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| author | Hugh Dickins <hughd@google.com> | 2014-03-03 15:38:24 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-03-04 07:55:47 -0800 |
| commit | ce48225fe3b1b0d1fc9fceb96ac3d8a879e45114 (patch) | |
| tree | 9272e2e025f1bc01e0930c60e070b2a5d767e375 /mm/memcontrol.c | |
| parent | 5f30fc94ca985974fd54de454c7a6070388443db (diff) | |
| download | lwn-ce48225fe3b1b0d1fc9fceb96ac3d8a879e45114.tar.gz lwn-ce48225fe3b1b0d1fc9fceb96ac3d8a879e45114.zip | |
memcg: fix endless loop in __mem_cgroup_iter_next()
Commit 0eef615665ed ("memcg: fix css reference leak and endless loop in
mem_cgroup_iter") got the interaction with the commit a few before it
d8ad30559715 ("mm/memcg: iteration skip memcgs not yet fully
initialized") slightly wrong, and we didn't notice at the time.
It's elusive, and harder to get than the original, but for a couple of
days before rc1, I several times saw a endless loop similar to that
supposedly being fixed.
This time it was a tighter loop in __mem_cgroup_iter_next(): because we
can get here when our root has already been offlined, and the ordering
of conditions was such that we then just cycled around forever.
Fixes: 0eef615665ed ("memcg: fix css reference leak and endless loop in mem_cgroup_iter").
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Greg Thelen <gthelen@google.com>
Cc: <stable@vger.kernel.org> [3.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memcontrol.c')
| -rw-r--r-- | mm/memcontrol.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index ce7a8cc7b404..9d17310be470 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1127,8 +1127,8 @@ skip_node: * skipping css reference should be safe. */ if (next_css) { - if ((next_css->flags & CSS_ONLINE) && - (next_css == &root->css || css_tryget(next_css))) + if ((next_css == &root->css) || + ((next_css->flags & CSS_ONLINE) && css_tryget(next_css))) return mem_cgroup_from_css(next_css); prev_css = next_css; |