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>
19 #if defined CONFIG_COMPACTION || defined CONFIG_CMA
21 #define CREATE_TRACE_POINTS
22 #include <trace/events/compaction.h>
24 static unsigned long release_freepages(struct list_head
*freelist
)
26 struct page
*page
, *next
;
27 unsigned long count
= 0;
29 list_for_each_entry_safe(page
, next
, freelist
, lru
) {
38 static void map_pages(struct list_head
*list
)
42 list_for_each_entry(page
, list
, lru
) {
43 arch_alloc_page(page
, 0);
44 kernel_map_pages(page
, 1, 1);
48 static inline bool migrate_async_suitable(int migratetype
)
50 return is_migrate_cma(migratetype
) || migratetype
== MIGRATE_MOVABLE
;
54 * Isolate free pages onto a private freelist. Caller must hold zone->lock.
55 * If @strict is true, will abort returning 0 on any invalid PFNs or non-free
56 * pages inside of the pageblock (even though it may still end up isolating
59 static unsigned long isolate_freepages_block(unsigned long blockpfn
,
60 unsigned long end_pfn
,
61 struct list_head
*freelist
,
64 int nr_scanned
= 0, total_isolated
= 0;
67 cursor
= pfn_to_page(blockpfn
);
69 /* Isolate free pages. This assumes the block is valid */
70 for (; blockpfn
< end_pfn
; blockpfn
++, cursor
++) {
72 struct page
*page
= cursor
;
74 if (!pfn_valid_within(blockpfn
)) {
81 if (!PageBuddy(page
)) {
87 /* Found a free page, break it into order-0 pages */
88 isolated
= split_free_page(page
);
89 if (!isolated
&& strict
)
91 total_isolated
+= isolated
;
92 for (i
= 0; i
< isolated
; i
++) {
93 list_add(&page
->lru
, freelist
);
97 /* If a page was split, advance to the end of it */
99 blockpfn
+= isolated
- 1;
100 cursor
+= isolated
- 1;
104 trace_mm_compaction_isolate_freepages(nr_scanned
, total_isolated
);
105 return total_isolated
;
109 * isolate_freepages_range() - isolate free pages.
110 * @start_pfn: The first PFN to start isolating.
111 * @end_pfn: The one-past-last PFN.
113 * Non-free pages, invalid PFNs, or zone boundaries within the
114 * [start_pfn, end_pfn) range are considered errors, cause function to
115 * undo its actions and return zero.
117 * Otherwise, function returns one-past-the-last PFN of isolated page
118 * (which may be greater then end_pfn if end fell in a middle of
122 isolate_freepages_range(unsigned long start_pfn
, unsigned long end_pfn
)
124 unsigned long isolated
, pfn
, block_end_pfn
, flags
;
125 struct zone
*zone
= NULL
;
128 if (pfn_valid(start_pfn
))
129 zone
= page_zone(pfn_to_page(start_pfn
));
131 for (pfn
= start_pfn
; pfn
< end_pfn
; pfn
+= isolated
) {
132 if (!pfn_valid(pfn
) || zone
!= page_zone(pfn_to_page(pfn
)))
136 * On subsequent iterations ALIGN() is actually not needed,
137 * but we keep it that we not to complicate the code.
139 block_end_pfn
= ALIGN(pfn
+ 1, pageblock_nr_pages
);
140 block_end_pfn
= min(block_end_pfn
, end_pfn
);
142 spin_lock_irqsave(&zone
->lock
, flags
);
143 isolated
= isolate_freepages_block(pfn
, block_end_pfn
,
145 spin_unlock_irqrestore(&zone
->lock
, flags
);
148 * In strict mode, isolate_freepages_block() returns 0 if
149 * there are any holes in the block (ie. invalid PFNs or
156 * If we managed to isolate pages, it is always (1 << n) *
157 * pageblock_nr_pages for some non-negative n. (Max order
158 * page may span two pageblocks).
