2 * linux/mm/compaction.c
4 * Memory compaction for the reduction of external fragmentation. Note that
5 * this heavily depends upon page migration to do all the real heavy
8 * Copyright IBM Corp. 2007-2010 Mel Gorman <mel@csn.ul.ie>
10 #include <linux/swap.h>
11 #include <linux/migrate.h>
12 #include <linux/compaction.h>
13 #include <linux/mm_inline.h>
14 #include <linux/backing-dev.h>
15 #include <linux/sysctl.h>
16 #include <linux/sysfs.h>
17 #include <linux/balloon_compaction.h>
18 #include <linux/page-isolation.h>
19 #include <linux/kasan.h>
22 #ifdef CONFIG_COMPACTION
23 static inline void count_compact_event(enum vm_event_item item)
28 static inline void count_compact_events(enum vm_event_item item, long delta)
30 count_vm_events(item, delta);
33 #define count_compact_event(item) do { } while (0)
34 #define count_compact_events(item, delta) do { } while (0)
37 #if defined CONFIG_COMPACTION || defined CONFIG_CMA
39 #define CREATE_TRACE_POINTS
40 #include <trace/events/compaction.h>
42 static unsigned long release_freepages(struct list_head *freelist)
44 struct page *page, *next;
45 unsigned long high_pfn = 0;
47 list_for_each_entry_safe(page, next, freelist, lru) {
48 unsigned long pfn = page_to_pfn(page);
58 static void map_pages(struct list_head *list)
62 list_for_each_entry(page, list, lru) {
63 arch_alloc_page(page, 0);
64 kernel_map_pages(page, 1, 1);
65 kasan_alloc_pages(page, 0);
69 static inline bool migrate_async_suitable(int migratetype)
71 return is_migrate_cma(migratetype) || migratetype == MIGRATE_MOVABLE;
75 * Check that the whole (or subset of) a pageblock given by the interval of
76 * [start_pfn, end_pfn) is valid and within the same zone, before scanning it
77 * with the migration of free compaction scanner. The scanners then need to
78 * use only pfn_valid_within() check for arches that allow holes within
81 * Return struct page pointer of start_pfn, or NULL if checks were not passed.
83 * It's possible on some configurations to have a setup like node0 node1 node0
84 * i.e. it's possible that all pages within a zones range of pages do not
85 * belong to a single zone. We assume that a border between node0 and node1
86 * can occur within a single pageblock, but not a node0 node1 node0
87 * interleaving within a single pageblock. It is therefore sufficient to check
88 * the first and last page of a pageblock and avoid checking each individual
89 * page in a pageblock.
91 static struct page *pageblock_pfn_to_page(unsigned long start_pfn,
92 unsigned long end_pfn, struct zone *zone)
94 struct page *start_page;
95 struct page *end_page;
97 /* end_pfn is one past the range we are checking */
100 if (!pfn_valid(start_pfn) || !pfn_valid(end_pfn))
103 start_page = pfn_to_page(start_pfn);
105 if (page_zone(start_page) != zone)
108 end_page = pfn_to_page(end_pfn);
110 /* This gives a shorter code than deriving page_zone(end_page) */
111 if (page_zone_id(start_page) != page_zone_id(end_page))
117 #ifdef CONFIG_COMPACTION
119 /* Do not skip compaction more than 64 times */
120 #define COMPACT_MAX_DEFER_SHIFT 6
123 * Compaction is deferred when compaction fails to result in a page
124 * allocation success. 1 << compact_defer_limit compactions are skipped up
125 * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
127 void defer_compaction(struct zone *zone, int order)
129 zone->compact_considered = 0;
130 zone->compact_defer_shift++;
132 if (order < zone->compact_order_failed)
133 zone->compact_order_failed = order;
135 if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
136 zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
138 trace_mm_compaction_defer_compaction(zone, order);
141 /* Returns true if compaction should be skipped this time */
142 bool compaction_deferred(struct zone *zone, int order)
144 unsigned long defer_limit = 1UL << zone->compact_defer_shift;
146 if (order < zone->compact_order_failed)
149 /* Avoid possible overflow */
150 if (++zone->compact_considered > defer_limit)
151 zone->compact_considered = defer_limit;
153 if (zone->compact_considered >= defer_limit)
156 trace_mm_compaction_deferred(zone, order);
162 * Update defer tracking counters after successful compaction of given order,
163 * which means an allocation either succeeded (alloc_success == true) or is
164 * expected to succeed.
166 void compaction_defer_reset(struct zone *zone, int order,
170 zone->compact_considered = 0;
171 zone->compact_defer_shift = 0;
173 if (order >= zone->compact_order_failed)
174 zone->compact_order_failed = order + 1;
176 trace_mm_compaction_defer_reset(zone, order);
179 /* Returns true if restarting compaction after many failures */
180 bool compaction_restarting(struct zone *zone, int order)
182 if (order < zone->compact_order_failed)
185 return zone->compact_defer_shift == COMPACT_MAX_DEFER_SHIFT &&
186 zone->compact_considered >= 1UL << zone->compact_defer_shift;
189 /* Returns true if the pageblock should be scanned for pages to isolate. */
190 static inline bool isolation_suitable(struct compact_control *cc,
193 if (cc->ignore_skip_hint)
196 return !get_pageblock_skip(page);
199 static void reset_cached_positions(struct zone *zone)
201 zone->compact_cached_migrate_pfn[0] = zone->zone_start_pfn;
202 zone->compact_cached_migrate_pfn[1] = zone->zone_start_pfn;
203 zone->compact_cached_free_pfn =
204 round_down(zone_end_pfn(zone) - 1, pageblock_nr_pages);
208 * This function is called to clear all cached information on pageblocks that
209 * should be skipped for page isolation when the migrate and free page scanner
212 static void __reset_isolation_suitable(struct zone *zone)
214 unsigned long start_pfn = zone->zone_start_pfn;
215 unsigned long end_pfn = zone_end_pfn(zone);
218 zone->compact_blockskip_flush = false;
220 /* Walk the zone and mark every pageblock as suitable for isolation */
221 for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
229 page = pfn_to_page(pfn);
230 if (zone != page_zone(page))
233 clear_pageblock_skip(page);
236 reset_cached_positions(zone);
239 void reset_isolation_suitable(pg_data_t *pgdat)
243 for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
244 struct zone *zone = &pgdat->node_zones[zoneid];
245 if (!populated_zone(zone))
248 /* Only flush if a full compaction finished recently */
249 if (zone->compact_blockskip_flush)
250 __reset_isolation_suitable(zone);
255 * If no pages were isolated then mark this pageblock to be skipped in the
256 * future. The information is later cleared by __reset_isolation_suitable().
