[logout]: black screen, hangs without falling back to sddm

[star-buck]

possible upstream report: https://bugs.launchpad.net/ubuntu/+source/sddm/+bug/1407152 https://bugs.launchpad.net/ubuntu/+source/casper/+bug/1436715

[star-buck]

still there as of kci 20150327, I tested with having firefox window still open, then logout, screen goes black for a second, then shows firefox window content without any other plasma components like panel, etc. only mouse cursor visible which can move, otherwise desktop seems frozen (no ALT-SPACE possible).

[star-buck]

still happening kci20150403

[davidedmundson]

yeah, it's not just Kubuntu. I've got some other reports here https://github.com/sddm/sddm/issues/385. I've been on it for the past 2 days but I'm rather stumped.

[davidedmundson]

After 3 solid days, I've found it! And for the 5th time in a row, the bug is caused by Kubuntu's replacement PAM files. Though in fairness, this time is probably the fault of someone else moving something in Vivid, and in a super surprise twist the fault of Gnome.

Kubuntu people packaged the sddm PAM file to include pam_gnome_keyring. common_password already included pam_gnome_keyring. sddm's pam file includes common_password.

The end result is session pam_gnome_keyring is included twice.

The first one sets up a signal handler, starts gnome-keyring and all is well. The second one sets up a signal handler, does nothing, then intercepts all of my SIGCHLD signals that I need in sddm-helper to know when our session ends. Our QProcess object never gets told the child exited so never wakes up and the session (startkde, openbox whatever) is in a defunct state waiting for us to read the exit state.

In upstream SDDM our sddm pam file doesn't include gnome-keyring, we just source system-login so it's not a problem there.

Fix: remove both lines referencing gnome_keyring in the sddm.pam file in the packaging patches. sddm-autologin should be left as-is.

[star-buck]

does it also fix these upstream cases: https://bugs.launchpad.net/ubuntu/+source/casper/+bug/1436715

[davidedmundson]

I don't think so. That message is long after SDDM has finished doing anything useful. Also it appears in that report to affect vanilla Ubuntu which wouldn't by running SDDM at all.

[star-buck]

okay, i just thought I sometimes experienced the freeze not only with logout, but also when shutdown or reboot.

[davidedmundson]

Heh. I just patched gnome-keyring to make sure it didn't leakily leave signal handlers on error. It's been fixed already will be in 3.15.92

upstream report, it broke mdm too https://bugzilla.gnome.org/show_bug.cgi?id=745673

[davidedmundson]

IMHO waiting for that patch to hit Vivid is probably the better fix.

[jriddell]

https://launchpad.net/ubuntu/+source/gnome-keyring 3.16 packaged and in with the fix

[star-buck]

works.