Hi, This is another report for a crash that happened right after I disconnected a device. It froze the computer with the call trace displayed on the screen and the message "BUG: unable to handle kernel NULL pointer dereference at 0000000000000139". The call trace shows that it happened inside of "media_remove_intf_links". All the relevant information from /var/log/kern.log can be found below: Apr 29 23:10:53 limus kernel: [ 0.000000] Linux version 4.9.0-6-amd64 (debian-kernel@xxxxxxxxxxxxxxxx) (gcc version 6.3.0 20170516 (Debian 6.3.0-18+deb9u1) ) #1 SMP Debian 4.9.82-1+deb9u3 (2018-03-02) Apr 29 23:12:04 limus kernel: [ 85.688050] usb 5-4: new high-speed USB device number 3 using ehci-pci Apr 29 23:12:04 limus kernel: [ 85.842950] usb 5-4: New USB device found, idVendor=093b, idProduct=a003 Apr 29 23:12:04 limus kernel: [ 85.842953] usb 5-4: New USB device strings: Mfr=2, Product=1, SerialNumber=0 Apr 29 23:12:04 limus kernel: [ 85.842956] usb 5-4: Product: ConvertX AV100U A/V Capture Apr 29 23:12:04 limus kernel: [ 85.842958] usb 5-4: Manufacturer: Plextor Apr 29 23:12:04 limus kernel: [ 85.965017] media: Linux media interface: v0.10 Apr 29 23:12:04 limus kernel: [ 85.998454] Linux video capture interface: v2.00 Apr 29 23:12:04 limus kernel: [ 86.053196] em28xx: New device Plextor ConvertX AV100U A/V Capture @ 480 Mbps (093b:a003, interface 0, class 0) Apr 29 23:12:04 limus kernel: [ 86.053198] em28xx: Video interface 0 found: bulk isoc Apr 29 23:12:04 limus kernel: [ 86.053361] em28xx: chip ID is em2710/2820 Apr 29 23:12:04 limus kernel: [ 86.197128] em2710/2820 #0: EEPROM ID = 1a eb 67 95, EEPROM hash = 0x439a4c10 Apr 29 23:12:04 limus kernel: [ 86.197130] em2710/2820 #0: EEPROM info: Apr 29 23:12:04 limus kernel: [ 86.197132] em2710/2820 #0: AC97 audio (5 sample rates) Apr 29 23:12:04 limus kernel: [ 86.197132] em2710/2820 #0: 500mA max power Apr 29 23:12:04 limus kernel: [ 86.197134] em2710/2820 #0: Table at offset 0x06, strings=0x3a7c, 0x126a, 0x0000 Apr 29 23:12:04 limus kernel: [ 86.197136] em2710/2820 #0: Identified as Pinnacle Dazzle DVC 90/100/101/107 / Kaiser Baas Video to DVD maker / Kworld DVD Maker 2 / Plextor ConvertX PX-AV100U (card=9) Apr 29 23:12:04 limus kernel: [ 86.197138] em2710/2820 #0: analog set to isoc mode. Apr 29 23:12:04 limus kernel: [ 86.197241] em28xx audio device (093b:a003): interface 1, class 1 Apr 29 23:12:04 limus kernel: [ 86.197254] em28xx audio device (093b:a003): interface 2, class 1 Apr 29 23:12:04 limus kernel: [ 86.197272] usbcore: registered new interface driver em28xx Apr 29 23:12:04 limus kernel: [ 86.240334] em2710/2820 #0: Registering V4L2 extension Apr 29 23:12:05 limus kernel: [ 86.595315] em2710/2820 #0: failed to get i2c transfer status from bridge register (error=-5) Apr 29 23:12:05 limus kernel: [ 86.851219] em2710/2820 #0: writing to i2c device at 0x4a failed (error=-5) Apr 29 23:12:05 limus kernel: [ 87.107254] em2710/2820 #0: writing to i2c device at 0x4a failed (error=-5) Apr 29 23:12:06 limus kernel: [ 87.391293] em2710/2820 #0: writing to i2c device at 0x4a failed (error=-5) Apr 29 23:12:06 limus kernel: [ 87.647328] em2710/2820 #0: writing to i2c device at 0x4a failed (error=-5) Apr 29 23:12:06 limus kernel: [ 87.903235] em2710/2820 #0: writing to i2c device at 0x4a failed (error=-5) Apr 29 23:12:06 limus kernel: [ 88.159276] em2710/2820 #0: writing to i2c device at 0x4a failed (error=-5) Apr 29 23:12:07 limus kernel: [ 88.415303] em2710/2820 #0: writing to i2c device at 0x4a failed (error=-5) Apr 29 23:12:07 limus kernel: [ 88.671333] em2710/2820 #0: writing to i2c device at 0x4a failed (error=-5) Apr 29 23:12:07 limus kernel: [ 88.927241] em2710/2820 #0: writing to i2c device at 0x4a failed (error=-5) Apr 29 23:12:07 limus kernel: [ 89.183272] em2710/2820 #0: writing to i2c device at 0x4a failed (error=-5) Apr 29 23:12:08 limus kernel: [ 89.439180] em2710/2820 #0: writing to i2c device at 0x4a failed (error=-5) Apr 29 23:12:08 limus kernel: [ 89.695212] em2710/2820 #0: writing to i2c device at 0x4a failed (error=-5) Apr 29 23:12:08 limus kernel: [ 89.951240] em2710/2820 #0: writing to i2c device at 0x4a failed (error=-5) Apr 29 23:12:08 limus kernel: [ 90.207269] em2710/2820 #0: writing to i2c device at 0x4a failed (error=-5) Apr 29 23:12:09 limus kernel: [ 90.463300] em2710/2820 #0: writing to i2c device at 0x4a failed (error=-5) Apr 29 23:12:09 limus kernel: [ 90.719212] em2710/2820 #0: writing to i2c device at 0x4a failed (error=-5) Apr 29 23:12:09 limus kernel: [ 90.975232] em2710/2820 #0: writing to i2c device at 0x4a failed (error=-5) Apr 29 23:12:09 limus kernel: [ 91.231262] em2710/2820 #0: writing to i2c device at 0x4a failed (error=-5) Apr 29 23:12:09 limus kernel: [ 91.372480] usbcore: registered new interface driver snd-usb-audio Apr 29 23:12:10 limus kernel: [ 91.524795] em2710/2820 #0: Config register raw data: 0x10 Apr 29 23:12:10 limus kernel: [ 91.556173] em2710/2820 #0: AC97 vendor ID = 0xffffffff Apr 29 23:12:10 limus kernel: [ 91.572175] em2710/2820 #0: AC97 features = 0x6a90 Apr 29 23:12:10 limus kernel: [ 91.572176] em2710/2820 #0: Empia 202 AC97 audio processor detected Apr 29 23:12:13 limus kernel: [ 94.600238] em2710/2820 #0: failed to create media graph Apr 29 23:12:13 limus kernel: [ 94.600245] em2710/2820 #0: V4L2 device video0 deregistered Apr 29 23:12:13 limus kernel: [ 94.600752] em28xx: Registered (Em28xx v4l2 Extension) extension Apr 29 23:13:07 limus kernel: [ 148.762772] usb 5-4: USB disconnect, device number 3 Apr 29 23:13:07 limus kernel: [ 148.762858] em2710/2820 #0: Disconnecting em2710/2820 #0 Apr 29 23:13:07 limus kernel: [ 148.762948] em2710/2820 #0: Freeing device Apr 29 23:13:09 limus kernel: [ 151.120023] usb 5-4: new high-speed USB device number 4 using ehci-pci Apr 29 23:13:09 limus kernel: [ 151.274979] usb 5-4: New USB device found, idVendor=093b, idProduct=a003 Apr 29 23:13:09 limus kernel: [ 151.274982] usb 5-4: New USB device strings: Mfr=2, Product=1, SerialNumber=0 Apr 29 23:13:09 limus kernel: [ 151.274984] usb 5-4: Product: ConvertX AV100U A/V Capture Apr 29 23:13:09 limus kernel: [ 151.274986] usb 5-4: Manufacturer: Plextor Apr 29 23:13:09 limus kernel: [ 151.275270] em28xx: New device Plextor ConvertX AV100U A/V Capture @ 480 Mbps (093b:a003, interface 0, class 0) Apr 29 23:13:09 limus kernel: [ 151.275272] em28xx: Video interface 0 found: bulk isoc Apr 29 23:13:09 limus kernel: [ 151.275352] em28xx: chip ID is em2710/2820 Apr 29 23:13:10 limus kernel: [ 151.417088] em2710/2820 #0: EEPROM ID = 1a eb 67 95, EEPROM hash = 0x439a4c10 Apr 29 23:13:10 limus kernel: [ 151.417089] em2710/2820 #0: EEPROM info: Apr 29 23:13:10 limus kernel: [ 151.417090] em2710/2820 #0: AC97 audio (5 sample rates) Apr 29 23:13:10 limus kernel: [ 151.417091] em2710/2820 #0: 500mA max power Apr 29 23:13:10 limus kernel: [ 151.417093] em2710/2820 #0: Table at offset 0x06, strings=0x3a7c, 0x126a, 0x0000 Apr 29 23:13:10 limus kernel: [ 151.417095] em2710/2820 #0: Identified as Pinnacle Dazzle DVC 90/100/101/107 / Kaiser Baas Video to DVD maker / Kworld DVD Maker 2 / Plextor ConvertX PX-AV100U (card=9) Apr 29 23:13:10 limus kernel: [ 151.417096] em2710/2820 #0: analog set to isoc mode. Apr 29 23:13:10 limus kernel: [ 151.417137] em2710/2820 #0: Registering V4L2 extension Apr 29 23:13:10 limus kernel: [ 151.417252] em28xx audio device (093b:a003): interface 1, class 1 Apr 29 23:13:10 limus kernel: [ 151.936534] saa7115 8-0025: saa7113 found @ 0x4a (em2710/2820 #0) Apr 29 23:13:11 limus kernel: [ 152.964287] em2710/2820 #0: Config register raw data: 0x10 Apr 29 23:13:11 limus kernel: [ 152.996158] em2710/2820 #0: AC97 vendor ID = 0xffffffff Apr 29 23:13:11 limus kernel: [ 153.012282] em2710/2820 #0: AC97 features = 0x6a90 Apr 29 23:13:11 limus kernel: [ 153.012283] em2710/2820 #0: Empia 202 AC97 audio processor detected Apr 29 23:13:14 limus kernel: [ 156.076288] em2710/2820 #0: V4L2 video device registered as video0 Apr 29 23:13:14 limus kernel: [ 156.076291] em2710/2820 #0: V4L2 extension successfully initialized Apr 29 23:21:07 limus kernel: [ 628.747954] perf: interrupt took too long (2533 > 2500), lowering kernel.perf_event_max_sample_rate to 78750 Apr 29 23:24:25 limus kernel: [ 826.617031] perf: interrupt took too long (3167 > 3166), lowering kernel.perf_event_max_sample_rate to 63000 Apr 29 23:35:58 limus kernel: [ 1519.576080] perf: interrupt took too long (3961 > 3958), lowering kernel.perf_event_max_sample_rate