gnome-session-check-accelerated crashed with SIGSEGV

[Wolf Pichler]

After Logout or Resume one ultimately ends up at a black screen on a completely unresponsive system.

Only the power button helps in this case - I guess the "Emergency Sync" in the attached syslog marks the point in time when the power button was pressed.

###

apt-cache policy gdm3:
gdm3:
  Installed: 3.28.2-0ubuntu1.4
  Candidate: 3.28.2-0ubuntu1.4
  Version table:
 *** 3.28.2-0ubuntu1.4 500
        500 http://archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
        500 http://archive.ubuntu.com/ubuntu bionic-security/main amd64 Packages
        100 /var/lib/dpkg/status
     3.28.0-0ubuntu1 500
        500 http://archive.ubuntu.com/ubuntu bionic/main amd64 Packages

lsb_release -rd:
Description: Ubuntu 18.04.1 LTS
Release: 18.04

[Daniel van Vugt (vanvugt)]

It looks like updating the screen is failing:

Sep 5 22:13:31 testclient02 /usr/lib/gdm3/gdm-x-session[1768]: (II) modeset(0): EDID vendor "NCP", prod id 28
Sep 5 22:13:31 testclient02 /usr/lib/gdm3/gdm-x-session[1768]: (II) modeset(0): Printing DDC gathered Modelines:
Sep 5 22:13:31 testclient02 /usr/lib/gdm3/gdm-x-session[1768]: (II) modeset(0): Modeline "1920x1080"x0.0 139.77 1920 1968 2000 2080 1080 1083 1089 1120 -hsync -vsync (67.2 kHz eP)
Sep 5 22:13:31 testclient02 /usr/lib/gdm3/gdm-x-session[1768]: (II) modeset(0): Modeline "1920x1080"x0.0 111.82 1920 1968 2000 2080 1080 1083 1089 1120 -hsync -vsync (53.8 kHz e)
Sep 5 22:13:31 testclient02 /usr/lib/gdm3/gdm-x-session[1087]: (WW) modeset(0): flip queue failed: Permission denied
Sep 5 22:13:31 testclient02 /usr/lib/gdm3/gdm-x-session[1087]: (WW) modeset(0): Page flip failed: Permission denied
Sep 5 22:13:31 testclient02 /usr/lib/gdm3/gdm-x-session[1087]: (EE) modeset(0): present flip failed
Sep 5 22:13:31 testclient02 /usr/lib/gdm3/gdm-x-session[1087]: (WW) modeset(0): flip queue failed: Permission denied
Sep 5 22:13:31 testclient02 /usr/lib/gdm3/gdm-x-session[1087]: (WW) modeset(0): Page flip failed: Permission denied
Sep 5 22:13:31 testclient02 /usr/lib/gdm3/gdm-x-session[1087]: (EE) modeset(0): failed to set mode: Permission denied
Sep 5 22:13:31 testclient02 /usr/lib/gdm3/gdm-x-session[1087]: (WW) modeset(0): flip queue failed: Permission denied
Sep 5 22:13:31 testclient02 /usr/lib/gdm3/gdm-x-session[1087]: (WW) modeset(0): Page flip failed: Permission denied
Sep 5 22:13:31 testclient02 /usr/lib/gdm3/gdm-x-session[1087]: (EE) modeset(0): present flip failed
Sep 5 22:13:31 testclient02 /usr/lib/gdm3/gdm-x-session[1087]: (WW) modeset(0): flip queue failed: Permission denied
Sep 5 22:13:31 testclient02 /usr/lib/gdm3/gdm-x-session[1087]: (WW) modeset(0): Page flip failed: Permission denied
Sep 5 22:13:31 testclient02 /usr/lib/gdm3/gdm-x-session[1087]: (EE) modeset(0): present flip failed
Sep 5 22:13:31 testclient02 /usr/lib/gdm3/gdm-x-session[1087]: (WW) modeset(0): flip queue failed: Permission denied
Sep 5 22:13:31 testclient02 /usr/lib/gdm3/gdm-x-session[1087]: (WW) modeset(0): Page flip failed: Permission denied
Sep 5 22:13:31 testclient02 /usr/lib/gdm3/gdm-x-session[1087]: (EE) modeset(0): present flip failed

[Daniel van Vugt (vanvugt)]

That might be a Xorg-specific problem. If you log into "Ubuntu on Wayland", does that work around it?

