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Date: Tue, 22 May 2012 21:17:01 -0400
From: Dave Jones <davej@redhat.com>
To: Ming Lei <tom.leiming@gmail.com>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>,
        Alan Cox <alan@linux.intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: 3.4+ tty lockdep trace
Message-ID: <20120523011701.GA15255@redhat.com>
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	Ming Lei <tom.leiming@gmail.com>,
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On Wed, May 23, 2012 at 09:06:22AM +0800, Ming Lei wrote:

 > > [   43.375802] stack backtrace:
 > > [   43.375841] Pid: 639, comm: sshd Not tainted 3.4.0+ #24
 > > [   43.375882] Call Trace:
 > > [   43.377572]  [<ffffffff810b4604>] __lock_acquire+0x1584/0x1aa0
 > > [   43.379286]  [<ffffffff810b51e2>] lock_acquire+0x92/0x1f0
 > > [   43.380995]  [<ffffffff81656d57>] ? tty_lock+0x37/0x80
 > > [   43.382700]  [<ffffffff816534f1>] mutex_lock_nested+0x71/0x3b0
 > > [   43.384403]  [<ffffffff81656d57>] ? tty_lock+0x37/0x80
 > > [   43.386094]  [<ffffffff81085521>] ? get_parent_ip+0x11/0x50
 > > [   43.387794]  [<ffffffff81656d57>] ? tty_lock+0x37/0x80
 > > [   43.389480]  [<ffffffff8165a68d>] ? sub_preempt_count+0x6d/0xd0
 > > [   43.391176]  [<ffffffff813b0243>] ? tty_release+0x1c3/0x5d0
 > > [   43.393003]  [<ffffffff81656d57>] tty_lock+0x37/0x80
 > > [   43.394867]  [<ffffffff81656dc3>] tty_lock_pair+0x23/0x5c
 > > [   43.396671]  [<ffffffff813b024e>] tty_release+0x1ce/0x5d0
 > > [   43.398462]  [<ffffffff811a765c>] fput+0x12c/0x300
 > > [   43.400292]  [<ffffffff811a23a9>] filp_close+0x69/0xa0
 > > [   43.402084]  [<ffffffff811a2f2d>] sys_close+0xad/0x1a0
 > > [   43.403871]  [<ffffffff8165e652>] system_call_fastpath+0x16/0x1b
 > 
 > We have one patch to address the problem, could you test it from the link below?
 > 
 >         http://marc.info/?l=linux-kernel&m=133765211309247&w=2

Yes, that seems to fix it. Thanks.

	Dave