Bug#803013: systemd should not destroy application created cgroups

[paul.szabo at sydney.edu.au]

Dear Michael,

>> I wonder how that line came to be missed on my machines: I upgraded from
>> wheezy (which was upgraded from previous releases).
>
> If that line was not automatically added it probably means you had made
> custom modifications to the file in the past.

Possible, but unlikely: the only difference between my 
  /etc/pam.d/common-session
file and that from the freshly installed jessie, is the
  session optional pam_systemd.so
line.

> Not having libpam-systemd installed probably means, that your user
> processes are not properly added to the correct cgroups.

I do have libpam-systemd installed (though not "active" because of my
"broken" common-session file).

With my "broken" /etc/pam.d/common-session file, systemd did not create
/sys/fs/cgroup/systemd/user.slice/user-N.slice/ directories. Why should
the lack of those interfere with my use of cgroups? If the PAM setting
is so important, should not it be set to required?

There is also a file
  /etc/pam.d/common-session-noninteractive
that does not contain the pam_systemd.so line, used for cron and sudo
(maybe others): can cgroups be used for or from those?

Cheers, Paul

Paul Szabo   psz at maths.usyd.edu.au   http://www.maths.usyd.edu.au/u/psz/
School of Mathematics and Statistics   University of Sydney    Australia