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

[Tejun Heo]

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.

-- 
tejun