162 /* split_free_page does not map the pages */
163 map_pages(&freelist
);
166 /* Loop terminated early, cleanup. */
167 release_freepages(&freelist
);
171 /* We don't use freelists for anything. */
175 /* Update the number of anon and file isolated pages in the zone */
176 static void acct_isolated(struct zone
*zone
, struct compact_control
*cc
)
179 unsigned int count
[2] = { 0, };
181 list_for_each_entry(page
, &cc
->migratepages
, lru
)
182 count
[!!page_is_file_cache(page
)]++;
184 __mod_zone_page_state(zone
, NR_ISOLATED_ANON
, count
[0]);
185 __mod_zone_page_state(zone
, NR_ISOLATED_FILE
, count
[1]);
188 /* Similar to reclaim, but different enough that they don't share logic */
189 static bool too_many_isolated(struct zone
*zone
)
191 unsigned long active
, inactive
, isolated
;
193 inactive
= zone_page_state(zone
, NR_INACTIVE_FILE
) +
194 zone_page_state(zone
, NR_INACTIVE_ANON
);
195 active
= zone_page_state(zone
, NR_ACTIVE_FILE
) +
196 zone_page_state(zone
, NR_ACTIVE_ANON
);
197 isolated
= zone_page_state(zone
, NR_ISOLATED_FILE
) +
198 zone_page_state(zone
, NR_ISOLATED_ANON
);
200 return isolated
> (inactive
+ active
) / 2;
204 * isolate_migratepages_range() - isolate all migrate-able pages in range.
205 * @zone: Zone pages are in.
206 * @cc: Compaction control structure.
207 * @low_pfn: The first PFN of the range.
208 * @end_pfn: The one-past-the-last PFN of the range.
210 * Isolate all pages that can be migrated from the range specified by
211 * [low_pfn, end_pfn). Returns zero if there is a fatal signal
212 * pending), otherwise PFN of the first page that was not scanned
213 * (which may be both less, equal to or more then end_pfn).
215 * Assumes that cc->migratepages is empty and cc->nr_migratepages is
218 * Apart from cc->migratepages and cc->nr_migratetypes this function
219 * does not modify any cc's fields, in particular it does not modify
220 * (or read for that matter) cc->migrate_pfn.
223 isolate_migratepages_range(struct zone
*zone
, struct compact_control
*cc
,
224 unsigned long low_pfn
, unsigned long end_pfn
)
226 unsigned long last_pageblock_nr
= 0, pageblock_nr
;
227 unsigned long nr_scanned
= 0, nr_isolated
= 0;
228 struct list_head
*migratelist
= &cc
->migratepages
;
229 isolate_mode_t mode
= 0;
230 struct lruvec
*lruvec
;
233 * Ensure that there are not too many pages isolated from the LRU
234 * list by either parallel reclaimers or compaction. If there are,
235 * delay for some time until fewer pages are isolated
237 while (unlikely(too_many_isolated(zone
))) {
238 /* async migration should just abort */
242 congestion_wait(BLK_RW_ASYNC
, HZ
/10);
244 if (fatal_signal_pending(current
))
248 /* Time to isolate some pages for migration */
250 spin_lock_irq(&zone
->lru_lock
);
251 for (; low_pfn
< end_pfn
; low_pfn
++) {
255 /* give a chance to irqs before checking need_resched() */
256 if (!((low_pfn
+1) % SWAP_CLUSTER_MAX
)) {
257 spin_unlock_irq(&zone
->lru_lock
);
260 if (need_resched() || spin_is_contended(&zone
->lru_lock
)) {
262 spin_unlock_irq(&zone
->lru_lock
);
264 spin_lock_irq(&zone
->lru_lock
);
265 if (fatal_signal_pending(current
))
268 spin_lock_irq(&zone
->lru_lock
);
271 * migrate_pfn does not necessarily start aligned to a
272 * pageblock. Ensure that pfn_valid is called when moving
273 * into a new MAX_ORDER_NR_PAGES range in case of large
274 * memory holes within the zone
276 if ((low_pfn
& (MAX_ORDER_NR_PAGES
- 1)) == 0) {
277 if (!pfn_valid(low_pfn
)) {
278 low_pfn
+= MAX_ORDER_NR_PAGES
- 1;
283 if (!pfn_valid_within(low_pfn
))
288 * Get the page and ensure the page is within the same zone.
