From: Vladimir Davydov <vdavydov@virtuozzo.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@vger.kernel.org, Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 1/3] mm: memcontrol: fix swap counter leak on swapout from offline cgroup
Date: Wed, 3 Aug 2016 15:34:45 +0300 [thread overview]
Message-ID: <20160803123445.GJ13263@esperanza> (raw)
In-Reply-To: <5336daa5c9a32e776067773d9da655d2dc126491.1470219853.git.vdavydov@virtuozzo.com>
On Wed, Aug 03, 2016 at 01:35:06PM +0300, Vladimir Davydov wrote:
> An offline memory cgroup might have anonymous memory or shmem left
> charged to it and no swap. Since only swap entries pin the id of an
> offline cgroup, such a cgroup will have no id and so an attempt to
> swapout its anon/shmem will not store memory cgroup info in the swap
> cgroup map. As a result, memcg->swap or memcg->memsw will never get
> uncharged from it and any of its ascendants.
>
> Fix this by always charging swapout to the first ancestor cgroup that
> hasn't released its id yet.
>
> [hannes@cmpxchg.org: add comment to mem_cgroup_swapout]
> Fixes: 73f576c04b941 ("mm: memcontrol: fix cgroup creation failure after many small jobs")
> Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
> Acked-by: Michal Hocko <mhocko@suse.com>
> Cc: <stable@vger.kernel.org> [3.19+]
Andrew, could you please fold this in?
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 1c0aa59fd333..8c8e68becee9 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4044,7 +4044,7 @@ static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg)
* The root cgroup cannot be destroyed, so it's refcount must
* always be >= 1.
*/
- if (memcg == root_mem_cgroup) {
+ if (WARN_ON_ONCE(memcg == root_mem_cgroup)) {
VM_BUG_ON(1);
break;
}
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prev parent reply other threads:[~2016-08-03 12:34 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-03 10:35 [PATCH v3 1/3] mm: memcontrol: fix swap counter leak on swapout from offline cgroup Vladimir Davydov
2016-08-03 10:35 ` [PATCH v3 2/3] mm: memcontrol: fix memcg id ref counter on swap charge move Vladimir Davydov
2016-08-03 10:35 ` [PATCH v3 3/3] mm: memcontrol: add sanity checks for memcg->id.ref on get/put Vladimir Davydov
2016-08-03 14:14 ` Johannes Weiner
2016-08-03 12:34 ` Vladimir Davydov [this message]
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