gnome-shell segfault in libgobject-2.0 g_type_check_instance_cast

[fermulator]

{{{
[13704.632087] gnome-shell[9051]: segfault at 82 ip 00007f3e7e900de2 sp 00007fff6078c200 error 4 in libgobject-2.0.so.0.5400.1[7f3e7e8cb000+52000]
}}}

Stack trace is roughly:
 * g_type_check_instance_cast() at libgobject-2.0.so.0
 * st_label_set_text() at libst-1.0.so
 ...

My setup:
 * dual monitors
 * multiple local users
 * often 2x users logged in at same time
 * flip between them using PTY (CTRL+ALT+ F2, F3, etc.)
 * CTRL+ALT+F1 gets us to the gdm login screen (user selection)

What happens:
 * eventually either by timeout (or after suspend), or manual lock screen
 * user hits CTRL+ALT+F2,3,X, to access their PTY
 * screen may or may not be locked; (user logs in)
 * user hits "ALT+F2", and types "r" + <ENTER> (gnome-shell --replace)

Reproducibility:
 * happened a few times since upgrade to Ubuntu 17.10
 * happened immediately after running "r"

Issue Analysis:
 * none - need guidance on how to debug/isolate next time it happens

---

System Information:

$ lsb_release -rd
Description: Ubuntu 17.10
Release: 17.10

$ uname -a
Linux fermmy 4.13.0-31-generic #34-Ubuntu SMP Fri Jan 19 16:34:46 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

$ apt-cache policy gdm3
gdm3:
  Installed: 3.26.1-3ubuntu3
  Candidate: 3.26.1-3ubuntu3
  Version table:
 *** 3.26.1-3ubuntu3 500
        500 http://ca.archive.ubuntu.com/ubuntu artful-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     3.26.1-3ubuntu2 500
        500 http://ca.archive.ubuntu.com/ubuntu artful/main amd64 Packages

$ apt-cache policy gnome-shell
gnome-shell:
  Installed: 3.24.2-0ubuntu0.1
  Candidate: 3.24.2-0ubuntu0.1
  Version table:
 *** 3.24.2-0ubuntu0.1 500
        500 http://ca.archive.ubuntu.com/ubuntu zesty-updates/universe amd64 Packages
        100 /var/lib/dpkg/status
     3.24.0-0ubuntu2 500
        500 http://ca.archive.ubuntu.com/ubuntu zesty/universe amd64 Packages

[fermulator (fermulator)]

(ran ubuntu-bug on the core file, awaiting UUID to show up in the system, will post here once it's available)

[fermulator (fermulator)]

Got 2x instances (1 from each unique user today)
, here's one online ubuntu-bug report:

https://errors.ubuntu.com/oops/a12896a4-fff3-11e7-b78e-fa163ef911dc

[Daniel van Vugt (vanvugt)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 1714989, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Feel free to continue to report any other bugs you may find.

[fermulator (fermulator)]

*accepted* - huh; not sure why that didn't turn up in my search results before submitting