cryptsetup: WARNING: could not determine root device from /etc/fstab

[Danny Howard]

My system can not reboot on its default kernel. I get a kernel panic:

VFS: Cannot open root device "md0p1" or unknown-block(0,0): error -6

I go to grub and boot the previous kernel successfully.

0-16:29 djh@c24-03-01 ~> uname -a
Linux c24-03-01.mtv.quantifind.com 5.3.0-47-generic #39~18.04.1-Ubuntu SMP Mon Apr 6 17:04:32 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
0-16:29 djh@c24-03-01 ~> sudo update-initramfs -u -k 5.3.0-51-generic
update-initramfs: Generating /boot/initrd.img-5.3.0-51-generic
cryptsetup: WARNING: failed to detect canonical device of /dev/md0p1
cryptsetup: WARNING: could not determine root device from /etc/fstab

Here is what I have got:

0-16:29 djh@c24-03-01 ~> cat /etc/fstab
# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point> <type> <options> <dump> <pass>
# / was on /dev/md0p1 during curtin installation
/dev/md0p1 / ext4 defaults 0 0
# /boot/efi was on /dev/sdc1 during curtin installation
/dev/disk/by-uuid/0386-D289 /boot/efi vfat defaults 0 0
/swap.img none swap sw 0 0
0-16:30 djh@c24-03-01 ~> cat /proc/mdstat
Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10]
md0 : active raid1 sdf2[0] sde2[1]
      233772032 blocks super 1.2 [2/2] [UU]
      bitmap: 2/2 pages [8KB], 65536KB chunk

unused devices: <none>
0-16:30 djh@c24-03-01 ~> cat /etc/crypttab
# <target name> <source device> <key file> <options>
luks-sda /dev/sda /etc/luks-keyfile luks
luks-sdb /dev/sdb /etc/luks-keyfile luks
luks-sdc /dev/sdc /etc/luks-keyfile luks
luks-sdd /dev/sdd /etc/luks-keyfile luks

The luks devices go into LVM and are used by ganeti.

0-16:30 djh@c24-03-01 ~> apt show cryptsetup
Package: cryptsetup
Version: 2:2.0.2-1ubuntu1.1
[ . . . ]
0-16:31 djh@c24-03-01 ~> apt show cryptsetup-bin
Package: cryptsetup-bin
Version: 2:2.0.2-1ubuntu1.1

Possibly-related issue upstream. It looks like debian has a newer version?

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=784881

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: linux-image-5.3.0-47-generic 5.3.0-47.39~18.04.1
ProcVersionSignature: Ubuntu 5.3.0-47.39~18.04.1-generic 5.3.18
Uname: Linux 5.3.0-47-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.14
Architecture: amd64
Date: Thu Apr 30 16:33:32 2020
InstallationDate: Installed on 2020-02-27 (63 days ago)
InstallationMedia: Ubuntu-Server 18.04.4 LTS "Bionic Beaver" - Release amd64 (20200203.1)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/usr/bin/fish
SourcePackage: linux-signed-hwe
UpgradeStatus: No upgrade log present (probably fresh install)

[Danny Howard (dannyman)]

If I set the UUID of /, the warnings from update-initramfs disappear.

0-16:40 djh@c24-03-01 ~> grep UUID /etc/fstab
# device; this may be used with UUID= as a more robust way to name devices
UUID="9d35e010-3466-4f75-8adb-cd770c67762c" / ext4 defaults 0 0
0-16:39 djh@c24-03-01 ~> sudo update-initramfs -u -k 5.3.0-51-generic
update-initramfs: Generating /boot/initrd.img-5.3.0-51-generic

Bootstrap on the kernel yields the same kernel panic, though.

[Danny Howard (dannyman)]

I have experienced this now, on a VM. Kernel Panic,with:

Cannot open root device "vda1" or unknown-block(0,0): error -6

5.3.0-53-generic

I reboot and manually select the older kernel from GRUB. (4.15.0-101-generic)

If I do this:

djh@stage-batchexecutionservice0 ~>
sudo update-initramfs -u -k 5.3.0-53-generic
[sudo] password for djh:
update-initramfs: Generating /boot/initrd.img-5.3.0-53-generic
djh@stage-batchexecutionservice0 ~> sudo reboot

I reproduce the kernel panic.