* [PATCH v3] mm: memcg/slab: Fix return child memcg objcg for root memcg
@ 2020-10-29 16:44 ` Muchun Song
0 siblings, 0 replies; 2+ messages in thread
From: Muchun Song @ 2020-10-29 16:44 UTC (permalink / raw)
To: hannes, mhocko, vdavydov.dev, akpm, shakeelb, guro,
iamjoonsoo.kim, laoar.shao, chris, christian.brauner, peterz,
mingo, keescook, tglx, esyr, surenb, areber, elver
Cc: linux-kernel, cgroups, linux-mm, Muchun Song
Consider the following memcg hierarchy.
root
/ \
A B
If we failed to get the reference on objcg of memcg A, 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 <songmuchun@bytedance.com>
Acked-by: Roman Gushchin <guro@fb.com>
---
changelog in v3:
1. Fix commit grammar, thanks to Shakeel.
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;
}
rcu_read_unlock();
--
2.20.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [PATCH v3] mm: memcg/slab: Fix return child memcg objcg for root memcg
@ 2020-10-29 16:44 ` Muchun Song
0 siblings, 0 replies; 2+ messages in thread
From: Muchun Song @ 2020-10-29 16:44 UTC (permalink / raw)
To: hannes-druUgvl0LCNAfugRpC6u6w, mhocko-DgEjT+Ai2ygdnm+yROfE0A,
vdavydov.dev-Re5JQEeQqe8AvxtiuMwx3w,
akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b,
shakeelb-hpIqsD4AKlfQT0dZR+AlfA, guro-b10kYP2dOMg,
iamjoonsoo.kim-Hm3cg6mZ9cc, laoar.shao-Re5JQEeQqe8AvxtiuMwx3w,
chris-6Bi1550iOqEnzZ6mRAm98g,
christian.brauner-GeWIH/nMZzLQT0dZR+AlfA,
peterz-wEGCiKHe2LqWVfeAwA7xHQ, mingo-DgEjT+Ai2ygdnm+yROfE0A,
keescook-F7+t8E8rja9g9hUCZPvPmw, tglx-hfZtesqFncYOwBW4kG4KsQ,
esyr-H+wXaHxf7aLQT0dZR+AlfA, surenb-hpIqsD4AKlfQT0dZR+AlfA,
areber-H+wXaHxf7aLQT0dZR+AlfA, elver-hpIqsD4AKlfQT0dZR+AlfA
Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA,
cgroups-u79uwXL29TY76Z2rM5mHXA, linux-mm-Bw31MaZKKs3YtjvyW6yDsg,
Muchun Song
Consider the following memcg hierarchy.
root
/ \
A B
If we failed to get the reference on objcg of memcg A, 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 <songmuchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org>
Acked-by: Roman Gushchin <guro-b10kYP2dOMg@public.gmane.org>
---
changelog in v3:
1. Fix commit grammar, thanks to Shakeel.
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;
}
rcu_read_unlock();
--
2.20.1
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2020-10-29 16:44 [PATCH v3] mm: memcg/slab: Fix return child memcg objcg for root memcg Muchun Song
2020-10-29 16:44 ` Muchun Song
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