gnome crashes when using qemu display

[Seth Forshee]

Using the qemu vga display under gnome is reliably causing gnome to crash on my laptop. I've seen this when using libvirt and also when invoking qemu from the command line. I've tried several display options for qemu:

 -vga qxl
 -vga virtio
 -display gtk

All result in the crash. No crash report is appearing in /var/crash after this happens, but I checked dmesg the last time and found this:

[15078.446564] gnome-shell[10327]: segfault at 8 ip 00007f4c53c794af sp 00007ffd7eb03e90 error 4 in libmutter-cogl-1.so[7f4c53c14000+a5000]

The crash usually doesn't happen right away. Sometimes it happens a few seconds after the display is opened, other times it's happened when I've moved to another window and then select the qemu display using Alt-Tab.

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: gnome-shell 3.26.0-0ubuntu1
ProcVersionSignature: Ubuntu 4.13.0-11.12-generic 4.13.1
Uname: Linux 4.13.0-11-generic x86_64
ApportVersion: 2.20.7-0ubuntu1
Architecture: amd64
CurrentDesktop: GNOME
Date: Mon Sep 18 08:11:44 2017
DisplayManager: gdm3
EcryptfsInUse: Yes
InstallationDate: Installed on 2017-03-30 (172 days ago)
InstallationMedia: Ubuntu 17.04 "Zesty Zapus" - Beta amd64 (20170329)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-shell
UpgradeStatus: Upgraded to artful on 2017-04-27 (143 days ago)

[Sebastien Bacher (seb128)]

Thank you for your bug report, could you try to get a backtrace (gdb from a vt for example)? Is that under xorg or wayland session? There was a xwayland issue that looks a bit similar on bug #1713981

[Daniel van Vugt (vanvugt)]

JournalErrors.txt is showing that Xwayland crashed, which is a fatal error for gnome-shell and it gives up. So that would make this a duplicate of bug 1505409 or bug 1556601.

However the same log shows other shell crashes too:

Sep 15 16:28:21 hostname gnome-shell[1393]: meta_renderer_native_release_onscreen: assertion 'onscreen_native->gbm.next_fb_id == 0' failed
Sep 15 16:28:21 hostname gnome-shell[1393]: _cogl_onscreen_free: assertion 'onscreen->winsys == ((void *)0)' failed

and

Sep 15 17:38:43 hostname gnome-shell[10327]: clutter_actor_is_visible: assertion 'CLUTTER_IS_ACTOR (self)' failed
Sep 15 17:39:02 hostname gnome-shell[10327]: remove_mnemonics: assertion 'label != NULL' failed

and

Sep 18 08:05:58 hostname gnome-shell[10327]: clutter_actor_lower: Actor of type ClutterActor is not inside a container
Sep 18 08:05:58 hostname gnome-shell[10327]: _cogl_pipeline_override_uniform: assertion 'cogl_is_pipeline (pipeline)' failed

So you're getting a bunch of different crashes that each need their own bug reports. I suggest we close this bug because it's become conflated, and then pursue each crash with separate bug reports. Either wait till you can get a .crash file or stack trace, or wait till one of those assertions reoccurs and log a new bug about that.

[Daniel van Vugt (vanvugt)]

Actually those assertions might not be fatal. Such is the way with glib and friends.

So let's call this a duplicate of the first issue: bug 1505409

Work is underway upstream to remove this dependency of gnome-shell on Xwayland, which will solve the problem. But it's not finished, or at least not enabled by default yet.

[Daniel van Vugt (vanvugt)]

Sorry, I am both in a hurry today and confused.

Please clarify which crash you would like this bug to be about. If it is the one mentioned in the description (libmutter-cogl-1.so) then more information is required in the form of a stack trace or .crash file.

If the problem is generally just gnome-shell crashing as a result of Xwayland crashing then keep an eye on bug 1505409 and bug 1556601 instead.

[Sebastien Bacher (seb128)]

The issue described there looks like the one fixed in
https://launchpad.net/ubuntu/+source/xorg-server/2:1.19.3-1ubuntu6