On 2/2/26 3:18 PM, Peter Zijlstra wrote:
On Mon, Feb 02, 2026 at 03:11:43PM -0500, Waiman Long wrote:@@ -1310,14 +1321,34 @@ static bool prstate_housekeeping_conflict(int prstate, struct cpumask *new_cpus) */ static void update_isolation_cpumasks(void) { - int ret; + static DECLARE_WORK(isolcpus_work, isolcpus_workfn);if (!isolated_cpus_updating)return;- ret = housekeeping_update(isolated_cpus);- WARN_ON_ONCE(ret < 0); + /* + * This function can be reached either directly from regular cpuset + * control file write or via CPU hotplug. In the latter case, it is + * the per-cpu kthread that calls cpuset_handle_hotplug() on behalf + * of the task that initiates CPU shutdown or bringup. + * + * To have better flexibility and prevent the possibility of deadlock + * when calling from CPU hotplug, we defer the housekeeping_update() + * call to after the current cpuset critical section has finished. + * This is done via workqueue. + */ + if (current->flags & PF_KTHREAD) {/* Serializes the static isolcpus_workfn. */ lockdep_assert_held(&cpuset_mutex);
Do we require synchronization between the the queue_work() call and the execution of the work function? I thought it is not needed, but I may be wrong.
Thanks, Longman
