mdadm hangs when update-initramfs was run inside apt-get upgrade.

[Scott Moser]

I've run a dist-upgrade on a system with mdadm installed. This system does not have any md used. It hangs like this:

Setting up iproute2 (4.3.0-1ubuntu3.16.04.2) ...
Setting up resolvconf (1.78ubuntu5) ...
Setting up lshw (02.17-1.1ubuntu3.4) ...
Setting up golang-1.6-src (1.6.2-0ubuntu5~16.04.4) ...
Setting up golang-1.6-go (1.6.2-0ubuntu5~16.04.4) ...
Setting up iptstate (2.2.5-1ubuntu0.1) ...
Setting up mdadm (3.3-2ubuntu7.5) ...
Installing new version of config file /etc/init.d/mdadm ...
update-initramfs: deferring update (trigger activated)
Generating grub configuration file ...
Found linux image: /boot/vmlinux-4.4.0-98-generic
Found initrd image: /boot/initrd.img-4.4.0-98-generic
Found linux image: /boot/vmlinux-4.4.0-97-generic
Found initrd image: /boot/initrd.img-4.4.0-97-generic
Found linux image: /boot/vmlinux-4.4.0-96-generic
Found initrd image: /boot/initrd.img-4.4.0-96-generic
done
update-rc.d: warning: start and stop actions are no longer supported; falling ba
ck to defaults
Setting up debootstrap (1.0.78+nmu1ubuntu1.5) ...
Setting up python3-distupgrade (1:16.04.23) ...
Setting up python3-update-manager (1:16.04.10) ...
Setting up ubuntu-release-upgrader-core (1:16.04.23) ...
Setting up update-manager-core (1:16.04.10) ...
Processing triggers for resolvconf (1.78ubuntu5) ...
Processing triggers for systemd (229-4ubuntu21) ...
Processing triggers for ureadahead (0.100.0-19) ...
Processing triggers for initramfs-tools (0.122ubuntu8.9) ...
update-initramfs: Generating /boot/initrd.img-4.4.0-98-generic
W: mdadm: /etc/mdadm/mdadm.conf defines no arrays.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: mdadm 3.3-2ubuntu7.5
ProcVersionSignature: User Name 4.4.0-97.120-generic 4.4.87
Uname: Linux 4.4.0-97-generic ppc64le
NonfreeKernelModules: zfs zunicode zcommon znvpair zavl
ApportVersion: 2.20.1-0ubuntu2.10
Architecture: ppc64el
Date: Fri Nov 10 20:08:36 2017
Lsusb:
 Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MDadmExamine.dev.sda: Error: command ['/sbin/mdadm', '-E', '/dev/sda'] failed with exit code 1: mdadm: cannot open /dev/sda: Permission denied
MDadmExamine.dev.sdb: Error: command ['/sbin/mdadm', '-E', '/dev/sdb'] failed with exit code 1: mdadm: cannot open /dev/sdb: Permission denied
MDadmExamine.dev.sdc: Error: command ['/sbin/mdadm', '-E', '/dev/sdc'] failed with exit code 1: mdadm: cannot open /dev/sdc: Permission denied
MDadmExamine.dev.sdd: Error: command ['/sbin/mdadm', '-E', '/dev/sdd'] failed with exit code 1: mdadm: cannot open /dev/sdd: Permission denied
MDadmExamine.dev.sde: Error: command ['/sbin/mdadm', '-E', '/dev/sde'] failed with exit code 1: mdadm: cannot open /dev/sde: Permission denied
MDadmExamine.dev.sdf: Error: command ['/sbin/mdadm', '-E', '/dev/sdf'] failed with exit code 1: mdadm: cannot open /dev/sdf: Permission denied
MDadmExamine.dev.sdg: Error: command ['/sbin/mdadm', '-E', '/dev/sdg'] failed with exit code 1: mdadm: cannot open /dev/sdg: Permission denied
MDadmExamine.dev.sdh: Error: command ['/sbin/mdadm', '-E', '/dev/sdh'] failed with exit code 1: mdadm: cannot open /dev/sdh: Permission denied
