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From: Srivatsa Vaddagiri <>
To: Heiko Carstens <>
Cc: Benjamin Gilbert <>,, Ingo Molnar <>,
	Gautham shenoy <>, Andrew Morton <>
Subject: Re: Failure to release lock after CPU hot-unplug canceled
Date: Tue, 9 Jan 2007 17:57:40 +0530	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

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

Looks like they are in latest mm tree. Perhaps the testcase should be
retried against latest mm.


  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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