On Tue, Jul 09, 2024 at 03:27:19PM +0100, Pavel Begunkov wrote: > io_uring can asynchronously add a task_work while the task is getting > freezed. TIF_NOTIFY_SIGNAL will prevent the task from sleeping in > do_freezer_trap(), and since the get_signal()'s relock loop doesn't > retry task_work, the task will spin there not being able to sleep > until the freezing is cancelled / the task is killed / etc. > > Cc: stable@xxxxxxxxxxxxxxx > Link: https://github.com/systemd/systemd/issues/33626 > Fixes: 12db8b690010c ("entry: Add support for TIF_NOTIFY_SIGNAL") > Reported-by: Julian Orth <ju.orth@xxxxxxxxx> > Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx> I haven't looked at the signal code for too long to be all that useful but the problem described and the patch does make sense to me. FWIW, Acked-by: Tejun Heo <tj@xxxxxxxxxx> Maybe note that this is structured specifically to ease backport and we need further cleanups? It's not great that this is special cased in do_freezer_trap() instead of being integrated into the outer loop. Thanks. -- tejun
