Removing kernel packages leads to initrd regens, reboot-required

[Daniel Richard G.]

This concerns linux-base 4.0ubuntu1 in Ubuntu Xenial.

Removing Linux kernel packages from the system leads to initrd generation and causes /var/run/reboot-required to appear. Neither of these side effects should occur if only kernel packages older than the running one are removed, a common operation in system maintenance.

Below is a terminal session illustrating the problem. Note the update-initramfs lines indicating that an initrd is being (re)generated. The removal process paused for a few seconds at these lines, because generating an initrd is somewhat disk- and CPU-intensive. (Look closely at the versions of the initrd that are generated---the system is refreshing initrd files for the kernel versions that are being removed!)

==== Terminal log begins ====

# ls /var/run/reboot-required
ls: cannot access '/var/run/reboot-required': No such file or directory

# apt-get --purge autoremove
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
  linux-headers-4.4.0-83* linux-headers-4.4.0-83-generic*
  linux-headers-4.4.0-87* linux-headers-4.4.0-87-generic*
  linux-headers-4.4.0-89* linux-headers-4.4.0-89-generic*
  linux-headers-4.4.0-91* linux-headers-4.4.0-91-generic*
  linux-image-4.4.0-83-generic* linux-image-4.4.0-87-generic*
  linux-image-4.4.0-89-generic* linux-image-4.4.0-91-generic*
  linux-image-extra-4.4.0-83-generic* linux-image-extra-4.4.0-87-generic*
  linux-image-extra-4.4.0-89-generic* linux-image-extra-4.4.0-91-generic*
0 upgraded, 0 newly installed, 16 to remove and 0 not upgraded.
After this operation, 1,188 MB disk space will be freed.
Do you want to continue? [Y/n]
(Reading database ... 353048 files and directories currently installed.)
Removing linux-headers-4.4.0-83-generic (4.4.0-83.106) ...
Removing linux-headers-4.4.0-83 (4.4.0-83.106) ...
Removing linux-headers-4.4.0-87-generic (4.4.0-87.110) ...
Removing linux-headers-4.4.0-87 (4.4.0-87.110) ...
Removing linux-headers-4.4.0-89-generic (4.4.0-89.112) ...
Removing linux-headers-4.4.0-89 (4.4.0-89.112) ...
Removing linux-headers-4.4.0-91-generic (4.4.0-91.114) ...
Removing linux-headers-4.4.0-91 (4.4.0-91.114) ...
Removing linux-image-extra-4.4.0-83-generic (4.4.0-83.106) ...
run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 4.4.0-83-generic /boot/vmlinuz-4.4.0-83-generic
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 4.4.0-83-generic /boot/vmlinuz-4.4.0-83-generic
update-initramfs: Generating /boot/initrd.img-4.4.0-83-generic
run-parts: executing /etc/kernel/postinst.d/pm-utils 4.4.0-83-generic /boot/vmlinuz-4.4.0-83-generic
run-parts: executing /etc/kernel/postinst.d/unattended-upgrades 4.4.0-83-generic /boot/vmlinuz-4.4.0-83-generic
run-parts: executing /etc/kernel/postinst.d/update-notifier 4.4.0-83-generic /boot/vmlinuz-4.4.0-83-generic
run-parts: executing /etc/kernel/postinst.d/zz-update-grub 4.4.0-83-generic /boot/vmlinuz-4.4.0-83-generic
Generating grub configuration file ...
Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported.
Found linux image: /boot/vmlinuz-4.4.0-96-generic
Found initrd image: /boot/initrd.img-4.4.0-96-generic
Found linux image: /boot/vmlinuz-4.4.0-93-generic
Found initrd image: /boot/initrd.img-4.4.0-93-generic
Found linux image: /boot/vmlinuz-4.4.0-92-generic
Found initrd image: /boot/initrd.img-4.4.0-92-generic
Found linux image: /boot/vmlinuz-4.4.0-91-generic
Found initrd image: /boot/initrd.img-4.4.0-91-generic
Found linux image: /boot/vmlinuz-4.4.0-89-generic
