From: Tejun Heo <[email protected]>
To: Pavel Begunkov <[email protected]>
Cc: [email protected], Jens Axboe <[email protected]>,
Oleg Nesterov <[email protected]>,
Andrew Morton <[email protected]>,
Christian Brauner <[email protected]>,
Tycho Andersen <[email protected]>,
Thomas Gleixner <[email protected]>,
[email protected], Julian Orth <[email protected]>,
Peter Zijlstra <[email protected]>
Subject: Re: [PATCH v2 2/2] kernel: rerun task_work while freezing in get_signal()
Date: Tue, 9 Jul 2024 14:57:24 -1000 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <149ff5a762997c723880751e8a4019907a0b6457.1720534425.git.asml.silence@gmail.com>
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: [email protected]
> Link: https://github.com/systemd/systemd/issues/33626
> Fixes: 12db8b690010c ("entry: Add support for TIF_NOTIFY_SIGNAL")
> Reported-by: Julian Orth <[email protected]>
> Signed-off-by: Pavel Begunkov <[email protected]>
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 <[email protected]>
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
next prev parent reply other threads:[~2024-07-10 0:57 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-09 14:27 [PATCH v2 0/2] fix task_work interation with freezing Pavel Begunkov
2024-07-09 14:27 ` [PATCH v2 1/2] io_uring/io-wq: limit retrying worker initialisation Pavel Begunkov
2024-07-09 14:27 ` [PATCH v2 2/2] kernel: rerun task_work while freezing in get_signal() Pavel Begunkov
2024-07-09 14:42 ` Oleg Nesterov
2024-07-10 0:57 ` Tejun Heo [this message]
2024-07-10 17:55 ` Pavel Begunkov
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