289 * See the comment in isolate_freepages about overlapping
290 * nodes. It is deliberate that the new zone lock is not taken
291 * as memory compaction should not move pages between nodes.
293 page
= pfn_to_page(low_pfn
);
294 if (page_zone(page
) != zone
)
302 * For async migration, also only scan in MOVABLE blocks. Async
303 * migration is optimistic to see if the minimum amount of work
304 * satisfies the allocation
306 pageblock_nr
= low_pfn
>> pageblock_order
;
307 if (!cc
->sync
&& last_pageblock_nr
!= pageblock_nr
&&
308 !migrate_async_suitable(get_pageblock_migratetype(page
))) {
309 low_pfn
+= pageblock_nr_pages
;
310 low_pfn
= ALIGN(low_pfn
, pageblock_nr_pages
) - 1;
311 last_pageblock_nr
= pageblock_nr
;
319 * PageLRU is set, and lru_lock excludes isolation,
320 * splitting and collapsing (collapsing has already
321 * happened if PageLRU is set).
323 if (PageTransHuge(page
)) {
324 low_pfn
+= (1 << compound_order(page
)) - 1;
329 mode
|= ISOLATE_ASYNC_MIGRATE
;
331 lruvec
= mem_cgroup_page_lruvec(page
, zone
);
333 /* Try isolate the page */
334 if (__isolate_lru_page(page
, mode
) != 0)
337 VM_BUG_ON(PageTransCompound(page
));
339 /* Successfully isolated */
340 del_page_from_lru_list(page
, lruvec
, page_lru(page
));
341 list_add(&page
->lru
, migratelist
);
342 cc
->nr_migratepages
++;
345 /* Avoid isolating too much */
346 if (cc
->nr_migratepages
== COMPACT_CLUSTER_MAX
) {
352 acct_isolated(zone
, cc
);
354 spin_unlock_irq(&zone
->lru_lock
);
356 trace_mm_compaction_isolate_migratepages(nr_scanned
, nr_isolated
);
361 #endif /* CONFIG_COMPACTION || CONFIG_CMA */
362 #ifdef CONFIG_COMPACTION
364 /* Returns true if the page is within a block suitable for migration to */
365 static bool suitable_migration_target(struct page
*page
)
368 int migratetype
= get_pageblock_migratetype(page
);
370 /* Don't interfere with memory hot-remove or the min_free_kbytes blocks */
371 if (migratetype
== MIGRATE_ISOLATE
|| migratetype
== MIGRATE_RESERVE
)
374 /* If the page is a large free page, then allow migration */
375 if (PageBuddy(page
) && page_order(page
) >= pageblock_order
)
378 /* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */
379 if (migrate_async_suitable(migratetype
))
382 /* Otherwise skip the block */
387 * Based on information in the current compact_control, find blocks
388 * suitable for isolating free pages from and then isolate them.
390 static void isolate_freepages(struct zone
*zone
,
391 struct compact_control
*cc
)
394 unsigned long high_pfn
, low_pfn
, pfn
, zone_end_pfn
, end_pfn
;
396 int nr_freepages
= cc
->nr_freepages
;
397 struct list_head
*freelist
= &cc
->freepages
;
400 * Initialise the free scanner. The starting point is where we last
401 * scanned from (or the end of the zone if starting). The low point
402 * is the end of the pageblock the migration scanner is using.
405 low_pfn
= cc
->migrate_pfn
+ pageblock_nr_pages
;
408 * Take care that if the migration scanner is at the end of the zone
409 * that the free scanner does not accidentally move to the next zone
410 * in the next isolation cycle.
412 high_pfn
= min(low_pfn
, pfn
);
414 zone_end_pfn
= zone
->zone_start_pfn
+ zone
->spanned_pages
;
417 * Isolate free pages until enough are available to migrate the
418 * pages on cc->migratepages. We stop searching if the migrate
419 * and free page scanners meet or enough free pages are isolated.
