From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755657Ab2CLOfY (ORCPT ); Mon, 12 Mar 2012 10:35:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:26994 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755504Ab2CLOfW (ORCPT ); Mon, 12 Mar 2012 10:35:22 -0400 Date: Mon, 12 Mar 2012 10:35:15 -0400 From: Dave Jones To: Linux Kernel Cc: tiwai@suse.de Subject: snd_pcm lockdep report from 3.3-rc6 Message-ID: <20120312143514.GA1881@redhat.com> Mail-Followup-To: Dave Jones , Linux Kernel , tiwai@suse.de MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I just hit this.. [ INFO: possible recursive locking detected ] 3.3.0-rc6+ #5 Not tainted --------------------------------------------- pulseaudio/1306 is trying to acquire lock: (&(&substream->self_group.lock)->rlock/1){......}, at: [] snd_pcm_action_group+0x9b/0x260 [snd_pcm] but task is already holding lock: (&(&substream->self_group.lock)->rlock/1){......}, at: [] snd_pcm_action_group+0x9b/0x260 [snd_pcm] other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&(&substream->self_group.lock)->rlock/1); lock(&(&substream->self_group.lock)->rlock/1); *** DEADLOCK *** May be due to missing lock nesting notation 4 locks held by pulseaudio/1306: #0: (snd_pcm_link_rwlock){......}, at: [] snd_pcm_drop+0x60/0x100 [snd_pcm] #1: (&(&substream->self_group.lock)->rlock){......}, at: [] snd_pcm_drop+0x68/0x100 [snd_pcm] #2: (&(&substream->group->lock)->rlock){......}, at: [] snd_pcm_action+0x3e/0xb0 [snd_pcm] #3: (&(&substream->self_group.lock)->rlock/1){......}, at: [] snd_pcm_action_group+0x9b/0x260 [snd_pcm] stack backtrace: Pid: 1306, comm: pulseaudio Not tainted 3.3.0-rc6+ #5 Call Trace: [] __lock_acquire+0xe47/0x1bb0 [] ? sched_clock_cpu+0xb8/0x130 [] lock_acquire+0x9d/0x220 [] ? snd_pcm_action_group+0x9b/0x260 [snd_pcm] [] ? put_lock_stats+0xe/0x40 [] _raw_spin_lock_nested+0x4d/0x90 [] ? snd_pcm_action_group+0x9b/0x260 [snd_pcm] [] snd_pcm_action_group+0x9b/0x260 [snd_pcm] [] snd_pcm_action+0x71/0xb0 [snd_pcm] [] snd_pcm_stop+0x1a/0x20 [snd_pcm] [] snd_pcm_drop+0x81/0x100 [snd_pcm] [] snd_pcm_common_ioctl1+0x678/0xc00 [snd_pcm] [] snd_pcm_playback_ioctl1+0x147/0x2e0 [snd_pcm] [] ? file_has_perm+0xdc/0xf0 [] snd_pcm_playback_ioctl+0x34/0x40 [snd_pcm] [] do_vfs_ioctl+0x98/0x570 [] sys_ioctl+0x91/0xa0 [] system_call_fastpath+0x16/0x1b I suspect this .. static int snd_pcm_action(struct action_ops *ops, struct snd_pcm_substream *substream, int state) { int res; if (snd_pcm_stream_linked(substream)) { --> if (!spin_trylock(&substream->group->lock)) { spin_unlock(&substream->self_group.lock); spin_lock(&substream->group->lock); spin_lock(&substream->self_group.lock); } res = snd_pcm_action_group(ops, substream, state, 1); spin_unlock(&substream->group->lock); } else { res = snd_pcm_action_single(ops, substream, state); } return res; } Should that trylock be on self_group.lock ? Dave