From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751941Ab2E0Sfp (ORCPT ); Sun, 27 May 2012 14:35:45 -0400 Received: from out3-smtp.messagingengine.com ([66.111.4.27]:36308 "EHLO out3-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751101Ab2E0Sfo (ORCPT ); Sun, 27 May 2012 14:35:44 -0400 X-Sasl-enc: s64DdKb3YeChAYey2TpKJIqHk/v9Rcxy0xUIZZXgwnsK 1338143743 Message-ID: <4FC273FD.8050806@fastmail.fm> Date: Sun, 27 May 2012 19:35:41 +0100 From: Jack Stone User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:12.0) Gecko/20120430 Thunderbird/12.0.1 MIME-Version: 1.0 To: gregkh@linuxfoundation.org, Linux Kernel , alan@linux.intel.com Subject: TTY Locking bug X-Enigmail-Version: 1.4.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi All, This has cropped up a few times now. The kernel is based on 786f02b from Linus' tree with a couple of networking patches from Eric Dumazet. [ 78.262987] ============================================= [ 78.264262] [ INFO: possible recursive locking detected ] [ 78.265386] 3.4.0-07822-g786f02b-dirty #2 Tainted: G C [ 78.266257] --------------------------------------------- [ 78.267065] plymouthd/214 is trying to acquire lock: [ 78.268027] (&tty->legacy_mutex){+.+.+.}, at: [] tty_lock+0x37/0x80 [ 78.268892] [ 78.268892] but task is already holding lock: [ 78.270467] (&tty->legacy_mutex){+.+.+.}, at: [] tty_lock+0x37/0x80 [ 78.271244] [ 78.271244] other info that might help us debug this: [ 78.272837] Possible unsafe locking scenario: [ 78.272837] [ 78.274420] CPU0 [ 78.275254] ---- [ 78.276038] lock(&tty->legacy_mutex); [ 78.276818] lock(&tty->legacy_mutex); [ 78.277585] [ 78.277585] *** DEADLOCK *** [ 78.277585] [ 78.279856] May be due to missing lock nesting notation [ 78.279856] [ 78.281407] 2 locks held by plymouthd/214: [ 78.282188] #0: (tty_mutex){+.+.+.}, at: [] tty_release+0x151/0x4b0 [ 78.282972] #1: (&tty->legacy_mutex){+.+.+.}, at: [] tty_lock+0x37/0x80 [ 78.283745] [ 78.283745] stack backtrace: [ 78.285291] Pid: 214, comm: plymouthd Tainted: G C 3.4.0-07822-g786f02b-dirty #2 [ 78.286073] Call Trace: [ 78.286875] [] print_deadlock_bug+0xf4/0x100 [ 78.287679] [] validate_chain+0x644/0x720 [ 78.288465] [] __lock_acquire+0x3ad/0x9f0 [ 78.289258] [] ? __lock_acquire+0x3ad/0x9f0 [ 78.290039] [] ? native_sched_clock+0x13/0x80 [ 78.290818] [] ? sched_clock+0x9/0x10 [ 78.291605] [] lock_acquire+0x9d/0x200 [ 78.292378] [] ? tty_lock+0x37/0x80 [ 78.293159] [] ? tty_lock+0x37/0x80 [ 78.293916] [] mutex_lock_nested+0x74/0x380 [ 78.294671] [] ? tty_lock+0x37/0x80 [ 78.295440] [] ? tty_release+0x151/0x4b0 [ 78.296206] [] tty_lock+0x37/0x80 [ 78.296961] [] tty_lock_pair+0x23/0x5c [ 78.297727] [] tty_release+0x15c/0x4b0 [ 78.298485] [] __fput+0xcc/0x290 [ 78.299250] [] fput+0x25/0x30 [ 78.299998] [] tioccons+0xc3/0xd0 [ 78.300741] [] tty_ioctl+0x560/0x960 [ 78.301491] [] ? kmem_cache_free+0x96/0x260 [ 78.302211] [] ? inode_has_perm.constprop.34+0x30/0x40 [ 78.302934] [] do_vfs_ioctl+0x8a/0x340 [ 78.303667] [] ? selinux_file_ioctl+0x71/0x150 [ 78.304369] [] sys_ioctl+0x91/0xa0 [ 78.305057] [] system_call_fastpath+0x16/0x1b Thanks, Jack