This is a note to let you know that I've just added the patch titled
mm/compaction: fix wrong order check in compact_finished()
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-compaction-fix-wrong-order-check-in-compact_finished.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 372549c2a3778fd3df445819811c944ad54609ca Mon Sep 17 00:00:00 2001
From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Date: Thu, 12 Feb 2015 14:59:50 -0800
Subject: mm/compaction: fix wrong order check in compact_finished()
From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
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@xxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Reviewed-by: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/compaction.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -881,7 +881,7 @@ static int compact_finished(struct 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;
}
Patches currently in stable-queue which might be from iamjoonsoo.kim@xxxxxxx are
queue-3.10/mm-compaction-fix-wrong-order-check-in-compact_finished.patch
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