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Message-ID: <20120523002645.GA3490@redhat.com>
Date: Tue, 22 May 2012 20:26:45 -0400
From: Dave Jones <davej@...hat.com>
To: Linux Kernel <linux-kernel@...r.kernel.org>
Cc: Alan Cox <alan@...ux/intel.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: 3.4+ tty lockdep trace
>From v3.4-4413-gfb09baf
[ 43.374948] =============================================
[ 43.374991] [ INFO: possible recursive locking detected ]
[ 43.375035] 3.4.0+ #24 Not tainted
[ 43.375065] ---------------------------------------------
[ 43.375108] sshd/639 is trying to acquire lock:
[ 43.375157] (&tty->legacy_mutex){+.+.+.}, at: [<ffffffff81656d57>] tty_lock+0x37/0x80
[ 43.375216]
[ 43.375216] but task is already holding lock:
[ 43.375268] (&tty->legacy_mutex){+.+.+.}, at: [<ffffffff81656d57>] tty_lock+0x37/0x80
[ 43.375327]
[ 43.375327] other info that might help us debug this:
[ 43.375378] Possible unsafe locking scenario:
[ 43.375378]
[ 43.375425] CPU0
[ 43.375447] ----
[ 43.375471] lock(&tty->legacy_mutex);
[ 43.375504] lock(&tty->legacy_mutex);
[ 43.375536]
[ 43.375536] *** DEADLOCK ***
[ 43.375536]
[ 43.375583] May be due to missing lock nesting notation
[ 43.375583]
[ 43.375637] 2 locks held by sshd/639:
[ 43.375675] #0: (tty_mutex){+.+.+.}, at: [<ffffffff813b0243>] tty_release+0x1c3/0x5d0
[ 43.375740] #1: (&tty->legacy_mutex){+.+.+.}, at: [<ffffffff81656d57>] tty_lock+0x37/0x80
[ 43.375802]
[ 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
--
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