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Date: Fri, 22 Jan 2010 12:42:22 +0800
Message-ID: <2375c9f91001212042y6dceee1bl54bc564dea54f11b@mail.gmail.com>
Subject: Re: [2.6.33-rc4] sysfs lockdep warnings on cpu hotplug
From: =?UTF-8?Q?Am=C3=A9rico_Wang?= <xiyou.wangcong@gmail.com>
To: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>, linux-kernel@vger.kernel.org,
       Greg KH <gregkh@suse.de>
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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?

Thanks.