From: Marco Crivellari Date: Fri, 5 Sep 2025 08:54:35 +0000 (+0200) Subject: cgroup: replace use of system_wq with system_percpu_wq X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d6256771d106172cf7b6e6bfc49f5a1f2ff8c76c;p=thirdparty%2Fkernel%2Fstable.git cgroup: replace use of system_wq with system_percpu_wq Currently if a user enqueue a work item using schedule_delayed_work() the used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to schedule_work() that is using system_wq and queue_work(), that makes use again of WORK_CPU_UNBOUND. This lack of consistentcy cannot be addressed without refactoring the API. system_wq is a per-CPU worqueue, yet nothing in its name tells about that CPU affinity constraint, which is very often not required by users. Make it clear by adding a system_percpu_wq. queue_work() / queue_delayed_work() mod_delayed_work() will now use the new per-cpu wq: whether the user still stick on the old name a warn will be printed along a wq redirect to the new one. This patch add the new system_percpu_wq except for mm, fs and net subsystem, whom are handled in separated patches. The old wq will be kept for a few release cylces. Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari Signed-off-by: Tejun Heo --- diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index e7acfaa495179..06a9b4a17d417 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -124,7 +124,7 @@ DEFINE_PERCPU_RWSEM(cgroup_threadgroup_rwsem); /* * cgroup destruction makes heavy use of work items and there can be a lot * of concurrent destructions. Use a separate workqueue so that cgroup - * destruction work items don't end up filling up max_active of system_wq + * destruction work items don't end up filling up max_active of system_percpu_wq * which may lead to deadlock. */ static struct workqueue_struct *cgroup_destroy_wq;