpage
);
1339 put_anon_vma(anon_vma
);
1341 if (rc
== MIGRATEPAGE_SUCCESS
) {
1342 hugetlb_cgroup_migrate(hpage
, new_hpage
);
1343 put_new_page
= NULL
;
1344 set_page_owner_migrate_reason(new_hpage
, reason
);
1351 putback_active_hugepage(hpage
);
1352 if (reason
== MR_MEMORY_FAILURE
&& !test_set_page_hwpoison(hpage
))
1353 num_poisoned_pages_inc();
1356 * If migration was not successful and there's a freeing callback, use
1357 * it. Otherwise, put_page() will drop the reference grabbed during
1361 put_new_page(new_hpage
, private);
1363 putback_active_hugepage(new_hpage
);
1369 *result
= page_to_nid(new_hpage
);
1375 * migrate_pages - migrate the pages specified in a list, to the free pages
1376 * supplied as the target for the page migration
1378 * @from: The list of pages to be migrated.
1379 * @get_new_page: The function used to allocate free pages to be used
1380 * as the target of the page migration.
1381 * @put_new_page: The function used to free target pages if migration
1382 * fails, or NULL if no special handling is necessary.
1383 * @private: Private data to be passed on to get_new_page()
1384 * @mode: The migration mode that specifies the constraints for
1385 * page migration, if any.
1386 * @reason: The reason for page migration.
1388 * The function returns after 10 attempts or if no pages are movable any more
1389 * because the list has become empty or no retryable pages exist any more.
1390 * The caller should call putback_movable_pages() to return pages to the LRU
1391 * or free list only if ret != 0.
1393 * Returns the number of pages that were not migrated, or an error code.
1395 int migrate_pages(struct list_head
*from
, new_page_t get_new_page
,
1396 free_page_t put_new_page
, unsigned long private,
1397 enum migrate_mode mode
, int reason
)
1401 int nr_succeeded
= 0;
1405 int swapwrite
= current
->flags
& PF_SWAPWRITE
;
1409 current
->flags
|= PF_SWAPWRITE
;
1411 for(pass
= 0; pass
< 10 && retry
; pass
++) {
1414 list_for_each_entry_safe(page
, page2
, from
, lru
) {
1418 rc
= unmap_and_move_huge_page(get_new_page
,
1419 put_new_page
, private, page
,
1420 pass
> 2, mode
, reason
);
1422 rc
= unmap_and_move(get_new_page
, put_new_page
,
1423 private, page
, pass
> 2, mode
,
1433 case MIGRATEPAGE_SUCCESS
:
1438 * Permanent failure (-EBUSY, -ENOSYS, etc.):
1439 * unlike -EAGAIN case, the failed page is
1440 * removed from migration page list and not
1441 * retried in the next outer loop.
1452 count_vm_events(PGMIGRATE_SUCCESS
, nr_succeeded
);
1454 count_vm_events(PGMIGRATE_FAIL
, nr_failed
);
1455 trace_mm_migrate_pages(nr_succeeded
, nr_failed
, mode
, reason
);
1458 current
->flags
&= ~PF_SWAPWRITE
;
1465 * Move a list of individual pages
1467 struct page_to_node
{
1474 static struct page
*new_page_node(struct page
*p
, unsigned long private,
1477 struct page_to_node
*pm
= (struct page_to_node
*)private;
1479 while (pm
->node
!= MAX_NUMNODES
&& pm
->page
!= p
)
1482 if (pm
->node
== MAX_NUMNODES
)
1485 *result
= &pm
->status
;
1488 return alloc_huge_page_node(page_hstate(compound_head(p
)),
1490 else if (thp_migration_supported() && PageTransHuge(p
)) {
1493 thp
= alloc_pages_node(pm
->node
,
1494 (GFP_TRANSHUGE
| __GFP_THISNODE
) & ~__GFP_RECLAIM
,
1498 prep_transhuge_page(thp
);
1501 return __alloc_pages_node(pm
->node
,
1502 GFP_HIGHUSER_MOVABLE
| __GFP_THISNODE
, 0);
1506 * Move a set of pages as indicated in the pm array. The addr
1507 * field must be set to the virtual address of the page to be moved
1508 * and the node number must contain a valid target node.
1509 * The pm array ends with node = MAX_NUMNODES.
1511 static int do_move_page_to_node_array(struct mm_struct
*mm
,
1512 struct page_to_node
*pm
,
1516 struct page_to_node
*pp
;
1517 LIST_HEAD(pagelist
);
1519 down_read(&mm
->mmap_sem
);
1522 * Build a list of pages to migrate
1524 for (pp
= pm
; pp
->node
!= MAX_NUMNODES
; pp
++) {
1525 struct vm_area_struct
*vma
;
1528 unsigned int follflags
;
1531 vma
= find_vma(mm
, pp
->addr
);
1532 if (!vma
|| pp
->addr
< vma
->vm_start
|| !vma_migratable(vma
))
1535 /* FOLL_DUMP to ignore special (like zero) pages */
1536 follflags
= FOLL_GET
| FOLL_DUMP
;
1537 if (!thp_migration_supported())
1538 follflags
|= FOLL_SPLIT
;
1539 page
= follow_page(vma
, pp
->addr
, follflags
);
1541 err
= PTR_ERR(page
);
1549 err
= page_to_nid(page
);
1551 if (err
== pp
->node
)
1553 * Node already in the right place
1558 if (page_mapcount(page
) > 1 &&
1562 if (PageHuge(page
)) {
1563 if (PageHead(page
)) {
1564 isolate_huge_page(page
, &pagelist
);
1571 pp
->page
= compound_head(page
);
1572 head
= compound_head(page
);
1573 err
= isolate_lru_page(head
);
1575 list_add_tail(&head
->lru
, &pagelist
);
1576 mod_node_page_state(page_pgdat(head
),
1577 NR_ISOLATED_ANON
+ page_is_file_cache(head
),
1578 hpage_nr_pages(head
));
1582 * Either remove the duplicate refcount from
1583 * isolate_lru_page() or drop the page ref if it was
1592 if (!list_empty(&pagelist
)) {
1593 err
= migrate_pages(&pagelist
, new_page_node
, NULL
,
1594 (unsigned long)pm
, MIGRATE_SYNC
, MR_SYSCALL
);
1596 putback_movable_pages(&pagelist
);
1599 up_read(&mm
->mmap_sem
);
1604 * Migrate an array of page address onto an array of nodes and fill
1605 * the corresponding array of status.
