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/compat.h>
38 #include <linux/hugetlb.h>
39 #include <linux/hugetlb_cgroup.h>
40 #include <linux/gfp.h>
41 #include <linux/pfn_t.h>
42 #include <linux/memremap.h>
43 #include <linux/userfaultfd_k.h>
44 #include <linux/balloon_compaction.h>
45 #include <linux/mmu_notifier.h>
46 #include <linux/page_idle.h>
47 #include <linux/page_owner.h>
48 #include <linux/sched/mm.h>
49 #include <linux/ptrace.h>
51 #include <asm/tlbflush.h>
53 #define CREATE_TRACE_POINTS
54 #include <trace/events/migrate.h>
59 * migrate_prep() needs to be called before we start compiling a list of pages
60 * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is
61 * undesirable, use migrate_prep_local()
63 int migrate_prep(void)
66 * Clear the LRU lists so pages can be isolated.
67 * Note that pages may be moved off the LRU after we have
68 * drained them. Those pages will fail to migrate like other
69 * pages that may be busy.
76 /* Do the necessary work of migrate_prep but not if it involves other CPUs */
77 int migrate_prep_local(void)
84 int isolate_movable_page(struct page
*page
, isolate_mode_t mode
)
86 struct address_space
*mapping
;
89 * Avoid burning cycles with pages that are yet under __free_pages(),
90 * or just got freed under us.
92 * In case we 'win' a race for a movable page being freed under us and
93 * raise its refcount preventing __free_pages() from doing its job
94 * the put_page() at the end of this block will take care of
95 * release this page, thus avoiding a nasty leakage.
97 if (unlikely(!get_page_unless_zero(page
)))
101 * Check PageMovable before holding a PG_lock because page's owner
102 * assumes anybody doesn't touch PG_lock of newly allocated page
103 * so unconditionally grabbing the lock ruins page's owner side.
105 if (unlikely(!__PageMovable(page
)))
108 * As movable pages are not isolated from LRU lists, concurrent
109 * compaction threads can race against page migration functions
110 * as well as race against the releasing a page.
112 * In order to avoid having an already isolated movable page
113 * being (wrongly) re-isolated while it is under migration,
114 * or to avoid attempting to isolate pages being released,
115 * lets be sure we have the page lock
116 * before proceeding with the movable page isolation steps.
118 if (unlikely(!trylock_page(page
)))
121 if (!PageMovable(page
) || PageIsolated(page
))
122 goto out_no_isolated
;
124 mapping
= page_mapping(page
);
125 VM_BUG_ON_PAGE(!mapping
, page
);
127 if (!mapping
->a_ops
->isolate_page(page
, mode
))
128 goto out_no_isolated
;
130 /* Driver shouldn't use PG_isolated bit of page->flags */
131 WARN_ON_ONCE(PageIsolated(page
));
132 __SetPageIsolated(page
);
145 /* It should be called on page which is PG_movable */
146 void putback_movable_page(struct page
*page
)
148 struct address_space
*mapping
;
150 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
151 VM_BUG_ON_PAGE(!PageMovable(page
), page
);
152 VM_BUG_ON_PAGE(!PageIsolated(page
), page
);
154 mapping
= page_mapping(page
);
155 mapping
->a_ops
->putback_page(page
);
156 __ClearPageIsolated(page
);
160 * Put previously isolated pages back onto the appropriate lists
161 * from where they were once taken off for compaction/migration.
163 * This function shall be used whenever the isolated pageset has been
164 * built from lru, balloon, hugetlbfs page. See isolate_migratepages_range()
165 * and isolate_huge_page().
167 void putback_movable_pages(struct list_head
*l
)
172 list_for_each_entry_safe(page
, page2
, l
, lru
) {
173 if (unlikely(PageHuge(page
))) {
174 putback_active_hugepage(page
);
177 list_del(&page
->lru
);
179 * We isolated non-lru movable page so here we can use
180 * __PageMovable because LRU page's mapping cannot have
181 * PAGE_MAPPING_MOVABLE.
183 if (unlikely(__PageMovable(page
))) {
184 VM_BUG_ON_PAGE(!PageIsolated(page
), page
);
186 if (PageMovable(page
))
187 putback_movable_page(page
);
189 __ClearPageIsolated(page
);
193 mod_node_page_state(page_pgdat(page
), NR_ISOLATED_ANON
+
194 page_is_file_cache(page
), -hpage_nr_pages(page
));
195 putback_lru_page(page
);
201 * Restore a potential migration pte to a working pte entry
203 static bool remove_migration_pte(struct page
*page
, struct vm_area_struct
*vma
,
204 unsigned long addr
, void *old
)
206 struct page_vma_mapped_walk pvmw
= {
210 .flags
= PVMW_SYNC
| PVMW_MIGRATION
,
216 VM_BUG_ON_PAGE(PageTail(page
), page
);
217 while (page_vma_mapped_walk(&pvmw
)) {
221 new = page
- pvmw
.page
->index
+
222 linear_page_index(vma
, pvmw
.address
);
224 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
225 /* PMD-mapped THP migration entry */
227 VM_BUG_ON_PAGE(PageHuge(page
) || !PageTransCompound(page
), page
);
228 remove_migration_pmd(&pvmw
, new);
234 pte
= pte_mkold(mk_pte(new, READ_ONCE(vma
->vm_page_prot
)));
235 if (pte_swp_soft_dirty(*pvmw
.pte
))
236 pte
= pte_mksoft_dirty(pte
);
239 * Recheck VMA as permissions can change since migration started
241 entry
= pte_to_swp_entry(*pvmw
.pte
);
242 if (is_write_migration_entry(entry
))
243 pte
= maybe_mkwrite(pte
, vma
);
245 if (unlikely(is_zone_device_page(new))) {
246 if (is_device_private_page(new)) {
247 entry
= make_device_private_entry(new, pte_write(pte
));
248 pte
= swp_entry_to_pte(entry
);
252 #ifdef CONFIG_HUGETLB_PAGE
254 pte
= pte_mkhuge(pte
);
255 pte
= arch_make_huge_pte(pte
, vma
, new, 0);
256 set_huge_pte_at(vma
->vm_mm
, pvmw
.address
, pvmw
.pte
, pte
);
258 hugepage_add_anon_rmap(new, vma
, pvmw
.address
);
260 page_dup_rmap(new, true);
264 set_pte_at(vma
->vm_mm
, pvmw
.address
, pvmw
.pte
, pte
);
267 page_add_anon_rmap(new, vma
, pvmw
.address
, false);
269 page_add_file_rmap(new, false);
271 if (vma
->vm_flags
& VM_LOCKED
&& !PageTransCompound(new))
274 if (PageTransHuge(page
) && PageMlocked(page
))
275 clear_page_mlock(page
);
277 /* No need to invalidate - it was non-present before */
278 update_mmu_cache(vma
, pvmw
.address
, pvmw
.pte
);
285 * Get rid of all migration entries and replace them by
286 * references to the indicated page.
288 void remove_migration_ptes(struct page
*old
, struct page
*new, bool locked
)
290 struct rmap_walk_control rwc
= {
291 .rmap_one
= remove_migration_pte
,
296 rmap_walk_locked(new, &rwc
);
298 rmap_walk(new, &rwc
);
302 * Something used the pte of a page under migration. We need to
303 * get to the page and wait until migration is finished.
304 * When we return from this function the fault will be retried.
306 void __migration_entry_wait(struct mm_struct
*mm
, pte_t
*ptep
,
315 if (!is_swap_pte(pte
))
318 entry
= pte_to_swp_entry(pte
);
319 if (!is_migration_entry(entry
))
322 page
= migration_entry_to_page(entry
);
325 * Once page cache replacement of page migration started, page_count
326 * is zero; but we must not call put_and_wait_on_page_locked() without
327 * a ref. Use get_page_unless_zero(), and just fault again if it fails.
329 if (!get_page_unless_zero(page
))
331 pte_unmap_unlock(ptep
, ptl
);
332 put_and_wait_on_page_locked(page
);
335 pte_unmap_unlock(ptep
, ptl
);
338 void migration_entry_wait(struct mm_struct
*mm
, pmd_t
*pmd
,
339 unsigned long address
)
341 spinlock_t
*ptl
= pte_lockptr(mm
, pmd
);
342 pte_t
*ptep
= pte_offset_map(pmd
, address
);
343 __migration_entry_wait(mm
, ptep
, ptl
);
346 void migration_entry_wait_huge(struct vm_area_struct
*vma
,
347 struct mm_struct
*mm
, pte_t
*pte
)
349 spinlock_t
*ptl
= huge_pte_lockptr(hstate_vma(vma
), mm
, pte
);
350 __migration_entry_wait(mm
, pte
, ptl
);
353 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
354 void pmd_migration_entry_wait(struct mm_struct
*mm
, pmd_t
*pmd
)
359 ptl
= pmd_lock(mm
, pmd
);
360 if (!is_pmd_migration_entry(*pmd
))
362 page
= migration_entry_to_page(pmd_to_swp_entry(*pmd
));
363 if (!get_page_unless_zero(page
))
366 put_and_wait_on_page_locked(page
);
373 static int expected_page_refs(struct address_space
*mapping
, struct page
*page
)
375 int expected_count
= 1;
378 * Device public or private pages have an extra refcount as they are
381 expected_count
+= is_device_private_page(page
);
383 expected_count
+= hpage_nr_pages(page
) + page_has_private(page
);
385 return expected_count
;
389 * Replace the page in the mapping.
391 * The number of remaining references must be:
392 * 1 for anonymous pages without a mapping
393 * 2 for pages with a mapping
394 * 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
396 int migrate_page_move_mapping(struct address_space
*mapping
,
397 struct page
*newpage
, struct page
*page
, enum migrate_mode mode
,
400 XA_STATE(xas
, &mapping
->i_pages
, page_index(page
));
401 struct zone
*oldzone
, *newzone
;
403 int expected_count
= expected_page_refs(mapping
, page
) + extra_count
;
406 /* Anonymous page without mapping */
407 if (page_count(page
) != expected_count
)
410 /* No turning back from here */
411 newpage
->index
= page
->index
;
412 newpage
->mapping
= page
->mapping
;
413 if (PageSwapBacked(page
))
414 __SetPageSwapBacked(newpage
);
416 return MIGRATEPAGE_SUCCESS
;
419 oldzone
= page_zone(page
);
420 newzone
= page_zone(newpage
);
423 if (page_count(page
) != expected_count
|| xas_load(&xas
) != page
) {
424 xas_unlock_irq(&xas
);
428 if (!page_ref_freeze(page
, expected_count
)) {
429 xas_unlock_irq(&xas
);
434 * Now we know that no one else is looking at the page:
435 * no turning back from here.
