Overnight, one of my machines locked up hard, and when I got it rebooted and examined the logs, I found this as the last syslog entry before the reboot:
Apr 27 01:51:59 cerberus kernel: [135061.355394] BUG: unable to handle kernel paging request at 1000
0010
Apr 27 01:51:59 cerberus kernel: [135061.356008] IP: [<c115bf51>] find_get_entry+0x31/0xa0
Apr 27 01:51:59 cerberus kernel: [135061.356008] *pdpt = 0000000033d16001 *pde = 0000000000000000
Apr 27 01:51:59 cerberus kernel: [135061.356008] Oops: 0000 [#1] SMP
Apr 27 01:51:59 cerberus kernel: [135061.356008] Modules linked in: xt_nat xt_tcpudp ipt_MASQUERADE
nf_nat_masquerade_ipv4 xt_conntrack iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 iptable
_filter ip_tables x_tables nf_nat_ftp nf_conntrack_ftp nf_nat nf_conntrack 8021q garp mrp bridge stp
llc arc4 ath5k ath mac80211 cfg80211 ppdev serio_raw matrox_w1 wire lpc_ich 8250_fintek parport_pc
mac_hid shpchp lp parport 8139too 8139cp e100 pata_acpi mii fjes
Apr 27 01:51:59 cerberus kernel: [135061.356008] CPU: 0 PID: 7080 Comm: bzip2 Not tainted 4.4.0-21-g
eneric #37~14.04.1-Ubuntu
Apr 27 01:51:59 cerberus kernel: [135061.356008] Hardware name: IBM 635033U/UV5AUL7I3DM, BIOS 20KT46
AUS 06/04/2004
Apr 27 01:51:59 cerberus kernel: [135061.356008] task: f56dd780 ti: f3182000 task.ti: f3182000
Apr 27 01:51:59 cerberus kernel: [135061.356008] EIP: 0060:[<c115bf51>] EFLAGS: 00010246 CPU: 0
Apr 27 01:51:59 cerberus kernel: [135061.356008] EIP is at find_get_entry+0x31/0xa0
Apr 27 01:51:59 cerberus kernel: [135061.356008] EAX: f34cdbb8 EBX: 0000000f ECX: 10000000 EDX: f34c
dbb8
Apr 27 01:51:59 cerberus kernel: [135061.356008] ESI: 024200ca EDI: 000001aa EBP: f3183d48 ESP: f318
3d30
Apr 27 01:51:59 cerberus kernel: [135061.356008] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
Apr 27 01:51:59 cerberus kernel: [135061.356008] CR0: 8005003b CR2: 10000010 CR3: 32fa90a0 CR4: 0000
06f0
Apr 27 01:51:59 cerberus kernel: [135061.356008] Stack:
Apr 27 01:51:59 cerberus kernel: [135061.356008] 00000000 00800001 f458f920 0000000f 024200ca 00000
000 f3183d6c c115ca14
Apr 27 01:51:59 cerberus kernel: [135061.356008] 00000000 f3183d88 000001aa f458f91c 024200ca f3c42300 00000000 f3183d7c
Apr 27 01:51:59 cerberus kernel: [135061.356008] c115cbcb 024200ca f458f838 f3183dc8 c123da0b 00001000 f3183dc8 c123e6b1
Apr 27 01:51:59 cerberus kernel: [135061.356008] Call Trace:
Apr 27 01:51:59 cerberus kernel: [135061.356008] [<c115ca14>] pagecache_get_page+0x24/0x1b0
Apr 27 01:51:59 cerberus kernel: [135061.356008] [<c115cbcb>] grab_cache_page_write_begin+0x2b/0x40
Apr 27 01:51:59 cerberus kernel: [135061.356008] [<c123da0b>] ext4_da_write_begin+0x7b/0x330
Apr 27 01:51:59 cerberus kernel: [135061.356008] [<c123e6b1>] ? ext4_da_write_end+0x131/0x310
Apr 27 01:51:59 cerberus kernel: [135061.356008] [<c115c0f4>] generic_perform_write+0xb4/0x180
Apr 27 01:51:59 cerberus kernel: [135061.356008] [<c115e32a>] __generic_file_write_iter+0x1aa/0x1f0
Apr 27 01:51:59 cerberus kernel: [135061.356008] [<c1233083>] ext4_file_write_iter+0x183/0x4a0
Apr 27 01:51:59 cerberus kernel: [135061.356008] [<c1099181>] ? set_next_entity+0x711/0xac0
Apr 27 01:51:59 cerberus kernel: [135061.356008] [<c1310dad>] ? common_file_perm+0x4d/0x180
Apr 27 01:51:59 cerberus kernel: [135061.356008] [<c11c227b>] new_sync_write+0x7b/0xb0
Apr 27 01:51:59 cerberus kernel: [135061.356008] [<c11c22ea>] __vfs_write+0x3a/0x50
Apr 27 01:51:59 cerberus kernel: [135061.356008] [<c11c2829>] vfs_write+0x89/0x1a0