1607 static int do_pages_move(struct mm_struct
*mm
, nodemask_t task_nodes
,
1608 unsigned long nr_pages
,
1609 const void __user
* __user
*pages
,
1610 const int __user
*nodes
,
1611 int __user
*status
, int flags
)
1613 struct page_to_node
*pm
;
1614 unsigned long chunk_nr_pages
;
1615 unsigned long chunk_start
;
1619 pm
= (struct page_to_node
*)__get_free_page(GFP_KERNEL
);
1626 * Store a chunk of page_to_node array in a page,
1627 * but keep the last one as a marker
1629 chunk_nr_pages
= (PAGE_SIZE
/ sizeof(struct page_to_node
)) - 1;
1631 for (chunk_start
= 0;
1632 chunk_start
< nr_pages
;
1633 chunk_start
+= chunk_nr_pages
) {
1636 if (chunk_start
+ chunk_nr_pages
> nr_pages
)
1637 chunk_nr_pages
= nr_pages
- chunk_start
;
1639 /* fill the chunk pm with addrs and nodes from user-space */
1640 for (j
= 0; j
< chunk_nr_pages
; j
++) {
1641 const void __user
*p
;
1645 if (get_user(p
, pages
+ j
+ chunk_start
))
1647 pm
[j
].addr
= (unsigned long) p
;
1649 if (get_user(node
, nodes
+ j
+ chunk_start
))
1653 if (node
< 0 || node
>= MAX_NUMNODES
)
1656 if (!node_state(node
, N_MEMORY
))
1660 if (!node_isset(node
, task_nodes
))
1666 /* End marker for this chunk */
1667 pm
[chunk_nr_pages
].node
= MAX_NUMNODES
;
1669 /* Migrate this chunk */
1670 err
= do_move_page_to_node_array(mm
, pm
,
1671 flags
& MPOL_MF_MOVE_ALL
);
1675 /* Return status information */
1676 for (j
= 0; j
< chunk_nr_pages
; j
++)
1677 if (put_user(pm
[j
].status
, status
+ j
+ chunk_start
)) {
1685 free_page((unsigned long)pm
);
1691 * Determine the nodes of an array of pages and store it in an array of status.
1693 static void do_pages_stat_array(struct mm_struct
*mm
, unsigned long nr_pages
,
1694 const void __user
**pages
, int *status
)
1698 down_read(&mm
->mmap_sem
);
1700 for (i
= 0; i
< nr_pages
; i
++) {
1701 unsigned long addr
= (unsigned long)(*pages
);
1702 struct vm_area_struct
*vma
;
1706 vma
= find_vma(mm
, addr
);
1707 if (!vma
|| addr
< vma
->vm_start
)
1710 /* FOLL_DUMP to ignore special (like zero) pages */
1711 page
= follow_page(vma
, addr
, FOLL_DUMP
);
1713 err
= PTR_ERR(page
);
1717 err
= page
? page_to_nid(page
) : -ENOENT
;
1725 up_read(&mm
->mmap_sem
);
1729 * Determine the nodes of a user array of pages and store it in
1730 * a user array of status.
1732 static int do_pages_stat(struct mm_struct
*mm
, unsigned long nr_pages
,
1733 const void __user
* __user
*pages
,
1736 #define DO_PAGES_STAT_CHUNK_NR 16
1737 const void __user
*chunk_pages
[DO_PAGES_STAT_CHUNK_NR
];
1738 int chunk_status
[DO_PAGES_STAT_CHUNK_NR
];
1741 unsigned long chunk_nr
;
1743 chunk_nr
= nr_pages
;
1744 if (chunk_nr
> DO_PAGES_STAT_CHUNK_NR
)
1745 chunk_nr
= DO_PAGES_STAT_CHUNK_NR
;
1747 if (copy_from_user(chunk_pages
, pages
, chunk_nr
* sizeof(*chunk_pages
)))
1750 do_pages_stat_array(mm
, chunk_nr
, chunk_pages
, chunk_status
);
1752 if (copy_to_user(status
, chunk_status
, chunk_nr
* sizeof(*status
)))
1757 nr_pages
-= chunk_nr
;
1759 return nr_pages
? -EFAULT
: 0;
1763 * Move a list of pages in the address space of the currently executing
1766 SYSCALL_DEFINE6(move_pages
, pid_t
, pid
, unsigned long, nr_pages
,
1767 const void __user
* __user
*, pages
,
1768 const int __user
*, nodes
,
1769 int __user
*, status
, int, flags
)
1771 struct task_struct
*task
;
1772 struct mm_struct
*mm
;
1774 nodemask_t task_nodes
;
1777 if (flags
& ~(MPOL_MF_MOVE
|MPOL_MF_MOVE_ALL
))
1780 if ((flags
& MPOL_MF_MOVE_ALL
) && !capable(CAP_SYS_NICE
))
1783 /* Find the mm_struct */
1785 task
= pid
? find_task_by_vpid(pid
) : current
;
1790 get_task_struct(task
);
1793 * Check if this process has the right to modify the specified
1794 * process. Use the regular "ptrace_may_access()" checks.
