path: root/mm
diff options
authorHugh Dickins <hughd@google.com>2014-03-03 15:38:24 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-03-04 07:55:47 -0800
commitce48225fe3b1b0d1fc9fceb96ac3d8a879e45114 (patch)
tree9272e2e025f1bc01e0930c60e070b2a5d767e375 /mm
parent5f30fc94ca985974fd54de454c7a6070388443db (diff)
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')
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index ce7a8cc7b40..9d17310be47 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;