| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.13 013/120] mm/memcg: iteration skip memcgs not yet fully initialized | Date | Tue, 11 Feb 2014 11:04:14 -0800 |
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3.13-stable review patch. If anyone has any objections, please let me know.
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From: Hugh Dickins <hughd@google.com>
commit d8ad30559715ce97afb7d1a93a12fd90e8fff312 upstream.
It is surprising that the mem_cgroup iterator can return memcgs which have not yet been fully initialized. By accident (or trial and error?) this appears not to present an actual problem; but it may be better to prevent such surprises, by skipping memcgs not yet online.
Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Tejun Heo <tj@kernel.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- mm/memcontrol.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)
--- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1100,10 +1100,8 @@ skip_node: * protected by css_get and the tree walk is rcu safe. */ if (next_css) { - struct mem_cgroup *mem = mem_cgroup_from_css(next_css); - - if (css_tryget(&mem->css)) - return mem; + if ((next_css->flags & CSS_ONLINE) && css_tryget(next_css)) + return mem_cgroup_from_css(next_css); else { prev_css = next_css; goto skip_node;
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