1796 if (!ptrace_may_access(task
, PTRACE_MODE_READ_REALCREDS
)) {
1803 err
= security_task_movememory(task
);
1807 task_nodes
= cpuset_mems_allowed(task
);
1808 mm
= get_task_mm(task
);
1809 put_task_struct(task
);
1815 err
= do_pages_move(mm
, task_nodes
, nr_pages
, pages
,
1816 nodes
, status
, flags
);
1818 err
= do_pages_stat(mm
, nr_pages
, pages
, status
);
1824 put_task_struct(task
);
1828 #ifdef CONFIG_NUMA_BALANCING
1830 * Returns true if this is a safe migration target node for misplaced NUMA
1831 * pages. Currently it only checks the watermarks which crude
1833 static bool migrate_balanced_pgdat(struct pglist_data
*pgdat
,
1834 unsigned long nr_migrate_pages
)
1838 for (z
= pgdat
->nr_zones
- 1; z
>= 0; z
--) {
1839 struct zone
*zone
= pgdat
->node_zones
+ z
;
1841 if (!populated_zone(zone
))
1844 /* Avoid waking kswapd by allocating pages_to_migrate pages. */
1845 if (!zone_watermark_ok(zone
, 0,
1846 high_wmark_pages(zone
) +
1855 static struct page
*alloc_misplaced_dst_page(struct page
*page
,
1859 int nid
= (int) data
;
1860 struct page
*newpage
;
1862 newpage
= __alloc_pages_node(nid
,
1863 (GFP_HIGHUSER_MOVABLE
|
1864 __GFP_THISNODE
| __GFP_NOMEMALLOC
|
1865 __GFP_NORETRY
| __GFP_NOWARN
) &
1872 * page migration rate limiting control.
1873 * Do not migrate more than @pages_to_migrate in a @migrate_interval_millisecs
1874 * window of time. Default here says do not migrate more than 1280M per second.
1876 static unsigned int migrate_interval_millisecs __read_mostly
= 100;
1877 static unsigned int ratelimit_pages __read_mostly
= 128 << (20 - PAGE_SHIFT
);
1879 /* Returns true if the node is migrate rate-limited after the update */
1880 static bool numamigrate_update_ratelimit(pg_data_t
*pgdat
,
1881 unsigned long nr_pages
)
1884 * Rate-limit the amount of data that is being migrated to a node.
1885 * Optimal placement is no good if the memory bus is saturated and
1886 * all the time is being spent migrating!
1888 if (time_after(jiffies
, pgdat
->numabalancing_migrate_next_window
)) {
1889 spin_lock(&pgdat
->numabalancing_migrate_lock
);
1890 pgdat
->numabalancing_migrate_nr_pages
= 0;
1891 pgdat
->numabalancing_migrate_next_window
= jiffies
+
1892 msecs_to_jiffies(migrate_interval_millisecs
);
1893 spin_unlock(&pgdat
->numabalancing_migrate_lock
);
1895 if (pgdat
->numabalancing_migrate_nr_pages
> ratelimit_pages
) {
1896 trace_mm_numa_migrate_ratelimit(current
, pgdat
->node_id
,
1902 * This is an unlocked non-atomic update so errors are possible.
1903 * The consequences are failing to migrate when we potentiall should
1904 * have which is not severe enough to warrant locking. If it is ever
1905 * a problem, it can be converted to a per-cpu counter.
1907 pgdat
->numabalancing_migrate_nr_pages
+= nr_pages
;
1911 static int numamigrate_isolate_page(pg_data_t
*pgdat
, struct page
*page
)
1915 VM_BUG_ON_PAGE(compound_order(page
) && !PageTransHuge(page
), page
);
1917 /* Avoid migrating to a node that is nearly full */
1918 if (!migrate_balanced_pgdat(pgdat
, 1UL << compound_order(page
)))
1921 if (isolate_lru_page(page
))
1925 * migrate_misplaced_transhuge_page() skips page migration's usual
1926 * check on page_count(), so we must do it here, now that the page
1927 * has been isolated: a GUP pin, or any other pin, prevents migration.
1928 * The expected page count is 3: 1 for page's mapcount and 1 for the
1929 * caller's pin and 1 for the reference taken by isolate_lru_page().
1931 if (PageTransHuge(page
) && page_count(page
) != 3) {
1932 putback_lru_page(page
);
1936 page_lru
= page_is_file_cache(page
);
1937 mod_node_page_state(page_pgdat(page
), NR_ISOLATED_ANON
+ page_lru
,
1938 hpage_nr_pages(page
));
1941 * Isolating the page has taken another reference, so the
1942 * caller's reference can be safely dropped without the page
1943 * disappearing underneath us during migration.
1949 bool pmd_trans_migrating(pmd_t pmd
)
1951 struct page
*page
= pmd_page(pmd
);
1952 return PageLocked(page
);
1956 * Attempt to migrate a misplaced page to the specified destination
1957 * node. Caller is expected to have an elevated reference count on
1958 * the page that will be dropped by this function before returning.
1960 int migrate_misplaced_page(struct page
*page
, struct vm_area_struct
*vma
,
1963 pg_data_t
*pgdat
= NODE_DATA(node
);
1966 LIST_HEAD(migratepages
);
1969 * Don't migrate file pages that are mapped in multiple processes
1970 * with execute permissions as they are probably shared libraries.
1972 if (page_mapcount(page
) != 1 && page_is_file_cache(page
) &&
1973 (vma
->vm_flags
& VM_EXEC
))
1977 * Rate-limit the amount of data that is being migrated to a node.
1978 * Optimal placement is no good if the memory bus is saturated and
1979 * all the time is being spent migrating!
1981 if (numamigrate_update_ratelimit(pgdat
, 1))
1984 isolated
= numamigrate_isolate_page(pgdat
, page
);
1988 list_add(&page
->lru
, &migratepages
);
1989 nr_remaining
= migrate_pages(&migratepages
, alloc_misplaced_dst_page
,
1990 NULL
, node
, MIGRATE_ASYNC
,
1993 if (!list_empty(&migratepages
)) {
1994 list_del(&page
->lru
);
1995 dec_node_page_state(page
, NR_ISOLATED_ANON
+
1996 page_is_file_cache(page
));
1997 putback_lru_page(page
);
2001 count_vm_numa_event(NUMA_PAGE_MIGRATE
);
2002 BUG_ON(!list_empty(&migratepages
));
2009 #endif /* CONFIG_NUMA_BALANCING */
2011 #if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
2013 * Migrates a THP to a given target node. page must be locked and is unlocked
2016 int migrate_misplaced_transhuge_page(struct mm_struct
*mm
,
2017 struct vm_area_struct
*vma
,
2018 pmd_t
*pmd
, pmd_t entry
,
2019 unsigned long address
,
2020 struct page
*page
, int node
)
2023 pg_data_t
*pgdat
= NODE_DATA(node
);
2025 struct page
*new_page
= NULL
;
2026 int page_lru
= page_is_file_cache(page
);
2027 unsigned long mmun_start
= address
& HPAGE_PMD_MASK
;
2028 unsigned long mmun_end
= mmun_start
+ HPAGE_PMD_SIZE
;
2031 * Rate-limit the amount of data that is being migrated to a node.
