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Sender: Tejun Heo <htejun@gmail.com>
Date:   Tue, 6 Sep 2022 08:30:41 -1000
From:   Tejun Heo <tj@kernel.org>
To:     Jing-Ting Wu <jing-ting.wu@mediatek.com>
Cc:     Mukesh Ojha <quic_mojha@quicinc.com>,
        Peter Zijlstra <peterz@infradead.org>,
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        wenju.xu@mediatek.com, Waiman Long <longman@redhat.com>
Subject: Re: BUG: HANG_DETECT waiting for migration_cpu_stop() complete
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Hello,

(cc'ing Waiman in case he has a better idea)

On Mon, Sep 05, 2022 at 04:22:29PM +0800, Jing-Ting Wu wrote:
> https://lore.kernel.org/lkml/YvrWaml3F+x9Dk+T@slm.duckdns.org/ is for
> fix cgroup_threadgroup_rwsem <-> cpus_read_lock() deadlock.
> But this issue is cgroup_threadgroup_rwsem <-> cpuset_rwsem deadlock.

If I'm understanding what you're writing correctly, this isn't a deadlock.
The cpuset_hotplug_workfn simply isn't being woken up while holding
cpuset_rwsem and others are just waiting for that lock to be released.

Thanks.

-- 
tejun