to 50250 Apr 29 23:36:20 limus kernel: [ 1541.832993] usb 5-4: USB disconnect, device number 4 Apr 29 23:36:20 limus kernel: [ 1541.834062] usb 5-4: cannot submit urb (err = -19) Apr 29 23:36:20 limus kernel: [ 1541.848040] usb 5-4: cannot submit urb 0, error -19: no device [Note: Removed 566 lines that had an identical message] Apr 29 23:36:20 limus kernel: [ 1541.872547] usb 5-4: cannot submit urb 0, error -19: no device Apr 29 23:36:20 limus kernel: [ 1541.872564] em2710/2820 #0: Disconnecting em2710/2820 #0 Apr 29 23:36:20 limus kernel: [ 1541.872566] em2710/2820 #0: Closing video extension Apr 29 23:36:20 limus kernel: [ 1541.872583] em2710/2820 #0: V4L2 device video0 deregistered Apr 29 23:36:35 limus kernel: [ 1556.925936] em2710/2820 #0: Freeing device Apr 29 23:36:35 limus kernel: [ 1556.925969] BUG: unable to handle kernel NULL pointer dereference at 0000000000000139 Apr 29 23:36:35 limus kernel: [ 1556.926019] IP: [<ffffffff98a0e8be>] mutex_lock+0xe/0x30 Apr 29 23:36:35 limus kernel: [ 1556.926048] PGD 0 Apr 29 23:36:35 limus kernel: [ 1556.926059] Apr 29 23:36:35 limus kernel: [ 1556.926069] Oops: 0002 [#1] SMP Apr 29 23:36:35 limus kernel: [ 1556.926084] Modules linked in: snd_usb_audio snd_usbmidi_lib snd_rawmidi snd_seq_device saa7115 em28xx_v4l videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videobuf2_core em28xx tveeprom v4l2_common videodev media coretemp kvm_intel iTCO_wdt kvm iTCO_vendor_support snd_hda_codec_analog snd_hda_codec_generic evdev snd_hda_intel snd_hda_codec dcdbas irqbypass serio_raw pcspkr snd_hda_core snd_hwdep snd_pcm snd_timer snd i915 video drm_kms_helper shpchp drm sg i2c_algo_bit lpc_ich mfd_core mei_me mei soundcore button parport_pc ppdev lp parport ip_tables x_tables autofs4 ext4 crc16 jbd2 crc32c_generic fscrypto ecb glue_helper lrw gf128mul ablk_helper cryptd aes_x86_64 mbcache sr_mod cdrom sd_mod hid_generic usbhid hid psmouse ahci i2c_i801 i2c_smbus libahci ehci_pci ata_generic uhci_hcd ehci_hcd libata Apr 29 23:36:35 limus kernel: [ 1556.926534] usbcore scsi_mod usb_common e1000e ptp pps_core Apr 29 23:36:35 limus kernel: [ 1556.926567] CPU: 1 PID: 1858 Comm: tvtime Not tainted 4.9.0-6-amd64 #1 Debian 4.9.82-1+deb9u3 Apr 29 23:36:35 limus kernel: [ 1556.926598] Hardware name: Dell Inc. OptiPlex 755 /0HX555, BIOS A11 08/04/2008 Apr 29 23:36:35 limus kernel: [ 1556.926629] task: ffff8d9936781080 task.stack: ffffb544014e8000 Apr 29 23:36:35 limus kernel: [ 1556.926651] RIP: 0010:[<ffffffff98a0e8be>] [<ffffffff98a0e8be>] mutex_lock+0xe/0x30 Apr 29 23:36:35 limus kernel: [ 1556.926684] RSP: 0018:ffffb544014ebde0 EFLAGS: 00010246 Apr 29 23:36:35 limus kernel: [ 1556.926705] RAX: 0000000000000000 RBX: 0000000000000139 RCX: ffffefb701df595f Apr 29 23:36:35 limus kernel: [ 1556.926731] RDX: 0000000080000000 RSI: ffff8d9976e1f980 