258 static void update_pageblock_skip(struct compact_control *cc,
259 struct page *page, unsigned long nr_isolated,
260 bool migrate_scanner)
262 struct zone *zone = cc->zone;
265 if (cc->ignore_skip_hint)
274 set_pageblock_skip(page);
276 pfn = page_to_pfn(page);
278 /* Update where async and sync compaction should restart */
279 if (migrate_scanner) {
280 if (pfn > zone->compact_cached_migrate_pfn[0])
281 zone->compact_cached_migrate_pfn[0] = pfn;
282 if (cc->mode != MIGRATE_ASYNC &&
283 pfn > zone->compact_cached_migrate_pfn[1])
284 zone->compact_cached_migrate_pfn[1] = pfn;
286 if (pfn < zone->compact_cached_free_pfn)
287 zone->compact_cached_free_pfn = pfn;
291 static inline bool isolation_suitable(struct compact_control *cc,
297 static void update_pageblock_skip(struct compact_control *cc,
298 struct page *page, unsigned long nr_isolated,
299 bool migrate_scanner)
302 #endif /* CONFIG_COMPACTION */
305 * Compaction requires the taking of some coarse locks that are potentially
306 * very heavily contended. For async compaction, back out if the lock cannot
307 * be taken immediately. For sync compaction, spin on the lock if needed.
309 * Returns true if the lock is held
310 * Returns false if the lock is not held and compaction should abort
312 static bool compact_trylock_irqsave(spinlock_t *lock, unsigned long *flags,
313 struct compact_control *cc)
315 if (cc->mode == MIGRATE_ASYNC) {
316 if (!spin_trylock_irqsave(lock, *flags)) {
317 cc->contended = COMPACT_CONTENDED_LOCK;
321 spin_lock_irqsave(lock, *flags);
328 * Compaction requires the taking of some coarse locks that are potentially
329 * very heavily contended. The lock should be periodically unlocked to avoid
330 * having disabled IRQs for a long time, even when there is nobody waiting on
331 * the lock. It might also be that allowing the IRQs will result in
332 * need_resched() becoming true. If scheduling is needed, async compaction
333 * aborts. Sync compaction schedules.
334 * Either compaction type will also abort if a fatal signal is pending.
335 * In either case if the lock was locked, it is dropped and not regained.
337 * Returns true if compaction should abort due to fatal signal pending, or
338 * async compaction due to need_resched()
339 * Returns false when compaction can continue (sync compaction might have
342 static bool compact_unlock_should_abort(spinlock_t *lock,
343 unsigned long flags, bool *locked, struct compact_control *cc)
346 spin_unlock_irqrestore(lock, flags);
350 if (fatal_signal_pending(current)) {
351 cc->contended = COMPACT_CONTENDED_SCHED;
355 if (need_resched()) {
356 if (cc->mode == MIGRATE_ASYNC) {
357 cc->contended = COMPACT_CONTENDED_SCHED;
367 * Aside from avoiding lock contention, compaction also periodically checks
368 * need_resched() and either schedules in sync compaction or aborts async
369 * compaction. This is similar to what compact_unlock_should_abort() does, but
370 * is used where no lock is concerned.
372 * Returns false when no scheduling was needed, or sync compaction scheduled.
373 * Returns true when async compaction should abort.
375 static inline bool compact_should_abort(struct compact_control *cc)
377 /* async compaction aborts if contended */
378 if (need_resched()) {
379 if (cc->mode == MIGRATE_ASYNC) {
380 cc->contended = COMPACT_CONTENDED_SCHED;
391 * Isolate free pages onto a private freelist. If @strict is true, will abort
392 * returning 0 on any invalid PFNs or non-free pages inside of the pageblock
393 * (even though it may still end up isolating some pages).
395 static unsigned long isolate_freepages_block(struct compact_control *cc,
396 unsigned long *start_pfn,
397 unsigned long end_pfn,
398 struct list_head *freelist,
401 int nr_scanned = 0, total_isolated = 0;
402 struct page *cursor, *valid_page = NULL;
403 unsigned long flags = 0;
405 unsigned long blockpfn = *start_pfn;
407 cursor = pfn_to_page(blockpfn);
409 /* Isolate free pages. */
410 for (; blockpfn < end_pfn; blockpfn++, cursor++) {
412 struct page *page = cursor;
415 * Periodically drop the lock (if held) regardless of its
416 * contention, to give chance to IRQs. Abort if fatal signal
417 * pending or async compaction detects need_resched()
419 if (!(blockpfn % SWAP_CLUSTER_MAX)
420 && compact_unlock_should_abort(&cc->zone->lock, flags,
425 if (!pfn_valid_within(blockpfn))
432 * For compound pages such as THP and hugetlbfs, we can save
433 * potentially a lot of iterations if we skip them at once.
434 * The check is racy, but we can consider only valid values
435 * and the only danger is skipping too much.
437 if (PageCompound(page)) {
438 unsigned int comp_order = compound_order(page);
440 if (likely(comp_order < MAX_ORDER)) {
441 blockpfn += (1UL << comp_order) - 1;
442 cursor += (1UL << comp_order) - 1;
448 if (!PageBuddy(page))
452 * If we already hold the lock, we can skip some rechecking.
453 * Note that if we hold the lock now, checked_pageblock was
454 * already set in some previous iteration (or strict is true),
455 * so it is correct to skip the suitable migration target
460 * The zone lock must be held to isolate freepages.