Found initrd image: /boot/initrd.img-4.4.0-89-generic
Found linux image: /boot/vmlinuz-4.4.0-87-generic
Found initrd image: /boot/initrd.img-4.4.0-87-generic
Found linux image: /boot/vmlinuz-4.4.0-83-generic
Found initrd image: /boot/initrd.img-4.4.0-83-generic
Found memtest86+ image: /boot/memtest86+.elf
Found memtest86+ image: /boot/memtest86+.bin
done
Purging configuration files for linux-image-extra-4.4.0-83-generic (4.4.0-83.106) ...
Removing linux-image-4.4.0-83-generic (4.4.0-83.106) ...
Examining /etc/kernel/postrm.d .
run-parts: executing /etc/kernel/postrm.d/initramfs-tools 4.4.0-83-generic /boot/vmlinuz-4.4.0-83-generic
update-initramfs: Deleting /boot/initrd.img-4.4.0-83-generic
run-parts: executing /etc/kernel/postrm.d/zz-update-grub 4.4.0-83-generic /boot/vmlinuz-4.4.0-83-generic
Generating grub configuration file ...
Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported.
Found linux image: /boot/vmlinuz-4.4.0-96-generic
Found initrd image: /boot/initrd.img-4.4.0-96-generic
Found linux image: /boot/vmlinuz-4.4.0-93-generic
Found initrd image: /boot/initrd.img-4.4.0-93-generic
Found linux image: /boot/vmlinuz-4.4.0-92-generic
Found initrd image: /boot/initrd.img-4.4.0-92-generic
Found linux image: /boot/vmlinuz-4.4.0-91-generic
Found initrd image: /boot/initrd.img-4.4.0-91-generic
Found linux image: /boot/vmlinuz-4.4.0-89-generic
Found initrd image: /boot/initrd.img-4.4.0-89-generic
Found linux image: /boot/vmlinuz-4.4.0-87-generic
Found initrd image: /boot/initrd.img-4.4.0-87-generic
Found memtest86+ image: /boot/memtest86+.elf
Found memtest86+ image: /boot/memtest86+.bin
done
Purging configuration files for linux-image-4.4.0-83-generic (4.4.0-83.106) ...
Examining /etc/kernel/postrm.d .
run-parts: executing /etc/kernel/postrm.d/initramfs-tools 4.4.0-83-generic /boot/vmlinuz-4.4.0-83-generic
run-parts: executing /etc/kernel/postrm.d/zz-update-grub 4.4.0-83-generic /boot/vmlinuz-4.4.0-83-generic
Removing linux-image-extra-4.4.0-87-generic (4.4.0-87.110) ...
run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 4.4.0-87-generic /boot/vmlinuz-4.4.0-87-generic
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 4.4.0-87-generic /boot/vmlinuz-4.4.0-87-generic
update-initramfs: Generating /boot/initrd.img-4.4.0-87-generic
run-parts: executing /etc/kernel/postinst.d/pm-utils 4.4.0-87-generic /boot/vmlinuz-4.4.0-87-generic
run-parts: executing /etc/kernel/postinst.d/unattended-upgrades 4.4.0-87-generic /boot/vmlinuz-4.4.0-87-generic
run-parts: executing /etc/kernel/postinst.d/update-notifier 4.4.0-87-generic /boot/vmlinuz-4.4.0-87-generic
run-parts: executing /etc/kernel/postinst.d/zz-update-grub 4.4.0-87-generic /boot/vmlinuz-4.4.0-87-generic
Generating grub configuration file ...
Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported.
Found linux image: /boot/vmlinuz-4.4.0-96-generic
Found initrd image: /boot/initrd.img-4.4.0-96-generic
Found linux image: /boot/vmlinuz-4.4.0-93-generic
Found initrd image: /boot/initrd.img-4.4.0-93-generic
Found linux image: /boot/vmlinuz-4.4.0-92-generic
Found initrd image: /boot/initrd.img-4.4.0-92-generic
Found linux image: /boot/vmlinuz-4.4.0-91-generic
Found initrd image: /boot/initrd.img-4.4.0-91-generic
Found linux image: /boot/vmlinuz-4.4.0-89-generic
Found initrd image: /boot/initrd.img-4.4.0-89-generic
Found linux image: /boot/vmlinuz-4.4.0-87-generic
Found initrd image: /boot/initrd.img-4.4.0-87-generic
Found memtest86+ image: /boot/memtest86+.elf
Found memtest86+ image: /boot/memtest86+.bin
done
Purging configuration files for linux-image-extra-4.4.0-87-generic (4.4.0-87.110) ...
