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From: Cong Wang <amwang@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: linux-kernel@vger.kernel.org, Tejun Heo <tj@kernel.org>,
	Greg Kroah-Hartman <gregkh@suse.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Miles Lane <miles.lane@gmail.com>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Larry Finger <Larry.Finger@lwfinger.net>,
	akpm@linux-foundation.org
Subject: Re: [Patch v2] sysfs: add lockdep class support to s_active
Date: Fri, 05 Feb 2010 17:37:00 +0800	[thread overview]
Message-ID: <4B6BE6BC.4070506@redhat.com> (raw)
In-Reply-To: <m1iqachx8k.fsf@fess.ebiederm.org>

Eric W. Biederman wrote:
> Amerigo Wang <amwang@redhat.com> writes:
> 
>> Recently we met a lockdep warning from sysfs during s2ram or cpu hotplug.
>> As reported by several people, it is something like:
> 
> The interesting case is the cpu hotplug is actually a problem.  It isn't
> useful to get a complaint about the non-problems code paths triggered
> by pm.  However my earlier review spotted a real deadlock case.  Where
> in one of the sysfs attributes we iterate over the list of online cpus
> and that appeared to an attribute that removing a cpu would remove
> from sysfs...
> 

You are referring this one:
http://marc.info/?l=linux-kernel&m=126474021428905&w=2
?

Hmm, yeah, I missed that the lock it is holding is not s_active, thus so
not be the case we are trying to fix here.

Thanks for pointing this out.

  reply	other threads:[~2010-02-05  9:34 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-02-05  6:42 [Patch v2] sysfs: add lockdep class support to s_active Amerigo Wang
2010-02-05  7:09 ` Xiaotian Feng
2010-02-05  7:27   ` Cong Wang
2010-02-05  9:39   ` Eric W. Biederman
2010-02-05  9:48     ` Cong Wang
2010-02-05 10:00     ` Xiaotian Feng
2010-02-08  3:12       ` Cong Wang
2010-02-05  8:57 ` Eric W. Biederman
2010-02-05  9:29   ` Cong Wang
2010-02-05  9:01 ` Eric W. Biederman
2010-02-05  9:37   ` Cong Wang [this message]
2010-02-05  9:59     ` Eric W. Biederman

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