461 * Unfortunately this is a very coarse lock and can be
462 * heavily contended if there are parallel allocations
463 * or parallel compactions. For async compaction do not
464 * spin on the lock and we acquire the lock as late as
467 locked = compact_trylock_irqsave(&cc->zone->lock,
472 /* Recheck this is a buddy page under lock */
473 if (!PageBuddy(page))
477 /* Found a free page, break it into order-0 pages */
478 isolated = split_free_page(page);
479 total_isolated += isolated;
480 for (i = 0; i < isolated; i++) {
481 list_add(&page->lru, freelist);
485 /* If a page was split, advance to the end of it */
487 cc->nr_freepages += isolated;
489 cc->nr_migratepages <= cc->nr_freepages) {
490 blockpfn += isolated;
494 blockpfn += isolated - 1;
495 cursor += isolated - 1;
508 * There is a tiny chance that we have read bogus compound_order(),
509 * so be careful to not go outside of the pageblock.
511 if (unlikely(blockpfn > end_pfn))
514 trace_mm_compaction_isolate_freepages(*start_pfn, blockpfn,
515 nr_scanned, total_isolated);
517 /* Record how far we have got within the block */
518 *start_pfn = blockpfn;
521 * If strict isolation is requested by CMA then check that all the
522 * pages requested were isolated. If there were any failures, 0 is
523 * returned and CMA will fail.
525 if (strict && blockpfn < end_pfn)
529 spin_unlock_irqrestore(&cc->zone->lock, flags);
531 /* Update the pageblock-skip if the whole pageblock was scanned */
532 if (blockpfn == end_pfn)
533 update_pageblock_skip(cc, valid_page, total_isolated, false);
535 count_compact_events(COMPACTFREE_SCANNED, nr_scanned);
537 count_compact_events(COMPACTISOLATED, total_isolated);
538 return total_isolated;
542 * isolate_freepages_range() - isolate free pages.
543 * @start_pfn: The first PFN to start isolating.
544 * @end_pfn: The one-past-last PFN.
546 * Non-free pages, invalid PFNs, or zone boundaries within the
547 * [start_pfn, end_pfn) range are considered errors, cause function to
548 * undo its actions and return zero.
550 * Otherwise, function returns one-past-the-last PFN of isolated page
551 * (which may be greater then end_pfn if end fell in a middle of
555 isolate_freepages_range(struct compact_control *cc,
556 unsigned long start_pfn, unsigned long end_pfn)
558 unsigned long isolated, pfn, block_end_pfn;
562 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
564 for (; pfn < end_pfn; pfn += isolated,
565 block_end_pfn += pageblock_nr_pages) {
566 /* Protect pfn from changing by isolate_freepages_block */
567 unsigned long isolate_start_pfn = pfn;
569 block_end_pfn = min(block_end_pfn, end_pfn);
572 * pfn could pass the block_end_pfn if isolated freepage
573 * is more than pageblock order. In this case, we adjust
574 * scanning range to right one.
576 if (pfn >= block_end_pfn) {
577 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
578 block_end_pfn = min(block_end_pfn, end_pfn);
581 if (!pageblock_pfn_to_page(pfn, block_end_pfn, cc->zone))
584 isolated = isolate_freepages_block(cc, &isolate_start_pfn,
585 block_end_pfn, &freelist, true);
588 * In strict mode, isolate_freepages_block() returns 0 if
589 * there are any holes in the block (ie. invalid PFNs or
596 * If we managed to isolate pages, it is always (1 << n) *
597 * pageblock_nr_pages for some non-negative n. (Max order
598 * page may span two pageblocks).
602 /* split_free_page does not map the pages */
603 map_pages(&freelist);
606 /* Loop terminated early, cleanup. */
607 release_freepages(&freelist);
611 /* We don't use freelists for anything. */
615 /* Update the number of anon and file isolated pages in the zone */
616 static void acct_isolated(struct zone *zone, struct compact_control *cc)
619 unsigned int count[2] = { 0, };
621 if (list_empty(&cc->migratepages))
624 list_for_each_entry(page, &cc->migratepages, lru)
625 count[!!page_is_file_cache(page)]++;
627 mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]);
628 mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]);
631 /* Similar to reclaim, but different enough that they don't share logic */
632 static bool too_many_isolated(struct zone *zone)
634 unsigned long active, inactive, isolated;
636 inactive = zone_page_state(zone, NR_INACTIVE_FILE) +
637 zone_page_state(zone, NR_INACTIVE_ANON);
638 active = zone_page_state(zone, NR_ACTIVE_FILE) +
639 zone_page_state(zone, NR_ACTIVE_ANON);
640 isolated = zone_page_state(zone, NR_ISOLATED_FILE) +
641 zone_page_state(zone, NR_ISOLATED_ANON);
643 return isolated > (inactive + active) / 2;
647 * isolate_migratepages_block() - isolate all migrate-able pages within
649 * @cc: Compaction control structure.
650 * @low_pfn: The first PFN to isolate
651 * @end_pfn: The one-past-the-last PFN to isolate, within same pageblock
652 * @isolate_mode: Isolation mode to be used.
654 * Isolate all pages that can be migrated from the range specified by
655 * [low_pfn, end_pfn). The range is expected to be within same pageblock.
656 * Returns zero if there is a fatal signal pending, otherwise PFN of the
657 * first page that was not scanned (which may be both less, equal to or more
660 * The pages are isolated on cc->migratepages list (not required to be empty),
661 * and cc->nr_migratepages is updated accordingly. The cc->migrate_pfn field
662 * is neither read nor updated.
665 isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
666 unsigned long end_pfn, isolate_mode_t isolate_mode)
668 struct zone *zone = cc->zone;
669 unsigned long nr_scanned = 0, nr_isolated = 0;
670 struct list_head *migratelist = &cc->migratepages;
671 struct lruvec *lruvec;
672 unsigned long flags = 0;
674 struct page *page = NULL, *valid_page = NULL;
675 unsigned long start_pfn = low_pfn;
678 * Ensure that there are not too many pages isolated from the LRU
679 * list by either parallel reclaimers or compaction. If there are,
680 * delay for some time until fewer pages are isolated
682 while (unlikely(too_many_isolated(zone))) {
683 /* async migration should just abort */
684 if (cc->mode == MIGRATE_ASYNC)
687 congestion_wait(BLK_RW_ASYNC, HZ/10);
689 if (fatal_signal_pending(current))
693 if (compact_should_abort(cc))
696 /* Time to isolate some pages for migration */
697 for (; low_pfn < end_pfn; low_pfn++) {
701 * Periodically drop the lock (if held) regardless of its
702 * contention, to give chance to IRQs. Abort async compaction
705 if (!(low_pfn % SWAP_CLUSTER_MAX)
706 && compact_unlock_should_abort(&zone->lru_lock, flags,
710 if (!pfn_valid_within(low_pfn))
714 page = pfn_to_page(low_pfn);
720 * Skip if free. We read page order here without zone lock
721 * which is generally unsafe, but the race window is small and
722 * the worst thing that can happen is that we skip some
723 * potential isolation targets.
