Re: [PATCH v10 3/9] cpuset: Simulate auto-off of sched.domain_root at cgroup removal

[Peter Zijlstra]

On Mon, Jun 18, 2018 at 12:14:02PM +0800, Waiman Long wrote:
> @@ -1058,7 +1060,12 @@ static int update_reserved_cpumask(struct cpuset *cpuset,
>  	 * Check if any CPUs in addmask or delmask are in the effective_cpus
>  	 * of a sibling cpuset. The implied cpu_exclusive of a scheduling
>  	 * domain root will ensure there are no overlap in cpus_allowed.
> +	 *
> +	 * This check is skipped if the cpuset is dying.

Comments that state what the code does are mostly useless; please
explain _why_ if anything.

>  	 */
> +	if (dying)
> +		goto updated_reserved_cpus;
> +
>  	rcu_read_lock();
>  	cpuset_for_each_child(sibling, pos_css, parent) {
>  		if ((sibling == cpuset) || !(sibling->css.flags & CSS_ONLINE))