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authorHugh Dickins <hughd@google.com>2016-05-05 16:22:15 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-05 17:38:53 -0700
commit14af4a5e9b26ad251f81c174e8a43f3e179434a5 (patch)
tree38edf026215bd254a7cbe13bb47aaf23c641f019
parentbc22af74f271ef76b2e6f72f3941f91f0da3f5f8 (diff)
mm, cma: prevent nr_isolated_* counters from going negative
/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> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/compaction.c10
1 files changed, 1 insertions, 9 deletions
diff --git a/mm/compaction.c b/mm/compaction.c
index ccf97b02b85f..4a0d4b8ccde8 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -852,16 +852,8 @@ isolate_migratepages_range(struct compact_control *cc, unsigned long start_pfn,
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;