2032 * Optimal placement is no good if the memory bus is saturated and
2033 * all the time is being spent migrating!
2035 if (numamigrate_update_ratelimit(pgdat
, HPAGE_PMD_NR
))
2038 new_page
= alloc_pages_node(node
,
2039 (GFP_TRANSHUGE_LIGHT
| __GFP_THISNODE
),
2043 prep_transhuge_page(new_page
);
2045 isolated
= numamigrate_isolate_page(pgdat
, page
);
2051 /* Prepare a page as a migration target */
2052 __SetPageLocked(new_page
);
2053 if (PageSwapBacked(page
))
2054 __SetPageSwapBacked(new_page
);
2056 /* anon mapping, we can simply copy page->mapping to the new page: */
2057 new_page
->mapping
= page
->mapping
;
2058 new_page
->index
= page
->index
;
2059 migrate_page_copy(new_page
, page
);
2060 WARN_ON(PageLRU(new_page
));
2062 /* Recheck the target PMD */
2063 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
2064 ptl
= pmd_lock(mm
, pmd
);
2065 if (unlikely(!pmd_same(*pmd
, entry
) || !page_ref_freeze(page
, 2))) {
2067 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2069 /* Reverse changes made by migrate_page_copy() */
2070 if (TestClearPageActive(new_page
))
2071 SetPageActive(page
);
2072 if (TestClearPageUnevictable(new_page
))
2073 SetPageUnevictable(page
);
2075 unlock_page(new_page
);
2076 put_page(new_page
); /* Free it */
2078 /* Retake the callers reference and putback on LRU */
2080 putback_lru_page(page
);
2081 mod_node_page_state(page_pgdat(page
),
2082 NR_ISOLATED_ANON
+ page_lru
, -HPAGE_PMD_NR
);
2087 entry
= mk_huge_pmd(new_page
, vma
->vm_page_prot
);
2088 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
2091 * Clear the old entry under pagetable lock and establish the new PTE.
2092 * Any parallel GUP will either observe the old page blocking on the
2093 * page lock, block on the page table lock or observe the new page.
2094 * The SetPageUptodate on the new page and page_add_new_anon_rmap
2095 * guarantee the copy is visible before the pagetable update.
2097 flush_cache_range(vma
, mmun_start
, mmun_end
);
2098 page_add_anon_rmap(new_page
, vma
, mmun_start
, true);
2099 pmdp_huge_clear_flush_notify(vma
, mmun_start
, pmd
);
2100 set_pmd_at(mm
, mmun_start
, pmd
, entry
);
2101 update_mmu_cache_pmd(vma
, address
, &entry
);
2103 page_ref_unfreeze(page
, 2);
2104 mlock_migrate_page(new_page
, page
);
2105 page_remove_rmap(page
, true);
2106 set_page_owner_migrate_reason(new_page
, MR_NUMA_MISPLACED
);
2109 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2111 /* Take an "isolate" reference and put new page on the LRU. */
2113 putback_lru_page(new_page
);
2115 unlock_page(new_page
);
2117 put_page(page
); /* Drop the rmap reference */
2118 put_page(page
); /* Drop the LRU isolation reference */
2120 count_vm_events(PGMIGRATE_SUCCESS
, HPAGE_PMD_NR
);
2121 count_vm_numa_events(NUMA_PAGE_MIGRATE
, HPAGE_PMD_NR
);
2123 mod_node_page_state(page_pgdat(page
),
2124 NR_ISOLATED_ANON
+ page_lru
,
2129 count_vm_events(PGMIGRATE_FAIL
, HPAGE_PMD_NR
);
2131 ptl
= pmd_lock(mm
, pmd
);
2132 if (pmd_same(*pmd
, entry
)) {
2133 entry
= pmd_modify(entry
, vma
->vm_page_prot
);
2134 set_pmd_at(mm
, mmun_start
, pmd
, entry
);
2135 update_mmu_cache_pmd(vma
, address
, &entry
);
2144 #endif /* CONFIG_NUMA_BALANCING */
2146 #endif /* CONFIG_NUMA */
2148 #if defined(CONFIG_MIGRATE_VMA_HELPER)
2149 struct migrate_vma
{
2150 struct vm_area_struct
*vma
;
2153 unsigned long cpages
;
2154 unsigned long npages
;
2155 unsigned long start
;
2159 static int migrate_vma_collect_hole(unsigned long start
,
2161 struct mm_walk
*walk
)
2163 struct migrate_vma
*migrate
= walk
->private;
2166 for (addr
= start
& PAGE_MASK
; addr
< end
; addr
+= PAGE_SIZE
) {
2167 migrate
->src
[migrate
->npages
] = MIGRATE_PFN_MIGRATE
;
2168 migrate
->dst
[migrate
->npages
] = 0;
2176 static int migrate_vma_collect_skip(unsigned long start
,
2178 struct mm_walk
*walk
)
2180 struct migrate_vma
*migrate
= walk
->private;
2183 for (addr
= start
& PAGE_MASK
; addr
< end
; addr
+= PAGE_SIZE
) {
2184 migrate
->dst
[migrate
->npages
] = 0;
2185 migrate
->src
[migrate
->npages
++] = 0;
2191 static int migrate_vma_collect_pmd(pmd_t
*pmdp
,
2192 unsigned long start
,
2194 struct mm_walk
*walk
)
2196 struct migrate_vma
*migrate
= walk
->private;
2197 struct vm_area_struct
*vma
= walk
->vma
;
2198 struct mm_struct
*mm
= vma
->vm_mm
;
2199 unsigned long addr
= start
, unmapped
= 0;
2204 if (pmd_none(*pmdp
))
2205 return migrate_vma_collect_hole(start
, end
, walk
);
2207 if (pmd_trans_huge(*pmdp
)) {
2210 ptl
= pmd_lock(mm
, pmdp
);
2211 if (unlikely(!pmd_trans_huge(*pmdp
))) {
2216 page
= pmd_page(*pmdp
);
2217 if (is_huge_zero_page(page
)) {
2219 split_huge_pmd(vma
, pmdp
, addr
);
2220 if (pmd_trans_unstable(pmdp
))
2221 return migrate_vma_collect_skip(start
, end
,
2228 if (unlikely(!trylock_page(page
)))
2229 return migrate_vma_collect_skip(start
, end
,
2231 ret
= split_huge_page(page
);
2235 return migrate_vma_collect_skip(start
, end
,
2237 if (pmd_none(*pmdp
))
2238 return migrate_vma_collect_hole(start
, end
,
2243 if (unlikely(pmd_bad(*pmdp
)))
2244 return migrate_vma_collect_skip(start
, end
, walk
);
2246 ptep
= pte_offset_map_lock(mm
, pmdp
, addr
, &ptl
);
2247 arch_enter_lazy_mmu_mode();
2249 for (; addr
< end
; addr
+= PAGE_SIZE
, ptep
++) {
2250 unsigned long mpfn
, pfn
;
2258 if (pte_none(pte
)) {
2259 mpfn
= MIGRATE_PFN_MIGRATE
;
2265 if (!pte_present(pte
)) {
2269 * Only care about unaddressable device page special
2270 * page table entry. Other special swap entries are not
2271 * migratable, and we ignore regular swapped page.
