Comment 0 for bug 1867916

After upgrading from kernel 4.15.0-88 to 4.15.0-91 one of our systems does not boot any longer. It always crashes during boot with a kernel panic.

I suspect that this crash might be related to Bcache because this is the only one of our systems where we use Bcache and the kernel panic appears right after Bcache initialization.

I already checked that this bug still exists in the 4.15.0-92.93 kernel from proposed.

Unfortunately, I cannot do a bisect because this is a critical production system and we do not have any other system with a similar configuration.

I attached a screenshot with the trace of the kernel panic.

The last message that appears before the kernel panic (or rather the last one that I can see - there is a rather long pause between that message and the panic and I cannot scroll up far enough to ensure that there are no other messages in between) is:

bcache: register_bcache() error /dev/dm-0: device already registered

When booting with kernel 4.15.0-88 that does not have this problem, the next message is

bcache: register_bcache() error /dev/dm-12: device already registered (emitting change event)

After that the next message is:

Begin: Loading essential drivers ... done

This message also appears after the kernel panic, but the boot process stalls and the system can only be recovered by doing a hardware reset.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: linux-image-4.15.0-88-generic 4.15.0-88.88
ProcVersionSignature: Ubuntu 4.15.0-88.88-generic 4.15.18
Uname: Linux 4.15.0-88-generic x86_64
AlsaDevices:
 total 0
 crw-rw---- 1 root audio 116, 1 Mar 17 21:08 seq
 crw-rw---- 1 root audio 116, 33 Mar 17 21:08 timer
AplayDevices: Error: [Errno 2] No such file or directory: 'aplay': 'aplay'
ApportVersion: 2.20.9-0ubuntu7.11
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord': 'arecord'
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
Date: Wed Mar 18 12:55:18 2020
HibernationDevice: RESUME=UUID=40512ea2-9fce-40f5-8362-5daf955cc26a
InstallationDate: Installed on 2013-07-02 (2450 days ago)
InstallationMedia: Ubuntu-Server 12.04.2 LTS "Precise Pangolin" - Release amd64 (20130214)
MachineType: HP ProLiant DL160 G6
PciMultimedia:

ProcFB: 0 mgadrmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.15.0-88-generic root=/dev/mapper/vg0-root ro nosmt nomdmonddf nomdmonisw nomdmonddf nomdmonisw nomdmonddf nomdmonisw nomdmonddf nomdmonisw nomdmonddf nomdmonisw
RelatedPackageVersions:
 linux-restricted-modules-4.15.0-88-generic N/A
 linux-backports-modules-4.15.0-88-generic N/A
 linux-firmware 1.173.16
RfKill: Error: [Errno 2] No such file or directory: 'rfkill': 'rfkill'
SourcePackage: linux
UpgradeStatus: Upgraded to bionic on 2018-09-23 (541 days ago)
dmi.bios.date: 11/06/2009
dmi.bios.vendor: HP
dmi.bios.version: O33
dmi.chassis.asset.tag: 0191525
dmi.chassis.type: 23
dmi.chassis.vendor: HP
dmi.modalias: dmi:bvnHP:bvrO33:bd11/06/2009:svnHP:pnProLiantDL160G6:pvr:cvnHP:ct23:cvr:
dmi.product.name: ProLiant DL160 G6
dmi.sys.vendor: HP