Commit 9bbc04ee authored Apr 07, 2014 by Weijie Yang Committed by Linus Torvalds Apr 07, 2014

mm/vmscan: do not check compaction_ready on promoted zones



We abort direct reclaim if we find the zone is ready for compaction.
Sometimes the zone is just a promoted highmem zone to force a scan of
highmem, which is not the intended zone the caller want to allocate a
page from.  In this situation, setting aborted_reclaim to indicate the
caller turned back to retry the allocation is waste of time and could
cause a loop in __alloc_pages_slowpath().

This patch does not check compaction_ready() on promoted zones to avoid
the above situation.  Only set aborted_reclaim if the caller intended
zone is ready for compaction.

Signed-off-by: Weijie Yang <weijie.yang@samsung.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 619d0d76

mm/vmscan.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -2318,6 +2318,7 @@ static bool shrink_zones(struct zonelist zonelist, struct scan_control sc)
		struct shrink_control shrink = {
		.gfp_mask = sc->gfp_mask,
		};
		enum zone_type requested_highidx = gfp_zone(sc->gfp_mask);

		/*
		* If the number of buffer_heads in the machine exceeds the maximum
		@@ -2358,7 +2359,8 @@ static bool shrink_zones(struct zonelist zonelist, struct scan_control sc)
		* noticeable problem, like transparent huge
		* page allocations.
		*/
		if (compaction_ready(zone, sc)) {
		if ((zonelist_zone_idx(z) <= requested_highidx)
		&& compaction_ready(zone, sc)) {
		aborted_reclaim = true;
		continue;
		}

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