725 if (PageBuddy(page)) {
726 unsigned long freepage_order = page_order_unsafe(page);
729 * Without lock, we cannot be sure that what we got is
730 * a valid page order. Consider only values in the
731 * valid order range to prevent low_pfn overflow.
733 if (freepage_order > 0 && freepage_order < MAX_ORDER)
734 low_pfn += (1UL << freepage_order) - 1;
739 * Check may be lockless but that's ok as we recheck later.
740 * It's possible to migrate LRU pages and balloon pages
741 * Skip any other type of page
743 is_lru = PageLRU(page);
745 if (unlikely(balloon_page_movable(page))) {
746 if (balloon_page_isolate(page)) {
747 /* Successfully isolated */
748 goto isolate_success;
754 * Regardless of being on LRU, compound pages such as THP and
755 * hugetlbfs are not to be compacted. We can potentially save
756 * a lot of iterations if we skip them at once. The check is
757 * racy, but we can consider only valid values and the only
758 * danger is skipping too much.
760 if (PageCompound(page)) {
761 unsigned int comp_order = compound_order(page);
763 if (likely(comp_order < MAX_ORDER))
764 low_pfn += (1UL << comp_order) - 1;
773 * Migration will fail if an anonymous page is pinned in memory,
774 * so avoid taking lru_lock and isolating it unnecessarily in an
775 * admittedly racy check.
777 if (!page_mapping(page) &&
778 page_count(page) > page_mapcount(page))
781 /* If we already hold the lock, we can skip some rechecking */
783 locked = compact_trylock_irqsave(&zone->lru_lock,
788 /* Recheck PageLRU and PageCompound under lock */
793 * Page become compound since the non-locked check,
794 * and it's on LRU. It can only be a THP so the order
795 * is safe to read and it's 0 for tail pages.
797 if (unlikely(PageCompound(page))) {
798 low_pfn += (1UL << compound_order(page)) - 1;
803 lruvec = mem_cgroup_page_lruvec(page, zone);
805 /* Try isolate the page */
806 if (__isolate_lru_page(page, isolate_mode) != 0)
809 VM_BUG_ON_PAGE(PageCompound(page), page);
811 /* Successfully isolated */
812 del_page_from_lru_list(page, lruvec, page_lru(page));
815 list_add(&page->lru, migratelist);
816 cc->nr_migratepages++;
819 /* Avoid isolating too much */
820 if (cc->nr_migratepages == COMPACT_CLUSTER_MAX) {
827 * The PageBuddy() check could have potentially brought us outside
828 * the range to be scanned.
830 if (unlikely(low_pfn > end_pfn))
834 spin_unlock_irqrestore(&zone->lru_lock, flags);
837 * Update the pageblock-skip information and cached scanner pfn,
838 * if the whole pageblock was scanned without isolating any page.
840 if (low_pfn == end_pfn)
841 update_pageblock_skip(cc, valid_page, nr_isolated, true);
843 trace_mm_compaction_isolate_migratepages(start_pfn, low_pfn,
844 nr_scanned, nr_isolated);
846 count_compact_events(COMPACTMIGRATE_SCANNED, nr_scanned);
848 count_compact_events(COMPACTISOLATED, nr_isolated);
854 * isolate_migratepages_range() - isolate migrate-able pages in a PFN range
855 * @cc: Compaction control structure.
856 * @start_pfn: The first PFN to start isolating.
857 * @end_pfn: The one-past-last PFN.
859 * Returns zero if isolation fails fatally due to e.g. pending signal.
860 * Otherwise, function returns one-past-the-last PFN of isolated page
861 * (which may be greater than end_pfn if end fell in a middle of a THP page).
864 isolate_migratepages_range(struct compact_control *cc, unsigned long start_pfn,
865 unsigned long end_pfn)
867 unsigned long pfn, block_end_pfn;
869 /* Scan block by block. First and last block may be incomplete */
871 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
873 for (; pfn < end_pfn; pfn = block_end_pfn,
874 block_end_pfn += pageblock_nr_pages) {
876 block_end_pfn = min(block_end_pfn, end_pfn);
878 if (!pageblock_pfn_to_page(pfn, block_end_pfn, cc->zone))
881 pfn = isolate_migratepages_block(cc, pfn, block_end_pfn,
882 ISOLATE_UNEVICTABLE);
885 * In case of fatal failure, release everything that might
886 * have been isolated in the previous iteration, and signal
887 * the failure back to caller.
890 putback_movable_pages(&cc->migratepages);
891 cc->nr_migratepages = 0;
895 if (cc->nr_migratepages == COMPACT_CLUSTER_MAX)
898 acct_isolated(cc->zone, cc);
903 #endif /* CONFIG_COMPACTION || CONFIG_CMA */
904 #ifdef CONFIG_COMPACTION
906 /* Returns true if the page is within a block suitable for migration to */
907 static bool suitable_migration_target(struct page *page)
909 /* If the page is a large free page, then disallow migration */
910 if (PageBuddy(page)) {
912 * We are checking page_order without zone->lock taken. But
913 * the only small danger is that we skip a potentially suitable
914 * pageblock, so it's not worth to check order for valid range.
916 if (page_order_unsafe(page) >= pageblock_order)
920 /* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */
921 if (migrate_async_suitable(get_pageblock_migratetype(page)))
924 /* Otherwise skip the block */
929 * Test whether the free scanner has reached the same or lower pageblock than
930 * the migration scanner, and compaction should thus terminate.
932 static inline bool compact_scanners_met(struct compact_control *cc)
934 return (cc->free_pfn >> pageblock_order)
935 <= (cc->migrate_pfn >> pageblock_order);
939 * Based on information in the current compact_control, find blocks
940 * suitable for isolating free pages from and then isolate them.