Apr 27 01:51:59 cerberus kernel: [135061.356008] [<c11c3126>] SyS_write+0x46/0x90
Apr 27 01:51:59 cerberus kernel: [135061.356008] [<c100368e>] do_fast_syscall_32+0x8e/0x130
Apr 27 01:51:59 cerberus kernel: [135061.356008] [<c1750c98>] sysenter_past_esp+0x3d/0x61
Apr 27 01:51:59 cerberus kernel: [135061.356008] Code: 83 ec 0c 3e 8d 74 26 00 83 c0 04 89 d7 89 45 f0 8b 45 f0 89 fa e8 00 8b 21 00 85 c0 89 c2 74 42 8b 08 85 c9 74 26 f6 c1 03 75 57 <8b> 59 10 85 db 74 de 8d 41 10 89 45 ec 8d 73 01 89 d8 3e 0f b1
Apr 27 01:51:59 cerberus kernel: [135061.356008] EIP: [<c115bf51>] find_get_entry+0x31/0xa0 SS:ESP 0068:f3183d30
Apr 27 01:51:59 cerberus kernel: [135061.356008] CR2: 0000000010000010
Apr 27 01:51:59 cerberus kernel: [135061.963988] ---[ end trace 35c634571be2cd81 ]---
ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-4.4.0-21-generic 4.4.0-21.37~14.04.1
ProcVersionSignature: Ubuntu 4.4.0-21.37~14.04.1-generic 4.4.6
Uname: Linux 4.4.0-21-generic i686
ApportVersion: 2.14.1-0ubuntu3.19
Architecture: i386
Date: Wed Apr 27 12:26:01 2016
ProcEnviron:
TERM=xterm-256color
PATH=(custom, no user)
XDG_RUNTIME_DIR=<set>
LANG=en_US.UTF-8
SHELL=/bin/bash
SourcePackage: linux-lts-xenial
UpgradeStatus: No upgrade log present (probably fresh install)
---
AlsaDevices:
total 0
crw-rw---- 1 root audio 116, 1 Apr 27 12:16 seq
crw-rw---- 1 root audio 116, 33 Apr 27 12:16 timer
AplayDevices: Error: [Errno 2] No such file or directory
ApportVersion: 2.14.1-0ubuntu3.19
Architecture: i386
ArecordDevices: Error: [Errno 2] No such file or directory
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
CurrentDmesg:
[ 36.959653] ip_tables: (C) 2000-2006 Netfilter Core Team
[ 42.419302] init: plymouth-upstart-bridge main process ended, respawning
[ 329.702769] perf interrupt took too long (2555 > 2500), lowering kernel.perf_event_max_sample_rate to 50000
DistroRelease: Ubuntu 14.04
HibernationDevice: RESUME=UUID=c05fc47c-c9dc-4c55-bd30-320e2185fa37
Lsusb:
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
MachineType: IBM 635033U
Package: linux (not installed)
PciMultimedia:
ProcEnviron:
TERM=xterm-256color
PATH=(custom, no user)
XDG_RUNTIME_DIR=<set>
LANG=en_US.UTF-8
SHELL=/bin/bash
ProcFB: 0 VESA VGA
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-21-generic root=UUID=147eee03-cadf-4d37-bf4e-ff2954ef8ac3 ro splash quiet vt.handoff=7
ProcVersionSignature: Ubuntu 4.4.0-21.37~14.04.1-generic 4.4.6
RelatedPackageVersions:
linux-restricted-modules-4.4.0-21-generic N/A
linux-backports-modules-4.4.0-21-generic N/A
linux-firmware 1.127.22
RfKill: Error: [Errno 2] No such file or directory
Tags: trusty
Uname: Linux 4.4.0-21-generic i686
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
_MarkForUpload: True
dmi.bios.date: 06/04/2004
dmi.bios.vendor: IBM
dmi.bios.version: 20KT46AUS
dmi.board.name: UV5AUL7I3DM
dmi.board.vendor: IBM
dmi.chassis.asset.tag: Tag 12345
dmi.chassis.type: 6
dmi.chassis.vendor: IBM
dmi.modalias: dmi:bvnIBM:bvr20KT46AUS:bd06/04/2004:svnIBM:pn635033U:pvr:rvnIBM:rnUV5AUL7I3DM:rvr:cvnIBM:ct6:cvr:
dmi.product.name: 635033U
dmi.sys.vendor: IBM
Note that, coincidentally, a Windows host on the same network *also* bluescreened last night. If there's any chance the above could have been cause by, say, a power brownout, it's entirely possibly both machines were a victim of circumstance rather than bad code. Still, the bit where the kernel was able to register a BUG in the ringbuffer before locking up seems to indicate something worth reporting.