From: Vladimir Davydov <vdavydov.dev@gmail.com>
To: Shakeel Butt <shakeelb@google.com>
Cc: Michal Hocko <mhocko@kernel.org>,
Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
Greg Thelen <gthelen@google.com>,
Johannes Weiner <hannes@cmpxchg.org>, Tejun Heo <tj@kernel.org>,
Linux MM <linux-mm@kvack.org>, Cgroups <cgroups@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4] mm: fix race between kmem_cache destroy, create and deactivate
Date: Tue, 12 Jun 2018 11:33:14 +0300 [thread overview]
Message-ID: <20180612083314.ftl4hmn4xwnehjdx@esperanza> (raw)
In-Reply-To: <20180611192951.195727-1-shakeelb@google.com>
On Mon, Jun 11, 2018 at 12:29:51PM -0700, Shakeel Butt wrote:
> The memcg kmem cache creation and deactivation (SLUB only) is
> asynchronous. If a root kmem cache is destroyed whose memcg cache is in
> the process of creation or deactivation, the kernel may crash.
>
> Example of one such crash:
> general protection fault: 0000 [#1] SMP PTI
> CPU: 1 PID: 1721 Comm: kworker/14:1 Not tainted 4.17.0-smp
> ...
> Workqueue: memcg_kmem_cache kmemcg_deactivate_workfn
> RIP: 0010:has_cpu_slab
> ...
> Call Trace:
> ? on_each_cpu_cond
> __kmem_cache_shrink
> kmemcg_cache_deact_after_rcu
> kmemcg_deactivate_workfn
> process_one_work
> worker_thread
> kthread
> ret_from_fork+0x35/0x40
>
> To fix this race, on root kmem cache destruction, mark the cache as
> dying and flush the workqueue used for memcg kmem cache creation and
> deactivation. SLUB's memcg kmem cache deactivation also includes RCU
> callback and thus make sure all previous registered RCU callbacks
> have completed as well.
>
> Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Thanks.
prev parent reply other threads:[~2018-06-12 8:33 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-11 19:29 Shakeel Butt
2018-06-12 8:33 ` Vladimir Davydov [this message]
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