421 for (; pfn
> low_pfn
&& cc
->nr_migratepages
> nr_freepages
;
422 pfn
-= pageblock_nr_pages
) {
423 unsigned long isolated
;
426 * Skip ahead if another thread is compacting in the area
427 * simultaneously. If we wrapped around, we can only skip
428 * ahead if zone->compact_cached_free_pfn also wrapped to
429 * above our starting point.
431 if (cc
->order
> 0 && (!cc
->wrapped
||
432 zone
->compact_cached_free_pfn
>
434 pfn
= min(pfn
, zone
->compact_cached_free_pfn
);
440 * Check for overlapping nodes/zones. It's possible on some
441 * configurations to have a setup like
443 * i.e. it's possible that all pages within a zones range of
444 * pages do not belong to a single zone.
446 page
= pfn_to_page(pfn
);
447 if (page_zone(page
) != zone
)
450 /* Check the block is suitable for migration */
451 if (!suitable_migration_target(page
))
455 * Found a block suitable for isolating free pages from. Now
456 * we disabled interrupts, double check things are ok and
457 * isolate the pages. This is to minimise the time IRQs
461 spin_lock_irqsave(&zone
->lock
, flags
);
462 if (suitable_migration_target(page
)) {
463 end_pfn
= min(pfn
+ pageblock_nr_pages
, zone_end_pfn
);
464 isolated
= isolate_freepages_block(pfn
, end_pfn
,
466 nr_freepages
+= isolated
;
468 spin_unlock_irqrestore(&zone
->lock
, flags
);
471 * Record the highest PFN we isolated pages from. When next
472 * looking for free pages, the search will restart here as
473 * page migration may have returned some pages to the allocator
476 high_pfn
= max(high_pfn
, pfn
);
478 zone
->compact_cached_free_pfn
= high_pfn
;
482 /* split_free_page does not map the pages */
485 cc
->free_pfn
= high_pfn
;
486 cc
->nr_freepages
= nr_freepages
;
490 * This is a migrate-callback that "allocates" freepages by taking pages
491 * from the isolated freelists in the block we are migrating to.
493 static struct page
*compaction_alloc(struct page
*migratepage
,
497 struct compact_control
*cc
= (struct compact_control
*)data
;
498 struct page
*freepage
;
500 /* Isolate free pages if necessary */
501 if (list_empty(&cc
->freepages
)) {
502 isolate_freepages(cc
->zone
, cc
);
504 if (list_empty(&cc
->freepages
))
508 freepage
= list_entry(cc
->freepages
.next
, struct page
, lru
);
509 list_del(&freepage
->lru
);
516 * We cannot control nr_migratepages and nr_freepages fully when migration is
517 * running as migrate_pages() has no knowledge of compact_control. When
518 * migration is complete, we count the number of pages on the lists by hand.
520 static void update_nr_listpages(struct compact_control
*cc
)
522 int nr_migratepages
= 0;
523 int nr_freepages
= 0;
526 list_for_each_entry(page
, &cc
->migratepages
, lru
)
528 list_for_each_entry(page
, &cc
->freepages
, lru
)
531 cc
->nr_migratepages
= nr_migratepages
;
532 cc
->nr_freepages
= nr_freepages
;
535 /* possible outcome of isolate_migratepages */
537 ISOLATE_ABORT
, /* Abort compaction now */
538 ISOLATE_NONE
, /* No pages isolated, continue scanning */
539 ISOLATE_SUCCESS
, /* Pages isolated, migrate */
543 * Isolate all pages that can be migrated from the block pointed to by
544 * the migrate scanner within compact_control.
