Re: [PATCH 06/17] cgroup/cpuset: Validate type changes against owned CPUs

[Waiman Long <longman@redhat.com>]

On 8/20/26 8:41 AM, Guopeng Zhang wrote:
> From: Guopeng Zhang <zhangguopeng@kylinos.cn>
>
> update_prstate() checks effective_xcpus against the housekeeping masks
> before changing a partition between root and isolated. effective_xcpus
> also contains CPUs granted to valid child partitions, although those
> CPUs are not affected by the parent's type change. A child-owned CPU can
> therefore reject an otherwise valid change.
>
> Run the nohz_full and boot-domain housekeeping checks against the mask
> of CPUs owned by the partition instead.
>
> Fixes: 103b08709e8a ("cgroup/cpuset: Fail if isolated and nohz_full don't leave any housekeeping")
> Fixes: b1034a690129 ("cgroup/cpuset: Ensure domain isolated CPUs stay in root or isolated partition")
> Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
> ---
>   kernel/cgroup/cpuset.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index 468272baadb2..853942c1afeb 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -3019,8 +3019,8 @@ static int update_prstate(struct cpuset *cs, int new_prs)
>   		 */
>   		compute_partition_owned_cpumask(cs, tmpmask.new_cpus);
>   		if (((new_prs == PRS_ISOLATED) &&
> -		     !isolated_cpus_can_update(cs->effective_xcpus, NULL)) ||
> -		    prstate_housekeeping_conflict(new_prs, cs->effective_xcpus))
> +		     !isolated_cpus_can_update(tmpmask.new_cpus, NULL)) ||
> +		    prstate_housekeeping_conflict(new_prs, tmpmask.new_cpus))
>   			err = PERR_HKEEPING;
>   		else
>   			isolcpus_updated = true;

This can be merged into patch 4. This is basically the same change as in 
patch 4.

Cheers,
Longman