Comment 9 for bug 1876018

focal:

with the reproducer hack from the description (comment out the 'goto' line in the udev rule), and the system rebooted:

ubuntu@lp1876018-f:~$ dpkg -l systemd|grep systemd
ii systemd 245.4-4ubuntu3.1 amd64 system and service manager
ubuntu@lp1876018-f:~$ journalctl -g vm-hotadd
-- Logs begin at Wed 2020-07-22 18:11:53 UTC, end at Wed 2020-07-22 18:46:23 UTC. --
Jul 22 18:45:15 lp1876018-f sudo[12380]: ubuntu : TTY=ttyS0 ; PWD=/home/ubuntu ; USER=root ; COMMAND=/usr/bin/vi /lib/udev/rules.d/40-vm-hotadd.rules
-- Reboot --
Jul 22 18:45:48 lp1876018-f systemd-udevd[457]: memory0: /usr/lib/udev/rules.d/40-vm-hotadd.rules:9 Failed to write ATTR{/sys/devices/system/memory/memory0/state}, ignoring: Invalid argument
Jul 22 18:45:48 lp1876018-f systemd-udevd[457]: memory1: /usr/lib/udev/rules.d/40-vm-hotadd.rules:9 Failed to write ATTR{/sys/devices/system/memory/memory1/state}, ignoring: Invalid argument
Jul 22 18:45:48 lp1876018-f systemd-udevd[457]: memory10: /usr/lib/udev/rules.d/40-vm-hotadd.rules:9 Failed to write ATTR{/sys/devices/system/memory/memory10/state}, ignoring: Invalid argument
...(many more)...

and with the udev rule again edited after the systemd upgrade (since it replaces the edited file), and the system rebooted:

ubuntu@lp1876018-f:~$ dpkg -l systemd|grep systemd
ii systemd 245.4-4ubuntu3.2 amd64 system and service manager
ubuntu@lp1876018-f:~$ journalctl -b -g vm-hotadd
-- Logs begin at Wed 2020-07-22 18:11:53 UTC, end at Wed 2020-07-22 18:50:00 UT>
-- No entries --