Shutdown hangs waiting for plymouth-shutdown

[Roman Fiedler]

This issue occurs with Ubuntu Trusty and xdm installed. The system reacts on [Ctrl]-[Alt]-[Del], which triggers

exec shutdown -h now "Control-Alt-Delete pressed"

without any additional checks via /etc/init/control-alt-delete.conf. An open SSH connection will then also report the "system is going down for halt NOW!" message, so shutdown initialization works as expected. After that, the system stays in that state forever

Procedure:
* Boot ubuntu-minimal with X/xdm installed
* Terminate xdm before logging in using [Ctrl]-R
* Send [Ctrl]-[Alt]-[Del]
* Wait ...

I've tried the reboot with both plymouth-disabler missing/installed, but result is the same.

See the list of running processes during shutdown, It looks like some deadlock waiting for events.

I failed to verify if the problem is specific to having xdm installed, the upstart package or some other component, so the bug/misconfiguration might be in some other package.

$ lsb_release -rd
Description: Ubuntu 14.04 LTS
Release: 14.04

$ apt-cache policy plymouth
plymouth:
  Installed: 0.8.8-0ubuntu17
  Candidate: 0.8.8-0ubuntu17
  Version table:
 *** 0.8.8-0ubuntu17 0
        500 http://archive.ubuntu.com/ubuntu/ trusty/main i386 Packages
        100 /var/lib/dpkg/status

[Steve Langasek (vorlon)]

Dimitri, please have a look at this bug. I can't figure out what the current plymouth-shutdown job is supposed to do; it has a start condition of:

start on (runlevel [016]
         and (stopped xdm
              or stopped uxlaunch))

And I have neither xdm or uxlaunch on my system, so I don't know how this job ever starts at all on an Ubuntu desktop... and on a desktop that does have xdm, it seems that it triggers and blocks the shutdown.

[Dimitri John Ledkov (xnox)]

On 8 May 2014 17:46, Steve Langasek <email address hidden> wrote:
> Dimitri, please have a look at this bug. I can't figure out what the
> current plymouth-shutdown job is supposed to do; it has a start
> condition of:
>
> start on (runlevel [016]
> and (stopped xdm
> or stopped uxlaunch))
>
> And I have neither xdm or uxlaunch on my system, so I don't know how
> this job ever starts at all on an Ubuntu desktop... and on a desktop
> that does have xdm, it seems that it triggers and blocks the shutdown.
>

On normal desktops plymouth-shutdown is started by rc.conf job, before
emitting runlevels 0, 1 or 6.
Which in-turn should stop lightdm (if present) and bring up plymouthd
in shutdown mode.

What is confusing however in the ps outputs attached is that in all
three process outputs:
 - plymouthd in boot mode is still running
 - /bin/plymouth quit has not completed

I'll experiment with such a minimal setup in a VM.

--
Regards,

Dimitri.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Mathieu Trudel-Lapierre (cyphermox)]

Setting to Medium and reassigning to myself. I'll kick off the tests Dimitri was planning on starting, Monday.

[Stefan Fleischmann (sfleischmann)]

>What is confusing however in the ps outputs attached is that in all three process outputs:
> - plymouthd in boot mode is still running
> - /bin/plymouth quit has not completed

I experience the same issue. This also causex 'plymouth --ping' to hang indefinitely. If I kill plymouthd manually reboot continues.

But it seems like this is a real corner case. I don't use the default "quiet splash" kernel commandline options. Instead I use "console=tty0 console=ttyS1,115200n8" in order to have a serial console for SOL (serial over LAN). And I use a custom Upstart file to start an X server instance. The problem disappears if I either:
 a) remove the second console option from the kernel commandline or
 b) delay start of the X server, for example by adding "started dbus and plymouth-ready" to the start conditions in my custom Xserver upstart config

$ apt-cache policy plymouth
plymouth:
  Installed: 0.8.8-0ubuntu17.1
  Candidate: 0.8.8-0ubuntu17.1