Re: [PATCH] sched/schedutil: Fix deadlock between cpuset and cpu hotplug when using schedutil

From: Lukasz Luba
Date: Mon Jul 11 2022 - 03:50:48 EST

On 7/11/22 08:43, Xuewen Yan wrote:
On Mon, Jul 11, 2022 at 3:32 PM Lukasz Luba <lukasz.luba@xxxxxxx> wrote:

Hi Xuewen,

On 7/11/22 08:21, Xuewen Yan wrote:
Hi all

This deadlock is inevitable, any comment?

Could you tell me how to reproduce this?
Is there a need of special cgroup setup?

This deadlock occurs when we run the monkey test on an Android phone,
at the same time, randomly put online or offline a cpu core.
Indeed the thread-A which get the cgroup_threadgroup_rwsem and waiting
for the cpu_hotplug_lock is the thread whose name is "OomAdjuster" in

Thanks, let me have a look. We have some hotplug stress tests in our
EAS mainline integration tests, which haven't triggered this issue.
I'll try to trigger this on mainline kernel.

And I see the cpu_hotplug_lock is added by the patch:

Thanks for the pointer.