2273 entry
= pte_to_swp_entry(pte
);
2274 if (!is_device_private_entry(entry
))
2277 page
= device_private_entry_to_page(entry
);
2278 mpfn
= migrate_pfn(page_to_pfn(page
))|
2279 MIGRATE_PFN_DEVICE
| MIGRATE_PFN_MIGRATE
;
2280 if (is_write_device_private_entry(entry
))
2281 mpfn
|= MIGRATE_PFN_WRITE
;
2283 if (is_zero_pfn(pfn
)) {
2284 mpfn
= MIGRATE_PFN_MIGRATE
;
2289 page
= _vm_normal_page(migrate
->vma
, addr
, pte
, true);
2290 mpfn
= migrate_pfn(pfn
) | MIGRATE_PFN_MIGRATE
;
2291 mpfn
|= pte_write(pte
) ? MIGRATE_PFN_WRITE
: 0;
2294 /* FIXME support THP */
2295 if (!page
|| !page
->mapping
|| PageTransCompound(page
)) {
2299 pfn
= page_to_pfn(page
);
2302 * By getting a reference on the page we pin it and that blocks
2303 * any kind of migration. Side effect is that it "freezes" the
2306 * We drop this reference after isolating the page from the lru
2307 * for non device page (device page are not on the lru and thus
2308 * can't be dropped from it).
2314 * Optimize for the common case where page is only mapped once
2315 * in one process. If we can lock the page, then we can safely
2316 * set up a special migration page table entry now.
2318 if (trylock_page(page
)) {
2321 mpfn
|= MIGRATE_PFN_LOCKED
;
2322 ptep_get_and_clear(mm
, addr
, ptep
);
2324 /* Setup special migration page table entry */
2325 entry
= make_migration_entry(page
, pte_write(pte
));
2326 swp_pte
= swp_entry_to_pte(entry
);
2327 if (pte_soft_dirty(pte
))
2328 swp_pte
= pte_swp_mksoft_dirty(swp_pte
);
2329 set_pte_at(mm
, addr
, ptep
, swp_pte
);
2332 * This is like regular unmap: we remove the rmap and
2333 * drop page refcount. Page won't be freed, as we took
2334 * a reference just above.
2336 page_remove_rmap(page
, false);
2339 if (pte_present(pte
))
2344 migrate
->dst
[migrate
->npages
] = 0;
2345 migrate
->src
[migrate
->npages
++] = mpfn
;
2347 arch_leave_lazy_mmu_mode();
2348 pte_unmap_unlock(ptep
- 1, ptl
);
2350 /* Only flush the TLB if we actually modified any entries */
2352 flush_tlb_range(walk
->vma
, start
, end
);
2358 * migrate_vma_collect() - collect pages over a range of virtual addresses
2359 * @migrate: migrate struct containing all migration information
2361 * This will walk the CPU page table. For each virtual address backed by a
2362 * valid page, it updates the src array and takes a reference on the page, in
2363 * order to pin the page until we lock it and unmap it.
2365 static void migrate_vma_collect(struct migrate_vma
*migrate
)
2367 struct mm_walk mm_walk
;
2369 mm_walk
.pmd_entry
= migrate_vma_collect_pmd
;
2370 mm_walk
.pte_entry
= NULL
;
2371 mm_walk
.pte_hole
= migrate_vma_collect_hole
;
2372 mm_walk
.hugetlb_entry
= NULL
;
2373 mm_walk
.test_walk
= NULL
;
2374 mm_walk
.vma
= migrate
->vma
;
2375 mm_walk
.mm
= migrate
->vma
->vm_mm
;
2376 mm_walk
.private = migrate
;
2378 mmu_notifier_invalidate_range_start(mm_walk
.mm
,
2381 walk_page_range(migrate
->start
, migrate
->end
, &mm_walk
);
2382 mmu_notifier_invalidate_range_end(mm_walk
.mm
,
2386 migrate
->end
= migrate
->start
+ (migrate
->npages
<< PAGE_SHIFT
);
2390 * migrate_vma_check_page() - check if page is pinned or not
2391 * @page: struct page to check
2393 * Pinned pages cannot be migrated. This is the same test as in
2394 * migrate_page_move_mapping(), except that here we allow migration of a
2397 static bool migrate_vma_check_page(struct page
*page
)
2400 * One extra ref because caller holds an extra reference, either from
2401 * isolate_lru_page() for a regular page, or migrate_vma_collect() for
2407 * FIXME support THP (transparent huge page), it is bit more complex to
2408 * check them than regular pages, because they can be mapped with a pmd
2409 * or with a pte (split pte mapping).
