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Sender: Tejun Heo <htejun@gmail.com>
Date:   Wed, 27 Jul 2022 12:05:41 -1000
From:   Tejun Heo <tj@kernel.org>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Qais Yousef <qais.yousef@arm.com>,
        Xuewen Yan <xuewen.yan@unisoc.com>, rafael@kernel.org,
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        rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
        bristot@redhat.com, linux-kernel@vger.kernel.org,
        ke.wang@unisoc.com, xuewyan@foxmail.com, linux-pm@vger.kernel.org,
        Waiman Long <longman@redhat.com>
Subject: Re: [PATCH] sched/schedutil: Fix deadlock between cpuset and cpu
 hotplug when using schedutil
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Hello,

On Thu, Jul 28, 2022 at 12:01:35AM +0200, Peter Zijlstra wrote:
> On Tue, Jul 12, 2022 at 06:13:46AM -1000, Tejun Heo wrote:
> 
> > But now we're failing user-initiated operations randomly. I have a hard time
> > seeing that as an acceptable solution. 
> 
> There (sadly) is precedent for that; grep for "cpu_hotplug_disable".

Yeah, there's another one in cpu cgroup controller attach path. We should
get better at not doing these. Low frequency arbitrary failures are really
difficult to handle reliably downstream.

Thanks.

-- 
tejun