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

[Xuewen Yan]

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
android.

And I see the cpu_hotplug_lock is added by the patch:
https://lore.kernel.org/all/20220121101210.84926-1-zhangqiao22@xxxxxxxxxx/

Thanks!

>
> Regards,
> Lukasz