Re: [PATCH] cgroup/cpuset: Free sched domains on rebuild guard failure

[Waiman Long]

On 5/28/26 5:37 AM, Guopeng Zhang wrote:
> From: Guopeng Zhang <zhangguopeng@xxxxxxxxxx>
>
> generate_sched_domains() returns sched-domain masks and optional
> attributes that are normally handed to partition_sched_domains(), which
> takes ownership of them.
>
> rebuild_sched_domains_locked() has a WARN guard after
> generate_sched_domains() and before partition_sched_domains() to avoid
> passing offline CPUs into the scheduler domain rebuild path. If that
> guard fires, the function currently returns directly without freeing
> the generated doms and attr.
>
> Free the generated sched-domain masks and attributes before returning
> from the guard failure path.
>
> Signed-off-by: Guopeng Zhang <zhangguopeng@xxxxxxxxxx>
> ---
>   kernel/cgroup/cpuset.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index 51327333980a..c5fdebc205d8 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -1004,8 +1004,11 @@ void rebuild_sched_domains_locked(void)
>   	* prevent the panic.
>   	*/
>   	for (i = 0; doms && i < ndoms; i++) {
> -		if (WARN_ON_ONCE(!cpumask_subset(doms[i], cpu_active_mask)))
> +		if (WARN_ON_ONCE(!cpumask_subset(doms[i], cpu_active_mask))) {
> +			free_sched_domains(doms, ndoms);
> +			kfree(attr);
>   			return;
> +		}
>   	}
>   
>   	/* Have scheduler rebuild the domains */
This WARN_ON_ONCE() is mainly used to catch bug during code update. It 
shouldn't be triggered in normal use. Anyway, it is a nice-to-have fix.

Reviewed-by:  Waiman Long <longman@xxxxxxxxxx>