437 newpage
->index
= page
->index
;
438 newpage
->mapping
= page
->mapping
;
439 page_ref_add(newpage
, hpage_nr_pages(page
)); /* add cache reference */
440 if (PageSwapBacked(page
)) {
441 __SetPageSwapBacked(newpage
);
442 if (PageSwapCache(page
)) {
443 SetPageSwapCache(newpage
);
444 set_page_private(newpage
, page_private(page
));
447 VM_BUG_ON_PAGE(PageSwapCache(page
), page
);
450 /* Move dirty while page refs frozen and newpage not yet exposed */
451 dirty
= PageDirty(page
);
453 ClearPageDirty(page
);
454 SetPageDirty(newpage
);
457 xas_store(&xas
, newpage
);
458 if (PageTransHuge(page
)) {
461 for (i
= 1; i
< HPAGE_PMD_NR
; i
++) {
463 xas_store(&xas
, newpage
+ i
);
468 * Drop cache reference from old page by unfreezing
469 * to one less reference.
470 * We know this isn't the last reference.
472 page_ref_unfreeze(page
, expected_count
- hpage_nr_pages(page
));
475 /* Leave irq disabled to prevent preemption while updating stats */
478 * If moved to a different zone then also account
479 * the page for that zone. Other VM counters will be
480 * taken care of when we establish references to the
481 * new page and drop references to the old page.
483 * Note that anonymous pages are accounted for
484 * via NR_FILE_PAGES and NR_ANON_MAPPED if they
485 * are mapped to swap space.
487 if (newzone
!= oldzone
) {
488 __dec_node_state(oldzone
->zone_pgdat
, NR_FILE_PAGES
);
489 __inc_node_state(newzone
->zone_pgdat
, NR_FILE_PAGES
);
490 if (PageSwapBacked(page
) && !PageSwapCache(page
)) {
491 __dec_node_state(oldzone
->zone_pgdat
, NR_SHMEM
);
492 __inc_node_state(newzone
->zone_pgdat
, NR_SHMEM
);
494 if (dirty
&& mapping_cap_account_dirty(mapping
)) {
495 __dec_node_state(oldzone
->zone_pgdat
, NR_FILE_DIRTY
);
496 __dec_zone_state(oldzone
, NR_ZONE_WRITE_PENDING
);
497 __inc_node_state(newzone
->zone_pgdat
, NR_FILE_DIRTY
);
498 __inc_zone_state(newzone
, NR_ZONE_WRITE_PENDING
);
503 return MIGRATEPAGE_SUCCESS
;
505 EXPORT_SYMBOL(migrate_page_move_mapping
);
508 * The expected number of remaining references is the same as that
509 * of migrate_page_move_mapping().
511 int migrate_huge_page_move_mapping(struct address_space
*mapping
,
512 struct page
*newpage
, struct page
*page
)
514 XA_STATE(xas
, &mapping
->i_pages
, page_index(page
));
518 expected_count
= 2 + page_has_private(page
);
519 if (page_count(page
) != expected_count
|| xas_load(&xas
) != page
) {
520 xas_unlock_irq(&xas
);
524 if (!page_ref_freeze(page
, expected_count
)) {
525 xas_unlock_irq(&xas
);
529 newpage
->index
= page
->index
;
530 newpage
->mapping
= page
->mapping
;
534 xas_store(&xas
, newpage
);
536 page_ref_unfreeze(page
, expected_count
- 1);
538 xas_unlock_irq(&xas
);
540 return MIGRATEPAGE_SUCCESS
;
544 * Gigantic pages are so large that we do not guarantee that page++ pointer
545 * arithmetic will work across the entire page. We need something more
548 static void __copy_gigantic_page(struct page
*dst
, struct page
*src
,
552 struct page
*dst_base
= dst
;
553 struct page
*src_base
= src
;
555 for (i
= 0; i
< nr_pages
; ) {
557 copy_highpage(dst
, src
);
560 dst
= mem_map_next(dst
, dst_base
, i
);
561 src
= mem_map_next(src
, src_base
, i
);
565 static void copy_huge_page(struct page
*dst
, struct page
*src
)
572 struct hstate
*h
= page_hstate(src
);
573 nr_pages
= pages_per_huge_page(h
);
575 if (unlikely(nr_pages
> MAX_ORDER_NR_PAGES
)) {
576 __copy_gigantic_page(dst
, src
, nr_pages
);
581 BUG_ON(!PageTransHuge(src
));
582 nr_pages
= hpage_nr_pages(src
);
585 for (i
= 0; i
< nr_pages
; i
++) {
587 copy_highpage(dst
+ i
, src
+ i
);
592 * Copy the page to its new location
594 void migrate_page_states(struct page
*newpage
, struct page
*page
)
599 SetPageError(newpage
);
600 if (PageReferenced(page
))
601 SetPageReferenced(newpage
);
602 if (PageUptodate(page
))
603 SetPageUptodate(newpage
);
604 if (TestClearPageActive(page
)) {
605 VM_BUG_ON_PAGE(PageUnevictable(page
), page
);
606 SetPageActive(newpage
);
607 } else if (TestClearPageUnevictable(page
))
608 SetPageUnevictable(newpage
);
609 if (PageWorkingset(page
))
610 SetPageWorkingset(newpage
);
611 if (PageChecked(page
))
612 SetPageChecked(newpage
);
613 if (PageMappedToDisk(page
))
614 SetPageMappedToDisk(newpage
);
616 /* Move dirty on pages not done by migrate_page_move_mapping() */
618 SetPageDirty(newpage
);
620 if (page_is_young(page
))
621 set_page_young(newpage
);
622 if (page_is_idle(page
))
623 set_page_idle(newpage
);
626 * Copy NUMA information to the new page, to prevent over-eager
627 * future migrations of this same page.
629 cpupid
= page_cpupid_xchg_last(page
, -1);
630 page_cpupid_xchg_last(newpage
, cpupid
);
632 ksm_migrate_page(newpage
, page
);
634 * Please do not reorder this without considering how mm/ksm.c's
635 * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache().
637 if (PageSwapCache(page
))
638 ClearPageSwapCache(page
);
639 ClearPagePrivate(page
);
640 set_page_private(page
, 0);
643 * If any waiters have accumulated on the new page then
646 if (PageWriteback(newpage
))
647 end_page_writeback(newpage
);
649 copy_page_owner(page
, newpage
);
651 mem_cgroup_migrate(page
, newpage
);
653 EXPORT_SYMBOL(migrate_page_states
);
655 void migrate_page_copy(struct page
*newpage
, struct page
*page
)
657 if (PageHuge(page
) || PageTransHuge(page
))
658 copy_huge_page(newpage
, page
);
660 copy_highpage(newpage
, page
);
662 migrate_page_states(newpage
, page
);
664 EXPORT_SYMBOL(migrate_page_copy
);
666 /************************************************************
667 * Migration functions
668 ***********************************************************/
671 * Common logic to directly migrate a single LRU page suitable for
672 * pages that do not use PagePrivate/PagePrivate2.
674 * Pages are locked upon entry and exit.
676 int migrate_page(struct address_space
*mapping
,
677 struct page
*newpage
, struct page
*page
,
678 enum migrate_mode mode
)
682 BUG_ON(PageWriteback(page
)); /* Writeback must be complete */
684 rc
= migrate_page_move_mapping(mapping
, newpage
, page
, mode
, 0);
686 if (rc
!= MIGRATEPAGE_SUCCESS
)
689 if (mode
!= MIGRATE_SYNC_NO_COPY
)
690 migrate_page_copy(newpage
, page
);
692 migrate_page_states(newpage
, page
);
693 return MIGRATEPAGE_SUCCESS
;
695 EXPORT_SYMBOL(migrate_page
);
698 /* Returns true if all buffers are successfully locked */
699 static bool buffer_migrate_lock_buffers(struct buffer_head
*head
,
700 enum migrate_mode mode
)
702 struct buffer_head
*bh
= head
;
704 /* Simple case, sync compaction */
705 if (mode
!= MIGRATE_ASYNC
) {
708 bh
= bh
->b_this_page
;
710 } while (bh
!= head
);
715 /* async case, we cannot block on lock_buffer so use trylock_buffer */
717 if (!trylock_buffer(bh
)) {
719 * We failed to lock the buffer and cannot stall in
720 * async migration. Release the taken locks
722 struct buffer_head
*failed_bh
= bh
;
724 while (bh
!= failed_bh
) {
726 bh
= bh
->b_this_page
;
731 bh
= bh
->b_this_page
;
732 } while (bh
!= head
);
736 static int __buffer_migrate_page(struct address_space
*mapping
,
737 struct page
*newpage
, struct page
*page
, enum migrate_mode mode
,
740 struct buffer_head
*bh
, *head
;
744 if (!page_has_buffers(page
))
745 return migrate_page(mapping
, newpage
, page
, mode
);
747 /* Check whether page does not have extra refs before we do more work */
748 expected_count
= expected_page_refs(mapping
, page
);
749 if (page_count(page
) != expected_count
)
752 head
= page_buffers(page
);
753 if (!buffer_migrate_lock_buffers(head
, mode
))
758 bool invalidated
= false;
762 spin_lock(&mapping
->private_lock
);
765 if (atomic_read(&bh
->b_count
)) {
769 bh
= bh
->b_this_page
;
770 } while (bh
!= head
);
771 spin_unlock(&mapping
->private_lock
);
777 invalidate_bh_lrus();
779 goto recheck_buffers
;
783 rc
= migrate_page_move_mapping(mapping
, newpage
, page
, mode
, 0);
784 if (rc
!= MIGRATEPAGE_SUCCESS
)
787 ClearPagePrivate(page
);
788 set_page_private(newpage
, page_private(page
));
789 set_page_private(page
, 0);
795 set_bh_page(bh
, newpage
, bh_offset(bh
));
796 bh
= bh
->b_this_page
;
798 } while (bh
!= head
);
800 SetPagePrivate(newpage
);
802 if (mode
!= MIGRATE_SYNC_NO_COPY
)
803 migrate_page_copy(newpage
, page
);
805 migrate_page_states(newpage
, page
);
807 rc
= MIGRATEPAGE_SUCCESS
;
812 bh
= bh
->b_this_page
;
814 } while (bh
!= head
);
820 * Migration function for pages with buffers. This function can only be used
821 * if the underlying filesystem guarantees that no other references to "page"
822 * exist. For example attached buffer heads are accessed only under page lock.
