Re: [PATCH v2 2/2] kernel: rerun task_work while freezing in get_signal()

[Pavel Begunkov]

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