From: Marco Crivellari Date: Fri, 5 Sep 2025 09:10:40 +0000 (+0200) Subject: tracing: replace use of system_wq with system_percpu_wq X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=70bd70c303ad4a00b299cb2468bc6475ff90b5b1;p=users%2Fhch%2Fmisc.git tracing: 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. Cc: Lai Jiangshan Cc: Frederic Weisbecker Cc: Sebastian Andrzej Siewior Cc: Michal Hocko Cc: Masami Hiramatsu Link: https://lore.kernel.org/20250905091040.109772-2-marco.crivellari@suse.com Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari Signed-off-by: Steven Rostedt (Google) --- diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c index af42aaa3d172..3169182229ad 100644 --- a/kernel/trace/trace_events_user.c +++ b/kernel/trace/trace_events_user.c @@ -835,7 +835,7 @@ void user_event_mm_remove(struct task_struct *t) * so we use a work queue after call_rcu() to run within. */ INIT_RCU_WORK(&mm->put_rwork, delayed_user_event_mm_put); - queue_rcu_work(system_wq, &mm->put_rwork); + queue_rcu_work(system_percpu_wq, &mm->put_rwork); } void user_event_mm_dup(struct task_struct *t, struct user_event_mm *old_mm)