2411 if (PageCompound(page
))
2414 /* Page from ZONE_DEVICE have one extra reference */
2415 if (is_zone_device_page(page
)) {
2417 * Private page can never be pin as they have no valid pte and
2418 * GUP will fail for those. Yet if there is a pending migration
2419 * a thread might try to wait on the pte migration entry and
2420 * will bump the page reference count. Sadly there is no way to
2421 * differentiate a regular pin from migration wait. Hence to
2422 * avoid 2 racing thread trying to migrate back to CPU to enter
2423 * infinite loop (one stoping migration because the other is
2424 * waiting on pte migration entry). We always return true here.
2426 * FIXME proper solution is to rework migration_entry_wait() so
2427 * it does not need to take a reference on page.
2429 if (is_device_private_page(page
))
2433 * Only allow device public page to be migrated and account for
2434 * the extra reference count imply by ZONE_DEVICE pages.
2436 if (!is_device_public_page(page
))
2441 /* For file back page */
2442 if (page_mapping(page
))
2443 extra
+= 1 + page_has_private(page
);
2445 if ((page_count(page
) - extra
) > page_mapcount(page
))
2452 * migrate_vma_prepare() - lock pages and isolate them from the lru
2453 * @migrate: migrate struct containing all migration information
2455 * This locks pages that have been collected by migrate_vma_collect(). Once each
2456 * page is locked it is isolated from the lru (for non-device pages). Finally,
2457 * the ref taken by migrate_vma_collect() is dropped, as locked pages cannot be
2458 * migrated by concurrent kernel threads.
2460 static void migrate_vma_prepare(struct migrate_vma
*migrate
)
2462 const unsigned long npages
= migrate
->npages
;
2463 const unsigned long start
= migrate
->start
;
2464 unsigned long addr
, i
, restore
= 0;
2465 bool allow_drain
= true;
2469 for (i
= 0; (i
< npages
) && migrate
->cpages
; i
++) {
2470 struct page
*page
= migrate_pfn_to_page(migrate
->src
[i
]);
2476 if (!(migrate
->src
[i
] & MIGRATE_PFN_LOCKED
)) {
2478 * Because we are migrating several pages there can be
2479 * a deadlock between 2 concurrent migration where each
2480 * are waiting on each other page lock.
2482 * Make migrate_vma() a best effort thing and backoff
2483 * for any page we can not lock right away.
2485 if (!trylock_page(page
)) {
2486 migrate
->src
[i
] = 0;
2492 migrate
->src
[i
] |= MIGRATE_PFN_LOCKED
;
2495 /* ZONE_DEVICE pages are not on LRU */
2496 if (!is_zone_device_page(page
)) {
2497 if (!PageLRU(page
) && allow_drain
) {
2498 /* Drain CPU's pagevec */
2499 lru_add_drain_all();
2500 allow_drain
= false;
2503 if (isolate_lru_page(page
)) {
2505 migrate
->src
[i
] &= ~MIGRATE_PFN_MIGRATE
;
2509 migrate
->src
[i
] = 0;
2517 /* Drop the reference we took in collect */
2521 if (!migrate_vma_check_page(page
)) {
2523 migrate
->src
[i
] &= ~MIGRATE_PFN_MIGRATE
;
2527 if (!is_zone_device_page(page
)) {
2529 putback_lru_page(page
);
2532 migrate
->src
[i
] = 0;
2536 if (!is_zone_device_page(page
))
2537 putback_lru_page(page
);
2544 for (i
= 0, addr
= start
; i
< npages
&& restore
; i
++, addr
+= PAGE_SIZE
) {
2545 struct page
*page
= migrate_pfn_to_page(migrate
->src
[i
]);
2547 if (!page
|| (migrate
->src
[i
] & MIGRATE_PFN_MIGRATE
))
2550 remove_migration_pte(page
, migrate
->vma
, addr
, page
);
2552 migrate
->src
[i
] = 0;
2560 * migrate_vma_unmap() - replace page mapping with special migration pte entry
2561 * @migrate: migrate struct containing all migration information
2563 * Replace page mapping (CPU page table pte) with a special migration pte entry
2564 * and check again if it has been pinned. Pinned pages are restored because we
2565 * cannot migrate them.
2567 * This is the last step before we call the device driver callback to allocate
2568 * destination memory and copy contents of original page over to new page.
2570 static void migrate_vma_unmap(struct migrate_vma
*migrate
)
2572 int flags
= TTU_MIGRATION
| TTU_IGNORE_MLOCK
| TTU_IGNORE_ACCESS
;
2573 const unsigned long npages
= migrate
->npages
;
2574 const unsigned long start
= migrate
->start
;
2575 unsigned long addr
, i
, restore
= 0;
2577 for (i
= 0; i
< npages
; i
++) {
2578 struct page
*page
= migrate_pfn_to_page(migrate
->src
[i
]);
2580 if (!page
|| !(migrate
->src
[i
] & MIGRATE_PFN_MIGRATE
))
2583 if (page_mapped(page
)) {
2584 try_to_unmap(page
, flags
);
2585 if (page_mapped(page
))
2589 if (migrate_vma_check_page(page
))
2593 migrate
->src
[i
] &= ~MIGRATE_PFN_MIGRATE
;
2598 for (addr
= start
, i
= 0; i
< npages
&& restore
; addr
+= PAGE_SIZE
, i
++) {
2599 struct page
*page
= migrate_pfn_to_page(migrate
->src
[i
]);
2601 if (!page
|| (migrate
->src
[i
] & MIGRATE_PFN_MIGRATE
))
2604 remove_migration_ptes(page
, page
, false);
2606 migrate
->src
[i
] = 0;
2610 if (is_zone_device_page(page
))
2613 putback_lru_page(page
);
2617 static void migrate_vma_insert_page(struct migrate_vma
*migrate
,
2623 struct vm_area_struct
*vma
= migrate
->vma
;
2624 struct mm_struct
*mm
= vma
->vm_mm
;
2625 struct mem_cgroup
*memcg
;
2635 /* Only allow populating anonymous memory */
2636 if (!vma_is_anonymous(vma
))
2639 pgdp
= pgd_offset(mm
, addr
);
2640 p4dp
= p4d_alloc(mm
, pgdp
, addr
);
2643 pudp
= pud_alloc(mm
, p4dp
, addr
);
2646 pmdp
= pmd_alloc(mm
, pudp
, addr
);
2650 if (pmd_trans_huge(*pmdp
) || pmd_devmap(*pmdp
))
2654 * Use pte_alloc() instead of pte_alloc_map(). We can't run
2655 * pte_offset_map() on pmds where a huge pmd might be created
2656 * from a different thread.
