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[PATCH 4.5 39/88] mm, cma: prevent nr_isolated_* counters from going negative

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4.5-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Hugh Dickins <hughd@google.com>

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@suse.cz: expanded the changelog]
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
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>

---
 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;

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[PATCH 4.5 00/88] 4.5.4-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-09 10:00 +0200
  [PATCH 4.5 26/88] clk: xgene: Add missing parenthesis when clearing divider value Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-09 10:00 +0200
  [PATCH 4.5 41/88] propogate_mnt: Handle the first propogated copy being a slave Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-09 10:00 +0200
  [PATCH 4.5 39/88] mm, cma: prevent nr_isolated_* counters from going negative Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-09 10:00 +0200
  [PATCH 4.5 35/88] tracing: Dont display trigger file for events that cant be enabled Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-09 10:00 +0200
  [PATCH 4.5 44/88] ARM: SoCFPGA: Fix secondary CPU startup in thumb2 kernel Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-09 10:00 +0200
  [PATCH 4.5 23/88] clk: versatile: sp810: support reentrance Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-09 10:00 +0200
  [PATCH 4.5 36/88] MD: make bio mergeable Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-09 10:00 +0200
  [PATCH 4.5 38/88] mm: memcontrol: let v2 cgroups follow changes in system swappiness Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-09 10:00 +0200
  Re: [PATCH 4.5 00/88] 4.5.4-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-09 10:10 +0200
    Re: [PATCH 4.5 00/88] 4.5.4-stable review Kevin Hilman <khilman@baylibre.com> - 2016-05-11 11:50 +0200
  Re: [PATCH 4.5 00/88] 4.5.4-stable review Guenter Roeck <linux@roeck-us.net> - 2016-05-09 15:10 +0200
    Re: [PATCH 4.5 00/88] 4.5.4-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-10 09:10 +0200
  Re: [PATCH 4.5 00/88] 4.5.4-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2016-05-09 21:50 +0200
    Re: [PATCH 4.5 00/88] 4.5.4-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-10 09:10 +0200

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