My Lenovo P50 laptop has a BIOS option to disable the microphone. When this option gets chosen, the snd_hda_intel driver causes high CPU load on a single kworker thread, spinning on "process_unsol_events", and system instability. This behavior occurs from the time that the snd_hda_intel module is loaded, irrespective of whether anything is attempting to access the mic. The sound output still works.
When in this state, the module cannot be removed cleanly; attempting to remove it (even without rmmod -f) triggers an oops.
I have attached two exemplary dmesg outputs. Strangely enough, the exact location of the oops varies, but further up the call chain, I always see process_unsol_events.
When the mic is not disabled in the BIOS, the module works stable, regardless whether or not the mic is muted in ALSA.
I wasn't able to pinpoint the root cause. Any pointers on where to start? Much appreciated.
Best regards Alexander
First dmesg:
[31592.691573] BUG: unable to handle kernel NULL pointer dereference at 000000000000020c [31592.691600] IP: mux_select+0x1d/0x190 [snd_hda_codec_generic] [31592.691601] PGD 0 P4D 0 [31592.691604] Oops: 0000 [#1] PREEMPT SMP [31592.691606] Modules linked in: snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel(-) snd_hda_codec snd_hwdep snd_hda_core snd_pcm snd_timer zfs(PO) zunicode(PO) zlua(PO) nvidia_drm(PO) nvidia_modeset(PO) nvidia(PO) iwlmvm mac80211 qmi_wwan iwlwifi cfg80211 thinkpad_acpi rfkill zcommon(PO) znvpair(PO) zavl(PO) icp(PO) spl(O) sdhci_pci cqhci sdhci mmc_block rtsx_pci_sdmmc rtsx_pci mfd_core [31592.691639] CPU: 3 PID: 11044 Comm: kworker/3:1 Tainted: P O 4.16.0-rc7-00206-gf461da3-dirty #33 [31592.691640] Hardware name: LENOVO 20ENCTO1WW/20ENCTO1WW, BIOS N1EET62W (1.35 ) 11/10/2016 [31592.691643] Workqueue: events process_unsol_events [snd_hda_core] [31592.691647] RIP: 0010:mux_select+0x1d/0x190 [snd_hda_codec_generic] [31592.691648] RSP: 0018:ffffc9000f0dfe08 EFLAGS: 00010292 [31592.691650] RAX: 0000000000000001 RBX: ffff880e44737300 RCX: 00000000ffffffff [31592.691651] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff880ee6368800 [31592.691652] RBP: 0000000000000000 R08: 0000000000000f09 R09: 0000000000000000 [31592.691653] R10: 0000000000000018 R11: 0000000000000003 R12: ffff880ee6368800 [31592.691655] R13: 0000000000000000 R14: ffff881053ce6100 R15: 0ffff881053ce610 [31592.691656] FS: 0000000000000000(0000) GS:ffff881053cc0000(0000) knlGS:0000000000000000 [31592.691658] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [31592.691659] CR2: 000000000000020c CR3: 000000000220a004 CR4: 00000000003606e0 [31592.691661] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [31592.691662] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [31592.691662] Call Trace: [31592.691668] ? snd_hda_jack_detect_state+0x4b/0x60 [snd_hda_codec] [31592.691672] call_jack_callback.isra.1+0x20/0xa0 [snd_hda_codec] [31592.691676] snd_hda_jack_unsol_event+0x62/0x70 [snd_hda_codec] [31592.691679] process_unsol_events+0x64/0x80 [snd_hda_core] [31592.691682] process_one_work+0x13e/0x380 [31592.691684] worker_thread+0x62/0x3e0 [31592.691686] ? rescuer_thread+0x2d0/0x2d0 [31592.691689] kthread+0x10d/0x140 [31592.691690] ? kthread_bind+0x10/0x10 [31592.691693] ret_from_fork+0x35/0x40 [31592.691695] Code: e2 01 e9 77 fb ff ff c3 66 0f 1f 44 00 00 0f 1f 44 00 00 41 57 41 56 41 55 41 54 49 89 fc 55 53 48 83 ec 08 48 8b af 08 04 00 00 <8b> 85 0c 02 00 00 85 c0 74 73 89 d3 41 89 f5 8d 50 ff 39 d8 89 [31592.691721] RIP: mux_select+0x1d/0x190 [snd_hda_codec_generic] RSP: ffffc9000f0dfe08 [31592.691723] CR2: 000000000000020c [31592.691725] ---[ end trace dee155e55b20eab8 ]---
Second dmesg:
