linux-kernel - Re: [PATCH v2 1/2] exit: change the release_task() paths to call flush

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Message-ID: <20250206165527.GD5209@redhat.com>
Date: Thu, 6 Feb 2025 17:55:28 +0100
From: Oleg Nesterov <oleg@...hat.com>
To: Frederic Weisbecker <frederic@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Mateusz Guzik <mjguzik@...il.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] exit: change the release_task() paths to call
 flush_sigqueue() lockless

On 02/06, Frederic Weisbecker wrote:
>
> > TODO:
> > 	- we can probably shift posix_cpu_timers_exit() as well
>
> Hmm, can't a timer be concurrently deleted between __exit_signal() set
> tsk->sighand = NULL and release sighand lock, and the actual call to
> posix_cpu_timer_exit() ? And then posix_cpu_timer_exit() calls timerqueue_del()
> on a node that don't exist anymore?

Can't answer right now, I will think about it when/if I will actually try to
make this change ;) This "TODO" note just tries to explain what else we could
try to do, and "probably" means that I am not sure yet. I can remove this spam
from the changelog, but I'd prefer to keep it as a reminder, at least for myself.

> Reviewed-by: Frederic Weisbecker <frederic@...nel.org>

Thanks Frederic!

Oleg.