RDI: 0000000000000139 Apr 29 23:36:35 limus kernel: [ 1556.926758] RBP: ffff8d9976e1fb40 R08: 0000000000000000 R09: 0000000000002064 Apr 29 23:36:35 limus kernel: [ 1556.926784] R10: ffffffff99118c80 R11: 0000000000000001 R12: ffff8d9977616108 Apr 29 23:36:35 limus kernel: [ 1556.926811] R13: ffff8d99776162d0 R14: ffff8d9961be5c00 R15: ffff8d997739e6c8 Apr 29 23:36:35 limus kernel: [ 1556.926838] FS: 00007fd539f22780(0000) GS:ffff8d997d240000(0000) knlGS:0000000000000000 Apr 29 23:36:35 limus kernel: [ 1556.926878] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 Apr 29 23:36:35 limus kernel: [ 1556.926900] CR2: 0000000000000139 CR3: 0000000076950000 CR4: 0000000000000670 Apr 29 23:36:35 limus kernel: [ 1556.926927] Stack: Apr 29 23:36:35 limus kernel: [ 1556.926941] 0000000000000139 ffffffffc098c041 ffff8d9976e1fb40 ffff8d9977616010 Apr 29 23:36:35 limus kernel: [ 1556.926980] ffffffffc098c06e ffff8d99776162c0 ffffffffc0aaa8b8 ffff8d99776162d0 Apr 29 23:36:35 limus kernel: [ 1556.927017] ffff8d99776162c0 ffff8d99761889c0 ffffffff98877b70 ffff8d9977616308 Apr 29 23:36:35 limus kernel: [ 1556.927053] Call Trace: Apr 29 23:36:35 limus kernel: [ 1556.927072] [<ffffffffc098c041>] ? media_remove_intf_links+0x21/0x40 [media] Apr 29 23:36:35 limus kernel: [ 1556.927100] [<ffffffffc098c06e>] ? media_devnode_remove+0xe/0x1f [media] Apr 29 23:36:35 limus kernel: [ 1556.927138] [<ffffffffc0aaa8b8>] ? v4l2_device_release+0x98/0x110 [videodev] Apr 29 23:36:35 limus kernel: [ 1556.927166] [<ffffffff98877b70>] ? device_release+0x30/0x90 Apr 29 23:36:35 limus kernel: [ 1556.927192] [<ffffffff98730648>] ? kobject_release+0x68/0x190 Apr 29 23:36:35 limus kernel: [ 1556.927219] [<ffffffffc0aa941c>] ? v4l2_release+0x4c/0x80 [videodev] Apr 29 23:36:35 limus kernel: [ 1556.927246] [<ffffffff98607968>] ? __fput+0xd8/0x220 Apr 29 23:36:35 limus kernel: [ 1556.927267] [<ffffffff984955cf>] ? task_work_run+0x7f/0xa0 Apr 29 23:36:35 limus kernel: [ 1556.927289] [<ffffffff984032c4>] ? exit_to_usermode_loop+0xa4/0xb0 Apr 29 23:36:35 limus kernel: [ 1556.927314] [<ffffffff98403bcf>] ? do_syscall_64+0xdf/0xf0 Apr 29 23:36:35 limus kernel: [ 1556.927337] [<ffffffff98a113b8>] ? entry_SYSCALL_64_after_swapgs+0x42/0xb0 Apr 29 23:36:35 limus kernel: [ 1556.927362] Code: 83 f8 01 0f 85 61 ff ff ff eb d5 e8 bd 8b a6 ff 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 66 66 66 66 90 53 48 89 fb e8 72 e4 ff ff <f0> ff 0b 79 08 48 89 df e8 b5 fe ff ff 65 48 8b 04 25 80 fb 00 Apr 29 23:36:35 limus kernel: [ 1556.927590] RIP [<ffffffff98a0e8be>] mutex_lock+0xe/0x30 Apr 29 23:36:35 limus kernel: [ 1556.927616] RSP <ffffb544014ebde0> Apr 29 23:36:35 limus kernel: [ 1556.927630] CR2: 0000000000000139 Apr 29 23:36:35 limus kernel: [ 1556.931207] ---[ end trace 035f1f95c7f9f0db ]--- Thanks, Alexandre-Xavier