824 int buffer_migrate_page(struct address_space
*mapping
,
825 struct page
*newpage
, struct page
*page
, enum migrate_mode mode
)
827 return __buffer_migrate_page(mapping
, newpage
, page
, mode
, false);
829 EXPORT_SYMBOL(buffer_migrate_page
);
832 * Same as above except that this variant is more careful and checks that there
833 * are also no buffer head references. This function is the right one for
834 * mappings where buffer heads are directly looked up and referenced (such as
835 * block device mappings).
837 int buffer_migrate_page_norefs(struct address_space
*mapping
,
838 struct page
*newpage
, struct page
*page
, enum migrate_mode mode
)
840 return __buffer_migrate_page(mapping
, newpage
, page
, mode
, true);
845 * Writeback a page to clean the dirty state
847 static int writeout(struct address_space
*mapping
, struct page
*page
)
849 struct writeback_control wbc
= {
850 .sync_mode
= WB_SYNC_NONE
,
853 .range_end
= LLONG_MAX
,
858 if (!mapping
->a_ops
->writepage
)
859 /* No write method for the address space */
862 if (!clear_page_dirty_for_io(page
))
863 /* Someone else already triggered a write */
867 * A dirty page may imply that the underlying filesystem has
868 * the page on some queue. So the page must be clean for
869 * migration. Writeout may mean we loose the lock and the
870 * page state is no longer what we checked for earlier.
871 * At this point we know that the migration attempt cannot
874 remove_migration_ptes(page
, page
, false);
876 rc
= mapping
->a_ops
->writepage(page
, &wbc
);
878 if (rc
!= AOP_WRITEPAGE_ACTIVATE
)
879 /* unlocked. Relock */
882 return (rc
< 0) ? -EIO
: -EAGAIN
;
886 * Default handling if a filesystem does not provide a migration function.
888 static int fallback_migrate_page(struct address_space
*mapping
,
889 struct page
*newpage
, struct page
*page
, enum migrate_mode mode
)
891 if (PageDirty(page
)) {
892 /* Only writeback pages in full synchronous migration */
895 case MIGRATE_SYNC_NO_COPY
:
900 return writeout(mapping
, page
);
904 * Buffers may be managed in a filesystem specific way.
905 * We must have no buffers or drop them.
907 if (page_has_private(page
) &&
908 !try_to_release_page(page
, GFP_KERNEL
))
909 return mode
== MIGRATE_SYNC
? -EAGAIN
: -EBUSY
;
911 return migrate_page(mapping
, newpage
, page
, mode
);
915 * Move a page to a newly allocated page
916 * The page is locked and all ptes have been successfully removed.
918 * The new page will have replaced the old page if this function
923 * MIGRATEPAGE_SUCCESS - success
925 static int move_to_new_page(struct page
*newpage
, struct page
*page
,
926 enum migrate_mode mode
)
928 struct address_space
*mapping
;
930 bool is_lru
= !__PageMovable(page
);
932 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
933 VM_BUG_ON_PAGE(!PageLocked(newpage
), newpage
);
935 mapping
= page_mapping(page
);
937 if (likely(is_lru
)) {
939 rc
= migrate_page(mapping
, newpage
, page
, mode
);
940 else if (mapping
->a_ops
->migratepage
)
942 * Most pages have a mapping and most filesystems
943 * provide a migratepage callback. Anonymous pages
944 * are part of swap space which also has its own
945 * migratepage callback. This is the most common path
946 * for page migration.
948 rc
= mapping
->a_ops
->migratepage(mapping
, newpage
,
951 rc
= fallback_migrate_page(mapping
, newpage
,
955 * In case of non-lru page, it could be released after
956 * isolation step. In that case, we shouldn't try migration.
958 VM_BUG_ON_PAGE(!PageIsolated(page
), page
);
959 if (!PageMovable(page
)) {
960 rc
= MIGRATEPAGE_SUCCESS
;
961 __ClearPageIsolated(page
);
965 rc
= mapping
->a_ops
->migratepage(mapping
, newpage
,
967 WARN_ON_ONCE(rc
== MIGRATEPAGE_SUCCESS
&&
968 !PageIsolated(page
));
972 * When successful, old pagecache page->mapping must be cleared before
973 * page is freed; but stats require that PageAnon be left as PageAnon.
975 if (rc
== MIGRATEPAGE_SUCCESS
) {
976 if (__PageMovable(page
)) {
977 VM_BUG_ON_PAGE(!PageIsolated(page
), page
);
980 * We clear PG_movable under page_lock so any compactor
981 * cannot try to migrate this page.
983 __ClearPageIsolated(page
);
987 * Anonymous and movable page->mapping will be cleard by
988 * free_pages_prepare so don't reset it here for keeping
989 * the type to work PageAnon, for example.
991 if (!PageMappingFlags(page
))
992 page
->mapping
= NULL
;
994 if (likely(!is_zone_device_page(newpage
)))
995 flush_dcache_page(newpage
);
1002 static int __unmap_and_move(struct page
*page
, struct page
*newpage
,
1003 int force
, enum migrate_mode mode
)
1006 int page_was_mapped
= 0;
1007 struct anon_vma
*anon_vma
= NULL
;
1008 bool is_lru
= !__PageMovable(page
);
1010 if (!trylock_page(page
)) {
1011 if (!force
|| mode
== MIGRATE_ASYNC
)
1015 * It's not safe for direct compaction to call lock_page.
1016 * For example, during page readahead pages are added locked
1017 * to the LRU. Later, when the IO completes the pages are
1018 * marked uptodate and unlocked. However, the queueing
1019 * could be merging multiple pages for one bio (e.g.
1020 * mpage_readpages). If an allocation happens for the
1021 * second or third page, the process can end up locking
1022 * the same page twice and deadlocking. Rather than
1023 * trying to be clever about what pages can be locked,
1024 * avoid the use of lock_page for direct compaction
1027 if (current
->flags
& PF_MEMALLOC
)
1033 if (PageWriteback(page
)) {
1035 * Only in the case of a full synchronous migration is it
1036 * necessary to wait for PageWriteback. In the async case,
1037 * the retry loop is too short and in the sync-light case,
1038 * the overhead of stalling is too much
1042 case MIGRATE_SYNC_NO_COPY
:
1050 wait_on_page_writeback(page
);
1054 * By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
1055 * we cannot notice that anon_vma is freed while we migrates a page.
1056 * This get_anon_vma() delays freeing anon_vma pointer until the end
1057 * of migration. File cache pages are no problem because of page_lock()
1058 * File Caches may use write_page() or lock_page() in migration, then,
1059 * just care Anon page here.
1061 * Only page_get_anon_vma() understands the subtleties of
1062 * getting a hold on an anon_vma from outside one of its mms.
1063 * But if we cannot get anon_vma, then we won't need it anyway,
1064 * because that implies that the anon page is no longer mapped
1065 * (and cannot be remapped so long as we hold the page lock).
1067 if (PageAnon(page
) && !PageKsm(page
))
1068 anon_vma
= page_get_anon_vma(page
);
1071 * Block others from accessing the new page when we get around to
1072 * establishing additional references. We are usually the only one
1073 * holding a reference to newpage at this point. We used to have a BUG
1074 * here if trylock_page(newpage) fails, but would like to allow for
1075 * cases where there might be a race with the previous use of newpage.
1076 * This is much like races on refcount of oldpage: just don't BUG().
1078 if (unlikely(!trylock_page(newpage
)))
1081 if (unlikely(!is_lru
)) {
1082 rc
= move_to_new_page(newpage
, page
, mode
);
1083 goto out_unlock_both
;
1087 * Corner case handling:
1088 * 1. When a new swap-cache page is read into, it is added to the LRU
1089 * and treated as swapcache but it has no rmap yet.
1090 * Calling try_to_unmap() against a page->mapping==NULL page will
1091 * trigger a BUG. So handle it here.
1092 * 2. An orphaned page (see truncate_complete_page) might have
1093 * fs-private metadata. The page can be picked up due to memory
1094 * offlining. Everywhere else except page reclaim, the page is
1095 * invisible to the vm, so the page can not be migrated. So try to
1096 * free the metadata, so the page can be freed.
1098 if (!page
->mapping
) {
1099 VM_BUG_ON_PAGE(PageAnon(page
), page
);
1100 if (page_has_private(page
)) {
1101 try_to_free_buffers(page
);
1102 goto out_unlock_both
;
1104 } else if (page_mapped(page
)) {
1105 /* Establish migration ptes */
1106 VM_BUG_ON_PAGE(PageAnon(page
) && !PageKsm(page
) && !anon_vma
,
1109 TTU_MIGRATION
|TTU_IGNORE_MLOCK
|TTU_IGNORE_ACCESS
);
1110 page_was_mapped
= 1;
1113 if (!page_mapped(page
))
1114 rc
= move_to_new_page(newpage
, page
, mode
);
1116 if (page_was_mapped
)
1117 remove_migration_ptes(page
,
1118 rc
== MIGRATEPAGE_SUCCESS
? newpage
: page
, false);
1121 unlock_page(newpage
);
1123 /* Drop an anon_vma reference if we took one */
1125 put_anon_vma(anon_vma
);
1129 * If migration is successful, decrease refcount of the newpage
1130 * which will not free the page because new page owner increased
1131 * refcounter. As well, if it is LRU page, add the page to LRU
1132 * list in here. Use the old state of the isolated source page to
1133 * determine if we migrated a LRU page. newpage was already unlocked
1134 * and possibly modified by its owner - don't rely on the page
1137 if (rc
== MIGRATEPAGE_SUCCESS
) {
1138 if (unlikely(!is_lru
))
1141 putback_lru_page(newpage
);
1148 * gcc 4.7 and 4.8 on arm get an ICEs when inlining unmap_and_move(). Work
1151 #if defined(CONFIG_ARM) && \
1152 defined(GCC_VERSION) && GCC_VERSION < 40900 && GCC_VERSION >= 40700
1153 #define ICE_noinline noinline
1155 #define ICE_noinline
1159 * Obtain the lock on page, remove all ptes and migrate the page
1160 * to the newly allocated page in newpage.
