Date: Fri, 22 Jan 2010 09:44:03 +0100
From: Heiko Carstens <heiko.carstens@de.ibm.com>
To: =?iso-8859-1?Q?Am=E9rico?= Wang <xiyou.wangcong@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>, linux-kernel@vger.kernel.org,
       Greg KH <gregkh@suse.de>
Subject: Re: [2.6.33-rc4] sysfs lockdep warnings on cpu hotplug
Message-ID: <20100122084402.GA6412@osiris.boeblingen.de.ibm.com>
References: <20100121155335.GB4471@osiris.boeblingen.de.ibm.com>
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On Fri, Jan 22, 2010 at 12:42:22PM +0800, Am?rico Wang wrote:
> On Thu, Jan 21, 2010 at 11:53 PM, Heiko Carstens
> <heiko.carstens@de.ibm.com> wrote:
> > Hi Eric,
> >
> > rumours are that you could be responsible for the following lockdep message:
> >
> > Happens on cpu hotplug on s390:
> >
> > =============================================
> > [ INFO: possible recursive locking detected ]
> > 2.6.33-rc4-00399-g24bc734 #1
> > ---------------------------------------------
> > bash/2576 is trying to acquire lock:
> > ?(s_active){++++.+}, at: [<000000000016c506>] sysfs_addrm_finish+0x5a/0xa8
> >
> > but task is already holding lock:
> > ?(s_active){++++.+}, at: [<000000000016c90c>] sysfs_get_active_two+0x64/0x88
> >
> > other info that might help us debug this:
> > 5 locks held by bash/2576:
> > ?#0: ?(&buffer->mutex){+.+.+.}, at: [<000000000016a912>] sysfs_write_file+0x4a/0x1a8
> > ?#1: ?(s_active){++++.+}, at: [<000000000016c90c>] sysfs_get_active_two+0x64/0x88
> > ?#2: ?(s_active){++++.+}, at: [<000000000016c8e6>] sysfs_get_active_two+0x3e/0x88
> > ?#3: ?(cpu_add_remove_lock){+.+.+.}, at: [<00000000003dd318>] cpu_down+0x44/0x88
> > ?#4: ?(cpu_hotplug.lock){+.+.+.}, at: [<0000000000056eee>] cpu_hotplug_begin+0x3e/0x74
> >
> 
> I think this is the same with the problem we met some days ago,
> 
> http://lkml.org/lkml/2010/1/10/282
> 
> does this patch from Erich help?

No, it doesn't help.
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