Re: [PATCH v2] cgroup/cpuset: remove kernfs active break

[Waiman Long]

On 1/8/25 3:00 PM, Tejun Heo wrote:
> Hello,
>
> On Wed, Jan 08, 2025 at 02:50:19PM -0500, Waiman Long wrote:
> ...
> > It is not the strict ordering that I am worrying about. It is all about the
> > possibility of hitting some race conditions.
> >
> > I am thinking of a scenario where a cpuset loses all its CPUs in hotunplug
> > and then restored by adding other CPUs. There is chance that the css will be
> > operated on concurrently by the auto-transfer task and another task moving
> > new task to the css. I am not sure if that will be a problem or not. Anyway,
> > it is very rare that we will be in such a situation.
> Hmm... I might be missing something but cgroup_transfer_tasks() is fully
> synchronized against migrations. I don't see anything dangerous there.
>
> Thanks.

I probably misread some of the code. Then it is not an issue anymore.

Thanks,
Longman