1162 static ICE_noinline
int unmap_and_move(new_page_t get_new_page
,
1163 free_page_t put_new_page
,
1164 unsigned long private, struct page
*page
,
1165 int force
, enum migrate_mode mode
,
1166 enum migrate_reason reason
)
1168 int rc
= MIGRATEPAGE_SUCCESS
;
1169 struct page
*newpage
;
1171 if (!thp_migration_supported() && PageTransHuge(page
))
1174 newpage
= get_new_page(page
, private);
1178 if (page_count(page
) == 1) {
1179 /* page was freed from under us. So we are done. */
1180 ClearPageActive(page
);
1181 ClearPageUnevictable(page
);
1182 if (unlikely(__PageMovable(page
))) {
1184 if (!PageMovable(page
))
1185 __ClearPageIsolated(page
);
1189 put_new_page(newpage
, private);
1195 rc
= __unmap_and_move(page
, newpage
, force
, mode
);
1196 if (rc
== MIGRATEPAGE_SUCCESS
)
1197 set_page_owner_migrate_reason(newpage
, reason
);
1200 if (rc
!= -EAGAIN
) {
1202 * A page that has been migrated has all references
1203 * removed and will be freed. A page that has not been
1204 * migrated will have kepts its references and be
1207 list_del(&page
->lru
);
1210 * Compaction can migrate also non-LRU pages which are
1211 * not accounted to NR_ISOLATED_*. They can be recognized
1214 if (likely(!__PageMovable(page
)))
1215 mod_node_page_state(page_pgdat(page
), NR_ISOLATED_ANON
+
1216 page_is_file_cache(page
), -hpage_nr_pages(page
));
1220 * If migration is successful, releases reference grabbed during
1221 * isolation. Otherwise, restore the page to right list unless
1224 if (rc
== MIGRATEPAGE_SUCCESS
) {
1226 if (reason
== MR_MEMORY_FAILURE
) {
1228 * Set PG_HWPoison on just freed page
1229 * intentionally. Although it's rather weird,
1230 * it's how HWPoison flag works at the moment.
1232 if (set_hwpoison_free_buddy_page(page
))
1233 num_poisoned_pages_inc();
1236 if (rc
!= -EAGAIN
) {
1237 if (likely(!__PageMovable(page
))) {
1238 putback_lru_page(page
);
1243 if (PageMovable(page
))
1244 putback_movable_page(page
);
1246 __ClearPageIsolated(page
);
1252 put_new_page(newpage
, private);
1261 * Counterpart of unmap_and_move_page() for hugepage migration.
1263 * This function doesn't wait the completion of hugepage I/O
1264 * because there is no race between I/O and migration for hugepage.
1265 * Note that currently hugepage I/O occurs only in direct I/O
1266 * where no lock is held and PG_writeback is irrelevant,
1267 * and writeback status of all subpages are counted in the reference
1268 * count of the head page (i.e. if all subpages of a 2MB hugepage are
1269 * under direct I/O, the reference of the head page is 512 and a bit more.)
1270 * This means that when we try to migrate hugepage whose subpages are
1271 * doing direct I/O, some references remain after try_to_unmap() and
1272 * hugepage migration fails without data corruption.
1274 * There is also no race when direct I/O is issued on the page under migration,
1275 * because then pte is replaced with migration swap entry and direct I/O code
1276 * will wait in the page fault for migration to complete.
1278 static int unmap_and_move_huge_page(new_page_t get_new_page
,
1279 free_page_t put_new_page
, unsigned long private,
1280 struct page
*hpage
, int force
,
1281 enum migrate_mode mode
, int reason
)
1284 int page_was_mapped
= 0;
1285 struct page
*new_hpage
;
1286 struct anon_vma
*anon_vma
= NULL
;
1289 * Migratability of hugepages depends on architectures and their size.
1290 * This check is necessary because some callers of hugepage migration
1291 * like soft offline and memory hotremove don't walk through page
1292 * tables or check whether the hugepage is pmd-based or not before
1293 * kicking migration.
1295 if (!hugepage_migration_supported(page_hstate(hpage
))) {
1296 putback_active_hugepage(hpage
);
1300 new_hpage
= get_new_page(hpage
, private);
1304 if (!trylock_page(hpage
)) {
1309 case MIGRATE_SYNC_NO_COPY
:
1318 * Check for pages which are in the process of being freed. Without
1319 * page_mapping() set, hugetlbfs specific move page routine will not
1320 * be called and we could leak usage counts for subpools.
1322 if (page_private(hpage
) && !page_mapping(hpage
)) {
1327 if (PageAnon(hpage
))
1328 anon_vma
= page_get_anon_vma(hpage
);
1330 if (unlikely(!trylock_page(new_hpage
)))
1333 if (page_mapped(hpage
)) {
1335 TTU_MIGRATION
|TTU_IGNORE_MLOCK
|TTU_IGNORE_ACCESS
);
1336 page_was_mapped
= 1;
1339 if (!page_mapped(hpage
))
1340 rc
= move_to_new_page(new_hpage
, hpage
, mode
);
1342 if (page_was_mapped
)
1343 remove_migration_ptes(hpage
,
1344 rc
== MIGRATEPAGE_SUCCESS
? new_hpage
: hpage
, false);
1346 unlock_page(new_hpage
);
1350 put_anon_vma(anon_vma
);
1352 if (rc
== MIGRATEPAGE_SUCCESS
) {
1353 move_hugetlb_state(hpage
, new_hpage
, reason
);
1354 put_new_page
= NULL
;
1361 putback_active_hugepage(hpage
);
1364 * If migration was not successful and there's a freeing callback, use
1365 * it. Otherwise, put_page() will drop the reference grabbed during
1369 put_new_page(new_hpage
, private);
1371 putback_active_hugepage(new_hpage
);
1377 * migrate_pages - migrate the pages specified in a list, to the free pages
1378 * supplied as the target for the page migration
1380 * @from: The list of pages to be migrated.
1381 * @get_new_page: The function used to allocate free pages to be used
1382 * as the target of the page migration.
1383 * @put_new_page: The function used to free target pages if migration
1384 * fails, or NULL if no special handling is necessary.
1385 * @private: Private data to be passed on to get_new_page()
1386 * @mode: The migration mode that specifies the constraints for
1387 * page migration, if any.
1388 * @reason: The reason for page migration.
1390 * The function returns after 10 attempts or if no pages are movable any more
1391 * because the list has become empty or no retryable pages exist any more.
1392 * The caller should call putback_movable_pages() to return pages to the LRU
1393 * or free list only if ret != 0.
1395 * Returns the number of pages that were not migrated, or an error code.
1397 int migrate_pages(struct list_head
*from
, new_page_t get_new_page
,
1398 free_page_t put_new_page
, unsigned long private,
1399 enum migrate_mode mode
, int reason
)
1403 int nr_succeeded
= 0;
1407 int swapwrite
= current
->flags
& PF_SWAPWRITE
;
1411 current
->flags
|= PF_SWAPWRITE
;
1413 for(pass
= 0; pass
< 10 && retry
; pass
++) {
1416 list_for_each_entry_safe(page
, page2
, from
, lru
) {
1421 rc
= unmap_and_move_huge_page(get_new_page
,
1422 put_new_page
, private, page
,
1423 pass
> 2, mode
, reason
);
1425 rc
= unmap_and_move(get_new_page
, put_new_page
,
1426 private, page
, pass
> 2, mode
,
1432 * THP migration might be unsupported or the
1433 * allocation could've failed so we should
1434 * retry on the same page with the THP split
1437 * Head page is retried immediately and tail
1438 * pages are added to the tail of the list so
1439 * we encounter them after the rest of the list
1442 if (PageTransHuge(page
) && !PageHuge(page
)) {
1444 rc
= split_huge_page_to_list(page
, from
);
1447 list_safe_reset_next(page
, page2
, lru
);
1456 case MIGRATEPAGE_SUCCESS
:
1461 * Permanent failure (-EBUSY, -ENOSYS, etc.):
1462 * unlike -EAGAIN case, the failed page is
1463 * removed from migration page list and not
1464 * retried in the next outer loop.
1475 count_vm_events(PGMIGRATE_SUCCESS
, nr_succeeded
);
1477 count_vm_events(PGMIGRATE_FAIL
, nr_failed
);
1478 trace_mm_migrate_pages(nr_succeeded
, nr_failed
, mode
, reason
);
1481 current
->flags
&= ~PF_SWAPWRITE
;
1488 static int store_status(int __user
*status
, int start
, int value
, int nr
)
1491 if (put_user(value
, status
+ start
))
1499 static int do_move_pages_to_node(struct mm_struct
*mm
,
1500 struct list_head
*pagelist
, int node
)
1504 if (list_empty(pagelist
))
1507 err
= migrate_pages(pagelist
, alloc_new_node_page
, NULL
, node
,
1508 MIGRATE_SYNC
, MR_SYSCALL
);
1510 putback_movable_pages(pagelist
);
1515 * Resolves the given address to a struct page, isolates it from the LRU and
1516 * puts it to the given pagelist.
1517 * Returns -errno if the page cannot be found/isolated or 0 when it has been
1518 * queued or the page doesn't need to be migrated because it is already on
1521 static int add_page_for_migration(struct mm_struct
*mm
, unsigned long addr
,
1522 int node
, struct list_head
*pagelist
, bool migrate_all
)
1524 struct vm_area_struct
*vma
;
1526 unsigned int follflags
;
1529 down_read(&mm
->mmap_sem
);
1531 vma
= find_vma(mm
, addr
);
1532 if (!vma
|| addr
< vma
->vm_start
|| !vma_migratable(vma
))
1535 /* FOLL_DUMP to ignore special (like zero) pages */
1536 follflags
= FOLL_GET
| FOLL_DUMP
;
1537 page
= follow_page(vma
, addr
, follflags
);
1539 err
= PTR_ERR(page
);
1548 if (page_to_nid(page
) == node
)
1552 if (page_mapcount(page
) > 1 && !migrate_all
)
1555 if (PageHuge(page
)) {
1556 if (PageHead(page
)) {
1557 isolate_huge_page(page
, pagelist
);
1563 head
= compound_head(page
);
1564 err
= isolate_lru_page(head
);
1569 list_add_tail(&head
->lru
, pagelist
);
1570 mod_node_page_state(page_pgdat(head
),
1571 NR_ISOLATED_ANON
+ page_is_file_cache(head
),
1572 hpage_nr_pages(head
));
1576 * Either remove the duplicate refcount from
1577 * isolate_lru_page() or drop the page ref if it was
1582 up_read(&mm
->mmap_sem
);
1587 * Migrate an array of page address onto an array of nodes and fill
1588 * the corresponding array of status.
