GNOME Bugzilla – Bug 747640
Shell crashes on screencast recording
Last modified: 2015-04-13 12:35:14 UTC
I installed GNOME 3.16 tonight when it arrived in the Arch Linux repos, and went to demonstrate something using a screencast but the shell either segfaulted or crashed shortly after starting the recording with Control-Alt-R. No screencast was recorded, but an empty file with the appropriate name was created in my ~/videos directory. This is what was recorded in the journal: Apr 10 21:45:22 paragon gnome-session[421]: (gnome-shell:515): mutter-ERROR **: Failed to spawn XWayland: No such file or directory Apr 10 21:45:22 paragon kernel: traps: gnome-shell[515] trap int3 ip:7f6d30c4fac0 sp:7ffe16d63860 error:0 Apr 10 21:45:22 paragon gnome-session[421]: (gnome-shell:459): mutter-ERROR **: X Wayland crashed; aborting Apr 10 21:45:22 paragon kernel: traps: gnome-shell[459] trap int3 ip:7f6d30c4fac0 sp:7ffe16d63720 error:0 Apr 10 21:45:22 paragon systemd-coredump[516]: Process 515 (gnome-shell) of user 120 dumped core. Apr 10 21:45:23 paragon systemd-coredump[517]: Process 459 (gnome-shell) of user 120 dumped core. Apr 10 21:45:23 paragon gnome-session[421]: WARNING: Application 'gnome-shell-wayland.desktop' killed by signal 5 Apr 10 21:45:23 paragon gnome-session[421]: Unrecoverable failure in required component gnome-shell-wayland.desktop Apr 10 21:45:23 paragon gnome-session[421]: gnome-session[421]: WARNING: Application 'gnome-shell-wayland.desktop' killed by signal 5 Apr 10 21:45:23 paragon /usr/lib/gdm/gdm-wayland-session[411]: Activating service name='ca.desrt.dconf' Apr 10 21:45:23 paragon gdm[343]: Child process 397 was already dead. Apr 10 21:45:23 paragon gdm[343]: Unable to kill session worker process Apr 10 21:45:23 paragon gdm[343]: Child process 397 was already dead. Apr 10 21:45:23 paragon gdm[343]: Unable to kill session worker process I can't replicate it on my laptop, which is running the same versions of all software, but it consistently causes a core dump of the shell on my desktop. Could this bug be related to #733772? Distribution is Arch Linux x86_64 GNOME 3.16.0
(In reply to Robbie Smith from comment #0) > Apr 10 21:45:22 paragon gnome-session[421]: (gnome-shell:515): mutter-ERROR > **: Failed to spawn XWayland: No such file or directory This might be a problem. Do you have /usr/bin/Xwayland ?
Yes. I noticed that and installed xorg-server-xwayland, which for some reason wasn't installed or a dependency, and tried again but the shell still crashes, so I reported this bug. The journal output was the only thing I could find in there that might have been relevant. There's a number of "systemd-coredump: Process 12345 (gnome-shell) of user 1000 dumped core" messages, but none of the coredumps shown by `coredumpctl list` match the time, date or process from these crashes. My laptop doesn't crash, and it doesn't have xorg-server-xwayland installed. I don't know if this would be relevant, but my graphics card is an nVidia GeForce 8800, and I'm using the open-source drivers (nouveau 1.0.11), and I'm running linux 3.19.3.
Can you use your laptop to ssh into the desktop, attach gdb and get a backtrace?
Created attachment 301392 [details] Trace from gdb The packages on Arch Linux don't come with debugging symbols, nor is there a repository with pre-built -debug packages, so I'm not sure how much use this will be. Interestingly enough, after I quit gdb the shell didn't crash and restart with a different PID.
Aha. Turns out it's fairly trivial (if time-consuming) to build the debug packages yourself so I'll do that and then give you a better trace than that attachment.
Created attachment 301398 [details] Hopefully better stack trace After spending all afternoon trying to figure this out, I managed to trigger the bug whilst in gdb, so here's an updated (and hopefully better) stack trace. I recompiled just the gnome-shell package that Arch Linux provides in their repositories to include the debug symbols, and then followed the guide at [1]. [1] https://wiki.gnome.org/Projects/GnomeShell/Debugging
(In reply to Robbie Smith from comment #6) > Created attachment 301398 [details] > Hopefully better stack trace Program received signal SIGILL, Illegal instruction. [Switching to Thread 0x7fffd93b6700 (LWP 2043)] 0x00007fffa580fda7 in ?? () from /usr/lib/libvpx.so.1 looks like it's a bug in libvpx and/or gstreamer. you should build those packages with debug symbols, get a new stack trace and report the bug there. Feel free to re-open this if the bug looks like it is in gnome-shell after all.