Re: [PATCH v2] mm: memcg/slab: Fix return child memcg objcg for root memcg
From: Shakeel Butt <hidden>
Date: 2020-10-29 15:49:01
Also in:
linux-mm, lkml
On Tue, Oct 27, 2020 at 8:50 PM Muchun Song [off-list ref] wrote:
Consider the following memcg hierarchy.
root
/ \
A B
If we get the objcg of memcg A failed,Please fix the above statement.
quoted hunk ↗ jump to hunk
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 <redacted> --- 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?
}
rcu_read_unlock();
--
2.20.1