I get this trace when I unplug my NuForce uDAC.
Dave
=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.39-rc4+ #9
-------------------------------------------------------
khubd/21 is trying to acquire lock:
(register_mutex#4){+.+.+.}, at: [<ffffffffa02f87e4>] snd_pcm_dev_disconnect+0x1e/0xdd [snd_pcm]
but task is already holding lock:
(&chip->shutdown_mutex){+.+.+.}, at: [<ffffffffa03541fc>] usb_audio_disconnect+0x4a/0x172 [snd_usb_audio]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #6 (&chip->shutdown_mutex){+.+.+.}:
[<ffffffff81086cdd>] lock_acquire+0xd0/0xfb
[<ffffffff814ba195>] __mutex_lock_common+0x4c/0x35b
[<ffffffff814ba568>] mutex_lock_nested+0x3e/0x43
[<ffffffffa035bea4>] snd_usb_hw_free+0x44/0x6a [snd_usb_audio]
[<ffffffffa02fce40>] snd_pcm_release_substream+0x44/0x99 [snd_pcm]
[<ffffffffa02fceff>] snd_pcm_release+0x6a/0xba [snd_pcm]
[<ffffffff81134171>] fput+0x127/0x1f5
[<ffffffff8110690e>] remove_vma+0x56/0x87
[<ffffffff81107c45>] do_munmap+0x2f2/0x30b
[<ffffffff81107d2b>] sys_munmap+0x49/0x60
[<ffffffff814c2782>] system_call_fastpath+0x16/0x1b
-> #5 (&pcm->open_mutex){+.+.+.}:
[<ffffffff81086cdd>] lock_acquire+0xd0/0xfb
[<ffffffff814ba195>] __mutex_lock_common+0x4c/0x35b
[<ffffffff814ba568>] mutex_lock_nested+0x3e/0x43
[<ffffffffa02fcef7>] snd_pcm_release+0x62/0xba [snd_pcm]
[<ffffffff81134171>] fput+0x127/0x1f5
[<ffffffff8110690e>] remove_vma+0x56/0x87
[<ffffffff81107c45>] do_munmap+0x2f2/0x30b
[<ffffffff81107d2b>] sys_munmap+0x49/0x60
[<ffffffff814c2782>] system_call_fastpath+0x16/0x1b
-> #4 (&mm->mmap_sem){++++++}:
[<ffffffff81086cdd>] lock_acquire+0xd0/0xfb
[<ffffffff81100b94>] might_fault+0x89/0xac
[<ffffffff811414cb>] filldir+0x6f/0xc7
[<ffffffff8114ff71>] dcache_readdir+0x67/0x204
[<ffffffff8114171d>] vfs_readdir+0x78/0xb1
[<ffffffff8114183c>] sys_getdents+0x7e/0xd1
[<ffffffff814c2782>] system_call_fastpath+0x16/0x1b
-> #3 (&sb->s_type->i_mutex_key#3){+.+.+.}:
[<ffffffff81086cdd>] lock_acquire+0xd0/0xfb
[<ffffffff814ba195>] __mutex_lock_common+0x4c/0x35b
[<ffffffff814ba568>] mutex_lock_nested+0x3e/0x43
[<ffffffff8131bed2>] devtmpfs_create_node+0x1c6/0x23f
[<ffffffff81315da9>] device_add+0x1bb/0x5b3
[<ffffffff813161bc>] device_register+0x1b/0x1f
[<ffffffff81316251>] device_create_vargs+0x91/0xc9
[<ffffffff813162ba>] device_create+0x31/0x33
[<ffffffff81304a80>] misc_register+0xc1/0x111
[<ffffffff81d77b0f>] vga_arb_device_init+0x15/0x8e
[<ffffffff81002099>] do_one_initcall+0x7f/0x13a
[<ffffffff81d3fcce>] kernel_init+0xf7/0x171
[<ffffffff814c3924>] kernel_thread_helper+0x4/0x10
-> #2 (&sb->s_type->i_mutex_key#2/1){+.+.+.}:
[<ffffffff81086cdd>] lock_acquire+0xd0/0xfb
[<ffffffff814ba195>] __mutex_lock_common+0x4c/0x35b
