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Subject: Re: [PATCH v4 11/19] sched/core: Make migrate disable and CPU
 hotplug cooperative
From:   Qian Cai <qcai@redhat.com>
To:     Valentin Schneider <valentin.schneider@arm.com>
Cc:     Peter Zijlstra <peterz@infradead.org>, tglx@linutronix.de,
        mingo@kernel.org, linux-kernel@vger.kernel.org,
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        mgorman@suse.de, bristot@redhat.com, vincent.donnefort@arm.com,
        tj@kernel.org, ouwen210@hotmail.com
Date:   Sat, 05 Dec 2020 20:17:18 -0500
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On Sat, 2020-12-05 at 18:37 +0000, Valentin Schneider wrote:
> From there I see:
> 
> [20798.166987][  T650] CPU127 nr_running=2
> [20798.171185][  T650]  p=migration/127
> [20798.175161][  T650]  p=kworker/127:1
> 
> so this might be another workqueue hurdle. This should be prevented by:
> 
>   06249738a41a ("workqueue: Manually break affinity on hotplug")

Well, since it was reproduced on the latest linux-next which has already
included the commit.

> Note that much earlier in your log, you have a softlockup on CPU127:
> 
> [   74.278367][  C127] watchdog: BUG: soft lockup - CPU#127 stuck for 23s!
> [swapper/0:1]

That's something separate. It was there all the time.

https://lore.kernel.org/linux-acpi/20200929183444.25079-1-cai@redhat.com/