1590 static int do_pages_move(struct mm_struct
*mm
, nodemask_t task_nodes
,
1591 unsigned long nr_pages
,
1592 const void __user
* __user
*pages
,
1593 const int __user
*nodes
,
1594 int __user
*status
, int flags
)
1596 int current_node
= NUMA_NO_NODE
;
1597 LIST_HEAD(pagelist
);
1603 for (i
= start
= 0; i
< nr_pages
; i
++) {
1604 const void __user
*p
;
1609 if (get_user(p
, pages
+ i
))
1611 if (get_user(node
, nodes
+ i
))
1613 addr
= (unsigned long)p
;
1616 if (node
< 0 || node
>= MAX_NUMNODES
)
1618 if (!node_state(node
, N_MEMORY
))
1622 if (!node_isset(node
, task_nodes
))
1625 if (current_node
== NUMA_NO_NODE
) {
1626 current_node
= node
;
1628 } else if (node
!= current_node
) {
1629 err
= do_move_pages_to_node(mm
, &pagelist
, current_node
);
1632 err
= store_status(status
, start
, current_node
, i
- start
);
1636 current_node
= node
;
1640 * Errors in the page lookup or isolation are not fatal and we simply
1641 * report them via status
1643 err
= add_page_for_migration(mm
, addr
, current_node
,
1644 &pagelist
, flags
& MPOL_MF_MOVE_ALL
);
1648 err
= store_status(status
, i
, err
, 1);
1652 err
= do_move_pages_to_node(mm
, &pagelist
, current_node
);
1656 err
= store_status(status
, start
, current_node
, i
- start
);
1660 current_node
= NUMA_NO_NODE
;
1663 if (list_empty(&pagelist
))
1666 /* Make sure we do not overwrite the existing error */
1667 err1
= do_move_pages_to_node(mm
, &pagelist
, current_node
);
1669 err1
= store_status(status
, start
, current_node
, i
- start
);
1677 * Determine the nodes of an array of pages and store it in an array of status.
1679 static void do_pages_stat_array(struct mm_struct
*mm
, unsigned long nr_pages
,
1680 const void __user
**pages
, int *status
)
1684 down_read(&mm
->mmap_sem
);
1686 for (i
= 0; i
< nr_pages
; i
++) {
1687 unsigned long addr
= (unsigned long)(*pages
);
1688 struct vm_area_struct
*vma
;
1692 vma
= find_vma(mm
, addr
);
1693 if (!vma
|| addr
< vma
->vm_start
)
1696 /* FOLL_DUMP to ignore special (like zero) pages */
1697 page
= follow_page(vma
, addr
, FOLL_DUMP
);
1699 err
= PTR_ERR(page
);
1703 err
= page
? page_to_nid(page
) : -ENOENT
;
1711 up_read(&mm
->mmap_sem
);
1715 * Determine the nodes of a user array of pages and store it in
1716 * a user array of status.
1718 static int do_pages_stat(struct mm_struct
*mm
, unsigned long nr_pages
,
1719 const void __user
* __user
*pages
,
1722 #define DO_PAGES_STAT_CHUNK_NR 16
1723 const void __user
*chunk_pages
[DO_PAGES_STAT_CHUNK_NR
];
1724 int chunk_status
[DO_PAGES_STAT_CHUNK_NR
];
1727 unsigned long chunk_nr
;
1729 chunk_nr
= nr_pages
;
1730 if (chunk_nr
> DO_PAGES_STAT_CHUNK_NR
)
1731 chunk_nr
= DO_PAGES_STAT_CHUNK_NR
;
1733 if (copy_from_user(chunk_pages
, pages
, chunk_nr
* sizeof(*chunk_pages
)))
1736 do_pages_stat_array(mm
, chunk_nr
, chunk_pages
, chunk_status
);
1738 if (copy_to_user(status
, chunk_status
, chunk_nr
* sizeof(*status
)))
1743 nr_pages
-= chunk_nr
;
1745 return nr_pages
? -EFAULT
: 0;
1749 * Move a list of pages in the address space of the currently executing
1752 static int kernel_move_pages(pid_t pid
, unsigned long nr_pages
,
1753 const void __user
* __user
*pages
,
1754 const int __user
*nodes
,
1755 int __user
*status
, int flags
)
1757 struct task_struct
*task
;
1758 struct mm_struct
*mm
;
1760 nodemask_t task_nodes
;
1763 if (flags
& ~(MPOL_MF_MOVE
|MPOL_MF_MOVE_ALL
))
1766 if ((flags
& MPOL_MF_MOVE_ALL
) && !capable(CAP_SYS_NICE
))
1769 /* Find the mm_struct */
1771 task
= pid
? find_task_by_vpid(pid
) : current
;
1776 get_task_struct(task
);
1779 * Check if this process has the right to modify the specified
1780 * process. Use the regular "ptrace_may_access()" checks.
1782 if (!ptrace_may_access(task
, PTRACE_MODE_READ_REALCREDS
)) {
1789 err
= security_task_movememory(task
);
1793 task_nodes
= cpuset_mems_allowed(task
);
1794 mm
= get_task_mm(task
);
1795 put_task_struct(task
);
1801 err
= do_pages_move(mm
, task_nodes
, nr_pages
, pages
,
1802 nodes
, status
, flags
);
1804 err
= do_pages_stat(mm
, nr_pages
, pages
, status
);
1810 put_task_struct(task
);
1814 SYSCALL_DEFINE6(move_pages
, pid_t
, pid
, unsigned long, nr_pages
,
1815 const void __user
* __user
*, pages
,
1816 const int __user
*, nodes
,
1817 int __user
*, status
, int, flags
)
1819 return kernel_move_pages(pid
, nr_pages
, pages
, nodes
, status
, flags
);
1822 #ifdef CONFIG_COMPAT
1823 COMPAT_SYSCALL_DEFINE6(move_pages
, pid_t
, pid
, compat_ulong_t
, nr_pages
,
1824 compat_uptr_t __user
*, pages32
,
1825 const int __user
*, nodes
,
1826 int __user
*, status
,
1829 const void __user
* __user
*pages
;
1832 pages
= compat_alloc_user_space(nr_pages
* sizeof(void *));
1833 for (i
= 0; i
< nr_pages
; i
++) {
1836 if (get_user(p
, pages32
+ i
) ||
1837 put_user(compat_ptr(p
), pages
+ i
))
1840 return kernel_move_pages(pid
, nr_pages
, pages
, nodes
, status
, flags
);
1842 #endif /* CONFIG_COMPAT */
1844 #ifdef CONFIG_NUMA_BALANCING
1846 * Returns true if this is a safe migration target node for misplaced NUMA
1847 * pages. Currently it only checks the watermarks which crude
1849 static bool migrate_balanced_pgdat(struct pglist_data
*pgdat
,
1850 unsigned long nr_migrate_pages
)
1854 for (z
= pgdat
->nr_zones
- 1; z
>= 0; z
--) {
1855 struct zone
*zone
= pgdat
->node_zones
+ z
;
1857 if (!populated_zone(zone
))
1860 /* Avoid waking kswapd by allocating pages_to_migrate pages. */
1861 if (!zone_watermark_ok(zone
, 0,
1862 high_wmark_pages(zone
) +
1871 static struct page
*alloc_misplaced_dst_page(struct page
*page
,
1874 int nid
= (int) data
;
1875 struct page
*newpage
;
1877 newpage
= __alloc_pages_node(nid
,
1878 (GFP_HIGHUSER_MOVABLE
|
1879 __GFP_THISNODE
| __GFP_NOMEMALLOC
|
1880 __GFP_NORETRY
| __GFP_NOWARN
) &
1886 static int numamigrate_isolate_page(pg_data_t
*pgdat
, struct page
*page
)
1890 VM_BUG_ON_PAGE(compound_order(page
) && !PageTransHuge(page
), page
);
1892 /* Avoid migrating to a node that is nearly full */
1893 if (!migrate_balanced_pgdat(pgdat
, 1UL << compound_order(page
)))
1896 if (isolate_lru_page(page
))
1900 * migrate_misplaced_transhuge_page() skips page migration's usual
1901 * check on page_count(), so we must do it here, now that the page
1902 * has been isolated: a GUP pin, or any other pin, prevents migration.
1903 * The expected page count is 3: 1 for page's mapcount and 1 for the
1904 * caller's pin and 1 for the reference taken by isolate_lru_page().
1906 if (PageTransHuge(page
) && page_count(page
) != 3) {
1907 putback_lru_page(page
);
1911 page_lru
= page_is_file_cache(page
);
1912 mod_node_page_state(page_pgdat(page
), NR_ISOLATED_ANON
+ page_lru
,
1913 hpage_nr_pages(page
));
1916 * Isolating the page has taken another reference, so the
1917 * caller's reference can be safely dropped without the page
1918 * disappearing underneath us during migration.
1924 bool pmd_trans_migrating(pmd_t pmd
)
1926 struct page
*page
= pmd_page(pmd
);
1927 return PageLocked(page
);
1931 * Attempt to migrate a misplaced page to the specified destination
1932 * node. Caller is expected to have an elevated reference count on
1933 * the page that will be dropped by this function before returning.
1935 int migrate_misplaced_page(struct page
*page
, struct vm_area_struct
*vma
,
1938 pg_data_t
*pgdat
= NODE_DATA(node
);
1941 LIST_HEAD(migratepages
);
1944 * Don't migrate file pages that are mapped in multiple processes
1945 * with execute permissions as they are probably shared libraries.
1947 if (page_mapcount(page
) != 1 && page_is_file_cache(page
) &&
1948 (vma
->vm_flags
& VM_EXEC
))
1952 * Also do not migrate dirty pages as not all filesystems can move
1953 * dirty pages in MIGRATE_ASYNC mode which is a waste of cycles.
