On Wed, Feb 1, 2023 at 8:56 PM Eric Biggers ebiggers@kernel.org wrote:
On Wed, Feb 01, 2023 at 07:00:23PM -0800, Munehisa Kamata wrote:
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c index 8ac8b81bfee6..6e66c15f6450 100644 --- a/kernel/sched/psi.c +++ b/kernel/sched/psi.c @@ -1343,10 +1343,11 @@ void psi_trigger_destroy(struct psi_trigger *t)
group = t->group; /*
* Wakeup waiters to stop polling. Can happen if cgroup is deleted* from under a polling process.
* Wakeup waiters to stop polling and clear the queue to prevent it from* being accessed later. Can happen if cgroup is deleted from under a* polling process otherwise. */
wake_up_interruptible(&t->event_wait);
wake_up_pollfree(&t->event_wait); mutex_lock(&group->trigger_lock);wake_up_pollfree() should only be used in extremely rare cases. Why can't the lifetime of the waitqueue be fixed instead?
waitqueue lifetime in this case is linked to cgroup_file_release(), which seems appropriate to me here. Unfortunately cgroup_file_release() is not directly linked to the file's lifetime. For more details see: https://lore.kernel.org/all/CAJuCfpFZ3B4530TgsSHqp5F_gwfrDujwRYewKReJru==MdE... . So, if we want to fix the lifetime of the waitqueue, we would have to tie cgroup_file_release() to the fput() somehow. IOW, the fix would have to be done at the cgroups or higher (kernfs?) layer. Thanks, Suren.
- Eric