How to debug a kernel panic? Ubuntu 14.04
https://askubuntu.com/questions/531249/how-to-debug-a-kernel-panic-ubuntu-14-04
So, I have been having kernel panics. My computer will suddenly come off and then a dmesg like output shows on the screen. The first two lines read
[20352.651631] BUG: Unable to handle kernel NULL pointer dereference at 0000000000000028
[20352.651667] IP: [<ffffffff8158a7bb>] input_event+0x2b/70
And the last two lines
[20352.662214] Kernel panic - not syncing: Fatal exception in interrupt.
[20352.662214] drm_kms_helper: panic occurred, switching to text console
Kernel panic - not syncing: Fatal exception in interrupt:
[20352.651631] BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
[20352.651687] IP: [<ffffffff8158a7bb>] input_event+0x2b/0x70
[20352.651685] PGD 32bc2b067 PUD 32499a067 PMD 0
[20352.651698] Oops: 0000 [#1] SMP
[20352.651715] Modules linked in: wacom hid alx mdio pci_stub vboxpci(OX) vboxnetadp(OX) vboxnetflt(OX) vboxdrv(OX) btrfs raid6_pq xor ufs qnx4 hfsplus hfs minix ntfs msdos jfs xfs libcrc32c bnep rfcomm dm_crypt uvcvideo videobuf2_vmalloc v
ideobuf2_memops arc4 videobuf2_core videodev iwldvm x86_pkg_temp_thermal intel_powerclamp kvm_intel mac80211 binfmt_misc brcmfmac brcmutil cfg80111 brcmfmac_pci_m1 mac80211 bluetooth ghash_clmulni_intel aes_x86_64 iulwifi iru gf128mul glue_
helper rtsx_pci_ms ablk_helper cfg80211 memstick cryptd toshiba_acpi sparse_keymap toshiba_bluetooth joydev nls_iso8859_1 snd_hda_codec_hdmi snd_hda_codec_conexant snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_page_alloc snd_seq_midi sn
d_seq_midi_event snd_rawmidi snd_seq snd_seq_device snd_timer snd mei_me soundcore mei lpc_ich serio_raw mac_hid rtsx_pci_sdmmc ahci psmouse libahci rtsx_pci i915(OX) i2c_algo_bit drm_kms_helper(OX) wmi
drm(OX) video [last unloaded: mdio]
[20352.652040] CPU: 0 PID: 6279 Comm: systemd-udevd Tainted: G IOX 3.13.0-36-generic #63-Ubuntu
[20352.652062] Hardware name: TOSHIBA Satellite P75-A/Type2 - Board Product Name1, BIOS 1.00 05/02/2013
[20352.652084] task: ffff8801fbde2000 ti: ffff8801fdbe2000 task.ti: ffff8801fdbe2000
[20352.652102] RIP: 0010: [<ffffffff8158a7bb>] [<ffffffff8158a7bb>] input_event+0x2b/0x70
[20352.652123] RSP: 0018:ffff88035f203cd0 EFLAGS: 00010082
[20352.652136] RAX: 0000000000000005 RBX: 0000000000000001 RCX: 0000000000000000
[20352.652154] RDX: 000000000000000e RSI: 0000000000000001 RDI: 0000000000000000
[20352.652171] RBP: ffff88035f203cf8 R08: 0000000000000009 R09: 000000000000000a
[20352.652187] R10: ffffea000d1fbc80 R11: ffff88010059fcc0 R12: 0000000000000000
[20352.652204] R13: ffff880256487030 R14: ffff880051dde420 R15: ffff88003fd561e8
[20352.652221] FS: 00007fe2e7698880(0000) GS:ffff88035f200000(0000) knlGS:0000000000000000
[20352.652241] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[20352.652259] CR2: 0000000000000028 CR3: 00000002bbabc000 CR4: 00000000001427f0
[20352.652286] Stack:
[20352.652292] 000000003bd7b9b8 000000050000000e ffff8803488ae800 0000000000000000
[20352.652312] ffff880256487030 ffff88035f203d60 ffffffff809e4907 000000005bddef00
[20352.652331] 0000000000000000 ffff88033bd7b9c8 ffff88033bd7b9c0 0000000000000046
[20352.652351] Call Trace:
[20352.652358] <IRQ>
[20352.652364] [<ffffffffa09e4907>] wacom_wac_irq+0x19b7/0x1af0 [wacom]