Removing linux-image-4.4.0-87-generic (4.4.0-87.110) ...
Examining /etc/kernel/postrm.d .
run-parts: executing /etc/kernel/postrm.d/initramfs-tools 4.4.0-87-generic /boot/vmlinuz-4.4.0-87-generic
update-initramfs: Deleting /boot/initrd.img-4.4.0-87-generic
run-parts: executing /etc/kernel/postrm.d/zz-update-grub 4.4.0-87-generic /boot/vmlinuz-4.4.0-87-generic
Generating grub configuration file ...
Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported.
Found linux image: /boot/vmlinuz-4.4.0-96-generic
Found initrd image: /boot/initrd.img-4.4.0-96-generic
Found linux image: /boot/vmlinuz-4.4.0-93-generic
Found initrd image: /boot/initrd.img-4.4.0-93-generic
Found linux image: /boot/vmlinuz-4.4.0-92-generic
Found initrd image: /boot/initrd.img-4.4.0-92-generic
Found linux image: /boot/vmlinuz-4.4.0-91-generic
Found initrd image: /boot/initrd.img-4.4.0-91-generic
Found linux image: /boot/vmlinuz-4.4.0-89-generic
Found initrd image: /boot/initrd.img-4.4.0-89-generic
Found memtest86+ image: /boot/memtest86+.elf
Found memtest86+ image: /boot/memtest86+.bin
done
Purging configuration files for linux-image-4.4.0-87-generic (4.4.0-87.110) ...
Examining /etc/kernel/postrm.d .
run-parts: executing /etc/kernel/postrm.d/initramfs-tools 4.4.0-87-generic /boot/vmlinuz-4.4.0-87-generic
run-parts: executing /etc/kernel/postrm.d/zz-update-grub 4.4.0-87-generic /boot/vmlinuz-4.4.0-87-generic
Removing linux-image-extra-4.4.0-89-generic (4.4.0-89.112) ...
run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 4.4.0-89-generic /boot/vmlinuz-4.4.0-89-generic
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 4.4.0-89-generic /boot/vmlinuz-4.4.0-89-generic
update-initramfs: Generating /boot/initrd.img-4.4.0-89-generic
run-parts: executing /etc/kernel/postinst.d/pm-utils 4.4.0-89-generic /boot/vmlinuz-4.4.0-89-generic
run-parts: executing /etc/kernel/postinst.d/unattended-upgrades 4.4.0-89-generic /boot/vmlinuz-4.4.0-89-generic
run-parts: executing /etc/kernel/postinst.d/update-notifier 4.4.0-89-generic /boot/vmlinuz-4.4.0-89-generic
run-parts: executing /etc/kernel/postinst.d/zz-update-grub 4.4.0-89-generic /boot/vmlinuz-4.4.0-89-generic
Generating grub configuration file ...
Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported.
Found linux image: /boot/vmlinuz-4.4.0-96-generic
Found initrd image: /boot/initrd.img-4.4.0-96-generic
Found linux image: /boot/vmlinuz-4.4.0-93-generic
Found initrd image: /boot/initrd.img-4.4.0-93-generic
Found linux image: /boot/vmlinuz-4.4.0-92-generic
Found initrd image: /boot/initrd.img-4.4.0-92-generic
Found linux image: /boot/vmlinuz-4.4.0-91-generic
Found initrd image: /boot/initrd.img-4.4.0-91-generic
Found linux image: /boot/vmlinuz-4.4.0-89-generic
Found initrd image: /boot/initrd.img-4.4.0-89-generic
Found memtest86+ image: /boot/memtest86+.elf
Found memtest86+ image: /boot/memtest86+.bin
done
Purging configuration files for linux-image-extra-4.4.0-89-generic (4.4.0-89.112) ...
Removing linux-image-4.4.0-89-generic (4.4.0-89.112) ...
Examining /etc/kernel/postrm.d .
run-parts: executing /etc/kernel/postrm.d/initramfs-tools 4.4.0-89-generic /boot/vmlinuz-4.4.0-89-generic
update-initramfs: Deleting /boot/initrd.img-4.4.0-89-generic
run-parts: executing /etc/kernel/postrm.d/zz-update-grub 4.4.0-89-generic /boot/vmlinuz-4.4.0-89-generic
Generating grub configuration file ...
Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported.
Found linux image: /boot/vmlinuz-4.4.0-96-generic
Found initrd image: /boot/initrd.img-4.4.0-96-generic