942 static void isolate_freepages(struct compact_control *cc)
944 struct zone *zone = cc->zone;
946 unsigned long block_start_pfn; /* start of current pageblock */
947 unsigned long isolate_start_pfn; /* exact pfn we start at */
948 unsigned long block_end_pfn; /* end of current pageblock */
949 unsigned long low_pfn; /* lowest pfn scanner is able to scan */
950 struct list_head *freelist = &cc->freepages;
953 * Initialise the free scanner. The starting point is where we last
954 * successfully isolated from, zone-cached value, or the end of the
955 * zone when isolating for the first time. For looping we also need
956 * this pfn aligned down to the pageblock boundary, because we do
957 * block_start_pfn -= pageblock_nr_pages in the for loop.
958 * For ending point, take care when isolating in last pageblock of a
959 * a zone which ends in the middle of a pageblock.
960 * The low boundary is the end of the pageblock the migration scanner
963 isolate_start_pfn = cc->free_pfn;
964 block_start_pfn = cc->free_pfn & ~(pageblock_nr_pages-1);
965 block_end_pfn = min(block_start_pfn + pageblock_nr_pages,
967 low_pfn = ALIGN(cc->migrate_pfn + 1, pageblock_nr_pages);
970 * Isolate free pages until enough are available to migrate the
971 * pages on cc->migratepages. We stop searching if the migrate
972 * and free page scanners meet or enough free pages are isolated.
974 for (; block_start_pfn >= low_pfn;
975 block_end_pfn = block_start_pfn,
976 block_start_pfn -= pageblock_nr_pages,
977 isolate_start_pfn = block_start_pfn) {
980 * This can iterate a massively long zone without finding any
981 * suitable migration targets, so periodically check if we need
982 * to schedule, or even abort async compaction.
984 if (!(block_start_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages))
985 && compact_should_abort(cc))
988 page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn,
993 /* Check the block is suitable for migration */
994 if (!suitable_migration_target(page))
997 /* If isolation recently failed, do not retry */
998 if (!isolation_suitable(cc, page))
1001 /* Found a block suitable for isolating free pages from. */
1002 isolate_freepages_block(cc, &isolate_start_pfn,
1003 block_end_pfn, freelist, false);
1006 * If we isolated enough freepages, or aborted due to async
1007 * compaction being contended, terminate the loop.
1008 * Remember where the free scanner should restart next time,
1009 * which is where isolate_freepages_block() left off.
1010 * But if it scanned the whole pageblock, isolate_start_pfn
1011 * now points at block_end_pfn, which is the start of the next
1013 * In that case we will however want to restart at the start
1014 * of the previous pageblock.
1016 if ((cc->nr_freepages >= cc->nr_migratepages)
1018 if (isolate_start_pfn >= block_end_pfn)
1020 block_start_pfn - pageblock_nr_pages;
1024 * isolate_freepages_block() should not terminate
1025 * prematurely unless contended, or isolated enough
1027 VM_BUG_ON(isolate_start_pfn < block_end_pfn);
1031 /* split_free_page does not map the pages */
1032 map_pages(freelist);
1035 * Record where the free scanner will restart next time. Either we
1036 * broke from the loop and set isolate_start_pfn based on the last
1037 * call to isolate_freepages_block(), or we met the migration scanner
1038 * and the loop terminated due to isolate_start_pfn < low_pfn
1040 cc->free_pfn = isolate_start_pfn;
1044 * This is a migrate-callback that "allocates" freepages by taking pages
1045 * from the isolated freelists in the block we are migrating to.
1047 static struct page *compaction_alloc(struct page *migratepage,
1051 struct compact_control *cc = (struct compact_control *)data;
1052 struct page *freepage;
1055 * Isolate free pages if necessary, and if we are not aborting due to
1058 if (list_empty(&cc->freepages)) {
1060 isolate_freepages(cc);
1062 if (list_empty(&cc->freepages))
1066 freepage = list_entry(cc->freepages.next, struct page, lru);
1067 list_del(&freepage->lru);
1074 * This is a migrate-callback that "frees" freepages back to the isolated
1075 * freelist. All pages on the freelist are from the same zone, so there is no
1076 * special handling needed for NUMA.
1078 static void compaction_free(struct page *page, unsigned long data)
1080 struct compact_control *cc = (struct compact_control *)data;
1082 list_add(&page->lru, &cc->freepages);
1086 /* possible outcome of isolate_migratepages */
1088 ISOLATE_ABORT, /* Abort compaction now */
1089 ISOLATE_NONE, /* No pages isolated, continue scanning */
1090 ISOLATE_SUCCESS, /* Pages isolated, migrate */
1091 } isolate_migrate_t;
1094 * Allow userspace to control policy on scanning the unevictable LRU for
1095 * compactable pages.
1097 int sysctl_compact_unevictable_allowed __read_mostly = 1;
1100 * Isolate all pages that can be migrated from the first suitable block,
1101 * starting at the block pointed to by the migrate scanner pfn within
1104 static isolate_migrate_t isolate_migratepages(struct zone *zone,
1105 struct compact_control *cc)
1107 unsigned long low_pfn, end_pfn;
1108 unsigned long isolate_start_pfn;
1110 const isolate_mode_t isolate_mode =
1111 (sysctl_compact_unevictable_allowed ? ISOLATE_UNEVICTABLE : 0) |
1112 (cc->mode == MIGRATE_ASYNC ? ISOLATE_ASYNC_MIGRATE : 0);
1115 * Start at where we last stopped, or beginning of the zone as
1116 * initialized by compact_zone()
1118 low_pfn = cc->migrate_pfn;
1120 /* Only scan within a pageblock boundary */
1121 end_pfn = ALIGN(low_pfn + 1, pageblock_nr_pages);
1124 * Iterate over whole pageblocks until we find the first suitable.
1125 * Do not cross the free scanner.
1127 for (; end_pfn <= cc->free_pfn;
1128 low_pfn = end_pfn, end_pfn += pageblock_nr_pages) {
1131 * This can potentially iterate a massively long zone with
1132 * many pageblocks unsuitable, so periodically check if we
1133 * need to schedule, or even abort async compaction.
