Preliminary note: I'm still trying to figure out what package/change is causing
this or when exactly this started. I'm updating on a daily basis. Unfortunately
so far I can only describe the symptom.

Problem: Shutdown scripts run in an infinite loop (ran at least for ~ 15
minutes) upon reboot or shutdown.

Console shows:
 Stopping MD /dev/md1 (9:1).
 Could not stop MD /dev/md1: Device or resource busy
 Not all MD devices stopped, 1 left.
 Detaching DM devices.
 Not all DM devices detached, 1 left.
 Stopping MD devices.
 Stopping MD /dev/md2 (9:2).
 md: md2 stopped.
 Stopping MD /dev/md1 (9:1).
 Could not stop MD /dev/md1: Device or resource busy
 Not all MD devices stopped, 1 left.
 Detaching DM devices.
 ...

The cycle repeats.

Now, /dev/md1 holds /dev/ssd/root and thus it might a busy because of some
other dependency (e.g. fs which couldn't be remounted and was re-mounted ro or
else).

Point is, reboot/shutdown did work previously until about a week or so where
busy MD devices were logged but then the sequence continued. This is how it
llooked like:

 Stopping MD /dev/md1 (9:1).
 Could not stop MD /dev/md1: Device or resource busy 
 Not all MD devices stopped, 1 left.
 Detaching DM deSuccessfully changed into root pivot.
 Returning to initrd...
 dracut: Taking over mdmon processes.
 dracut Warning: Killing all remaining processes
 dracut Warning: Killing all remaining processes
 dracut Warning: Unmounted /oldroot.
 dracut Warning: Unmounted /oldroot.
 dracut: Disassembling device-mapper devices
 dracut: Waiting for mdraid devices to be clean.
 dracut: Disassembling mdraid devices.
 md1: detected capacity change from 440139776 to 0
 md: md1 stopped.
 mdadm: stopped /dev/md1
 Rebooting.

Any hints for howto further debug this are appreciated.