[<ffffffff814ba568>] mutex_lock_nested+0x3e/0x43
[<ffffffff8113cb3d>] lookup_create+0x28/0x99
[<ffffffff8131be7c>] devtmpfs_create_node+0x170/0x23f
[<ffffffff81315da9>] device_add+0x1bb/0x5b3
[<ffffffff813161bc>] device_register+0x1b/0x1f
[<ffffffff81316251>] device_create_vargs+0x91/0xc9
[<ffffffff813162ba>] device_create+0x31/0x33
[<ffffffffa021a445>] snd_register_device_for_dev+0x145/0x1b4 [snd]
[<ffffffffa025210f>] dell_rfkill_set+0x68/0x9c [dell_laptop]
[<ffffffff81002099>] do_one_initcall+0x7f/0x13a
[<ffffffff81091de5>] sys_init_module+0x132/0x283
[<ffffffff814c2782>] system_call_fastpath+0x16/0x1b
-> #1 (sound_mutex){+.+.+.}:
[<ffffffff81086cdd>] lock_acquire+0xd0/0xfb
[<ffffffff814ba195>] __mutex_lock_common+0x4c/0x35b
[<ffffffff814ba568>] mutex_lock_nested+0x3e/0x43
[<ffffffffa021a3c7>] snd_register_device_for_dev+0xc7/0x1b4 [snd]
[<ffffffffa02f8a25>] snd_pcm_dev_register+0x182/0x24a [snd_pcm]
[<ffffffffa0220273>] snd_device_register_all+0x61/0x81 [snd]
[<ffffffffa021ae67>] snd_card_register+0x88/0x1bb [snd]
[<ffffffffa0354b53>] usb_audio_probe+0x67f/0x72c [snd_usb_audio]
[<ffffffff81377d5c>] usb_probe_interface+0x150/0x1bd
[<ffffffff813185ca>] driver_probe_device+0x132/0x214
[<ffffffff8131870a>] __driver_attach+0x5e/0x82
[<ffffffff8131760a>] bus_for_each_dev+0x59/0x8f
[<ffffffff813181b3>] driver_attach+0x1e/0x20
[<ffffffff81317db5>] bus_add_driver+0xd4/0x22a
[<ffffffff81318bb2>] driver_register+0x98/0x105
[<ffffffff81376ea3>] usb_register_driver+0xb8/0x17c
[<ffffffffa0371040>] ipv6_defrag+0x35/0xe1 [nf_defrag_ipv6]
[<ffffffff81002099>] do_one_initcall+0x7f/0x13a
[<ffffffff81091de5>] sys_init_module+0x132/0x283
[<ffffffff814c2782>] system_call_fastpath+0x16/0x1b
-> #0 (register_mutex#4){+.+.+.}:
[<ffffffff8108656a>] __lock_acquire+0x99e/0xc81
[<ffffffff81086cdd>] lock_acquire+0xd0/0xfb
[<ffffffff814ba195>] __mutex_lock_common+0x4c/0x35b
[<ffffffff814ba568>] mutex_lock_nested+0x3e/0x43
[<ffffffffa02f87e4>] snd_pcm_dev_disconnect+0x1e/0xdd [snd_pcm]
[<ffffffffa02201ac>] snd_device_disconnect+0x79/0xdf [snd]
[<ffffffffa02202fc>] snd_device_disconnect_all+0x69/0x8d [snd]
[<ffffffffa021b81c>] snd_card_disconnect+0x1a8/0x218 [snd]
[<ffffffffa0354228>] usb_audio_disconnect+0x76/0x172 [snd_usb_audio]
[<ffffffff81377854>] usb_unbind_interface+0x5c/0x124
[<ffffffff8131810a>] __device_release_driver+0x7c/0xd5
[<ffffffff81318188>] device_release_driver+0x25/0x32
[<ffffffff81317cd1>] bus_remove_device+0xc4/0xd4
[<ffffffff813151bd>] device_del+0x13d/0x18b
[<ffffffff81375aaa>] usb_disable_device+0x8c/0x178
[<ffffffff8136e406>] usb_disconnect+0xd0/0x135
[<ffffffff813703e4>] hub_thread+0x741/0x119d
[<ffffffff81072d21>] kthread+0xa8/0xb0