546 static isolate_migrate_t
isolate_migratepages(struct zone
*zone
,
547 struct compact_control
*cc
)
549 unsigned long low_pfn
, end_pfn
;
551 /* Do not scan outside zone boundaries */
552 low_pfn
= max(cc
->migrate_pfn
, zone
->zone_start_pfn
);
554 /* Only scan within a pageblock boundary */
555 end_pfn
= ALIGN(low_pfn
+ pageblock_nr_pages
, pageblock_nr_pages
);
557 /* Do not cross the free scanner or scan within a memory hole */
558 if (end_pfn
> cc
->free_pfn
|| !pfn_valid(low_pfn
)) {
559 cc
->migrate_pfn
= end_pfn
;
563 /* Perform the isolation */
564 low_pfn
= isolate_migratepages_range(zone
, cc
, low_pfn
, end_pfn
);
566 return ISOLATE_ABORT
;
568 cc
->migrate_pfn
= low_pfn
;
570 return ISOLATE_SUCCESS
;
574 * Returns the start pfn of the last page block in a zone. This is the starting
575 * point for full compaction of a zone. Compaction searches for free pages from
576 * the end of each zone, while isolate_freepages_block scans forward inside each
579 static unsigned long start_free_pfn(struct zone
*zone
)
581 unsigned long free_pfn
;
582 free_pfn
= zone
->zone_start_pfn
+ zone
->spanned_pages
;
583 free_pfn
&= ~(pageblock_nr_pages
-1);
587 static int compact_finished(struct zone
*zone
,
588 struct compact_control
*cc
)
591 unsigned long watermark
;
593 if (fatal_signal_pending(current
))
594 return COMPACT_PARTIAL
;
597 * A full (order == -1) compaction run starts at the beginning and
598 * end of a zone; it completes when the migrate and free scanner meet.
599 * A partial (order > 0) compaction can start with the free scanner
600 * at a random point in the zone, and may have to restart.
602 if (cc
->free_pfn
<= cc
->migrate_pfn
) {
603 if (cc
->order
> 0 && !cc
->wrapped
) {
604 /* We started partway through; restart at the end. */
605 unsigned long free_pfn
= start_free_pfn(zone
);
606 zone
->compact_cached_free_pfn
= free_pfn
;
607 cc
->free_pfn
= free_pfn
;
609 return COMPACT_CONTINUE
;
611 return COMPACT_COMPLETE
;
614 /* We wrapped around and ended up where we started. */
615 if (cc
->wrapped
&& cc
->free_pfn
<= cc
->start_free_pfn
)
616 return COMPACT_COMPLETE
;
619 * order == -1 is expected when compacting via
620 * /proc/sys/vm/compact_memory
623 return COMPACT_CONTINUE
;
625 /* Compaction run is not finished if the watermark is not met */
626 watermark
= low_wmark_pages(zone
);
627 watermark
+= (1 << cc
->order
);
629 if (!zone_watermark_ok(zone
, cc
->order
, watermark
, 0, 0))
630 return COMPACT_CONTINUE
;
632 /* Direct compactor: Is a suitable page free? */
633 for (order
= cc
->order
; order
< MAX_ORDER
; order
++) {
634 /* Job done if page is free of the right migratetype */
635 if (!list_empty(&zone
->free_area
[order
].free_list
[cc
->migratetype
]))
636 return COMPACT_PARTIAL
;
638 /* Job done if allocation would set block type */
639 if (order
>= pageblock_order
&& zone
->free_area
[order
].nr_free
)
640 return COMPACT_PARTIAL
;
643 return COMPACT_CONTINUE
;
647 * compaction_suitable: Is this suitable to run compaction on this zone now?
649 * COMPACT_SKIPPED - If there are too few free pages for compaction
650 * COMPACT_PARTIAL - If the allocation would succeed without compaction
651 * COMPACT_CONTINUE - If compaction should run now
653 unsigned long compaction_suitable(struct zone
*zone
, int order
)
656 unsigned long watermark
;
659 * order == -1 is expected when compacting via
660 * /proc/sys/vm/compact_memory
663 return COMPACT_CONTINUE
;
666 * Watermarks for order-0 must be met for compaction. Note the 2UL.
667 * This is because during migration, copies of pages need to be
668 * allocated and for a short time, the footprint is higher
670 watermark
= low_wmark_pages(zone
) + (2UL << order
);
671 if (!zone_watermark_ok(zone
, 0, watermark
, 0, 0))
672 return COMPACT_SKIPPED
;
675 * fragmentation index determines if allocation failures are due to
676 * low memory or external fragmentation
678 * index of -1000 implies allocations might succeed depending on
680 * index towards 0 implies failure is due to lack of memory
681 * index towards 1000 implies failure is due to fragmentation
683 * Only compact if a failure would be due to fragmentation.
