systemd timers hang on start

[certanan <certanan@proton.me>]

Dear community,

I encountered an issue while upgrading the 'util-linux' package using Apt - it 
hanged until I terminated it by force. This was resolved by commenting out 
lines from dpkg's corresponding postinst script which tries to start
fstrim.timer. Namely this one:
/var/lib/dpkg/info/util-linux.postinst:37 deb-systemd-invoke $_dh_action 'fstrim.timer' >/dev/null || true

The same problem materialised again when another postinst script tried starting
'apt-daily.timer'. None of the systemd's timers can be started manually either.


# systemctl status | head -n8
machine
    State: starting
    Units: 394 loaded (incl. loaded aliases)
     Jobs: 12 queued
   Failed: 3 units
    Since: Thu 2023-07-20 12:34:28 CEST; 10h ago
  systemd: 254~rc2-3
   CGroup: /
# cat /proc/version
Linux version 6.3.11 (root@machine) (gcc (Debian 12.3.0-5) 12.3.0, GNU ld (GNU Binutils for Debian) 2.40.50.20230625) #17 SMP PREEMPT_DYNAMIC Tue Jul 18 21:21:53 CEST 2023


- I pull packages from the official unstable main repository
- I use a custom-built kernel but the issue persists on the current stock one

Should you have the need to know any more details, I will be more than happy
to try my best at filling them in.
The aim of this message is a plea for help regarding the above-described
problem.

Thank you for your time.

Kind regards,
certanan