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authorJoonsoo Kim <iamjoonsoo.kim@lge.com>2015-02-12 14:59:50 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-03-18 13:22:28 +0100
commit2295074e4465734d4cb83cba15e055b4b2a87737 (patch)
tree09c4c49a1bc525b2971a21eb6c94003e52b52c86 /mm
parentae9c2f1fe9a11848a29f04e67940220a3985bfee (diff)
downloadlinux-linaro-stable-2295074e4465734d4cb83cba15e055b4b2a87737.tar.gz
mm/compaction: fix wrong order check in compact_finished()
commit 372549c2a3778fd3df445819811c944ad54609ca upstream. What we want to check here is whether there is highorder freepage in buddy list of other migratetype in order to steal it without fragmentation. But, current code just checks cc->order which means allocation request order. So, this is wrong. Without this fix, non-movable synchronous compaction below pageblock order would not stopped until compaction is complete, because migratetype of most pageblocks are movable and high order freepage made by compaction is usually on movable type buddy list. There is some report related to this bug. See below link. http://www.spinics.net/lists/linux-mm/msg81666.html Although the issued system still has load spike comes from compaction, this makes that system completely stable and responsive according to his report. stress-highalloc test in mmtests with non movable order 7 allocation doesn't show any notable difference in allocation success rate, but, it shows more compaction success rate. Compaction success rate (Compaction success * 100 / Compaction stalls, %) 18.47 : 28.94 Fixes: 1fb3f8ca0e92 ("mm: compaction: capture a suitable high-order page immediately when it is made available") Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: Mel Gorman <mgorman@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/compaction.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/compaction.c b/mm/compaction.c
index fb797a32362f..eeaaa929d1de 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -881,7 +881,7 @@ static int compact_finished(struct zone *zone,
return COMPACT_PARTIAL;
/* Job done if allocation would set block type */
- if (cc->order >= pageblock_order && area->nr_free)
+ if (order >= pageblock_order && area->nr_free)
return COMPACT_PARTIAL;
}