[115121.084841] BUG: unable to handle kernel NULL pointer dereference at 00000000000005f8 [115121.084844] PGD 0 P4D 0 [115121.084847] Oops: 0000 [#1] PREEMPT SMP [115121.084850] CPU: 2 PID: 12228 Comm: kworker/2:1 Tainted: P O 4.18.0-rc2-00223-g1904148-dirty #39 [115121.084851] Hardware name: LENOVO 20ENCTO1WW/20ENCTO1WW, BIOS N1EET62W (1.35 ) 11/10/2016 [115121.084856] Workqueue: events process_unsol_events [snd_hda_core] [115121.084859] RIP: 0010:set_path_power+0x24/0x120 [snd_hda_codec_generic] [115121.084860] Code: 66 0f 1f 44 00 00 0f 1f 44 00 00 41 57 41 89 f7 41 56 41 55 41 54 55 48 89 fd 53 48 83 ec 08 4c 8b b7 08 04 00 00 89 54 24 04 <41> 8b be f8 05 00 00 49 8b b6 08 06 00 00 85 ff 0f 84 ce 00 00 00 [115121.084901] RSP: 0018:ffffc900243e3de8 EFLAGS: 00010296 [115121.084903] RAX: 0000000000000000 RBX: 0000000000000018 RCX: 00000000ffffffff [115121.084904] RDX: 0000000000000000 RSI: 0000000000000018 RDI: ffff880f993a2800 [115121.084906] RBP: ffff880f993a2800 R08: 0000000000000f09 R09: 0000000000000000 [115121.084907] R10: 0000000000000019 R11: 0000000000000000 R12: 0000000000000000 [115121.084908] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000018 [115121.084910] FS: 0000000000000000(0000) GS:ffff881053c80000(0000) knlGS:0000000000000000 [115121.084911] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [115121.084912] CR2: 00000000000005f8 CR3: 000000000260a004 CR4: 00000000003606e0 [115121.084914] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [115121.084915] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [115121.084916] Call Trace: [115121.084922] pin_power_callback+0x4f/0x80 [snd_hda_codec_generic] [115121.084926] call_jack_callback.isra.1+0x20/0xa0 [snd_hda_codec] [115121.084930] snd_hda_jack_unsol_event+0x62/0x70 [snd_hda_codec] [115121.084933] process_unsol_events+0x64/0x80 [snd_hda_core] [115121.084937] process_one_work+0x157/0x390 [115121.084939] worker_thread+0x64/0x3e0 [115121.084942] ? rescuer_thread+0x2e0/0x2e0 [115121.084944] kthread+0x10d/0x140 [115121.084946] ? kthread_bind+0x10/0x10 [115121.084948] ret_from_fork+0x35/0x40 [115121.084951] Modules linked in: snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel(-) snd_hda_codec snd_hwdep snd_hda_core snd_pcm snd_timer tun nvidia_modeset(PO) nvidia(PO) iwlmvm mac80211 iwlwifi btusb btrtl btbcm btintel bluetooth cfg80211 qmi_wwan ecdh_generic thinkpad_acpi rfkill sdhci_pci cqhci sdhci mmc_block rtsx_pci_sdmmc rtsx_pci mfd_core [115121.084969] CR2: 00000000000005f8 [115121.084971] ---[ end trace 010d684599325728 ]--- [115121.084975] RIP: 0010:set_path_power+0x24/0x120 [snd_hda_codec_generic] [115121.084976] Code: 66 0f 1f 44 00 00 0f 1f 44 00 00 41 57 41 89 f7 41 56 41 55 41 54 55 48 89 fd 53 48 83 ec 08 4c 8b b7 08 04 00 00 89 54 24 04 <41> 8b be f8 05 00 00 49 8b b6 08 06 00 00 85 ff 0f 84 ce 00 00 00 [115121.085000] RSP: 0018:ffffc900243e3de8 EFLAGS: 00010296 [115121.085001] RAX: 0000000000000000 RBX: 0000000000000018 RCX: 00000000ffffffff [115121.085002] RDX: 0000000000000000 RSI: 0000000000000018 RDI: ffff880f993a2800 [115121.085003] RBP: ffff880f993a2800 R08: 0000000000000f09 R09: 0000000000000000 [115121.085004] R10: 0000000000000019 R11: 0000000000000000 R12: 0000000000000000 [115121.085005] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000018 [115121.085006] FS: 0000000000000000(0000) GS:ffff881053c80000(0000) knlGS:0000000000000000 [115121.085007] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [115121.085008] CR2: 00000000000005f8 CR3: 000000000260a004 CR4: 00000000003606e0 [115121.085009] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [115121.085010] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400