Comment # 62 on bug 906900 from Dr. Werner Fink

(In reply to Achim Klausmann from comment #61)

Ah ... the usage of su explains a lot as in this case the pam configuration
falls in (compare /etc/pam.d/su and /etc/pam.d/su-l).  And this pam based
commands should be avoided for SysVinit/LSB services as with pam the login
manager will handle the user session.  All sessions do belong to the user.slice
and this will be terminated before the system.slice.

This can be viewed with e.g.

   systemd-cgls

or

   systemd-cgtop

or

   ps awx -eo pid,args,cgroup

maybe the command

   systemd-run

may help as replacement for the `su' or `runuser' command:

   systemd-run --uid=oracle

as a test I've executed two commands

   runuser nobody -c '/usr/bin/sleep 1000 &'
   systemd-run --uid=nobody /usr/bin/sleep 1000

and indeed

   ps awx -eo pid,args,cgroup  | grep sleep
   13381 /usr/bin/sleep 1000        
1:name=systemd:/user.slice/user-0.slice/session-375.scope
   13718 /usr/bin/sleep 1000        
1:name=systemd:/system.slice/run-13717.service
   13722 grep --color=auto sleep    
1:name=systemd:/user.slice/user-223.slice/session-382.scope