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| author | Hugh Dickins <hughd@google.com> | 2015-02-12 15:00:28 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-02-12 18:54:11 -0800 |
| commit | ff59909a077b3c51c168cb658601c6b63136a347 (patch) | |
| tree | fdd8e3279f54c3458789592306b93bcb637cef8e | |
| parent | 9ab3b598d2dfbdb0153ffa7e4b1456bbff59a25d (diff) | |
| download | op-kernel-dev-ff59909a077b3c51c168cb658601c6b63136a347.zip op-kernel-dev-ff59909a077b3c51c168cb658601c6b63136a347.tar.gz | |
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>
| -rw-r--r-- | mm/compaction.c | 4 |
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 |