1135 if (!(low_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages))
1136 && compact_should_abort(cc))
1139 page = pageblock_pfn_to_page(low_pfn, end_pfn, zone);
1143 /* If isolation recently failed, do not retry */
1144 if (!isolation_suitable(cc, page))
1148 * For async compaction, also only scan in MOVABLE blocks.
1149 * Async compaction is optimistic to see if the minimum amount
1150 * of work satisfies the allocation.
1152 if (cc->mode == MIGRATE_ASYNC &&
1153 !migrate_async_suitable(get_pageblock_migratetype(page)))
1156 /* Perform the isolation */
1157 isolate_start_pfn = low_pfn;
1158 low_pfn = isolate_migratepages_block(cc, low_pfn, end_pfn,
1161 if (!low_pfn || cc->contended) {
1162 acct_isolated(zone, cc);
1163 return ISOLATE_ABORT;
1167 * Record where we could have freed pages by migration and not
1168 * yet flushed them to buddy allocator.
1169 * - this is the lowest page that could have been isolated and
1170 * then freed by migration.
1172 if (cc->nr_migratepages && !cc->last_migrated_pfn)
1173 cc->last_migrated_pfn = isolate_start_pfn;
1176 * Either we isolated something and proceed with migration. Or
1177 * we failed and compact_zone should decide if we should
1183 acct_isolated(zone, cc);
1184 /* Record where migration scanner will be restarted. */
1185 cc->migrate_pfn = low_pfn;
1187 return cc->nr_migratepages ? ISOLATE_SUCCESS : ISOLATE_NONE;
1191 * order == -1 is expected when compacting via
1192 * /proc/sys/vm/compact_memory
1194 static inline bool is_via_compact_memory(int order)
1199 static int __compact_finished(struct zone *zone, struct compact_control *cc,
1200 const int migratetype)
1203 unsigned long watermark;
1205 if (cc->contended || fatal_signal_pending(current))
1206 return COMPACT_CONTENDED;
1208 /* Compaction run completes if the migrate and free scanner meet */
1209 if (compact_scanners_met(cc)) {
1210 /* Let the next compaction start anew. */
1211 reset_cached_positions(zone);
1214 * Mark that the PG_migrate_skip information should be cleared
1215 * by kswapd when it goes to sleep. kswapd does not set the
1216 * flag itself as the decision to be clear should be directly
1217 * based on an allocation request.
1219 if (!current_is_kswapd())
1220 zone->compact_blockskip_flush = true;
1222 return COMPACT_COMPLETE;
1225 if (is_via_compact_memory(cc->order))
1226 return COMPACT_CONTINUE;
1228 /* Compaction run is not finished if the watermark is not met */
1229 watermark = low_wmark_pages(zone);
1231 if (!zone_watermark_ok(zone, cc->order, watermark, cc->classzone_idx,
1233 return COMPACT_CONTINUE;
1235 /* Direct compactor: Is a suitable page free? */
1236 for (order = cc->order; order < MAX_ORDER; order++) {
1237 struct free_area *area = &zone->free_area[order];
1240 /* Job done if page is free of the right migratetype */
1241 if (!list_empty(&area->free_list[migratetype]))
1242 return COMPACT_PARTIAL;
1245 /* MIGRATE_MOVABLE can fallback on MIGRATE_CMA */
1246 if (migratetype == MIGRATE_MOVABLE &&
1247 !list_empty(&area->free_list[MIGRATE_CMA]))
1248 return COMPACT_PARTIAL;
1251 * Job done if allocation would steal freepages from
1252 * other migratetype buddy lists.
1254 if (find_suitable_fallback(area, order, migratetype,
1255 true, &can_steal) != -1)
1256 return COMPACT_PARTIAL;
1259 return COMPACT_NO_SUITABLE_PAGE;
1262 static int compact_finished(struct zone *zone, struct compact_control *cc,
1263 const int migratetype)
1267 ret = __compact_finished(zone, cc, migratetype);
1268 trace_mm_compaction_finished(zone, cc->order, ret);
1269 if (ret == COMPACT_NO_SUITABLE_PAGE)
1270 ret = COMPACT_CONTINUE;
1276 * compaction_suitable: Is this suitable to run compaction on this zone now?
1278 * COMPACT_SKIPPED - If there are too few free pages for compaction
1279 * COMPACT_PARTIAL - If the allocation would succeed without compaction
1280 * COMPACT_CONTINUE - If compaction should run now
1282 static unsigned long __compaction_suitable(struct zone *zone, int order,
1283 int alloc_flags, int classzone_idx)
1286 unsigned long watermark;
1288 if (is_via_compact_memory(order))
1289 return COMPACT_CONTINUE;
1291 watermark = low_wmark_pages(zone);
1293 * If watermarks for high-order allocation are already met, there
1294 * should be no need for compaction at all.
1296 if (zone_watermark_ok(zone, order, watermark, classzone_idx,
1298 return COMPACT_PARTIAL;
1301 * Watermarks for order-0 must be met for compaction. Note the 2UL.
1302 * This is because during migration, copies of pages need to be
1303 * allocated and for a short time, the footprint is higher
1305 watermark += (2UL << order);
1306 if (!zone_watermark_ok(zone, 0, watermark, classzone_idx, alloc_flags))
1307 return COMPACT_SKIPPED;
1310 * fragmentation index determines if allocation failures are due to
1311 * low memory or external fragmentation
1313 * index of -1000 would imply allocations might succeed depending on
1314 * watermarks, but we already failed the high-order watermark check
1315 * index towards 0 implies failure is due to lack of memory
1316 * index towards 1000 implies failure is due to fragmentation
1318 * Only compact if a failure would be due to fragmentation.
