[Bug 1925211] Missing required logs.

[Ubuntu Kernel Bot]

This bug is missing log files that will aid in diagnosing the problem.
While running an Ubuntu kernel (not a mainline or third-party kernel)
please enter the following command in a terminal window:

apport-collect 1925211

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This change has been made by an automated script, maintained by the
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** Changed in: linux (Ubuntu)
       Status: New => Incomplete

** Tags added: hirsute

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https://bugs.launchpad.net/bugs/1925211

Title:
  Hot-unplug of disks leaves broken block devices around in Hirsute

Status in linux package in Ubuntu:
  Incomplete
Status in systemd package in Ubuntu:
  New
Status in udev package in Ubuntu:
  New

Bug description:
  Repro:
  # Prep a backing disk
  $ sudo fallocate -l 100M /tmp/zfsbase1
  $ sudo fallocate -l 100M /tmp/zfsbase2
  $ sudo zpool create zfsmirrortest mirror /tmp/zfsbase1 /tmp/zfsbase2
  $ sudo zfs create -V 20M zfsmirrortest/vol1
  $ cat > disk-zfs.xml << EOF
        <disk type='block' device='disk'>
           <driver name='qemu' type='raw'/>
           <source dev='/dev/zvol/zfsmirrortest/vol1'/>
           <target dev='vdc' bus='virtio'/>
        </disk>
  EOF
  # Get a guest
  $ uvt-kvm create --disk 5  --password=ubuntu h release=hirsute arch=s390x label=daily
  $ uvt-kvm wait h release=hirsute arch=s390x label=daily
  # Attach and Detach disk
  $ virsh attach-device h disk-zfs.xml
  Device attached successfully
  $ virsh detach-device h disk-zfs.xml
  Device detached successfully

  
  From libvirts POV it is gone at this point
  $ virsh domblklist h
   Target   Source
  ------------------------------------------------------------------
   vda      /var/lib/uvtool/libvirt/images/hirsute-2nd-zfs.qcow
   vdb      /var/lib/uvtool/libvirt/images/hirsute-2nd-zfs-ds.qcow

  
  But the guest thinks still it is present
  $ uvt-kvm ssh --insecure hirsute-2nd-zfs lsblk
    ...
    vdc    252:32   0   20M  0 disk

  This even remains a while after (not a race).

  Any access to it in the guest will hang (as you'd expect of a non-existing blockdev)
  4     0    1758    1739  20   0  12140  4800 -      S+   pts/0      0:00  |           \_ sudo mkfs.ext4 /dev/vdc
  4     0    1759    1758  20   0   6924  1044 -      D+   pts/0      0:00  |               \_ mkfs.ext4 /dev/vdc

  
  The result above was originally found with hirsute-guest at hirsute-host on s390x

  I do NOT see the same with  groovy-guest at hirsute-host on s390x
  I DO see the same with hirsute-guest at groovy-host on s390x
    => Guest version dependent not Host/Hipervisor dependent
  I DO see the same with ZFS disks AND LVM disks being added&removed
    => not type dependent
  I do NOT see the same on x86.
    => Arch dependent ??

  ... the evidence slowly points towards an issue in the guest, damn we are so
  close to release - but non-fully detaching disks are critical in my POV :-/

  Filing this as-is for awareness, but certainly this will need more debugging.
  Unsure where this is going to eventually I'll now file it for kernel/udev/systemd.
  If there are any known issues/components that are related let me know please!

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