[alsa-devel] pcm_lock deadlock

[Ville Syrjälä]

Hi Takashi,

I just got this deadlock when I tried to modprobe i915 on an ELK:

[  203.716416] ============================================
[  203.716417] WARNING: possible recursive locking detected
[  203.716418] 5.4.0-rc5-elk+ #206 Not tainted
[  203.716419] --------------------------------------------
[  203.716420] kworker/0:1/12 is trying to acquire lock:
[  203.716421] efb1c138 (&spec->pcm_lock){+.+.}, at: generic_hdmi_init+0x21/0x140 [snd_hda_codec_hdmi]
[  203.716426] 
               but task is already holding lock:
[  203.716427] efb1c138 (&spec->pcm_lock){+.+.}, at: check_presence_and_report+0x67/0xb0 [snd_hda_codec_hdmi]
[  203.716430] 
               other info that might help us debug this:
[  203.716431]  Possible unsafe locking scenario:

[  203.716431]        CPU0
[  203.716432]        ----
[  203.716432]   lock(&spec->pcm_lock);
[  203.716433]   lock(&spec->pcm_lock);
[  203.716434] 
                *** DEADLOCK ***

[  203.716435]  May be due to missing lock nesting notation

[  203.716436] 3 locks held by kworker/0:1/12:
[  203.716436]  #0: f14096a0 ((wq_completion)events){+.+.}, at: process_one_work+0x1b8/0x530
[  203.716442]  #1: f14dbf4c ((work_completion)(&bus->unsol_work)){+.+.}, at: process_one_work+0x1b8/0x530
[  203.716444]  #2: efb1c138 (&spec->pcm_lock){+.+.}, at: check_presence_and_report+0x67/0xb0 [snd_hda_codec_hdmi]
[  203.716448] 
               stack backtrace:
[  203.716449] CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.4.0-rc5-elk+ #206
[  203.716450] Hardware name: System manufacturer P5Q-EM/P5Q-EM, BIOS 2203    07/08/2009
[  203.716457] Workqueue: events snd_hdac_bus_process_unsol_events [snd_hda_core]
[  203.716459] Call Trace:
[  203.716463]  dump_stack+0x66/0x8e
[  203.716466]  __lock_acquire.cold.62+0x3bf/0x3c7
[  203.716468]  ? mark_held_locks+0x3f/0x60
[  203.716470]  ? _raw_spin_unlock_irq+0x22/0x30
[  203.716478]  ? azx_rirb_get_response+0xd7/0x220 [snd_hda_codec]
[  203.716479]  ? lockdep_hardirqs_on+0xec/0x1a0
[  203.716480]  ? _raw_spin_unlock_irq+0x22/0x30
[  203.716483]  ? trace_hardirqs_on+0x4a/0xf0
[  203.716484]  ? find_held_lock+0x26/0xb0
[  203.716486]  lock_acquire+0x74/0x150
[  203.716488]  ? generic_hdmi_init+0x21/0x140 [snd_hda_codec_hdmi]
[  203.716490]  __mutex_lock+0x60/0x810
[  203.716492]  ? generic_hdmi_init+0x21/0x140 [snd_hda_codec_hdmi]
[  203.716496]  ? snd_hdac_exec_verb+0x16/0x40 [snd_hda_core]
[  203.716499]  ? codec_read+0x29/0x40 [snd_hda_core]
[  203.716501]  mutex_lock_nested+0x14/0x20
[  203.716503]  ? generic_hdmi_init+0x21/0x140 [snd_hda_codec_hdmi]
[  203.716505]  generic_hdmi_init+0x21/0x140 [snd_hda_codec_hdmi]
[  203.716507]  generic_hdmi_resume+0x18/0x60 [snd_hda_codec_hdmi]
[  203.716512]  hda_call_codec_resume+0xc2/0x130 [snd_hda_codec]
[  203.716517]  hda_codec_runtime_resume+0x2a/0x60 [snd_hda_codec]
[  203.716520]  __rpm_callback+0x7a/0x140
[  203.716524]  ? snd_hda_codec_device_new+0x2a0/0x2a0 [snd_hda_codec]
[  203.716529]  ? snd_hda_codec_device_new+0x2a0/0x2a0 [snd_hda_codec]
[  203.716531]  rpm_callback+0x1a/0x70
[  203.716535]  ? snd_hda_codec_device_new+0x2a0/0x2a0 [snd_hda_codec]
[  203.716537]  rpm_resume+0x52c/0x700
[  203.716538]  ? _raw_spin_lock_irqsave+0x32/0x40
[  203.716540]  __pm_runtime_resume+0x43/0x90
[  203.716543]  snd_hdac_power_up_pm+0x4d/0x50 [snd_hda_core]
[  203.716546]  hdmi_present_sense+0x34/0x340 [snd_hda_codec_hdmi]
[  203.716548]  ? finish_task_switch+0x89/0x210
[  203.716550]  check_presence_and_report+0x7a/0xb0 [snd_hda_codec_hdmi]
[  203.716553]  hdmi_unsol_event+0x57/0x60 [snd_hda_codec_hdmi]
[  203.716557]  ? hda_codec_match+0x70/0x70 [snd_hda_codec]
[  203.716561]  hda_codec_unsol_event+0x12/0x20 [snd_hda_codec]
[  203.716564]  snd_hdac_bus_process_unsol_events+0x51/0x60 [snd_hda_core]
[  203.716566]  process_one_work+0x230/0x530
[  203.716567]  worker_thread+0x37/0x410
[  203.716569]  kthread+0xf5/0x110
[  203.716570]  ? process_one_work+0x530/0x530
[  203.716572]  ? kthread_create_worker_on_cpu+0x20/0x20
[  203.716574]  ret_from_fork+0x2e/0x38

Looks like commit ade49db337a9 ("ALSA: hda/hdmi - Allow audio
component for AMD/ATI and Nvidia HDMI") introduced pcm_lock
to generic_hdmi_init().

-- 
Ville Syrjälä
Intel