From: Andrew Morton <akpm@osdl.org>
To: Hannes Reinecke <Hannes.Reinecke@suse.de>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Dumb question: BKL on reboot ?
Date: Wed, 20 Aug 2003 11:29:18 -0700 [thread overview]
Message-ID: <20030820112918.0f7ce4fe.akpm@osdl.org> (raw)
In-Reply-To: <3F434BD1.9050704@suse.de>
Hannes Reinecke <Hannes.Reinecke@suse.de> wrote:
>
> Hiya,
>
> I've got a dumb question: Why is the BKL held on entering sys_reboot()
> in kernel/sys.c:405 ?
Probably for no good reason.
> It is getting especially interesting on SMP, when one cpu is entering
> sys_reboot, acquires the BKL and then waits (via machine_restart) for
> all other cpus to shut down. If any of the other cpus is executing a
> task which also needs the BKL, we have a nice deadlock.
> We've seen this here on 2-way s390, where the other cpu tried to execute
> kupdated() (what did it try that for? Anyway...), which of course
> resulted in a deadlock.
I guess that dropping the BKL around the machine_restart() call would be an
appropriate 2.4 fix.
Where exactly does the rebooting CPU get stuck in machine_restart()? If
someone has done lock_kernel() with local interrupts disabled then yes,
it'll deadlock. But that's unlikely? Confused.
next prev parent reply other threads:[~2003-08-20 18:27 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-08-20 10:22 Dumb question: BKL on reboot ? Hannes Reinecke
2003-08-20 18:29 ` Andrew Morton [this message]
2003-08-20 18:35 ` David S. Miller
2003-08-20 20:23 ` Dave Hansen
2003-08-21 8:05 ` Hannes Reinecke
2003-08-21 15:41 ` Andrea Arcangeli
2003-08-21 15:55 ` Hannes Reinecke
2003-08-21 16:39 ` Andrea Arcangeli
2003-08-21 16:58 ` Andrea Arcangeli
2003-08-22 6:39 ` Hannes Reinecke
2003-08-22 13:57 ` Andrea Arcangeli
2003-08-24 21:43 ` Andrea Arcangeli
2003-08-21 15:33 ` Andrea Arcangeli
[not found] <3F434BD1.9050704@suse.de.suse.lists.linux.kernel>
2003-08-20 10:49 ` Andi Kleen
2003-08-20 11:51 ` Hannes Reinecke
2003-08-20 12:03 ` Andi Kleen
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