Found linux image: /boot/vmlinuz-4.4.0-93-generic
Found initrd image: /boot/initrd.img-4.4.0-93-generic
Found linux image: /boot/vmlinuz-4.4.0-92-generic
Found initrd image: /boot/initrd.img-4.4.0-92-generic
Found linux image: /boot/vmlinuz-4.4.0-91-generic
Found initrd image: /boot/initrd.img-4.4.0-91-generic
Found memtest86+ image: /boot/memtest86+.elf
Found memtest86+ image: /boot/memtest86+.bin
done
Purging configuration files for linux-image-4.4.0-89-generic (4.4.0-89.112) ...
Examining /etc/kernel/postrm.d .
run-parts: executing /etc/kernel/postrm.d/initramfs-tools 4.4.0-89-generic /boot/vmlinuz-4.4.0-89-generic
run-parts: executing /etc/kernel/postrm.d/zz-update-grub 4.4.0-89-generic /boot/vmlinuz-4.4.0-89-generic
Removing linux-image-extra-4.4.0-91-generic (4.4.0-91.114) ...
run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 4.4.0-91-generic /boot/vmlinuz-4.4.0-91-generic
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 4.4.0-91-generic /boot/vmlinuz-4.4.0-91-generic
update-initramfs: Generating /boot/initrd.img-4.4.0-91-generic
run-parts: executing /etc/kernel/postinst.d/pm-utils 4.4.0-91-generic /boot/vmlinuz-4.4.0-91-generic
run-parts: executing /etc/kernel/postinst.d/unattended-upgrades 4.4.0-91-generic /boot/vmlinuz-4.4.0-91-generic
run-parts: executing /etc/kernel/postinst.d/update-notifier 4.4.0-91-generic /boot/vmlinuz-4.4.0-91-generic
run-parts: executing /etc/kernel/postinst.d/zz-update-grub 4.4.0-91-generic /boot/vmlinuz-4.4.0-91-generic
Generating grub configuration file ...
Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported.
Found linux image: /boot/vmlinuz-4.4.0-96-generic
Found initrd image: /boot/initrd.img-4.4.0-96-generic
Found linux image: /boot/vmlinuz-4.4.0-93-generic
Found initrd image: /boot/initrd.img-4.4.0-93-generic
Found linux image: /boot/vmlinuz-4.4.0-92-generic
Found initrd image: /boot/initrd.img-4.4.0-92-generic
Found linux image: /boot/vmlinuz-4.4.0-91-generic
Found initrd image: /boot/initrd.img-4.4.0-91-generic
Found memtest86+ image: /boot/memtest86+.elf
Found memtest86+ image: /boot/memtest86+.bin
done
Purging configuration files for linux-image-extra-4.4.0-91-generic (4.4.0-91.114) ...
Removing linux-image-4.4.0-91-generic (4.4.0-91.114) ...
Examining /etc/kernel/postrm.d .
run-parts: executing /etc/kernel/postrm.d/initramfs-tools 4.4.0-91-generic /boot/vmlinuz-4.4.0-91-generic
update-initramfs: Deleting /boot/initrd.img-4.4.0-91-generic
run-parts: executing /etc/kernel/postrm.d/zz-update-grub 4.4.0-91-generic /boot/vmlinuz-4.4.0-91-generic
Generating grub configuration file ...
Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported.
Found linux image: /boot/vmlinuz-4.4.0-96-generic
Found initrd image: /boot/initrd.img-4.4.0-96-generic
Found linux image: /boot/vmlinuz-4.4.0-93-generic
Found initrd image: /boot/initrd.img-4.4.0-93-generic
Found linux image: /boot/vmlinuz-4.4.0-92-generic
Found initrd image: /boot/initrd.img-4.4.0-92-generic
Found memtest86+ image: /boot/memtest86+.elf
Found memtest86+ image: /boot/memtest86+.bin
done
Purging configuration files for linux-image-4.4.0-91-generic (4.4.0-91.114) ...
Examining /etc/kernel/postrm.d .
run-parts: executing /etc/kernel/postrm.d/initramfs-tools 4.4.0-91-generic /boot/vmlinuz-4.4.0-91-generic
run-parts: executing /etc/kernel/postrm.d/zz-update-grub 4.4.0-91-generic /boot/vmlinuz-4.4.0-91-generic

# cat /var/run/reboot-required
*** System restart required ***

# cat /var/run/reboot-required.pkgs
linux-base
linux-base
linux-base
linux-base

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.