Commit 1d2047fe authored Jul 28, 2016 by Hugh Dickins Committed by Linus Torvalds Jul 28, 2016

mm, compaction: don't isolate PageWriteback pages in MIGRATE_SYNC_LIGHT mode

At present MIGRATE_SYNC_LIGHT is allowing __isolate_lru_page() to
isolate a PageWriteback page, which __unmap_and_move() then rejects with
-EBUSY: of course the writeback might complete in between, but that's
not what we usually expect, so probably better not to isolate it.

When tested by stress-highalloc from mmtests, this has reduced the
number of page migrate failures by 60-70%.

Link: http://lkml.kernel.org/r/20160721073614.24395-2-vbabka@suse.cz


Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 7c7fd825

mm/compaction.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1200,7 +1200,7 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
		struct page *page;
		const isolate_mode_t isolate_mode =
		(sysctl_compact_unevictable_allowed ? ISOLATE_UNEVICTABLE : 0) \|
		(cc->mode == MIGRATE_ASYNC ? ISOLATE_ASYNC_MIGRATE : 0);
		(cc->mode != MIGRATE_SYNC ? ISOLATE_ASYNC_MIGRATE : 0);

		/*
		* Start at where we last stopped, or beginning of the zone as

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