On 7/10/24 01:57, Tejun Heo wrote:
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
I'll add a couple of words
do_freezer_trap() instead of being integrated into the outer loop.
v1 had it in the common loop, but might actually be good it's
limited to freezing, need more digging.
--
Pavel Begunkov