[20352.652384] [<ffffffffa09e57ac>] wacom_sys_irq+0x4c/0x110 [wacom]
[20352.652401] [<ffffffff81541397>] __usb_hcd_giveback_urb+0x77/0x100
[20352.652417] [<ffffffff8154145f>] usb_hcd_giveback_urb+0x3f/0x140
[20352.652433] [<ffffffff8157bf5b>] handle_tx_event+0x41b/0x1380
[20352.652448] [<ffffffff8157d176>] xhci_irq+0x2b6/0x4a0
[20352.652463] [<ffffffff814d8c50>] ? scsi_finish_command+0xb0/0x110
[20352.652479] [<ffffffff8157d931>] xhci_msi_irq+0x11/0x20
[20352.652494] [<ffffffff810bf88e>] handle_irq_event_percpu+0x3e/0x1d0
[20352.652510] [<ffffffff810bfa8d>] handle_irq_event+0x3d/0x60
[20352.652525] [<ffffffff810c2517>] handle_edge_irq+0x77/0x130
[20352.652541] [<ffffffff81015cde>] handle_irq+0x1e/0x30
[20352.652556] [<ffffffff817312cd>] do_IRQ+0x4d/0xc0
[20352.652569] [<ffffffff81726a6d>] common_interrupt+0x6d/0x6d
[20352.652582] <EOI>
[20352.652587] [<ffffffff8132cbd7>] ? sha512_transform+0x117/0x560
[20352.652608] [<ffffffff8132d1f1>] crypto_sha512_update+0xd1/0x100
[20352.652624] [<ffffffff81320988>] shash_update+0x38/0x100
[20352.652640] [<ffffffff81320b17>] shash_finup_unaligned+0x17/0x30
[20352.652655] [<ffffffff81320b4f>] crypto_shash_finup+0x1f/0x40
[20352.652671] [<ffffffff810e3518>] mod_verify_sig+0x278/0x440
[20352.652685] [<ffffffff810e3be7>] load_module+0x1eb/0x1b40
[20352.652700] [<ffffffff811bd0be>] ? vfs_read+0xee/0x160
[20352.652713] [<ffffffff811c2db1>] ? kernel_read+0x41/0x60
[20352.652728] [<ffffffff810e582b>] ? copy_module_from_fd.isra.46+0x12a/0x190
[20352.652745] [<ffffffff810e5b63>] SyS_finit_module+0x83/0xb0
[20352.652760] [<ffffffff8172efad>] system_call_fastpath+0x1a/0x1f
[20352.652774] Code: 0f 1f 44 00 00 83 fe 1f 76 06 c3 0f 1f 44 00 00 55 89 f0 48 89 e5 41 55 41 54 53 48 89 fb 48 83 ec 10 89 4d dc 89 55 e0 89 75 e4 <48> 8b 4f 28 47 28 19 c0 85 c0 74 2e 4c 8d a7 10 02 00 00 4c 89 e7
[20352.652845] RIP [<ffffffff8158a7bb>] input_event+0x2b/0x70
[20352.652860] RSP <ffff88035f203cd0>
[20352.652869] CR2: 0000000000000028
[20352.662195] Kernel panic - not syncing: Fatal exception in interrupt
[20352.662214] drm_kms_helper: panic occurred, switching back to text console
I would post directly but it doesn't let me. Also, I can't find the dmesg output. I ran
sudo grep -nri panic /var/log/
zgrep -ni panic /var/log/dmesg.*.gz
zgrep -ni panic /var/log/kern.log.*.gz
All I got was registered panic notifier but nothing about the crash.
It happened a few times in the last month, and I haven't been doing anything in particular that I can see for this to happen. Usually I'm browsing the web or watching videos or writing up homework and suddenly, crash. The screen goes dark, text outputs, and I can't do anything until I manually switch the computer off and on. When it comes back on, everything seems to be perfectly normal and it won't crash again for a week or so.
I have also been reading https://wiki.ubuntu.com/Kernel/KernelDebuggingTricks but I can't make much out of it. I'll go over it with some more detail, but I'd really appreciate some advice on how to get started with the debugging.
It happened again. I've posted a picture and corrected what it said. I finally have time since it's the weekend. I'll run memtest and try to reproduce the panic at home. Just to be clear, my computer boots and works just fine. Nothing weird happens that I can notice, until it crashes, that is.