[<ffffffff814c3924>] kernel_thread_helper+0x4/0x10
other info that might help us debug this:
5 locks held by khubd/21:
#0: (&__lockdep_no_validate__){+.+.+.}, at: [<ffffffff8136fde6>] hub_thread+0x143/0x119d
#1: (&__lockdep_no_validate__){+.+.+.}, at: [<ffffffff8136e3ba>] usb_disconnect+0x84/0x135
#2: (&__lockdep_no_validate__){+.+.+.}, at: [<ffffffff81318180>] device_release_driver+0x1d/0x32
#3: (register_mutex#3){+.+.+.}, at: [<ffffffffa03541f2>] usb_audio_disconnect+0x40/0x172 [snd_usb_audio]
#4: (&chip->shutdown_mutex){+.+.+.}, at: [<ffffffffa03541fc>] usb_audio_disconnect+0x4a/0x172 [snd_usb_audio]
stack backtrace:
Pid: 21, comm: khubd Not tainted 2.6.39-rc4+ #9
Call Trace:
[<ffffffff814b1573>] print_circular_bug+0xa6/0xb5
[<ffffffff8108656a>] __lock_acquire+0x99e/0xc81
[<ffffffff81013f1b>] ? save_stack_trace+0x2c/0x49
[<ffffffffa02f87e4>] ? snd_pcm_dev_disconnect+0x1e/0xdd [snd_pcm]
[<ffffffff81086cdd>] lock_acquire+0xd0/0xfb
[<ffffffffa02f87e4>] ? snd_pcm_dev_disconnect+0x1e/0xdd [snd_pcm]
[<ffffffff8100ec13>] ? native_sched_clock+0x34/0x36
[<ffffffffa02f87e4>] ? snd_pcm_dev_disconnect+0x1e/0xdd [snd_pcm]
[<ffffffff814ba195>] __mutex_lock_common+0x4c/0x35b
[<ffffffffa02f87e4>] ? snd_pcm_dev_disconnect+0x1e/0xdd [snd_pcm]
[<ffffffff81086f9a>] ? mark_held_locks+0x4b/0x6d
[<ffffffff814ba67f>] ? __mutex_unlock_slowpath+0x112/0x122
[<ffffffff810870c7>] ? trace_hardirqs_on_caller+0x10b/0x12f
[<ffffffff814ba568>] mutex_lock_nested+0x3e/0x43
[<ffffffffa02f87e4>] snd_pcm_dev_disconnect+0x1e/0xdd [snd_pcm]
[<ffffffffa02201ac>] snd_device_disconnect+0x79/0xdf [snd]
[<ffffffffa02202fc>] snd_device_disconnect_all+0x69/0x8d [snd]
[<ffffffffa021b81c>] snd_card_disconnect+0x1a8/0x218 [snd]
[<ffffffffa0354228>] usb_audio_disconnect+0x76/0x172 [snd_usb_audio]
[<ffffffff81377854>] usb_unbind_interface+0x5c/0x124
[<ffffffff8131810a>] __device_release_driver+0x7c/0xd5
[<ffffffff81318188>] device_release_driver+0x25/0x32
[<ffffffff81317cd1>] bus_remove_device+0xc4/0xd4
[<ffffffff813151bd>] device_del+0x13d/0x18b
[<ffffffff81375aaa>] usb_disable_device+0x8c/0x178
[<ffffffff8136e406>] usb_disconnect+0xd0/0x135
[<ffffffff813703e4>] hub_thread+0x741/0x119d
[<ffffffff810870f8>] ? trace_hardirqs_on+0xd/0xf
[<ffffffff81073490>] ? __init_waitqueue_head+0x4b/0x4b
[<ffffffff8136fca3>] ? usb_remote_wakeup+0x64/0x64
[<ffffffff81072d21>] kthread+0xa8/0xb0
[<ffffffff814c3924>] kernel_thread_helper+0x4/0x10
[<ffffffff814bbfd4>] ? retint_restore_args+0x13/0x13
[<ffffffff81072c79>] ? __init_kthread_worker+0x5a/0x5a
[<ffffffff814c3920>] ? gs_change+0x13/0x13
Am Dienstag, 19. April 2011, 20:07:45 schrieb Dave Jones:
> I get this trace when I unplug my NuForce uDAC.
