[Bug 1791959] Re: remove /boot/initrd.img-*.old-dkms files left behind

[Brian Murray]

** Description changed:

  [Impact]
- If a dkms package is installed which has REMAKE_INITRD or the same setting has be manually configured by a user then when a kernel is removed its possible for an ".old-dkms" file to be left in /boot with no associated kernel.
+ If a dkms package is installed which has REMAKE_INITRD or the same setting has been manually configured by a user then when a kernel is removed its possible for an ".old-dkms" file to be left in /boot with no associated kernel.
  
  bug 1515513 dealt with removing initrd.img-<version>.old-dkms files
  using the kernel's prerm hook, but that is only executed for the kernel
  version being removed: any other old-dkms file generated prior to that
  would not be removed by the hook, taking space in the /boot directory.
  
  Note: Filling up the /boot partition causes updates to fail.
  
  [Test Case]
  As the fix for bug 1515513 is available on Xenial it is no longer possible to reproduce this by simply installing and updating kernels (dkms 2.2.0.3-2ubuntu11.3 would be required for that). In order to replicate it an old dkms file will be created by hand.
  
  This assumes a new Xenial schroot.
  
  1) create a file to work as a placeholder for the initrd.img old dkms file
  sudo touch /boot/initrd.img-4.0.0-0-generic.old-dkms
  
  2) install 3 old kernels, r8168-dkms, and the current initramfs-tools
  sudo apt-get install -y linux-image-4.4.0-21-generic linux-image-4.4.0-22-generic linux-image-4.4.0-24-generic r8168-dkms initramfs-tools=0.122ubuntu8.12
  
  3) install the headers for the old kernels (forces dkms to run)
  sudo apt-get install -y linux-headers-4.4.0-21-generic linux-headers-4.4.0-22-generic linux-headers-4.4.0-24-generic
  
  4) verify that there are 4 old-dkms, the manually created and one for each installed kernel
  ls /boot/*.old-dkms
  
  5) install the initramfs-tools that contains this fix
  sudo apt-get install -y initramfs-tools
  
  6) verify that the manually created old-dkms file was removed and that there are only 3 files now, one for each installed kernel
  ls /boot/*.old-dkms
  
  7) autoremove the older kernel
  sudo apt-get autoremove -y
  
  8) verify that there are now only 2 old-dkms, one for each installed kernel
  ls /boot/*.old-dkms
  
  [Regression Potential]
  Somebody out there might expect the .old-dkms file to be kept, but that seems like an odd expectation.
  
  One notices *.old-dkms files being left behind still sitting on the disk
  after purging the related kernel. This can cause /boot to become full,
  and when it gets really bad, even sudo apt-get autoremove won't fix the
  problem - only deleting the old-dkms files manually solves the problem.

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https://bugs.launchpad.net/bugs/1791959

Title:
  remove /boot/initrd.img-*.old-dkms files left behind

Status in dkms package in Ubuntu:
  Invalid
Status in initramfs-tools package in Ubuntu:
  Confirmed

Bug description:
  [Impact]
  If a dkms package is installed which has REMAKE_INITRD or the same setting has been manually configured by a user then when a kernel is removed its possible for an ".old-dkms" file to be left in /boot with no associated kernel.

  bug 1515513 dealt with removing initrd.img-<version>.old-dkms files
  using the kernel's prerm hook, but that is only executed for the
  kernel version being removed: any other old-dkms file generated prior
  to that would not be removed by the hook, taking space in the /boot
  directory.

  Note: Filling up the /boot partition causes updates to fail.

  [Test Case]
  As the fix for bug 1515513 is available on Xenial it is no longer possible to reproduce this by simply installing and updating kernels (dkms 2.2.0.3-2ubuntu11.3 would be required for that). In order to replicate it an old dkms file will be created by hand.

  This assumes a new Xenial schroot.

  1) create a file to work as a placeholder for the initrd.img old dkms file
  sudo touch /boot/initrd.img-4.0.0-0-generic.old-dkms

  2) install 3 old kernels, r8168-dkms, and the current initramfs-tools
  sudo apt-get install -y linux-image-4.4.0-21-generic linux-image-4.4.0-22-generic linux-image-4.4.0-24-generic r8168-dkms initramfs-tools=0.122ubuntu8.12

  3) install the headers for the old kernels (forces dkms to run)
  sudo apt-get install -y linux-headers-4.4.0-21-generic linux-headers-4.4.0-22-generic linux-headers-4.4.0-24-generic

  4) verify that there are 4 old-dkms, the manually created and one for each installed kernel
  ls /boot/*.old-dkms

  5) install the initramfs-tools that contains this fix
  sudo apt-get install -y initramfs-tools

  6) verify that the manually created old-dkms file was removed and that there are only 3 files now, one for each installed kernel
  ls /boot/*.old-dkms

  7) autoremove the older kernel
  sudo apt-get autoremove -y

  8) verify that there are now only 2 old-dkms, one for each installed kernel
  ls /boot/*.old-dkms

  [Regression Potential]
  Somebody out there might expect the .old-dkms file to be kept, but that seems like an odd expectation.

  One notices *.old-dkms files being left behind still sitting on the
  disk after purging the related kernel. This can cause /boot to become
  full, and when it gets really bad, even sudo apt-get autoremove won't
  fix the problem - only deleting the old-dkms files manually solves the
  problem.

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