1955 if (page_is_file_cache(page
) && PageDirty(page
))
1958 isolated
= numamigrate_isolate_page(pgdat
, page
);
1962 list_add(&page
->lru
, &migratepages
);
1963 nr_remaining
= migrate_pages(&migratepages
, alloc_misplaced_dst_page
,
1964 NULL
, node
, MIGRATE_ASYNC
,
1967 if (!list_empty(&migratepages
)) {
1968 list_del(&page
->lru
);
1969 dec_node_page_state(page
, NR_ISOLATED_ANON
+
1970 page_is_file_cache(page
));
1971 putback_lru_page(page
);
1975 count_vm_numa_event(NUMA_PAGE_MIGRATE
);
1976 BUG_ON(!list_empty(&migratepages
));
1983 #endif /* CONFIG_NUMA_BALANCING */
1985 #if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
1987 * Migrates a THP to a given target node. page must be locked and is unlocked
1990 int migrate_misplaced_transhuge_page(struct mm_struct
*mm
,
1991 struct vm_area_struct
*vma
,
1992 pmd_t
*pmd
, pmd_t entry
,
1993 unsigned long address
,
1994 struct page
*page
, int node
)
1997 pg_data_t
*pgdat
= NODE_DATA(node
);
1999 struct page
*new_page
= NULL
;
2000 int page_lru
= page_is_file_cache(page
);
2001 unsigned long start
= address
& HPAGE_PMD_MASK
;
2003 new_page
= alloc_pages_node(node
,
2004 (GFP_TRANSHUGE_LIGHT
| __GFP_THISNODE
),
2008 prep_transhuge_page(new_page
);
2010 isolated
= numamigrate_isolate_page(pgdat
, page
);
2016 /* Prepare a page as a migration target */
2017 __SetPageLocked(new_page
);
2018 if (PageSwapBacked(page
))
2019 __SetPageSwapBacked(new_page
);
2021 /* anon mapping, we can simply copy page->mapping to the new page: */
2022 new_page
->mapping
= page
->mapping
;
2023 new_page
->index
= page
->index
;
2024 /* flush the cache before copying using the kernel virtual address */
2025 flush_cache_range(vma
, start
, start
+ HPAGE_PMD_SIZE
);
2026 migrate_page_copy(new_page
, page
);
2027 WARN_ON(PageLRU(new_page
));
2029 /* Recheck the target PMD */
2030 ptl
= pmd_lock(mm
, pmd
);
2031 if (unlikely(!pmd_same(*pmd
, entry
) || !page_ref_freeze(page
, 2))) {
2034 /* Reverse changes made by migrate_page_copy() */
2035 if (TestClearPageActive(new_page
))
2036 SetPageActive(page
);
2037 if (TestClearPageUnevictable(new_page
))
2038 SetPageUnevictable(page
);
2040 unlock_page(new_page
);
2041 put_page(new_page
); /* Free it */
2043 /* Retake the callers reference and putback on LRU */
2045 putback_lru_page(page
);
2046 mod_node_page_state(page_pgdat(page
),
2047 NR_ISOLATED_ANON
+ page_lru
, -HPAGE_PMD_NR
);
2052 entry
= mk_huge_pmd(new_page
, vma
->vm_page_prot
);
2053 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
2056 * Overwrite the old entry under pagetable lock and establish
2057 * the new PTE. Any parallel GUP will either observe the old
2058 * page blocking on the page lock, block on the page table
2059 * lock or observe the new page. The SetPageUptodate on the
2060 * new page and page_add_new_anon_rmap guarantee the copy is
2061 * visible before the pagetable update.
2063 page_add_anon_rmap(new_page
, vma
, start
, true);
2065 * At this point the pmd is numa/protnone (i.e. non present) and the TLB
2066 * has already been flushed globally. So no TLB can be currently
2067 * caching this non present pmd mapping. There's no need to clear the
2068 * pmd before doing set_pmd_at(), nor to flush the TLB after
2069 * set_pmd_at(). Clearing the pmd here would introduce a race
2070 * condition against MADV_DONTNEED, because MADV_DONTNEED only holds the
2071 * mmap_sem for reading. If the pmd is set to NULL at any given time,
2072 * MADV_DONTNEED won't wait on the pmd lock and it'll skip clearing this
2075 set_pmd_at(mm
, start
, pmd
, entry
);
2076 update_mmu_cache_pmd(vma
, address
, &entry
);
2078 page_ref_unfreeze(page
, 2);
2079 mlock_migrate_page(new_page
, page
);
2080 page_remove_rmap(page
, true);
2081 set_page_owner_migrate_reason(new_page
, MR_NUMA_MISPLACED
);
2085 /* Take an "isolate" reference and put new page on the LRU. */
2087 putback_lru_page(new_page
);
2089 unlock_page(new_page
);
2091 put_page(page
); /* Drop the rmap reference */
2092 put_page(page
); /* Drop the LRU isolation reference */
2094 count_vm_events(PGMIGRATE_SUCCESS
, HPAGE_PMD_NR
);
2095 count_vm_numa_events(NUMA_PAGE_MIGRATE
, HPAGE_PMD_NR
);
2097 mod_node_page_state(page_pgdat(page
),
2098 NR_ISOLATED_ANON
+ page_lru
,
2103 count_vm_events(PGMIGRATE_FAIL
, HPAGE_PMD_NR
);
2104 ptl
= pmd_lock(mm
, pmd
);
2105 if (pmd_same(*pmd
, entry
)) {
2106 entry
= pmd_modify(entry
, vma
->vm_page_prot
);
2107 set_pmd_at(mm
, start
, pmd
, entry
);
2108 update_mmu_cache_pmd(vma
, address
, &entry
);
2117 #endif /* CONFIG_NUMA_BALANCING */
2119 #endif /* CONFIG_NUMA */
2121 #if defined(CONFIG_MIGRATE_VMA_HELPER)
2122 struct migrate_vma
{
2123 struct vm_area_struct
*vma
;
2126 unsigned long cpages
;
2127 unsigned long npages
;
2128 unsigned long start
;
2132 static int migrate_vma_collect_hole(unsigned long start
,
2134 struct mm_walk
*walk
)
2136 struct migrate_vma
*migrate
= walk
->private;
2139 for (addr
= start
& PAGE_MASK
; addr
< end
; addr
+= PAGE_SIZE
) {
2140 migrate
->src
[migrate
->npages
] = MIGRATE_PFN_MIGRATE
;
2141 migrate
->dst
[migrate
->npages
] = 0;
2149 static int migrate_vma_collect_skip(unsigned long start
,
2151 struct mm_walk
*walk
)
2153 struct migrate_vma
*migrate
= walk
->private;
2156 for (addr
= start
& PAGE_MASK
; addr
< end
; addr
+= PAGE_SIZE
) {
2157 migrate
->dst
[migrate
->npages
] = 0;
2158 migrate
->src
[migrate
->npages
++] = 0;
2164 static int migrate_vma_collect_pmd(pmd_t
*pmdp
,
2165 unsigned long start
,
2167 struct mm_walk
*walk
)
2169 struct migrate_vma
*migrate
= walk
->private;
2170 struct vm_area_struct
*vma
= walk
->vma
;
2171 struct mm_struct
*mm
= vma
->vm_mm
;
2172 unsigned long addr
= start
, unmapped
= 0;
2177 if (pmd_none(*pmdp
))
2178 return migrate_vma_collect_hole(start
, end
, walk
);
2180 if (pmd_trans_huge(*pmdp
)) {
2183 ptl
= pmd_lock(mm
, pmdp
);
2184 if (unlikely(!pmd_trans_huge(*pmdp
))) {
2189 page
= pmd_page(*pmdp
);
2190 if (is_huge_zero_page(page
)) {
2192 split_huge_pmd(vma
, pmdp
, addr
);
2193 if (pmd_trans_unstable(pmdp
))
2194 return migrate_vma_collect_skip(start
, end
,
2201 if (unlikely(!trylock_page(page
)))
2202 return migrate_vma_collect_skip(start
, end
,
2204 ret
= split_huge_page(page
);
2208 return migrate_vma_collect_skip(start
, end
,
2210 if (pmd_none(*pmdp
))
2211 return migrate_vma_collect_hole(start
, end
,
2216 if (unlikely(pmd_bad(*pmdp
)))
2217 return migrate_vma_collect_skip(start
, end
, walk
);
2219 ptep
= pte_offset_map_lock(mm
, pmdp
, addr
, &ptl
);
2220 arch_enter_lazy_mmu_mode();
2222 for (; addr
< end
; addr
+= PAGE_SIZE
, ptep
++) {
2223 unsigned long mpfn
, pfn
;
2231 if (pte_none(pte
)) {
2232 mpfn
= MIGRATE_PFN_MIGRATE
;
2238 if (!pte_present(pte
)) {
2242 * Only care about unaddressable device page special
2243 * page table entry. Other special swap entries are not
2244 * migratable, and we ignore regular swapped page.
2246 entry
= pte_to_swp_entry(pte
);
2247 if (!is_device_private_entry(entry
))
2250 page
= device_private_entry_to_page(entry
);
2251 mpfn
= migrate_pfn(page_to_pfn(page
))|
2252 MIGRATE_PFN_DEVICE
| MIGRATE_PFN_MIGRATE
;
2253 if (is_write_device_private_entry(entry
))
2254 mpfn
|= MIGRATE_PFN_WRITE
;
2256 if (is_zero_pfn(pfn
)) {
2257 mpfn
= MIGRATE_PFN_MIGRATE
;
2262 page
= vm_normal_page(migrate
->vma
, addr
, pte
);
2263 mpfn
= migrate_pfn(pfn
) | MIGRATE_PFN_MIGRATE
;
2264 mpfn
|= pte_write(pte
) ? MIGRATE_PFN_WRITE
: 0;
2267 /* FIXME support THP */
2268 if (!page
|| !page
->mapping
|| PageTransCompound(page
)) {
2272 pfn
= page_to_pfn(page
);
2275 * By getting a reference on the page we pin it and that blocks
2276 * any kind of migration. Side effect is that it "freezes" the
2279 * We drop this reference after isolating the page from the lru
2280 * for non device page (device page are not on the lru and thus
2281 * can't be dropped from it).
2287 * Optimize for the common case where page is only mapped once
2288 * in one process. If we can lock the page, then we can safely
2289 * set up a special migration page table entry now.
