WARNING: CPU: 0 PID: 71 at /build/buildd/linux-3.13.0/fs/sysfs/group.c:214 sysfs_remove_group+0xc6/0xd0()

[Chris J Arges]

[Impact]

This impacts 3.16 and 3.13 series kernels.

When powering off a USB audio device that is plugged into the computer the following kernel WARNs are displayed:
[ 410.508315] usb 1-1.4: USB disconnect, device number 4
[ 410.510722] ------------[ cut here ]------------
[ 410.510731] WARNING: CPU: 0 PID: 71 at /build/buildd/linux-3.13.0/fs/sysfs/group.c:214 sysfs_remove_group+0xc6/0xd0()
[ 410.510733] sysfs group ffffffff81cabae0 not found for kobject 'midiC3D0'
[ 410.510734] Modules linked in: xt_conntrack ipt_REJECT ip6table_filter ip6_tables ebtable_nat ebtables hid_logitech_dj hid_generic usbhid hid xt_CHECKSUM iptable_mangle ipt_MASQUERADE iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack xt_tcpudp bridge stp llc iptable_filter ip_tables x_tables usb_storage dm_crypt gpio_ich intel_rapl x86_pkg_temp_thermal coretemp kvm_intel uvcvideo videobuf2_vmalloc kvm videobuf2_memops snd_usb_audio videobuf2_core videodev snd_usbmidi_lib crct10dif_pclmul crc32_pclmul ghash_clmulni_intel nvidia(POF) bnep rfcomm snd_hda_codec_hdmi aesni_intel bluetooth aes_x86_64 lrw gf128mul glue_helper ablk_helper snd_hda_codec_realtek cryptd serio_raw snd_seq_midi snd_hda_intel snd_seq_midi_event snd_hda_codec snd_hwdep snd_rawmidi snd_pcm mei_me snd_seq lpc_ich mei snd_page_alloc snd_seq_device snd_timer snd soundcore mac_hid wmi parport_pc ppdev binfmt_misc lp parport i915 video i2c_algo_bit ahci drm_kms_helper libahci firewire_ohci e1000e drm psmouse firewire_core ptp crc_itu_t pps_core
[ 410.510801] CPU: 0 PID: 71 Comm: khubd Tainted: PF O 3.13.0-32-generic #57-Ubuntu
[ 410.510803] Hardware name: LENOVO 7052B9U/ , BIOS 9HKT47AUS 01/10/2012
[ 410.510805] 0000000000000009 ffff8804275b1990 ffffffff8171bcb4 ffff8804275b19d8
[ 410.510809] ffff8804275b19c8 ffffffff810676cd 0000000000000000 ffffffff81cabae0
[ 410.510813] ffff880424710c10 ffff880424710000 ffff880422c1bcf8 ffff8804275b1a28
[ 410.510816] Call Trace:
[ 410.510824] [<ffffffff8171bcb4>] dump_stack+0x45/0x56
[ 410.510829] [<ffffffff810676cd>] warn_slowpath_common+0x7d/0xa0
[ 410.510832] [<ffffffff8106773c>] warn_slowpath_fmt+0x4c/0x50
[ 410.510836] [<ffffffff8123446e>] ? sysfs_get_dirent_ns+0x4e/0x70
[ 410.510839] [<ffffffff81235756>] sysfs_remove_group+0xc6/0xd0
[ 410.510844] [<ffffffff814998c3>] dpm_sysfs_remove+0x43/0x50
[ 410.510849] [<ffffffff8148f2c5>] device_del+0x45/0x1c0
[ 410.510852] [<ffffffff8148f45e>] device_unregister+0x1e/0x60
[ 410.510856] [<ffffffff8148f51c>] device_destroy+0x3c/0x50
[ 410.510866] [<ffffffffa02142ed>] snd_unregister_device+0x4d/0xa0 [snd]
[ 410.510872] [<ffffffffa029fc76>] snd_rawmidi_dev_disconnect+0xc6/0xf0 [snd_rawmidi]
[ 410.510881] [<ffffffffa021b2ea>] snd_device_disconnect+0x6a/0xf0 [snd]
[ 410.510889] [<ffffffffa021b43c>] snd_device_disconnect_all+0x4c/0x90 [snd]
[ 410.510896] [<ffffffffa0214861>] snd_card_disconnect+0x131/0x1e0 [snd]
[ 410.510904] [<ffffffffa0ead480>] usb_audio_disconnect+0x80/0x1b0 [snd_usb_audio]
[ 410.510909] [<ffffffff81546a14>] usb_unbind_interface+0x64/0x1c0
[ 410.510913] [<ffffffff81492fdf>] __device_release_driver+0x7f/0xf0
[ 410.510916] [<ffffffff81493073>] device_release_driver+0x23/0x30
[ 410.510918] [<ffffffff814928f8>] bus_remove_device+0x108/0x180
[ 410.510922] [<ffffffff8148f3a9>] device_del+0x129/0x1c0
[ 410.510925] [<ffffffff815443f0>] usb_disable_device+0xb0/0x290
[ 410.510929] [<ffffffff81538f4d>] usb_disconnect+0xad/0x200
[ 410.510933] [<ffffffff8153b9f5>] hub_port_connect_change+0xd5/0xb50
[ 410.510937] [<ffffffff81542df4>] ? usb_control_msg+0xd4/0x110
[ 410.510941] [<ffffffff8153c934>] hub_events+0x4c4/0xa20
[ 410.510944] [<ffffffff8153cec5>] hub_thread+0x35/0x160
[ 410.510950] [<ffffffff810aaf00>] ? prepare_to_wait_event+0x100/0x100
[ 410.510953] [<ffffffff8153ce90>] ? hub_events+0xa20/0xa20
[ 410.510957] [<ffffffff8108b3d2>] kthread+0xd2/0xf0
[ 410.510961] [<ffffffff8108b300>] ? kthread_create_on_node+0x1d0/0x1d0
[ 410.510966] [<ffffffff8172c5bc>] ret_from_fork+0x7c/0xb0
[ 410.510969] [<ffffffff8108b300>] ? kthread_create_on_node+0x1d0/0x1d0
[ 410.510971] ---[ end trace 68a53e3235c146ed ]---
[ 410.511060] ------------[ cut here ]------------

