Re: Deadlock due to "cpuset: Make cpuset hotplug synchronous"

[Tejun Heo <tj@kernel.org>]

On Thu, Mar 26, 2020 at 10:15:32AM +0000, Qais Yousef wrote:
> On 03/25/20 15:19, Tejun Heo wrote:
> > On Wed, Mar 25, 2020 at 03:16:56PM -0400, Qian Cai wrote:
> > > The linux-next commit a49e4629b5ed (“cpuset: Make cpuset hotplug synchronous”)
> > > introduced real deadlocks with CPU hotplug as showed in the lockdep splat, since it is
> > > now making a relation from cpu_hotplug_lock —> cgroup_mutex.
> > 
> > Prateek, can you please take a look? Given that the merge window is just around
> > the corner, we might have to revert and retry later if it can't be resolved
> > quickly.
> 
> I've ran cpuset_hotplug and cpuhotplug LTP tests using next-20200325 but
> couldn't reproduce it.
> 
> Hopefully that can be fixed, but if you had to revert it, do you mind picking
> this instead to fix the LTP issue I encountered before?
> 
> 	https://lore.kernel.org/lkml/20200211141554.24181-1-qais.yousef@arm.com/

So, I'd rather not, for now anyway. It isn't a real problem and I don't wanna
add a wait vector there.

Thanks.

-- 
tejun