2658 * pte_alloc_map() is safe to use under down_write(mmap_sem) or when
2659 * parallel threads are excluded by other means.
2661 * Here we only have down_read(mmap_sem).
2663 if (pte_alloc(mm
, pmdp
, addr
))
2666 /* See the comment in pte_alloc_one_map() */
2667 if (unlikely(pmd_trans_unstable(pmdp
)))
2670 if (unlikely(anon_vma_prepare(vma
)))
2672 if (mem_cgroup_try_charge(page
, vma
->vm_mm
, GFP_KERNEL
, &memcg
, false))
2676 * The memory barrier inside __SetPageUptodate makes sure that
2677 * preceding stores to the page contents become visible before
2678 * the set_pte_at() write.
2680 __SetPageUptodate(page
);
2682 if (is_zone_device_page(page
)) {
2683 if (is_device_private_page(page
)) {
2684 swp_entry_t swp_entry
;
2686 swp_entry
= make_device_private_entry(page
, vma
->vm_flags
& VM_WRITE
);
2687 entry
= swp_entry_to_pte(swp_entry
);
2688 } else if (is_device_public_page(page
)) {
2689 entry
= pte_mkold(mk_pte(page
, READ_ONCE(vma
->vm_page_prot
)));
2690 if (vma
->vm_flags
& VM_WRITE
)
2691 entry
= pte_mkwrite(pte_mkdirty(entry
));
2692 entry
= pte_mkdevmap(entry
);
2695 entry
= mk_pte(page
, vma
->vm_page_prot
);
2696 if (vma
->vm_flags
& VM_WRITE
)
2697 entry
= pte_mkwrite(pte_mkdirty(entry
));
2700 ptep
= pte_offset_map_lock(mm
, pmdp
, addr
, &ptl
);
2702 if (pte_present(*ptep
)) {
2703 unsigned long pfn
= pte_pfn(*ptep
);
2705 if (!is_zero_pfn(pfn
)) {
2706 pte_unmap_unlock(ptep
, ptl
);
2707 mem_cgroup_cancel_charge(page
, memcg
, false);
2711 } else if (!pte_none(*ptep
)) {
2712 pte_unmap_unlock(ptep
, ptl
);
2713 mem_cgroup_cancel_charge(page
, memcg
, false);
2718 * Check for usefaultfd but do not deliver the fault. Instead,
2721 if (userfaultfd_missing(vma
)) {
2722 pte_unmap_unlock(ptep
, ptl
);
2723 mem_cgroup_cancel_charge(page
, memcg
, false);
2727 inc_mm_counter(mm
, MM_ANONPAGES
);
2728 page_add_new_anon_rmap(page
, vma
, addr
, false);
2729 mem_cgroup_commit_charge(page
, memcg
, false, false);
2730 if (!is_zone_device_page(page
))
2731 lru_cache_add_active_or_unevictable(page
, vma
);
2735 flush_cache_page(vma
, addr
, pte_pfn(*ptep
));
2736 ptep_clear_flush_notify(vma
, addr
, ptep
);
2737 set_pte_at_notify(mm
, addr
, ptep
, entry
);
2738 update_mmu_cache(vma
, addr
, ptep
);
2740 /* No need to invalidate - it was non-present before */
2741 set_pte_at(mm
, addr
, ptep
, entry
);
2742 update_mmu_cache(vma
, addr
, ptep
);
2745 pte_unmap_unlock(ptep
, ptl
);
2746 *src
= MIGRATE_PFN_MIGRATE
;
2750 *src
&= ~MIGRATE_PFN_MIGRATE
;
2754 * migrate_vma_pages() - migrate meta-data from src page to dst page
2755 * @migrate: migrate struct containing all migration information
2757 * This migrates struct page meta-data from source struct page to destination
2758 * struct page. This effectively finishes the migration from source page to the
2761 static void migrate_vma_pages(struct migrate_vma
*migrate
)
2763 const unsigned long npages
= migrate
->npages
;
2764 const unsigned long start
= migrate
->start
;
2765 struct vm_area_struct
*vma
= migrate
->vma
;
2766 struct mm_struct
*mm
= vma
->vm_mm
;
2767 unsigned long addr
, i
, mmu_start
;
2768 bool notified
= false;
2770 for (i
= 0, addr
= start
; i
< npages
; addr
+= PAGE_SIZE
, i
++) {
2771 struct page
*newpage
= migrate_pfn_to_page(migrate
->dst
[i
]);
2772 struct page
*page
= migrate_pfn_to_page(migrate
->src
[i
]);
2773 struct address_space
*mapping
;
2777 migrate
->src
[i
] &= ~MIGRATE_PFN_MIGRATE
;
2782 if (!(migrate
->src
[i
] & MIGRATE_PFN_MIGRATE
)) {
2788 mmu_notifier_invalidate_range_start(mm
,
2792 migrate_vma_insert_page(migrate
, addr
, newpage
,
2798 mapping
= page_mapping(page
);
2800 if (is_zone_device_page(newpage
)) {
2801 if (is_device_private_page(newpage
)) {
2803 * For now only support private anonymous when
2804 * migrating to un-addressable device memory.