2291 if (trylock_page(page
)) {
2294 mpfn
|= MIGRATE_PFN_LOCKED
;
2295 ptep_get_and_clear(mm
, addr
, ptep
);
2297 /* Setup special migration page table entry */
2298 entry
= make_migration_entry(page
, mpfn
&
2300 swp_pte
= swp_entry_to_pte(entry
);
2301 if (pte_soft_dirty(pte
))
2302 swp_pte
= pte_swp_mksoft_dirty(swp_pte
);
2303 set_pte_at(mm
, addr
, ptep
, swp_pte
);
2306 * This is like regular unmap: we remove the rmap and
2307 * drop page refcount. Page won't be freed, as we took
2308 * a reference just above.
2310 page_remove_rmap(page
, false);
2313 if (pte_present(pte
))
2318 migrate
->dst
[migrate
->npages
] = 0;
2319 migrate
->src
[migrate
->npages
++] = mpfn
;
2321 arch_leave_lazy_mmu_mode();
2322 pte_unmap_unlock(ptep
- 1, ptl
);
2324 /* Only flush the TLB if we actually modified any entries */
2326 flush_tlb_range(walk
->vma
, start
, end
);
2332 * migrate_vma_collect() - collect pages over a range of virtual addresses
2333 * @migrate: migrate struct containing all migration information
2335 * This will walk the CPU page table. For each virtual address backed by a
2336 * valid page, it updates the src array and takes a reference on the page, in
2337 * order to pin the page until we lock it and unmap it.
2339 static void migrate_vma_collect(struct migrate_vma
*migrate
)
2341 struct mmu_notifier_range range
;
2342 struct mm_walk mm_walk
;
2344 mm_walk
.pmd_entry
= migrate_vma_collect_pmd
;
2345 mm_walk
.pte_entry
= NULL
;
2346 mm_walk
.pte_hole
= migrate_vma_collect_hole
;
2347 mm_walk
.hugetlb_entry
= NULL
;
2348 mm_walk
.test_walk
= NULL
;
2349 mm_walk
.vma
= migrate
->vma
;
2350 mm_walk
.mm
= migrate
->vma
->vm_mm
;
2351 mm_walk
.private = migrate
;
2353 mmu_notifier_range_init(&range
, MMU_NOTIFY_CLEAR
, 0, NULL
, mm_walk
.mm
,
2356 mmu_notifier_invalidate_range_start(&range
);
2357 walk_page_range(migrate
->start
, migrate
->end
, &mm_walk
);
2358 mmu_notifier_invalidate_range_end(&range
);
2360 migrate
->end
= migrate
->start
+ (migrate
->npages
<< PAGE_SHIFT
);
2364 * migrate_vma_check_page() - check if page is pinned or not
2365 * @page: struct page to check
2367 * Pinned pages cannot be migrated. This is the same test as in
2368 * migrate_page_move_mapping(), except that here we allow migration of a
2371 static bool migrate_vma_check_page(struct page
*page
)
2374 * One extra ref because caller holds an extra reference, either from
2375 * isolate_lru_page() for a regular page, or migrate_vma_collect() for
2381 * FIXME support THP (transparent huge page), it is bit more complex to
2382 * check them than regular pages, because they can be mapped with a pmd
2383 * or with a pte (split pte mapping).
2385 if (PageCompound(page
))
2388 /* Page from ZONE_DEVICE have one extra reference */
2389 if (is_zone_device_page(page
)) {
2391 * Private page can never be pin as they have no valid pte and
2392 * GUP will fail for those. Yet if there is a pending migration
2393 * a thread might try to wait on the pte migration entry and
2394 * will bump the page reference count. Sadly there is no way to
2395 * differentiate a regular pin from migration wait. Hence to
2396 * avoid 2 racing thread trying to migrate back to CPU to enter
2397 * infinite loop (one stoping migration because the other is
2398 * waiting on pte migration entry). We always return true here.
2400 * FIXME proper solution is to rework migration_entry_wait() so
2401 * it does not need to take a reference on page.
2403 return is_device_private_page(page
);
2406 /* For file back page */
2407 if (page_mapping(page
))
2408 extra
+= 1 + page_has_private(page
);
2410 if ((page_count(page
) - extra
) > page_mapcount(page
))
2417 * migrate_vma_prepare() - lock pages and isolate them from the lru
2418 * @migrate: migrate struct containing all migration information
2420 * This locks pages that have been collected by migrate_vma_collect(). Once each
2421 * page is locked it is isolated from the lru (for non-device pages). Finally,
2422 * the ref taken by migrate_vma_collect() is dropped, as locked pages cannot be
2423 * migrated by concurrent kernel threads.
2425 static void migrate_vma_prepare(struct migrate_vma
*migrate
)
2427 const unsigned long npages
= migrate
->npages
;
2428 const unsigned long start
= migrate
->start
;
2429 unsigned long addr
, i
, restore
= 0;
2430 bool allow_drain
= true;
2434 for (i
= 0; (i
< npages
) && migrate
->cpages
; i
++) {
2435 struct page
*page
= migrate_pfn_to_page(migrate
->src
[i
]);
2441 if (!(migrate
->src
[i
] & MIGRATE_PFN_LOCKED
)) {
2443 * Because we are migrating several pages there can be
2444 * a deadlock between 2 concurrent migration where each
2445 * are waiting on each other page lock.
2447 * Make migrate_vma() a best effort thing and backoff
2448 * for any page we can not lock right away.
2450 if (!trylock_page(page
)) {
2451 migrate
->src
[i
] = 0;
2457 migrate
->src
[i
] |= MIGRATE_PFN_LOCKED
;
2460 /* ZONE_DEVICE pages are not on LRU */
2461 if (!is_zone_device_page(page
)) {
2462 if (!PageLRU(page
) && allow_drain
) {
2463 /* Drain CPU's pagevec */
2464 lru_add_drain_all();
2465 allow_drain
= false;
2468 if (isolate_lru_page(page
)) {
2470 migrate
->src
[i
] &= ~MIGRATE_PFN_MIGRATE
;
2474 migrate
->src
[i
] = 0;
2482 /* Drop the reference we took in collect */
2486 if (!migrate_vma_check_page(page
)) {
2488 migrate
->src
[i
] &= ~MIGRATE_PFN_MIGRATE
;
2492 if (!is_zone_device_page(page
)) {
2494 putback_lru_page(page
);
2497 migrate
->src
[i
] = 0;
2501 if (!is_zone_device_page(page
))
2502 putback_lru_page(page
);
2509 for (i
= 0, addr
= start
; i
< npages
&& restore
; i
++, addr
+= PAGE_SIZE
) {
2510 struct page
*page
= migrate_pfn_to_page(migrate
->src
[i
]);
2512 if (!page
|| (migrate
->src
[i
] & MIGRATE_PFN_MIGRATE
))
2515 remove_migration_pte(page
, migrate
->vma
, addr
, page
);
2517 migrate
->src
[i
] = 0;
2525 * migrate_vma_unmap() - replace page mapping with special migration pte entry
2526 * @migrate: migrate struct containing all migration information
2528 * Replace page mapping (CPU page table pte) with a special migration pte entry
2529 * and check again if it has been pinned. Pinned pages are restored because we
2530 * cannot migrate them.
2532 * This is the last step before we call the device driver callback to allocate
2533 * destination memory and copy contents of original page over to new page.
2535 static void migrate_vma_unmap(struct migrate_vma
*migrate
)
2537 int flags
= TTU_MIGRATION
| TTU_IGNORE_MLOCK
| TTU_IGNORE_ACCESS
;
2538 const unsigned long npages
= migrate
->npages
;
2539 const unsigned long start
= migrate
->start
;
2540 unsigned long addr
, i
, restore
= 0;
2542 for (i
= 0; i
< npages
; i
++) {
2543 struct page
*page
= migrate_pfn_to_page(migrate
->src
[i
]);
2545 if (!page
|| !(migrate
->src
[i
] & MIGRATE_PFN_MIGRATE
))
2548 if (page_mapped(page
)) {
2549 try_to_unmap(page
, flags
);
2550 if (page_mapped(page
))
2554 if (migrate_vma_check_page(page
))
2558 migrate
->src
[i
] &= ~MIGRATE_PFN_MIGRATE
;
2563 for (addr
= start
, i
= 0; i
< npages
&& restore
; addr
+= PAGE_SIZE
, i
++) {
2564 struct page
*page
= migrate_pfn_to_page(migrate
->src
[i
]);
2566 if (!page
|| (migrate
->src
[i
] & MIGRATE_PFN_MIGRATE
))
2569 remove_migration_ptes(page
, page
, false);
2571 migrate
->src
[i
] = 0;
2575 if (is_zone_device_page(page
))
2578 putback_lru_page(page
);
2582 static void migrate_vma_insert_page(struct migrate_vma
*migrate
,
2588 struct vm_area_struct
*vma
= migrate
->vma
;
2589 struct mm_struct
*mm
= vma
->vm_mm
;
2590 struct mem_cgroup
*memcg
;
2600 /* Only allow populating anonymous memory */
2601 if (!vma_is_anonymous(vma
))
2604 pgdp
= pgd_offset(mm
, addr
);
2605 p4dp
= p4d_alloc(mm
, pgdp
, addr
);
2608 pudp
= pud_alloc(mm
, p4dp
, addr
);
2611 pmdp
= pmd_alloc(mm
, pudp
, addr
);
2615 if (pmd_trans_huge(*pmdp
) || pmd_devmap(*pmdp
))
2619 * Use pte_alloc() instead of pte_alloc_map(). We can't run
2620 * pte_offset_map() on pmds where a huge pmd might be created
2621 * from a different thread.
2623 * pte_alloc_map() is safe to use under down_write(mmap_sem) or when
2624 * parallel threads are excluded by other means.
2626 * Here we only have down_read(mmap_sem).
2628 if (pte_alloc(mm
, pmdp
))
2631 /* See the comment in pte_alloc_one_map() */
2632 if (unlikely(pmd_trans_unstable(pmdp
)))
2635 if (unlikely(anon_vma_prepare(vma
)))
2637 if (mem_cgroup_try_charge(page
, vma
->vm_mm
, GFP_KERNEL
, &memcg
, false))
2641 * The memory barrier inside __SetPageUptodate makes sure that
2642 * preceding stores to the page contents become visible before
2643 * the set_pte_at() write.
