Re: [PATCH v4 3/3] cgroup/cpuset: Keep user set cpus affinity

[Tejun Heo]

Hello,

On Tue, Aug 16, 2022 at 01:38:17PM -0400, Waiman Long wrote:
> Yes, a race like this is possible. To completely eliminate the race may
> require taking task_rq_lock() and then calling
> __set_cpus_allowed_ptr_locked() which is internal to kernel/sched/core.c.
> 
> Alternatively, we can check user_cpus_ptr again after the scond
> set_cpus_allowed_ptr() and retry it with the other path if set. That will
> probably address your concern. Please let me know if you are OK with that.

I think this would look better if structured the other way around - make the
scheduler side call out to cpuset to query the current restrictions and
apply it atomically.

Thanks.

-- 
tejun