2807 migrate
->src
[i
] &= ~MIGRATE_PFN_MIGRATE
;
2810 } else if (!is_device_public_page(newpage
)) {
2812 * Other types of ZONE_DEVICE page are not
2815 migrate
->src
[i
] &= ~MIGRATE_PFN_MIGRATE
;
2820 r
= migrate_page(mapping
, newpage
, page
, MIGRATE_SYNC_NO_COPY
);
2821 if (r
!= MIGRATEPAGE_SUCCESS
)
2822 migrate
->src
[i
] &= ~MIGRATE_PFN_MIGRATE
;
2826 mmu_notifier_invalidate_range_end(mm
, mmu_start
,
2831 * migrate_vma_finalize() - restore CPU page table entry
2832 * @migrate: migrate struct containing all migration information
2834 * This replaces the special migration pte entry with either a mapping to the
2835 * new page if migration was successful for that page, or to the original page
2838 * This also unlocks the pages and puts them back on the lru, or drops the extra
2839 * refcount, for device pages.
2841 static void migrate_vma_finalize(struct migrate_vma
*migrate
)
2843 const unsigned long npages
= migrate
->npages
;
2846 for (i
= 0; i
< npages
; i
++) {
2847 struct page
*newpage
= migrate_pfn_to_page(migrate
->dst
[i
]);
2848 struct page
*page
= migrate_pfn_to_page(migrate
->src
[i
]);
2852 unlock_page(newpage
);
2858 if (!(migrate
->src
[i
] & MIGRATE_PFN_MIGRATE
) || !newpage
) {
2860 unlock_page(newpage
);
2866 remove_migration_ptes(page
, newpage
, false);
2870 if (is_zone_device_page(page
))
2873 putback_lru_page(page
);
2875 if (newpage
!= page
) {
2876 unlock_page(newpage
);
2877 if (is_zone_device_page(newpage
))
2880 putback_lru_page(newpage
);
2886 * migrate_vma() - migrate a range of memory inside vma
2888 * @ops: migration callback for allocating destination memory and copying
2889 * @vma: virtual memory area containing the range to be migrated
2890 * @start: start address of the range to migrate (inclusive)
2891 * @end: end address of the range to migrate (exclusive)
2892 * @src: array of hmm_pfn_t containing source pfns
2893 * @dst: array of hmm_pfn_t containing destination pfns
2894 * @private: pointer passed back to each of the callback
2895 * Returns: 0 on success, error code otherwise
2897 * This function tries to migrate a range of memory virtual address range, using
2898 * callbacks to allocate and copy memory from source to destination. First it
2899 * collects all the pages backing each virtual address in the range, saving this
2900 * inside the src array. Then it locks those pages and unmaps them. Once the pages
2901 * are locked and unmapped, it checks whether each page is pinned or not. Pages
2902 * that aren't pinned have the MIGRATE_PFN_MIGRATE flag set (by this function)
2903 * in the corresponding src array entry. It then restores any pages that are
2904 * pinned, by remapping and unlocking those pages.
2906 * At this point it calls the alloc_and_copy() callback. For documentation on
2907 * what is expected from that callback, see struct migrate_vma_ops comments in
2908 * include/linux/migrate.h
2910 * After the alloc_and_copy() callback, this function goes over each entry in
2911 * the src array that has the MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag
2912 * set. If the corresponding entry in dst array has MIGRATE_PFN_VALID flag set,
2913 * then the function tries to migrate struct page information from the source
2914 * struct page to the destination struct page. If it fails to migrate the struct
2915 * page information, then it clears the MIGRATE_PFN_MIGRATE flag in the src
2918 * At this point all successfully migrated pages have an entry in the src
2919 * array with MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag set and the dst
2920 * array entry with MIGRATE_PFN_VALID flag set.
2922 * It then calls the finalize_and_map() callback. See comments for "struct
2923 * migrate_vma_ops", in include/linux/migrate.h for details about
2924 * finalize_and_map() behavior.
2926 * After the finalize_and_map() callback, for successfully migrated pages, this
2927 * function updates the CPU page table to point to new pages, otherwise it
2928 * restores the CPU page table to point to the original source pages.
2930 * Function returns 0 after the above steps, even if no pages were migrated
2931 * (The function only returns an error if any of the arguments are invalid.)
2933 * Both src and dst array must be big enough for (end - start) >> PAGE_SHIFT
2934 * unsigned long entries.
2936 int migrate_vma(const struct migrate_vma_ops
*ops
,
2937 struct vm_area_struct
*vma
,
2938 unsigned long start
,
2944 struct migrate_vma migrate
;
2946 /* Sanity check the arguments */
2949 if (!vma
|| is_vm_hugetlb_page(vma
) || (vma
->vm_flags
& VM_SPECIAL
))
2951 if (start
< vma
->vm_start
|| start
>= vma
->vm_end
)
2953 if (end
<= vma
->vm_start
|| end
> vma
->vm_end
)
2955 if (!ops
|| !src
|| !dst
|| start
>= end
)
2958 memset(src
, 0, sizeof(*src
) * ((end
- start
) >> PAGE_SHIFT
));
2961 migrate
.start
= start
;
2967 /* Collect, and try to unmap source pages */
2968 migrate_vma_collect(&migrate
);
2969 if (!migrate
.cpages
)
2972 /* Lock and isolate page */
2973 migrate_vma_prepare(&migrate
);
2974 if (!migrate
.cpages
)
2978 migrate_vma_unmap(&migrate
);
2979 if (!migrate
.cpages
)
2983 * At this point pages are locked and unmapped, and thus they have
2984 * stable content and can safely be copied to destination memory that
2985 * is allocated by the callback.
2987 * Note that migration can fail in migrate_vma_struct_page() for each
2990 ops
->alloc_and_copy(vma
, src
, dst
, start
, end
, private);
2992 /* This does the real migration of struct page */
2993 migrate_vma_pages(&migrate
);
2995 ops
->finalize_and_map(vma
, src
, dst
, start
, end
, private);
2997 /* Unlock and remap pages */
2998 migrate_vma_finalize(&migrate
);
3002 EXPORT_SYMBOL(migrate_vma
);
3003 #endif /* defined(MIGRATE_VMA_HELPER) */