gnome-shell crashed with SIGABRT in g_assertion_message()

StacktraceTop:
 g_once_init_enter (location=<optimized out>) at /build/buildd/glib2.0-2.40.0+git20140410.c938e742/./glib/gthread.c:645
 ?? () from /home/darkxst/gnome3-amd64/usr/lib/libmutter.so.0
 __FUNCTION__.11789 () from /home/darkxst/gnome3-amd64/lib/x86_64-linux-gnu/libglib-2.0.so.0
 __FUNCTION__.4488 () from /home/darkxst/gnome3-amd64/lib/x86_64-linux-gnu/libglib-2.0.so.0
 ?? ()

Yup, ug-bot's stack trace is bogus. I'll try apport-retrace locally.

BTW bug 1286098 was about the same assertion message (n_outputs == config->n_outputs).

Bug 1294115 might be another duplicate (Apport showed it as a DuplicateOf during one of the previous crashes), but I can't see it because it's private.

I've seen more gnome-shell crashes right after resume, but the above are the only ones where I paid attention to the stack trace and made a note about the failed n_outputs assertion in my diary.

I'm attaching a full and correct stack trace, produced in gdb with debug symbols by entering

    set pagination off
    set logging file ~/lp1319897.log
    set logging on
    bt
    t a a bt full

The failing assertion is in meta_monitor_config_assign_crtcs in libmutter (core/monitor-config.c:1822)

At that point n_outputs == 1 but config->n_outputs == 0.

Filed upstream at https://bugzilla.gnome.org/show_bug.cgi?id=730214

Upstream says this is a duplicate of https://bugzilla.gnome.org/show_bug.cgi?id=725637, which was fixed in 3.13.1 with the following two commits:
- https://github.com/GNOME/mutter/commit/01cd4b2ba02a729dcbcc06afa3aec315bc70ef2f
- https://github.com/GNOME/mutter/commit/2ca2c18c2adf23d7a5a215822255e17a1f49b0cd

I built a mutter with the two upstream patches backported (the only change necessary was in the file name). I'm about to test it.

Brief test with fixed package:
1. plug in external monitor
2. suspend laptop
3. unplug monitor
4. resume laptop

Outcome: no crash. Yay!

Marius, thanks for your work on this, it seems that both those patches are included in mutter 3.12.2, which I just uploaded to the ppa.

Status changed to 'Confirmed' because the bug affects multiple users.

This also affects 3.10 in utopic and trusty. Marius, Can you test your debdiff against the 3.10 packages?

The attachment "Debdiff with backported upstream patches" seems to be a debdiff. The ubuntu-sponsors team has been subscribed to the bug report so that they can review and hopefully sponsor the debdiff. If the attachment isn't a patch, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are member of the ~ubuntu-sponsors, unsubscribe the team.

[This is an automated message performed by a Launchpad user owned by ~brian-murray, for any issue please contact him.]

When my other laptop gets back from the repair shop, I'll upgrade it to stock Ubuntu GNOME 14.04 and see if I can reproduce this crash and test the fix.

I don't want to start ppa-purging GNOME 3.12 on my primary laptop for reasons.

Marius, given you have already test the patches against 3.12, it should be enough to make sure they apply cleanly to 3.10 packages and build ok (use pbuilder or sbuild).

Once we SRU it back into trusty it will need testing though..

mutter 3.10.4 from trusty (no PPA) builds with the two patches applied (here's a debdiff). I tested with debuild wile waiting for 'pbuilder-dist create trusty', now I'm waiting for 'pbuilder-dist build trusty mutter_3.10.4-0ubuntu2mg1.dsc'... Ok, this builds too.

I uploaded the fixed mutter package to my PPA (https://launchpad.net/~mgedmin/+archive/ppa) if anyone with stock 14.04 has this problem (gnome-shell crashes on monitor hotplug/unplug) and wants to test it. It's building now.

Thanks Marius! Uploaded, can you add the SRU paperwork to the bug description
see https://wiki.ubuntu.com/StableReleaseUpdates#SRU_Bug_Template

Fixed in utopic

mutter (3.10.4-0ubuntu4) utopic; urgency=medium

  * debian/patches/git-fix-crash-on-hotplug-*.patch:
    - Backport crasher fix from upstream git (LP: #1319897, BGO#725637)

 -- Marius Gedminas <email address hidden> Fri, 16 May 2014 18:08:32 +0300

This really should have had a mutter task so the Launchpad janitor would close the bug tasks automatically. I've added one for the SRU process.

Hello Marius, or anyone else affected,

Accepted mutter into trusty-proposed. The package will build now and be available at http://launchpad.net/ubuntu/+source/mutter/3.10.4-0ubuntu2.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

Package 3.10.4-0ubuntu2.1 from trusty-proposed fixes the bug for me.

It fixes both:

1) suspend
2) unplug monitor
3) resume

and:

1) unplug monitor
2) suspend
3) resume

Marking verification done, based on Jasper's results above

This bug was fixed in the package mutter - 3.10.4-0ubuntu2.1

---------------
mutter (3.10.4-0ubuntu2.1) trusty; urgency=medium

  * debian/patches/git-fix-crash-on-hotplug-*.patch:
    - Backport crasher fix from upstream git (LP: #1319897, BGO#725637)
 -- Marius Gedminas <email address hidden> Fri, 16 May 2014 18:08:32 +0300

The verification of the Stable Release Update for mutter has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regresssions.