685 fragindex
= fragmentation_index(zone
, order
);
686 if (fragindex
>= 0 && fragindex
<= sysctl_extfrag_threshold
)
687 return COMPACT_SKIPPED
;
689 if (fragindex
== -1000 && zone_watermark_ok(zone
, order
, watermark
,
691 return COMPACT_PARTIAL
;
693 return COMPACT_CONTINUE
;
696 static int compact_zone(struct zone
*zone
, struct compact_control
*cc
)
700 ret
= compaction_suitable(zone
, cc
->order
);
702 case COMPACT_PARTIAL
:
703 case COMPACT_SKIPPED
:
704 /* Compaction is likely to fail */
706 case COMPACT_CONTINUE
:
707 /* Fall through to compaction */
711 /* Setup to move all movable pages to the end of the zone */
712 cc
->migrate_pfn
= zone
->zone_start_pfn
;
715 /* Incremental compaction. Start where the last one stopped. */
716 cc
->free_pfn
= zone
->compact_cached_free_pfn
;
717 cc
->start_free_pfn
= cc
->free_pfn
;
719 /* Order == -1 starts at the end of the zone. */
720 cc
->free_pfn
= start_free_pfn(zone
);
723 migrate_prep_local();
725 while ((ret
= compact_finished(zone
, cc
)) == COMPACT_CONTINUE
) {
726 unsigned long nr_migrate
, nr_remaining
;
729 switch (isolate_migratepages(zone
, cc
)) {
731 ret
= COMPACT_PARTIAL
;
735 case ISOLATE_SUCCESS
:
739 nr_migrate
= cc
->nr_migratepages
;
740 err
= migrate_pages(&cc
->migratepages
, compaction_alloc
,
741 (unsigned long)cc
, false,
742 cc
->sync
? MIGRATE_SYNC_LIGHT
: MIGRATE_ASYNC
);
743 update_nr_listpages(cc
);
744 nr_remaining
= cc
->nr_migratepages
;
746 count_vm_event(COMPACTBLOCKS
);
747 count_vm_events(COMPACTPAGES
, nr_migrate
- nr_remaining
);
749 count_vm_events(COMPACTPAGEFAILED
, nr_remaining
);
750 trace_mm_compaction_migratepages(nr_migrate
- nr_remaining
,
753 /* Release LRU pages not migrated */
755 putback_lru_pages(&cc
->migratepages
);
756 cc
->nr_migratepages
= 0;
757 if (err
== -ENOMEM
) {
758 ret
= COMPACT_PARTIAL
;
765 /* Release free pages and check accounting */
766 cc
->nr_freepages
-= release_freepages(&cc
->freepages
);
767 VM_BUG_ON(cc
->nr_freepages
!= 0);
772 static unsigned long compact_zone_order(struct zone
*zone
,
773 int order
, gfp_t gfp_mask
,
776 struct compact_control cc
= {
778 .nr_migratepages
= 0,
780 .migratetype
= allocflags_to_migratetype(gfp_mask
),
784 INIT_LIST_HEAD(&cc
.freepages
);
785 INIT_LIST_HEAD(&cc
.migratepages
);
787 return compact_zone(zone
, &cc
);
790 int sysctl_extfrag_threshold
= 500;
793 * try_to_compact_pages - Direct compact to satisfy a high-order allocation
794 * @zonelist: The zonelist used for the current allocation
795 * @order: The order of the current allocation
796 * @gfp_mask: The GFP mask of the current allocation
797 * @nodemask: The allowed nodes to allocate from
798 * @sync: Whether migration is synchronous or not
800 * This is the main entry point for direct page compaction.