2645 __SetPageUptodate(page
);
2647 if (is_zone_device_page(page
)) {
2648 if (is_device_private_page(page
)) {
2649 swp_entry_t swp_entry
;
2651 swp_entry
= make_device_private_entry(page
, vma
->vm_flags
& VM_WRITE
);
2652 entry
= swp_entry_to_pte(swp_entry
);
2655 entry
= mk_pte(page
, vma
->vm_page_prot
);
2656 if (vma
->vm_flags
& VM_WRITE
)
2657 entry
= pte_mkwrite(pte_mkdirty(entry
));
2660 ptep
= pte_offset_map_lock(mm
, pmdp
, addr
, &ptl
);
2662 if (pte_present(*ptep
)) {
2663 unsigned long pfn
= pte_pfn(*ptep
);
2665 if (!is_zero_pfn(pfn
)) {
2666 pte_unmap_unlock(ptep
, ptl
);
2667 mem_cgroup_cancel_charge(page
, memcg
, false);
2671 } else if (!pte_none(*ptep
)) {
2672 pte_unmap_unlock(ptep
, ptl
);
2673 mem_cgroup_cancel_charge(page
, memcg
, false);
2678 * Check for usefaultfd but do not deliver the fault. Instead,
2681 if (userfaultfd_missing(vma
)) {
2682 pte_unmap_unlock(ptep
, ptl
);
2683 mem_cgroup_cancel_charge(page
, memcg
, false);
2687 inc_mm_counter(mm
, MM_ANONPAGES
);
2688 page_add_new_anon_rmap(page
, vma
, addr
, false);
2689 mem_cgroup_commit_charge(page
, memcg
, false, false);
2690 if (!is_zone_device_page(page
))
2691 lru_cache_add_active_or_unevictable(page
, vma
);
2695 flush_cache_page(vma
, addr
, pte_pfn(*ptep
));
2696 ptep_clear_flush_notify(vma
, addr
, ptep
);
2697 set_pte_at_notify(mm
, addr
, ptep
, entry
);
2698 update_mmu_cache(vma
, addr
, ptep
);
2700 /* No need to invalidate - it was non-present before */
2701 set_pte_at(mm
, addr
, ptep
, entry
);
2702 update_mmu_cache(vma
, addr
, ptep
);
2705 pte_unmap_unlock(ptep
, ptl
);
2706 *src
= MIGRATE_PFN_MIGRATE
;
2710 *src
&= ~MIGRATE_PFN_MIGRATE
;
2714 * migrate_vma_pages() - migrate meta-data from src page to dst page
2715 * @migrate: migrate struct containing all migration information
2717 * This migrates struct page meta-data from source struct page to destination
2718 * struct page. This effectively finishes the migration from source page to the
2721 static void migrate_vma_pages(struct migrate_vma
*migrate
)
2723 const unsigned long npages
= migrate
->npages
;
2724 const unsigned long start
= migrate
->start
;
2725 struct mmu_notifier_range range
;
2726 unsigned long addr
, i
;
2727 bool notified
= false;
2729 for (i
= 0, addr
= start
; i
< npages
; addr
+= PAGE_SIZE
, i
++) {
2730 struct page
*newpage
= migrate_pfn_to_page(migrate
->dst
[i
]);
2731 struct page
*page
= migrate_pfn_to_page(migrate
->src
[i
]);
2732 struct address_space
*mapping
;
2736 migrate
->src
[i
] &= ~MIGRATE_PFN_MIGRATE
;
2741 if (!(migrate
->src
[i
] & MIGRATE_PFN_MIGRATE
)) {
2747 mmu_notifier_range_init(&range
,
2748 MMU_NOTIFY_CLEAR
, 0,
2750 migrate
->vma
->vm_mm
,
2751 addr
, migrate
->end
);
2752 mmu_notifier_invalidate_range_start(&range
);
2754 migrate_vma_insert_page(migrate
, addr
, newpage
,
2760 mapping
= page_mapping(page
);
2762 if (is_zone_device_page(newpage
)) {
2763 if (is_device_private_page(newpage
)) {
2765 * For now only support private anonymous when
2766 * migrating to un-addressable device memory.
2769 migrate
->src
[i
] &= ~MIGRATE_PFN_MIGRATE
;
2774 * Other types of ZONE_DEVICE page are not
2777 migrate
->src
[i
] &= ~MIGRATE_PFN_MIGRATE
;
2782 r
= migrate_page(mapping
, newpage
, page
, MIGRATE_SYNC_NO_COPY
);
2783 if (r
!= MIGRATEPAGE_SUCCESS
)
2784 migrate
->src
[i
] &= ~MIGRATE_PFN_MIGRATE
;
2788 * No need to double call mmu_notifier->invalidate_range() callback as
2789 * the above ptep_clear_flush_notify() inside migrate_vma_insert_page()
2790 * did already call it.
2793 mmu_notifier_invalidate_range_only_end(&range
);
2797 * migrate_vma_finalize() - restore CPU page table entry
2798 * @migrate: migrate struct containing all migration information
2800 * This replaces the special migration pte entry with either a mapping to the
2801 * new page if migration was successful for that page, or to the original page
2804 * This also unlocks the pages and puts them back on the lru, or drops the extra
2805 * refcount, for device pages.
2807 static void migrate_vma_finalize(struct migrate_vma
*migrate
)
2809 const unsigned long npages
= migrate
->npages
;
2812 for (i
= 0; i
< npages
; i
++) {
2813 struct page
*newpage
= migrate_pfn_to_page(migrate
->dst
[i
]);
2814 struct page
*page
= migrate_pfn_to_page(migrate
->src
[i
]);
2818 unlock_page(newpage
);
2824 if (!(migrate
->src
[i
] & MIGRATE_PFN_MIGRATE
) || !newpage
) {
2826 unlock_page(newpage
);
2832 remove_migration_ptes(page
, newpage
, false);
2836 if (is_zone_device_page(page
))
2839 putback_lru_page(page
);
2841 if (newpage
!= page
) {
2842 unlock_page(newpage
);
2843 if (is_zone_device_page(newpage
))
2846 putback_lru_page(newpage
);
2852 * migrate_vma() - migrate a range of memory inside vma
2854 * @ops: migration callback for allocating destination memory and copying
2855 * @vma: virtual memory area containing the range to be migrated
2856 * @start: start address of the range to migrate (inclusive)
2857 * @end: end address of the range to migrate (exclusive)
2858 * @src: array of hmm_pfn_t containing source pfns
2859 * @dst: array of hmm_pfn_t containing destination pfns
2860 * @private: pointer passed back to each of the callback
2861 * Returns: 0 on success, error code otherwise
2863 * This function tries to migrate a range of memory virtual address range, using
2864 * callbacks to allocate and copy memory from source to destination. First it
2865 * collects all the pages backing each virtual address in the range, saving this
2866 * inside the src array. Then it locks those pages and unmaps them. Once the pages
2867 * are locked and unmapped, it checks whether each page is pinned or not. Pages
2868 * that aren't pinned have the MIGRATE_PFN_MIGRATE flag set (by this function)
2869 * in the corresponding src array entry. It then restores any pages that are
2870 * pinned, by remapping and unlocking those pages.
2872 * At this point it calls the alloc_and_copy() callback. For documentation on
2873 * what is expected from that callback, see struct migrate_vma_ops comments in
2874 * include/linux/migrate.h
2876 * After the alloc_and_copy() callback, this function goes over each entry in
2877 * the src array that has the MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag
2878 * set. If the corresponding entry in dst array has MIGRATE_PFN_VALID flag set,
2879 * then the function tries to migrate struct page information from the source
2880 * struct page to the destination struct page. If it fails to migrate the struct
2881 * page information, then it clears the MIGRATE_PFN_MIGRATE flag in the src
2884 * At this point all successfully migrated pages have an entry in the src
2885 * array with MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag set and the dst
2886 * array entry with MIGRATE_PFN_VALID flag set.
2888 * It then calls the finalize_and_map() callback. See comments for "struct
2889 * migrate_vma_ops", in include/linux/migrate.h for details about
2890 * finalize_and_map() behavior.
2892 * After the finalize_and_map() callback, for successfully migrated pages, this
2893 * function updates the CPU page table to point to new pages, otherwise it
2894 * restores the CPU page table to point to the original source pages.
2896 * Function returns 0 after the above steps, even if no pages were migrated
2897 * (The function only returns an error if any of the arguments are invalid.)
2899 * Both src and dst array must be big enough for (end - start) >> PAGE_SHIFT
2900 * unsigned long entries.
2902 int migrate_vma(const struct migrate_vma_ops
*ops
,
2903 struct vm_area_struct
*vma
,
2904 unsigned long start
,
2910 struct migrate_vma migrate
;
2912 /* Sanity check the arguments */
2915 if (!vma
|| is_vm_hugetlb_page(vma
) || (vma
->vm_flags
& VM_SPECIAL
) ||
2918 if (start
< vma
->vm_start
|| start
>= vma
->vm_end
)
2920 if (end
<= vma
->vm_start
|| end
> vma
->vm_end
)
2922 if (!ops
|| !src
|| !dst
|| start
>= end
)
2925 memset(src
, 0, sizeof(*src
) * ((end
- start
) >> PAGE_SHIFT
));
2928 migrate
.start
= start
;
2934 /* Collect, and try to unmap source pages */
2935 migrate_vma_collect(&migrate
);
2936 if (!migrate
.cpages
)
2939 /* Lock and isolate page */
2940 migrate_vma_prepare(&migrate
);
2941 if (!migrate
.cpages
)
2945 migrate_vma_unmap(&migrate
);
2946 if (!migrate
.cpages
)
2950 * At this point pages are locked and unmapped, and thus they have
2951 * stable content and can safely be copied to destination memory that
2952 * is allocated by the callback.
2954 * Note that migration can fail in migrate_vma_struct_page() for each
2957 ops
->alloc_and_copy(vma
, src
, dst
, start
, end
, private);
2959 /* This does the real migration of struct page */
2960 migrate_vma_pages(&migrate
);
2962 ops
->finalize_and_map(vma
, src
, dst
, start
, end
, private);
2964 /* Unlock and remap pages */
2965 migrate_vma_finalize(&migrate
);
2969 EXPORT_SYMBOL(migrate_vma
);
2970 #endif /* defined(MIGRATE_VMA_HELPER) */