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authorHugh Dickins <hughd@google.com>2015-02-12 23:00:28 (GMT)
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-13 02:54:11 (GMT)
commitff59909a077b3c51c168cb658601c6b63136a347 (patch)
treefdd8e3279f54c3458789592306b93bcb637cef8e /mm
parent9ab3b598d2dfbdb0153ffa7e4b1456bbff59a25d (diff)
mm: fix negative nr_isolated counts
The vmstat interfaces are good at hiding negative counts (at least when CONFIG_SMP); but if you peer behind the curtain, you find that nr_isolated_anon and nr_isolated_file soon go negative, and grow ever more negative: so they can absorb larger and larger numbers of isolated pages, yet still appear to be zero. I'm happy to avoid a congestion_wait() when too_many_isolated() myself; but I guess it's there for a good reason, in which case we ought to get too_many_isolated() working again. The imbalance comes from isolate_migratepages()'s ISOLATE_ABORT case: putback_movable_pages() decrements the NR_ISOLATED counts, but we forgot to call acct_isolated() to increment them. It is possible that the bug whcih this patch fixes could cause OOM kills when the system still has a lot of reclaimable page cache. Fixes: edc2ca612496 ("mm, compaction: move pageblock checks up from isolate_migratepages_range()") Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: <stable@vger.kernel.org> [3.18+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/compaction.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/mm/compaction.c b/mm/compaction.c
index 782772d..d50d6de 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1103,8 +1103,10 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
low_pfn = isolate_migratepages_block(cc, low_pfn, end_pfn,
isolate_mode);
- if (!low_pfn || cc->contended)
+ if (!low_pfn || cc->contended) {
+ acct_isolated(zone, cc);
return ISOLATE_ABORT;
+ }
/*
* Either we isolated something and proceed with migration. Or

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