MDadmExamine.dev.sdi: Error: command ['/sbin/mdadm', '-E', '/dev/sdi'] failed with exit code 1: mdadm: cannot open /dev/sdi: Permission denied
MDadmExamine.dev.sdj: Error: command ['/sbin/mdadm', '-E', '/dev/sdj'] failed with exit code 1: mdadm: cannot open /dev/sdj: Permission denied
MDadmExamine.dev.sdk: Error: command ['/sbin/mdadm', '-E', '/dev/sdk'] failed with exit code 1: mdadm: cannot open /dev/sdk: Permission denied
MDadmExamine.dev.sdl: Error: command ['/sbin/mdadm', '-E', '/dev/sdl'] failed with exit code 1: mdadm: cannot open /dev/sdl: Permission denied
MDadmExamine.dev.sdm: Error: command ['/sbin/mdadm', '-E', '/dev/sdm'] failed with exit code 1: mdadm: cannot open /dev/sdm: Permission denied
MDadmExamine.dev.sdn: Error: command ['/sbin/mdadm', '-E', '/dev/sdn'] failed with exit code 1: mdadm: cannot open /dev/sdn: Permission denied
MDadmExamine.dev.sdo: Error: command ['/sbin/mdadm', '-E', '/dev/sdo'] failed with exit code 1: mdadm: cannot open /dev/sdo: Permission denied
MDadmExamine.dev.sdp: Error: command ['/sbin/mdadm', '-E', '/dev/sdp'] failed with exit code 1: mdadm: cannot open /dev/sdp: Permission denied
ProcEnviron:
 TERM=screen
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: root=/dev/mapper/mpath0-part2 ro console=hvc0
ProcLoadAvg: 1.02 0.63 0.27 1/2906 154130
ProcMDstat:
 Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
 unused devices: <none>
ProcSwaps:
 Filename Type Size Used Priority
 /swap.img file 8388544 0 -1
ProcVersion: Linux version 4.4.0-97-generic (buildd@bos01-ppc64el-013) (gcc version 5.4.0 20160609 (User Name/IBM 5.4.0-6ubuntu1~16.04.4) ) #120-User Name SMP Tue Sep 19 17:26:02 UTC 2017
SourcePackage: mdadm
UpgradeStatus: No upgrade log present (probably fresh install)
cpu_cores: Number of cores present = 20
cpu_coreson: Number of cores online = 20
cpu_smt: SMT is off
etc.blkid.tab: Error: [Errno 2] No such file or directory: '/etc/blkid.tab'

[Scott Moser (smoser)]

I ended up kill -9'ing the process. and eventually it went on (not even recording an error).

Then the subsequent 'apt-get autoremove' hung again.

Reading package lists...
Building dependency tree...
Reading state information...
The following packages will be REMOVED:
  linux-headers-4.4.0-96 linux-headers-4.4.0-96-generic
  linux-image-4.4.0-96-generic linux-image-extra-4.4.0-96-generic
0 upgraded, 0 newly installed, 4 to remove and 0 not upgraded.
                                                              After this operation, 339 MB disk space will be freed.
(Reading database ... 170214 files and directories currently installed.)
Removing linux-headers-4.4.0-96-generic (4.4.0-96.119) ...
Removing linux-headers-4.4.0-96 (4.4.0-96.119) ...
Removing linux-image-extra-4.4.0-96-generic (4.4.0-96.119) ...
run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 4.4.0-96-generic /boot/vmlinux-4.4.0-96-generic
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 4.4.0-96-generic /boot/vmlinux-4.4.0-96-generic
update-initramfs: Generating /boot/initrd.img-4.4.0-96-generic
W: mdadm: /etc/mdadm/mdadm.conf defines no arrays.