From: Srivatsa Vaddagiri <vatsa@in.ibm.com>
To: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Benjamin Gilbert <bgilbert@cs.cmu.edu>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
Gautham shenoy <ego@in.ibm.com>, Andrew Morton <akpm@osdl.org>
Subject: Re: Failure to release lock after CPU hot-unplug canceled
Date: Tue, 9 Jan 2007 17:57:40 +0530 [thread overview]
Message-ID: <20070109122740.GC22080@in.ibm.com> (raw)
In-Reply-To: <20070109121738.GC9563@osiris.boeblingen.de.ibm.com>
On Tue, Jan 09, 2007 at 01:17:38PM +0100, Heiko Carstens wrote:
> missing in kernel cpu.c in _cpu_down() in case CPU_DOWN_PREPARE
> returned with NOTIFY_BAD. However... this reveals that there is just a
> more fundamental problem.
>
> The workqueue code grabs a lock on CPU_[UP|DOWN]_PREPARE and releases it
> again on CPU_DOWN_FAILED/CPU_UP_CANCELED. If something in the callchain
> returns NOTIFY_BAD the rest of the entries in the callchain won't be
> called anymore. But DOWN_FAILED/UP_CANCELED will be called for every
> entry.
> So we might even end up with a mutex_unlock(&workqueue_mutex) even if
> mutex_lock(&workqueue_mutex) hasn't been called...
This is a known problem. Gautham had sent out patches to address them
http://lkml.org/lkml/2006/11/14/93
Looks like they are in latest mm tree. Perhaps the testcase should be
retried against latest mm.
--
Regards,
vatsa
next prev parent reply other threads:[~2007-01-09 12:27 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-08 17:07 Failure to release lock after CPU hot-unplug canceled Benjamin Gilbert
2007-01-09 12:17 ` Heiko Carstens
2007-01-09 12:27 ` Srivatsa Vaddagiri [this message]
2007-01-09 15:03 ` Heiko Carstens
2007-01-09 15:05 ` [patch -mm] call cpu_chain with CPU_DOWN_FAILED if CPU_DOWN_PREPARE failed Heiko Carstens
2007-01-09 15:06 ` [patch -mm] slab: use CPU_LOCK_[ACQUIRE|RELEASE] Heiko Carstens
2007-01-10 18:20 ` Christoph Lameter
2007-01-11 2:30 ` Srivatsa Vaddagiri
2007-01-09 16:34 ` Failure to release lock after CPU hot-unplug canceled Benjamin Gilbert
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