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From: Tejun Heo <tj@kernel.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Denys Vlasenko <vda.linux@googlemail.com>,
	mtk.manpages@gmail.com,
	Jan Kratochvil <jan.kratochvil@redhat.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] ptrace: do_wait(traced_leader_killed_by_mt_exec) can block forever
Date: Fri, 22 Jul 2011 10:44:30 +0200	[thread overview]
Message-ID: <20110722084430.GF2622@htj.dyndns.org> (raw)
In-Reply-To: <20110721180043.GB1319@redhat.com>

Hello,

On Thu, Jul 21, 2011 at 08:00:43PM +0200, Oleg Nesterov wrote:
> It is racy, exit_notify() does __wake_up_parent() too. But in the
> likely case it triggers the problem: de_thread() does release_task()
> and the old leader goes away without the notification, the tracer
> sleeps in do_wait() without children/tracees.
> 
> Change de_thread() to do __wake_up_parent(traced_leader->parent).
> Since it is already EXIT_DEAD we can do this without ptrace_unlink(),
> EXIT_DEAD threads do not exist from do_wait's pov.
> 
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>

Nice catch as always. :)

Acked-by: Tejun Heo <tj@kernel.org>

Thanks.

-- 
tejun

  reply	other threads:[~2011-07-22  8:44 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-07-21 11:09 [PATCH] man ptrace: add extended description of various ptrace quirks Denys Vlasenko
2011-07-21 16:51 ` Oleg Nesterov
2011-07-21 18:00   ` [PATCH 0/1] (Was: man ptrace: add extended description of various ptrace quirks) Oleg Nesterov
2011-07-21 18:00     ` [PATCH 1/1] ptrace: do_wait(traced_leader_killed_by_mt_exec) can block forever Oleg Nesterov
2011-07-22  8:44       ` Tejun Heo [this message]
2011-09-21  5:10   ` [PATCH] man ptrace: add extended description of various ptrace quirks Michael Kerrisk
2011-09-23  9:31     ` Denys Vlasenko
2011-09-25  6:10 ` Michael Kerrisk
2011-09-29 19:08 ` Michael Kerrisk
2011-09-30 14:14   ` Denys Vlasenko
2011-10-03  5:27     ` Michael Kerrisk
2012-02-13 22:02       ` Denys Vlasenko
2012-02-26 18:25         ` Michael Kerrisk
2012-02-26 18:42           ` Michael Kerrisk
2012-02-27  0:58             ` Denys Vlasenko
2012-03-05 17:33               ` Michael Kerrisk (man-pages)
2011-09-30 14:28   ` Denys Vlasenko
2011-10-03  5:35     ` Michael Kerrisk

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