4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Hugh Dickins <hu...@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()")
[vba...@suse.cz: expanded the changelog]
Signed-off-by: Hugh Dickins <hu...@google.com>
Signed-off-by: Vlastimil Babka <vba...@suse.cz>
Acked-by: Joonsoo Kim <iamjoonsoo....@lge.com>
Cc: Michal Hocko <mho...@kernel.org>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gre...@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;
