Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Wed, 25 Mar 2020 15:19:22 -0400
From:   Tejun Heo <tj@kernel.org>
To:     Qian Cai <cai@lca.pw>
Cc:     Prateek Sood <prsood@codeaurora.org>,
        Li Zefan <lizefan@huawei.com>, cgroups@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <peterz@infradead.org>
Subject: Re: Deadlock due to "cpuset: Make cpuset hotplug synchronous"
Message-ID: <20200325191922.GM162390@mtj.duckdns.org>
References: <F0388D99-84D7-453B-9B6B-EEFF0E7BE4CC@lca.pw>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <F0388D99-84D7-453B-9B6B-EEFF0E7BE4CC@lca.pw>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, Mar 25, 2020 at 03:16:56PM -0400, Qian Cai wrote:
> The linux-next commit a49e4629b5ed (“cpuset: Make cpuset hotplug synchronous”)
> introduced real deadlocks with CPU hotplug as showed in the lockdep splat, since it is
> now making a relation from cpu_hotplug_lock —> cgroup_mutex.

Prateek, can you please take a look? Given that the merge window is just around
the corner, we might have to revert and retry later if it can't be resolved
quickly.

Thanks.

-- 
tejun