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charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Oct 29, 2020 at 10:10 AM Roman Gushchin wrote: > > On Thu, Oct 29, 2020 at 08:48:45AM -0700, Shakeel Butt wrote: > > On Tue, Oct 27, 2020 at 8:50 PM Muchun Song wrote: > > > > > > Consider the following memcg hierarchy. > > > > > > root > > > / \ > > > A B > > > > > > If we get the objcg of memcg A failed, > > > > Please fix the above statement. > > > > > the get_obj_cgroup_from_current > > > can return the wrong objcg for the root memcg. > > > > > > Fixes: bf4f059954dc ("mm: memcg/slab: obj_cgroup API") > > > Signed-off-by: Muchun Song > > > --- > > > changelog in v2: > > > 1. Do not use a comparison with the root_mem_cgroup > > > > > > mm/memcontrol.c | 1 + > > > 1 file changed, 1 insertion(+) > > > > > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > > index 1337775b04f3..8c8b4c3ed5a0 100644 > > > --- a/mm/memcontrol.c > > > +++ b/mm/memcontrol.c > > > @@ -2961,6 +2961,7 @@ __always_inline struct obj_cgroup *get_obj_cgroup_from_current(void) > > > objcg = rcu_dereference(memcg->objcg); > > > if (objcg && obj_cgroup_tryget(objcg)) > > > break; > > > + objcg = NULL; > > > > Roman, in your cleanup, are you planning to have objcg for root memcg as well? > > Yes. I'll just change the for loop to include the root_mem_cgroup. > Then do we really need this patch since it's not tagged for stable?