From: John Stultz <john.stultz@linaro.org>
To: Alan Cox <alan@linux.intel.com>
Cc: Jiri Slaby <jslaby@suse.cz>, lkml <linux-kernel@vger.kernel.org>
Subject: tty_lock lockdep warning
Date: Thu, 24 May 2012 21:43:37 -0700 [thread overview]
Message-ID: <4FBF0DF9.5040806@linaro.org> (raw)
Hey Alan,
I've been seeing the following lockdep warning w/ Linus' 3.5-rc HEAD
from today. This is running x86_64 in a kvm environment.
Let me know if there are any other details you'd like from me.
thanks
-john
=============================================
[ INFO: possible recursive locking detected ]
3.4.0john+ #347 Not tainted
---------------------------------------------
plymouthd/1345 is trying to acquire lock:
(&tty->legacy_mutex){+.+.+.}, at: [<ffffffff81b10091>] tty_lock+0x61/0xb0
but task is already holding lock:
(&tty->legacy_mutex){+.+.+.}, at: [<ffffffff81b10091>] tty_lock+0x61/0xb0
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&tty->legacy_mutex);
lock(&tty->legacy_mutex);
*** DEADLOCK ***
May be due to missing lock nesting notation
2 locks held by plymouthd/1345:
#0: (tty_mutex){+.+.+.}, at: [<ffffffff81417122>] tty_release+0x1e2/0x600
#1: (&tty->legacy_mutex){+.+.+.}, at: [<ffffffff81b10091>]
tty_lock+0x61/0xb0
stack backtrace:
Pid: 1345, comm: plymouthd Not tainted 3.4.0john+ #347
Call Trace:
[<ffffffff81044727>] ? vprintk_emit+0x287/0x5d0
[<ffffffff810b63b6>] validate_chain+0xf36/0x1380
[<ffffffff8108b433>] ? sched_clock_local+0x43/0xb0
[<ffffffff8108b6df>] ? local_clock+0x6f/0x80
[<ffffffff810b0ee9>] ? trace_hardirqs_off_caller+0x29/0x140
[<ffffffff810b6c3e>] __lock_acquire+0x43e/0xb80
[<ffffffff810b7431>] lock_acquire+0xb1/0x210
[<ffffffff81b10091>] ? tty_lock+0x61/0xb0
[<ffffffff81b0c273>] mutex_lock_nested+0x73/0x4b0
[<ffffffff81b10091>] ? tty_lock+0x61/0xb0
[<ffffffff81b10091>] ? tty_lock+0x61/0xb0
[<ffffffff81b10091>] tty_lock+0x61/0xb0
[<ffffffff81b1013d>] tty_lock_pair+0x5d/0x64
[<ffffffff8141712d>] tty_release+0x1ed/0x600
[<ffffffff811851e8>] fput+0x138/0x2e0
[<ffffffff81416d18>] tty_ioctl+0xb68/0xd40
[<ffffffff81b0fee1>] ? _raw_spin_unlock_irqrestore+0x71/0xa0
[<ffffffff81198d94>] do_vfs_ioctl+0xa4/0x5c0
[<ffffffff8141d12c>] ? put_ldisc+0x11c/0x190
[<ffffffff8141d1de>] ? tty_ldisc_deref+0xe/0x10
[<ffffffff81413887>] ? tty_compat_ioctl+0xc7/0xf0
[<ffffffff811ded87>] compat_sys_ioctl+0x257/0x1220
[<ffffffff81b12138>] ? sysenter_dispatch+0x19/0x26
[<ffffffff81392ffd>] ? trace_hardirqs_off_thunk+0x3a/0x3c
[<ffffffff81b12126>] sysenter_dispatch+0x7/0x26
[<ffffffff81392fbe>] ? trace_hardirqs_on_thunk+0x3a/0x3f
next reply other threads:[~2012-05-25 4:45 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-25 4:43 John Stultz [this message]
2012-05-25 7:06 ` tty_lock lockdep warning Greg KH
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