Commit 7335084d authored Jan 12, 2012 by Mel Gorman Committed by Linus Torvalds Jan 12, 2012

mm: vmscan: do not OOM if aborting reclaim to start compaction



During direct reclaim it is possible that reclaim will be aborted so that
compaction can be attempted to satisfy a high-order allocation.  If this
decision is made before any pages are reclaimed, it is possible that 0 is
returned to the page allocator potentially triggering an OOM.  This has
not been observed but it is a possibility so this patch addresses it.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Andy Isaacson <adi@hexapodia.org>
Cc: Nai Xia <nai.xia@gmail.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 50134731

mm/vmscan.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -2263,6 +2263,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
		struct zoneref *z;
		struct zone *zone;
		unsigned long writeback_threshold;
		bool should_abort_reclaim;

		get_mems_allowed();
		delayacct_freepages_start();
		@@ -2274,7 +2275,8 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
		sc->nr_scanned = 0;
		if (!priority)
		disable_swap_token(sc->target_mem_cgroup);
		if (shrink_zones(priority, zonelist, sc))
		should_abort_reclaim = shrink_zones(priority, zonelist, sc);
		if (should_abort_reclaim)
		break;

		/*
		@@ -2342,6 +2344,10 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
		if (oom_killer_disabled)
		return 0;

		/* Aborting reclaim to try compaction? don't OOM, then */
		if (should_abort_reclaim)
		return 1;

		/* top priority shrink_zones still had more to do? don't OOM, then */
		if (global_reclaim(sc) && !all_unreclaimable(zonelist, sc))
		return 1;