Messages in this thread | | | Date | Mon, 11 Jun 2012 09:34:47 +0200 | From | Michal Hocko <> | Subject | Re: [PATCH] memcg: fix use_hierarchy css_is_ancestor oops regression |
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On Sun 10-06-12 11:54:47, Hugh Dickins wrote: > If use_hierarchy is set, reclaim testing soon oopses in css_is_ancestor() > called from __mem_cgroup_same_or_subtree() called from page_referenced(): > when processes are exiting, it's easy for mm_match_cgroup() to pass along > a NULL memcg coming from a NULL mm->owner. > > Check for that in __mem_cgroup_same_or_subtree(). Return true or false? > False because we cannot know if it was in the hierarchy, but also false > because it's better not to count a reference from an exiting process. > > Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Thanks
> --- > This a 3.5-rc issue: not needed for stable. > > mm/memcontrol.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- 3.5-rc2/mm/memcontrol.c 2012-05-30 08:17:19.400008280 -0700 > +++ linux/mm/memcontrol.c 2012-06-10 08:39:39.618182396 -0700 > @@ -1148,7 +1148,7 @@ bool __mem_cgroup_same_or_subtree(const > { > if (root_memcg == memcg) > return true; > - if (!root_memcg->use_hierarchy) > + if (!root_memcg->use_hierarchy || !memcg) > return false; > return css_is_ancestor(&memcg->css, &root_memcg->css); > }
-- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic
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