[systemd-devel] Zombie process still exists after stopping gdm.service

[Lennart Poettering]

On Sun, 19.04.15 09:34, Andrei Borzenkov (arvidjaar at gmail.com) wrote:

> В Fri, 17 Apr 2015 14:04:18 -0600
> Daniel Drake <drake at endlessm.com> пишет:
> 
> > Hi,
> > 
> > I'm investigating why "systemctl stop gdm; Xorg" usually fails. The
> > new X process complains that X is still running.
> > 
> > Here's what I think is happening:
> > 
> > 1. systemd sends SIGTERM to gdm to stop the service
> > 
> > 2. gdm exits - it has a simple SIGTERM handler which just quits the
> > mainloop without doing any cleanup (as far as I can see, it doesn't
> > make any attempt to kill the child X server)
> > 
> > 3. X exits because of PR_SET_PDEATHSIG (i.e. it's set to be
> > automatically killed when the parent goes away). The killed process
> > enters defunct state and is reparented to PID 1, presumably also
> > moving it out of the gdm cgroup.
> > 
> 
> No, it remains in cgroup. Otherwise systemd service management would
> not be possible at all ...
> 
> > 4. systemd notes that gdm's cgroup is empty and decides that gdm is
> > now successfully stopped.
> > 
> 
> I looked at display-manager.service here and it sets KillMode=process.
> That is better explanation to your observation.

Hmm, it does? It does not on Fedora. Also "display-manager.service" is
just an alias to "gdm.service" on Fedora.

Daniel, can you check with "systemctl cat gdm" what your distro
configures there?

Lennart

-- 
Lennart Poettering, Red Hat