[Wolf Pichler (w-pichler)]

For a while Logout/Resume/Switch User worked fine with Wayland (as well as with Xorg when I cross-checked it).

But finally, when I tried "Switch User" again with Wayland, I got stuck on the Login-Page of the current user - it was not possible to get the page displaying all available users.

To be sure I made no mistake I checked:
echo $XDG_SESSION_TYPE
wayland

The first line in the attached syslog should be the moment when I clicked "Switch User".
The last line seems to be the moment when I logged in as original user again.
Both lines contain the same error message.

[Daniel van Vugt (vanvugt)]

The new issue in comment #4 looks like it is caused by:

Sep 7 20:56:44 testclient02 kernel: [ 8033.083994] gnome-session-c[17886]: segfault at 0 ip 0000000000000000 sp 00007fff3e56c0c8 error 14 in gnome-session-check-accelerated[55a3aab07000+2000]
Sep 7 20:56:44 testclient02 kernel: [ 8033.280184] gnome-session-c[17894]: segfault at 0 ip 0000000000000000 sp 00007ffec18dc608 error 14 in gnome-session-check-accelerated[55f0ca8b7000+2000]
Sep 7 20:56:44 testclient02 gnome-session[17885]: gnome-session-binary[17885]: WARNING: software acceleration check failed: Child process killed by signal 11
Sep 7 20:56:44 testclient02 gnome-session[17885]: gnome-session-binary[17885]: CRITICAL: We failed, but the fail whale is dead. Sorry....
Sep 7 20:56:44 testclient02 gnome-session-binary[17885]: WARNING: software acceleration check failed: Child process killed by signal 11
Sep 7 20:56:44 testclient02 gnome-session-binary[17885]: CRITICAL: We failed, but the fail whale is dead. Sorry....

For that, please look in /var/crash for crash files, and then run:

  ubuntu-bug /var/crash/YOURFILE.crash

and tell us any new bug IDs.

[Daniel van Vugt (vanvugt)]

Thanks for that but it's better to not share your whoopsie-id. Still, I was able to use it to find your most recent crash report:

https://errors.ubuntu.com/oops/854ff42a-b4ea-11e8-901f-fa163ee63de6

which unfortunately is not traceable:

https://errors.ubuntu.com/bucket/?id=failed%3A/usr/lib/gnome-session/gnome-session-check-accelerated%3A11%3A/usr/lib/x86_64-linux-gnu/libglib-2.0.so.0.5600.1%2B3a884%3A/usr/lib/x86_64-linux-gnu/libgdk-3.so.0.2200.30%2B6e450%3A/usr/lib/gnome-session/gnome-session-check-accelerated%2B13aa%3A/lib/x86_64-linux-gnu/libc-2.27.so%2B21b97%3A/usr/lib/gnome-session/gnome-session-check-accelerated%2B18da

However, we might get more information from a proper crash file and retracing in Launchpad. To do that, please look in /var/crash for crash files, and then for each one run:

  ubuntu-bug /var/crash/YOURFILE.crash

and tell us any new bug IDs that you created in your web browser...

[Daniel van Vugt (vanvugt)]

That big long link above turns out to be the top crash report against gnome-session. It has 8300 crash reports from 18.04 this year. So "confirmed" but still incomplete because we don't have enough information to debug it yet.

[Daniel van Vugt (vanvugt)]

It appears very likely this is bug 1715365, which has a nice stack trace. So let's assume it is...