Please test this patch.
Regards
Oliver
At Wed, 20 Apr 2011 12:32:44 +0200,
Oliver Neukum wrote:
>
> Am Dienstag, 19. April 2011, 20:07:45 schrieb Dave Jones:
> > I get this trace when I unplug my NuForce uDAC.
>
> Please test this patch.
Well, no, it would break the real fix for disconnection race we've
done recently.
Such a lockdep warning is sometimes seen, but I haven't seen the real
deadlock by this in practice. It's a path from munmap -> release, and
hits many other subsystems like NFS, if not fixed yet...
thanks,
Takashi
>
> Regards
> Oliver
> [2 0001-usb-audio-fix-potential-deadlock-on-unplug.patch <text/x-patch; UTF-8 (quoted-printable)>]
> From 24d036ccb418d7cfa5a821d5a70b3d3da2d63bb3 Mon Sep 17 00:00:00 2001
> From: Oliver Neukum <[email protected]>
> Date: Wed, 20 Apr 2011 12:29:22 +0200
> Subject: [PATCH] usb-audio:fix potential deadlock on unplug
>
> Decrease the scope of a lock to fix a deadlock
>
> Signed-off-by: Oliver Neukum <[email protected]>
> ---
> sound/usb/card.c | 3 +--
> 1 files changed, 1 insertions(+), 2 deletions(-)
>
> diff --git a/sound/usb/card.c b/sound/usb/card.c
> index a90662a..1d3d9f0 100644
> --- a/sound/usb/card.c
> +++ b/sound/usb/card.c
> @@ -554,6 +554,7 @@ static void snd_usb_audio_disconnect(struct usb_device *dev, void *ptr)
> mutex_lock(&chip->shutdown_mutex);
> chip->shutdown = 1;
> chip->num_interfaces--;
> + mutex_unlock(&chip->shutdown_mutex);
> if (chip->num_interfaces <= 0) {
> snd_card_disconnect(card);
> /* release the pcm resources */
> @@ -569,11 +570,9 @@ static void snd_usb_audio_disconnect(struct usb_device *dev, void *ptr)
> snd_usb_mixer_disconnect(p);
> }
> usb_chip[chip->index] = NULL;
> - mutex_unlock(&chip->shutdown_mutex);
> mutex_unlock(®ister_mutex);
> snd_card_free_when_closed(card);
> } else {
> - mutex_unlock(&chip->shutdown_mutex);
> mutex_unlock(®ister_mutex);
> }
> }
> --
> 1.7.1
>
On wtorek, 19 kwietnia 2011 o 20:07:45 Dave Jones wrote:
> I get this trace when I unplug my NuForce uDAC.
>
> Dave
>
> =======================================================
> [ INFO: possible circular locking dependency detected ]
I created a Bugzilla entry at
https://bugzilla.kernel.org/show_bug.cgi?id=33792
for your bug report, please add your address to the CC list in there, thanks!
--
Maciej Rutecki
http://www.maciek.unixy.pl