From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tejun Heo <tj@kernel.org>
Subject: Re: [PATCH v4 3/7] cgroup: protect cgroup->nr_(dying_)descendants by
 css_set_lock
Date: Mon, 3 Dec 2018 08:17:06 -0800
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To: Roman Gushchin <guroan@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>, Dan Carpenter <dan.carpenter@oracle.com>, Mike Rapoport <rppt@linux.vnet.ibm.com>, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, Roman Gushchin <guro@fb.com>

On Fri, Nov 30, 2018 at 03:47:41PM -0800, Roman Gushchin wrote:
> +	 * nr_descendants and nr_dying_descendants are protected
> +	 * by cgroup_mutex and css_set_lock.

Can you be a bit more specific - hold both for writes, either for
reads.

Thanks.

-- 
tejun