802 unsigned long try_to_compact_pages(struct zonelist
*zonelist
,
803 int order
, gfp_t gfp_mask
, nodemask_t
*nodemask
,
806 enum zone_type high_zoneidx
= gfp_zone(gfp_mask
);
807 int may_enter_fs
= gfp_mask
& __GFP_FS
;
808 int may_perform_io
= gfp_mask
& __GFP_IO
;
811 int rc
= COMPACT_SKIPPED
;
814 * Check whether it is worth even starting compaction. The order check is
815 * made because an assumption is made that the page allocator can satisfy
816 * the "cheaper" orders without taking special steps
818 if (!order
|| !may_enter_fs
|| !may_perform_io
)
821 count_vm_event(COMPACTSTALL
);
823 /* Compact each zone in the list */
824 for_each_zone_zonelist_nodemask(zone
, z
, zonelist
, high_zoneidx
,
828 status
= compact_zone_order(zone
, order
, gfp_mask
, sync
);
829 rc
= max(status
, rc
);
831 /* If a normal allocation would succeed, stop compacting */
832 if (zone_watermark_ok(zone
, order
, low_wmark_pages(zone
), 0, 0))
840 /* Compact all zones within a node */
841 static int __compact_pgdat(pg_data_t
*pgdat
, struct compact_control
*cc
)
846 for (zoneid
= 0; zoneid
< MAX_NR_ZONES
; zoneid
++) {
848 zone
= &pgdat
->node_zones
[zoneid
];
849 if (!populated_zone(zone
))
852 cc
->nr_freepages
= 0;
853 cc
->nr_migratepages
= 0;
855 INIT_LIST_HEAD(&cc
->freepages
);
856 INIT_LIST_HEAD(&cc
->migratepages
);
858 if (cc
->order
== -1 || !compaction_deferred(zone
, cc
->order
))
859 compact_zone(zone
, cc
);
862 int ok
= zone_watermark_ok(zone
, cc
->order
,
863 low_wmark_pages(zone
), 0, 0);
864 if (ok
&& cc
->order
> zone
->compact_order_failed
)
865 zone
->compact_order_failed
= cc
->order
+ 1;
866 /* Currently async compaction is never deferred. */
867 else if (!ok
&& cc
->sync
)
868 defer_compaction(zone
, cc
->order
);
871 VM_BUG_ON(!list_empty(&cc
->freepages
));
872 VM_BUG_ON(!list_empty(&cc
->migratepages
));
878 int compact_pgdat(pg_data_t
*pgdat
, int order
)
880 struct compact_control cc
= {
885 return __compact_pgdat(pgdat
, &cc
);
888 static int compact_node(int nid
)
890 struct compact_control cc
= {
895 return __compact_pgdat(NODE_DATA(nid
), &cc
);
898 /* Compact all nodes in the system */
899 static int compact_nodes(void)
903 /* Flush pending updates to the LRU lists */
906 for_each_online_node(nid
)
909 return COMPACT_COMPLETE
;
912 /* The written value is actually unused, all memory is compacted */
913 int sysctl_compact_memory
;
915 /* This is the entry point for compacting all nodes via /proc/sys/vm */
916 int sysctl_compaction_handler(struct ctl_table
*table
, int write
,
917 void __user
*buffer
, size_t *length
, loff_t
*ppos
)
920 return compact_nodes();
925 int sysctl_extfrag_handler(struct ctl_table
*table
, int write
,
926 void __user
*buffer
, size_t *length
, loff_t
*ppos
)
928 proc_dointvec_minmax(table
, write
, buffer
, length
, ppos
);
933 #if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
934 ssize_t
sysfs_compact_node(struct device
*dev
,
935 struct device_attribute
*attr
,
936 const char *buf
, size_t count
)
940 if (nid
>= 0 && nid
< nr_node_ids
&& node_online(nid
)) {
941 /* Flush pending updates to the LRU lists */
949 static DEVICE_ATTR(compact
, S_IWUSR
, NULL
, sysfs_compact_node
);
951 int compaction_register_node(struct node
*node
)
953 return device_create_file(&node
->dev
, &dev_attr_compact
);
956 void compaction_unregister_node(struct node
*node
)
958 return device_remove_file(&node
->dev
, &dev_attr_compact
);
960 #endif /* CONFIG_SYSFS && CONFIG_NUMA */
962 #endif /* CONFIG_COMPACTION */
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