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Commit e64c5237 authored by Shaohua Li's avatar Shaohua Li Committed by Linus Torvalds
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mm: compaction: abort compaction loop if lock is contended or run too long 



isolate_migratepages_range() might isolate no pages if for example when
zone->lru_lock is contended and running asynchronous compaction. In this
case, we should abort compaction, otherwise, compact_zone will run a
useless loop and make zone->lru_lock is even contended.

An additional check is added to ensure that cc.migratepages and
cc.freepages get properly drained whan compaction is aborted.

[minchan@kernel.org: Putback pages isolated for migration if aborting]
[akpm@linux-foundation.org: compact_zone_order requires non-NULL arg contended]
[akpm@linux-foundation.org: make compact_zone_order() require non-NULL arg `contended']
[minchan@kernel.org: Putback pages isolated for migration if aborting]
Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Signed-off-by: default avatarShaohua Li <shli@fusionio.com>
Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
Acked-by: default avatarMinchan Kim <minchan@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f2d52fe5

mm/compaction.c

+12 −5
Original line number Diff line number Diff line
@@ -70,8 +70,7 @@ static bool compact_checklock_irqsave(spinlock_t *lock, unsigned long *flags, 


		/* async aborts if taking too long or contended */

		if (!cc->sync) {

			if (cc->contended)

				*cc->contended = true;

			cc->contended = true;

			return false;

		}
@@ -688,7 +687,7 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone, 


	/* Perform the isolation */

	low_pfn = isolate_migratepages_range(zone, cc, low_pfn, end_pfn);

	if (!low_pfn)

	if (!low_pfn || cc->contended)

		return ISOLATE_ABORT;



	cc->migrate_pfn = low_pfn;
@@ -848,6 +847,8 @@ static int compact_zone(struct zone *zone, struct compact_control *cc) 
		switch (isolate_migratepages(zone, cc)) {

		case ISOLATE_ABORT:

			ret = COMPACT_PARTIAL;

			putback_lru_pages(&cc->migratepages);

			cc->nr_migratepages = 0;

			goto out;

		case ISOLATE_NONE:

			continue;
@@ -896,6 +897,7 @@ static unsigned long compact_zone_order(struct zone *zone, 
				 bool sync, bool *contended,

				 struct page **page)

{

	unsigned long ret;

	struct compact_control cc = {

		.nr_freepages = 0,

		.nr_migratepages = 0,
@@ -903,13 +905,18 @@ static unsigned long compact_zone_order(struct zone *zone, 
		.migratetype = allocflags_to_migratetype(gfp_mask),

		.zone = zone,

		.sync = sync,

		.contended = contended,

		.page = page,

	};

	INIT_LIST_HEAD(&cc.freepages);

	INIT_LIST_HEAD(&cc.migratepages);



	return compact_zone(zone, &cc);

	ret = compact_zone(zone, &cc);



	VM_BUG_ON(!list_empty(&cc.freepages));

	VM_BUG_ON(!list_empty(&cc.migratepages));



	*contended = cc.contended;

	return ret;

}



int sysctl_extfrag_threshold = 500;

mm/internal.h

+1 −1
Original line number Diff line number Diff line
@@ -130,7 +130,7 @@ struct compact_control { 
	int order;			/* order a direct compactor needs */

	int migratetype;		/* MOVABLE, RECLAIMABLE etc */

	struct zone *zone;

	bool *contended;		/* True if a lock was contended */

	bool contended;			/* True if a lock was contended */

	struct page **page;		/* Page captured of requested size */

};