Re: [PATCH] cgroup/cpuset: Replace use of system_unbound_wq with system_dfl_wq

[Waiman Long]

On 3/13/26 11:45 AM, Marco Crivellari wrote:
> This patch continues the effort to refactor workqueue APIs, which has begun
> with the changes introducing new workqueues and a new alloc_workqueue flag:
>
>     commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
>     commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")
>
> The point of the refactoring is to eventually alter the default behavior of
> workqueues to become unbound by default so that their workload placement is
> optimized by the scheduler.
>
> Before that to happen, workqueue users must be converted to the better named
> new workqueues with no intended behaviour changes:
>
>     system_wq -> system_percpu_wq
>     system_unbound_wq -> system_dfl_wq
>
> This way the old obsolete workqueues (system_wq, system_unbound_wq) can be
> removed in the future.
>
> Link: https://lore.kernel.org/all/20250221112003.1dSuoGyc@xxxxxxxxxxxxx/
> Suggested-by: Tejun Heo <tj@xxxxxxxxxx>
> Signed-off-by: Marco Crivellari <marco.crivellari@xxxxxxxx>
> ---
>   kernel/cgroup/cpuset.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index e200de7c60b6..b399f5d0a158 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -3937,7 +3937,7 @@ static void cpuset_handle_hotplug(void)
>   	 * item at all, this is not a problem.
>   	 */
>   	if (update_housekeeping || force_sd_rebuild)
> -		queue_work(system_unbound_wq, &hk_sd_work);
> +		queue_work(system_dfl_wq, &hk_sd_work);
>   
>   	free_tmpmasks(ptmp);
>   }

Thanks for the patch, but there is another patch that makes the
same change as part of a larger fix to the cpuset code. See commit
ca174c705db5 ("cgroup/cpuset: Call rebuild_sched_domains() directly in
hotplug")  in the cgroup tree.

Thanks,
Longman