Comment 0 for bug 1651435

I have a KVM guest system which was running for some time now (142 days uptime).

Today, I logged in for the first time since months, and got an error message in syslog (and console):

kernel: BTRFS error (device vda2): could not find root 8

The error happened together with my login (in respect to the date of the log entry).

The system was running with kernel 4.4.0-31-generic when the problem occured.

When googling around, I found some similar results, but nowhere is mentioned that this got fixed somehow.

So far, I could not find anything harmful (I did not reboot yet, however).

I updated the kernel now, eventually that helps.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: linux-image-4.4.0-31-generic 4.4.0-31.50
ProcVersionSignature: Ubuntu 4.4.0-31.50-generic 4.4.13
Uname: Linux 4.4.0-31-generic x86_64
AlsaDevices:
 total 0
 crw-rw----+ 1 root audio 116, 1 Dec 20 13:00 seq
 crw-rw----+ 1 root audio 116, 33 Dec 20 13:00 timer
AplayDevices: Error: [Errno 2] No such file or directory: 'aplay'
ApportVersion: 2.20.1-0ubuntu2.4
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord'
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
Date: Tue Dec 20 13:40:44 2016
HibernationDevice: RESUME=UUID=419693f3-cd92-4870-a16a-7bede16d9b8a
InstallationDate: Installed on 2016-06-20 (182 days ago)
InstallationMedia: Ubuntu-Server 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.3)
IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig'
Lsusb:
 Bus 001 Device 002: ID 0627:0001 Adomax Technology Co., Ltd
 Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
MachineType: QEMU Standard PC (i440FX + PIIX, 1996)
PciMultimedia:

ProcEnviron:
 TERM=linux
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcFB: 0 cirrusdrmfb
ProcKernelCmdLine: BOOT_IMAGE=/@/boot/vmlinuz-4.4.0-31-generic root=UUID=ebfbbec2-f4df-4e40-92a5-3db6b57eb8f5 ro rootflags=subvol=@
RelatedPackageVersions:
 linux-restricted-modules-4.4.0-31-generic N/A
 linux-backports-modules-4.4.0-31-generic N/A
 linux-firmware 1.157.6
RfKill: Error: [Errno 2] No such file or directory: 'rfkill'
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/01/2014
dmi.bios.vendor: SeaBIOS
dmi.bios.version: 1.7.5-20140531_083030-gandalf
dmi.chassis.type: 1
dmi.chassis.vendor: QEMU
dmi.chassis.version: pc-i440fx-2.1
dmi.modalias: dmi:bvnSeaBIOS:bvr1.7.5-20140531_083030-gandalf:bd04/01/2014:svnQEMU:pnStandardPC(i440FX+PIIX,1996):pvrpc-i440fx-2.1:cvnQEMU:ct1:cvrpc-i440fx-2.1:
dmi.product.name: Standard PC (i440FX + PIIX, 1996)
dmi.product.version: pc-i440fx-2.1
dmi.sys.vendor: QEMU