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

[Lukasz Luba]

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
> android.

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:
> https://lore.kernel.org/all/20220121101210.84926-1-zhangqiao22@xxxxxxxxxx/

Thanks for the pointer.