1320 fragindex = fragmentation_index(zone, order);
1321 if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold)
1322 return COMPACT_NOT_SUITABLE_ZONE;
1324 return COMPACT_CONTINUE;
1327 unsigned long compaction_suitable(struct zone *zone, int order,
1328 int alloc_flags, int classzone_idx)
1332 ret = __compaction_suitable(zone, order, alloc_flags, classzone_idx);
1333 trace_mm_compaction_suitable(zone, order, ret);
1334 if (ret == COMPACT_NOT_SUITABLE_ZONE)
1335 ret = COMPACT_SKIPPED;
1340 static int compact_zone(struct zone *zone, struct compact_control *cc)
1343 unsigned long start_pfn = zone->zone_start_pfn;
1344 unsigned long end_pfn = zone_end_pfn(zone);
1345 const int migratetype = gfpflags_to_migratetype(cc->gfp_mask);
1346 const bool sync = cc->mode != MIGRATE_ASYNC;
1348 ret = compaction_suitable(zone, cc->order, cc->alloc_flags,
1351 case COMPACT_PARTIAL:
1352 case COMPACT_SKIPPED:
1353 /* Compaction is likely to fail */
1355 case COMPACT_CONTINUE:
1356 /* Fall through to compaction */
1361 * Clear pageblock skip if there were failures recently and compaction
1362 * is about to be retried after being deferred. kswapd does not do
1363 * this reset as it'll reset the cached information when going to sleep.
1365 if (compaction_restarting(zone, cc->order) && !current_is_kswapd())
1366 __reset_isolation_suitable(zone);
1369 * Setup to move all movable pages to the end of the zone. Used cached
1370 * information on where the scanners should start but check that it
1371 * is initialised by ensuring the values are within zone boundaries.
1373 cc->migrate_pfn = zone->compact_cached_migrate_pfn[sync];
1374 cc->free_pfn = zone->compact_cached_free_pfn;
1375 if (cc->free_pfn < start_pfn || cc->free_pfn >= end_pfn) {
1376 cc->free_pfn = round_down(end_pfn - 1, pageblock_nr_pages);
1377 zone->compact_cached_free_pfn = cc->free_pfn;
1379 if (cc->migrate_pfn < start_pfn || cc->migrate_pfn >= end_pfn) {
1380 cc->migrate_pfn = start_pfn;
1381 zone->compact_cached_migrate_pfn[0] = cc->migrate_pfn;
1382 zone->compact_cached_migrate_pfn[1] = cc->migrate_pfn;
1384 cc->last_migrated_pfn = 0;
1386 trace_mm_compaction_begin(start_pfn, cc->migrate_pfn,
1387 cc->free_pfn, end_pfn, sync);
1389 migrate_prep_local();
1391 while ((ret = compact_finished(zone, cc, migratetype)) ==
1395 switch (isolate_migratepages(zone, cc)) {
1397 ret = COMPACT_CONTENDED;
1398 putback_movable_pages(&cc->migratepages);
1399 cc->nr_migratepages = 0;
1403 * We haven't isolated and migrated anything, but
1404 * there might still be unflushed migrations from
1405 * previous cc->order aligned block.
1408 case ISOLATE_SUCCESS:
1412 err = migrate_pages(&cc->migratepages, compaction_alloc,
1413 compaction_free, (unsigned long)cc, cc->mode,
1416 trace_mm_compaction_migratepages(cc->nr_migratepages, err,
1419 /* All pages were either migrated or will be released */
1420 cc->nr_migratepages = 0;
1422 putback_movable_pages(&cc->migratepages);
1424 * migrate_pages() may return -ENOMEM when scanners meet
1425 * and we want compact_finished() to detect it
1427 if (err == -ENOMEM && !compact_scanners_met(cc)) {
1428 ret = COMPACT_CONTENDED;
1435 * Has the migration scanner moved away from the previous
1436 * cc->order aligned block where we migrated from? If yes,
1437 * flush the pages that were freed, so that they can merge and
1438 * compact_finished() can detect immediately if allocation
1441 if (cc->order > 0 && cc->last_migrated_pfn) {
1443 unsigned long current_block_start =
1444 cc->migrate_pfn & ~((1UL << cc->order) - 1);
1446 if (cc->last_migrated_pfn < current_block_start) {
1448 lru_add_drain_cpu(cpu);
1449 drain_local_pages(zone);
1451 /* No more flushing until we migrate again */
1452 cc->last_migrated_pfn = 0;
1460 * Release free pages and update where the free scanner should restart,
1461 * so we don't leave any returned pages behind in the next attempt.
1463 if (cc->nr_freepages > 0) {
1464 unsigned long free_pfn = release_freepages(&cc->freepages);
1466 cc->nr_freepages = 0;
1467 VM_BUG_ON(free_pfn == 0);
1468 /* The cached pfn is always the first in a pageblock */
1469 free_pfn &= ~(pageblock_nr_pages-1);
1471 * Only go back, not forward. The cached pfn might have been
1472 * already reset to zone end in compact_finished()
1474 if (free_pfn > zone->compact_cached_free_pfn)
1475 zone->compact_cached_free_pfn = free_pfn;
1478 trace_mm_compaction_end(start_pfn, cc->migrate_pfn,
1479 cc->free_pfn, end_pfn, sync, ret);
1481 if (ret == COMPACT_CONTENDED)
1482 ret = COMPACT_PARTIAL;
1487 static unsigned long compact_zone_order(struct zone *zone, int order,
1488 gfp_t gfp_mask, enum migrate_mode mode, int *contended,
1489 int alloc_flags, int classzone_idx)
1492 struct compact_control cc = {
1494 .nr_migratepages = 0,
1496 .gfp_mask = gfp_mask,
1499 .alloc_flags = alloc_flags,
1500 .classzone_idx = classzone_idx,
1502 INIT_LIST_HEAD(&cc.freepages);
1503 INIT_LIST_HEAD(&cc.migratepages);
1505 ret = compact_zone(zone, &cc);
1507 VM_BUG_ON(!list_empty(&cc.freepages));
1508 VM_BUG_ON(!list_empty(&cc.migratepages));
1510 *contended = cc.contended;
1514 int sysctl_extfrag_threshold = 500;
1517 * try_to_compact_pages - Direct compact to satisfy a high-order allocation
1518 * @gfp_mask: The GFP mask of the current allocation
1519 * @order: The order of the current allocation
1520 * @alloc_flags: The allocation flags of the current allocation
1521 * @ac: The context of current allocation
1522 * @mode: The migration mode for async, sync light, or sync migration
1523 * @contended: Return value that determines if compaction was aborted due to
1524 * need_resched() or lock contention
1526 * This is the main entry point for direct page compaction.
