[Bug 1867542] [NEW] grub stuck on loading kernel, fails to ls zfs partition

[Andreas Hasenack]

Public bug reported:

I did a fresh install on a test laptop of 20.04 a while back, and after
today's update, it no longer boots. Today's update included
2.31-0ubuntu6, but other 20.04 machines of mine also applied that and
didn't fail, so I can't really be sure it's the cause.

I also have zsys installed, and I noticed there are many snapshots of my
datasets, and grub has a new menu entry about history.

All that being said, I'm still troubleshooting and so far these are the
facts:

- partition layout:
Device       Start       End   Sectors   Size Type
/dev/sda1     2048   1050623   1048576   512M EFI System
/dev/sda2  1050624   5244927   4194304     2G Linux swap
/dev/sda3  5244928   9439231   4194304     2G Solaris boot
/dev/sda4  9439232 937703054 928263823 442.6G Solaris root

- grub hangs when doing an ls on (hd0,gpt2), which is swap
- grub hangs when doing an ls on (hd0,gpt4).
- zfs-info (from grub's command line) on gpt3 is happy. It identifies it as bpool
- zfs-info on gpt4 complains it has unsupported features, but does not hang

When booting the system, it hangs right after I select a menu entry in
grub, regardless of which one. Even the history ones from zfs hang,
although I didn't try all. It looks just like the hang on the simple ls
command.

This is grub2 2.04-1ubuntu22, and zsys 0.4.1. I'll see if I can run collect from inside the mounted system in a chroot from a rescue image, and attach info to this log.
--- 
ProblemType: Bug
ApportVersion: 2.20.11-0ubuntu20
Architecture: amd64
DistroRelease: Ubuntu 20.04
InstallationDate: Installed on 2020-02-29 (15 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Alpha amd64 (20200228)
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
Package: grub2-common 2.04-1ubuntu22
PackageArchitecture: amd64
ProcVersionSignature: Ubuntu 5.4.0-14.17-generic 5.4.18
Tags:  focal
Uname: Linux 5.4.0-14-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups:
 
_MarkForUpload: True

** Affects: grub2 (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: apport-collected focal

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https://bugs.launchpad.net/bugs/1867542

Title:
  grub stuck on loading kernel, fails to ls zfs partition

Status in grub2 package in Ubuntu:
  New

Bug description:
  I did a fresh install on a test laptop of 20.04 a while back, and
  after today's update, it no longer boots. Today's update included
  2.31-0ubuntu6, but other 20.04 machines of mine also applied that and
  didn't fail, so I can't really be sure it's the cause.

  I also have zsys installed, and I noticed there are many snapshots of
  my datasets, and grub has a new menu entry about history.

  All that being said, I'm still troubleshooting and so far these are
  the facts:

  - partition layout:
  Device       Start       End   Sectors   Size Type
  /dev/sda1     2048   1050623   1048576   512M EFI System
  /dev/sda2  1050624   5244927   4194304     2G Linux swap
  /dev/sda3  5244928   9439231   4194304     2G Solaris boot
  /dev/sda4  9439232 937703054 928263823 442.6G Solaris root

  - grub hangs when doing an ls on (hd0,gpt2), which is swap
  - grub hangs when doing an ls on (hd0,gpt4).
  - zfs-info (from grub's command line) on gpt3 is happy. It identifies it as bpool
  - zfs-info on gpt4 complains it has unsupported features, but does not hang

  When booting the system, it hangs right after I select a menu entry in
  grub, regardless of which one. Even the history ones from zfs hang,
  although I didn't try all. It looks just like the hang on the simple
  ls command.

  This is grub2 2.04-1ubuntu22, and zsys 0.4.1. I'll see if I can run collect from inside the mounted system in a chroot from a rescue image, and attach info to this log.
  --- 
  ProblemType: Bug
  ApportVersion: 2.20.11-0ubuntu20
  Architecture: amd64
  DistroRelease: Ubuntu 20.04
  InstallationDate: Installed on 2020-02-29 (15 days ago)
  InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Alpha amd64 (20200228)
  NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
  Package: grub2-common 2.04-1ubuntu22
  PackageArchitecture: amd64
  ProcVersionSignature: Ubuntu 5.4.0-14.17-generic 5.4.18
  Tags:  focal
  Uname: Linux 5.4.0-14-generic x86_64
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups:
   
  _MarkForUpload: True

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