[ Test Case ]
1) Use a USB Audio device.
2) Turn the power of the device on and off.
3) Check dmesg for output.

[Fix]
commit 0725dda207e95ff25f1aa01432250323e0ec49d6 upstream

--

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-3.13.0-32-generic 3.13.0-32.57
ProcVersionSignature: Ubuntu 3.13.0-32.57-generic 3.13.11.4
Uname: Linux 3.13.0-32-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.14.1-0ubuntu3.2
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: arges 2670 F.... pulseaudio
 /dev/snd/controlC2: arges 2670 F.... pulseaudio
 /dev/snd/controlC0: arges 2670 F.... pulseaudio
CurrentDesktop: Unity
Date: Sat Jul 19 12:35:49 2014
EcryptfsInUse: Yes
InstallationDate: Installed on 2014-07-18 (1 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
MachineType: LENOVO 7052B9U
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-32-generic root=UUID=8012e371-1ce8-4a24-ac05-13305882aad6 ro quiet splash
RelatedPackageVersions:
 linux-restricted-modules-3.13.0-32-generic N/A
 linux-backports-modules-3.13.0-32-generic N/A
 linux-firmware 1.127.4
RfKill:

SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 01/10/2012
dmi.bios.vendor: LENOVO
dmi.bios.version: 9HKT47AUS
dmi.board.vendor: LENOVO
dmi.chassis.type: 3
dmi.chassis.vendor: To Be Filled By O.E.M.
dmi.chassis.version: To Be Filled By O.E.M.
dmi.modalias: dmi:bvnLENOVO:bvr9HKT47AUS:bd01/10/2012:svnLENOVO:pn7052B9U:pvrThinkCentreM91p:rvnLENOVO:rn:rvr:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.:
dmi.product.name: 7052B9U
dmi.product.version: ThinkCentre M91p
dmi.sys.vendor: LENOVO

[Chris J Arges (arges)]

Tested mainline kernel and problem still exists.

[Chris J Arges (arges)]

What I've found is that the USB audio device I am using doesn't properly create a mixer which in turn causing these sysfs remove errors (due to another patch that emits these WARNs).

If I try to quirk it (for example using a test patch like this):
https://lkml.org/lkml/2013/7/17/590

However the following commits allow the mixer creation to be skipped without a quirk:
4d7b86c98 "ALSA: snd-usb: mixer: propagate errors up the call chain"
83ea5d18d "ALSA: snd-usb: mixer: ignore -EINVAL in snd_usb_mixer_controls()"
61ac51301 "ALSA: usb: Parse UAC2 extension unit like for UAC1"

Which renders that above patch unnecessary. So what's needed is a way to properly remove those sysfs entries without causing a warn even if we have a USB Audio device with a bogus UAC2 extensions.

[Chris J Arges (arges)]

This is included in 3.18-rc4. It is applied to 3.16.y stable, and I've requested inclusion in 3.13.y stable.

[Chris J Arges (arges)]

This is fixed in trusty/utopic via upstream stable updates.