This is a note to let you know that I've just added the patch titled
mm, cma: prevent nr_isolated_* counters from going negative
to the 4.5-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-cma-prevent-nr_isolated_-counters-from-going-negative.patch
and it can be found in the queue-4.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 14af4a5e9b26ad251f81c174e8a43f3e179434a5 Mon Sep 17 00:00:00 2001
From: Hugh Dickins <hughd@xxxxxxxxxx>
Date: Thu, 5 May 2016 16:22:15 -0700
Subject: mm, cma: prevent nr_isolated_* counters from going negative
From: Hugh Dickins <hughd@xxxxxxxxxx>
commit 14af4a5e9b26ad251f81c174e8a43f3e179434a5 upstream.
/proc/sys/vm/stat_refresh warns nr_isolated_anon and nr_isolated_file go
increasingly negative under compaction: which would add delay when
should be none, or no delay when should delay. The bug in compaction
was due to a recent mmotm patch, but much older instance of the bug was
also noticed in isolate_migratepages_range() which is used for CMA and
gigantic hugepage allocations.
The bug is caused by putback_movable_pages() in an error path
decrementing the isolated counters without them being previously
incremented by acct_isolated(). Fix isolate_migratepages_range() by
removing the error-path putback, thus reaching acct_isolated() with
migratepages still isolated, and leaving putback to caller like most
other places do.
Fixes: edc2ca612496 ("mm, compaction: move pageblock checks up from isolate_migratepages_range()")
[vbabka@xxxxxxx: expanded the changelog]
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Michal Hocko <mhocko@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 | 10 +---------
1 file changed, 1 insertion(+), 9 deletions(-)
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -880,16 +880,8 @@ isolate_migratepages_range(struct compac
pfn = isolate_migratepages_block(cc, pfn, block_end_pfn,
ISOLATE_UNEVICTABLE);
- /*
- * In case of fatal failure, release everything that might
- * have been isolated in the previous iteration, and signal
- * the failure back to caller.
- */
- if (!pfn) {
- putback_movable_pages(&cc->migratepages);
- cc->nr_migratepages = 0;
+ if (!pfn)
break;
- }
if (cc->nr_migratepages == COMPACT_CLUSTER_MAX)
break;
Patches currently in stable-queue which might be from hughd@xxxxxxxxxx are
queue-4.5/mm-cma-prevent-nr_isolated_-counters-from-going-negative.patch
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