1528 unsigned long try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
1529 int alloc_flags, const struct alloc_context *ac,
1530 enum migrate_mode mode, int *contended)
1532 int may_enter_fs = gfp_mask & __GFP_FS;
1533 int may_perform_io = gfp_mask & __GFP_IO;
1536 int rc = COMPACT_DEFERRED;
1537 int all_zones_contended = COMPACT_CONTENDED_LOCK; /* init for &= op */
1539 *contended = COMPACT_CONTENDED_NONE;
1541 /* Check if the GFP flags allow compaction */
1542 if (!order || !may_enter_fs || !may_perform_io)
1543 return COMPACT_SKIPPED;
1545 trace_mm_compaction_try_to_compact_pages(order, gfp_mask, mode);
1547 /* Compact each zone in the list */
1548 for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, ac->high_zoneidx,
1553 if (compaction_deferred(zone, order))
1556 status = compact_zone_order(zone, order, gfp_mask, mode,
1557 &zone_contended, alloc_flags,
1559 rc = max(status, rc);
1561 * It takes at least one zone that wasn't lock contended
1562 * to clear all_zones_contended.
1564 all_zones_contended &= zone_contended;
1566 /* If a normal allocation would succeed, stop compacting */
1567 if (zone_watermark_ok(zone, order, low_wmark_pages(zone),
1568 ac->classzone_idx, alloc_flags)) {
1570 * We think the allocation will succeed in this zone,
1571 * but it is not certain, hence the false. The caller
1572 * will repeat this with true if allocation indeed
1573 * succeeds in this zone.
1575 compaction_defer_reset(zone, order, false);
1577 * It is possible that async compaction aborted due to
1578 * need_resched() and the watermarks were ok thanks to
1579 * somebody else freeing memory. The allocation can
1580 * however still fail so we better signal the
1581 * need_resched() contention anyway (this will not
1582 * prevent the allocation attempt).
1584 if (zone_contended == COMPACT_CONTENDED_SCHED)
1585 *contended = COMPACT_CONTENDED_SCHED;
1590 if (mode != MIGRATE_ASYNC && status == COMPACT_COMPLETE) {
1592 * We think that allocation won't succeed in this zone
1593 * so we defer compaction there. If it ends up
1594 * succeeding after all, it will be reset.
1596 defer_compaction(zone, order);
1600 * We might have stopped compacting due to need_resched() in
1601 * async compaction, or due to a fatal signal detected. In that
1602 * case do not try further zones and signal need_resched()
1605 if ((zone_contended == COMPACT_CONTENDED_SCHED)
1606 || fatal_signal_pending(current)) {
1607 *contended = COMPACT_CONTENDED_SCHED;
1614 * We might not have tried all the zones, so be conservative
1615 * and assume they are not all lock contended.
1617 all_zones_contended = 0;
1622 * If at least one zone wasn't deferred or skipped, we report if all
1623 * zones that were tried were lock contended.
1625 if (rc > COMPACT_SKIPPED && all_zones_contended)
1626 *contended = COMPACT_CONTENDED_LOCK;
1632 /* Compact all zones within a node */
1633 static void __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc)
1638 for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
1640 zone = &pgdat->node_zones[zoneid];
1641 if (!populated_zone(zone))
1644 cc->nr_freepages = 0;
1645 cc->nr_migratepages = 0;
1647 INIT_LIST_HEAD(&cc->freepages);
1648 INIT_LIST_HEAD(&cc->migratepages);
1651 * When called via /proc/sys/vm/compact_memory
1652 * this makes sure we compact the whole zone regardless of
1653 * cached scanner positions.
1655 if (is_via_compact_memory(cc->order))
1656 __reset_isolation_suitable(zone);
1658 if (is_via_compact_memory(cc->order) ||
1659 !compaction_deferred(zone, cc->order))
1660 compact_zone(zone, cc);
1662 VM_BUG_ON(!list_empty(&cc->freepages));
1663 VM_BUG_ON(!list_empty(&cc->migratepages));
1665 if (is_via_compact_memory(cc->order))
1668 if (zone_watermark_ok(zone, cc->order,
1669 low_wmark_pages(zone), 0, 0))
1670 compaction_defer_reset(zone, cc->order, false);
1674 void compact_pgdat(pg_data_t *pgdat, int order)
1676 struct compact_control cc = {
1678 .mode = MIGRATE_ASYNC,
1684 __compact_pgdat(pgdat, &cc);
1687 static void compact_node(int nid)
1689 struct compact_control cc = {
1691 .mode = MIGRATE_SYNC,
1692 .ignore_skip_hint = true,
1695 __compact_pgdat(NODE_DATA(nid), &cc);
1698 /* Compact all nodes in the system */
1699 static void compact_nodes(void)
1703 /* Flush pending updates to the LRU lists */
1704 lru_add_drain_all();
1706 for_each_online_node(nid)
1710 /* The written value is actually unused, all memory is compacted */
1711 int sysctl_compact_memory;
1714 * This is the entry point for compacting all nodes via
1715 * /proc/sys/vm/compact_memory
1717 int sysctl_compaction_handler(struct ctl_table *table, int write,
1718 void __user *buffer, size_t *length, loff_t *ppos)
1726 int sysctl_extfrag_handler(struct ctl_table *table, int write,
1727 void __user *buffer, size_t *length, loff_t *ppos)
1729 proc_dointvec_minmax(table, write, buffer, length, ppos);
1734 #if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
1735 static ssize_t sysfs_compact_node(struct device *dev,
1736 struct device_attribute *attr,
1737 const char *buf, size_t count)
1741 if (nid >= 0 && nid < nr_node_ids && node_online(nid)) {
1742 /* Flush pending updates to the LRU lists */
1743 lru_add_drain_all();
1750 static DEVICE_ATTR(compact, S_IWUSR, NULL, sysfs_compact_node);
1752 int compaction_register_node(struct node *node)
1754 return device_create_file(&node->dev, &dev_attr_compact);
1757 void compaction_unregister_node(struct node *node)
1759 return device_remove_file(&node->dev, &dev_attr_compact);
1761 #endif /* CONFIG_SYSFS && CONFIG_NUMA */
1763 #endif /* CONFIG_COMPACTION */