[systemd-devel] Occasion hang an reboot - related to user at 0.service

[NeilBrown]

Hi,
 I'm using openSUSE-13.1 which has systemd-208 (plus assorted patches, most
 from later releases I think) and Linux 3.11.6.

 I have a minimal install with no GUI - I just log in as root on the text
 console.

 Sometimes when I type "reboot" it takes 90 seconds before the reboot
 completes.
 This doesn't always happen, but happens often enough to be annoying.
 I haven't managed to find any pattern suggesting when it does or doesn't
 hang.

 If I enable debugging I find that user at 0.service is responsible.
 e.g. I see:

[   24.628214] systemd[1]: user at 0.service changed running -> stop-sigterm

and then after the 90 seconds:

[  114.628465] systemd[1]: user at 0.service stopping timed out. Killing.
[  114.628961] systemd[1]: user at 0.service changed stop-sigterm -> stop-sigkill
[  114.629695] systemd[1]: Received SIGCHLD from PID 828 (systemd).
[  114.629742] systemd[1]: Got SIGCHLD for process 828 (systemd)
[  114.629819] systemd[1]: Child 828 died (code=killed, status=9/KILL)
[  114.629826] systemd[1]: Child 828 belongs to user at 0.service
[  114.629842] systemd[1]: user at 0.service: main process exited, code=killed, status=9/KILL
[  114.629858] systemd[1]: user at 0.service changed stop-sigkill -> failed
[  114.630223] systemd[1]: Job user at 0.service/stop finished, result=done
[  114.630252] systemd[1]: Stopped User Manager for 0.


It sounds similar to 
 http://lists.freedesktop.org/archives/systemd-devel/2013-July/012309.html

but the fix mentioned their appears to be present in 208.

I added some extra tracing, and it is definitely sending SIGTERM (but not
SIGHUP) to the "/usr/lib/systemd/systemd --user" but that process sometimes
doesn't die until the SIGKILL is sent.

Any idea what is happening, or how I can extract extra relevant tracing?

Thanks,
NeilBrown
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