Bug#888199: gnome-shell crashes at different circumstances (not usable anymore)

[Simon McVittie]

Control: reassign 888199 libgjs0g 1.50.3-1
Control: severity 888199 grave
Control: tags 888199 + moreinfo
Control: affects 888199 gnome-shell

On Thu, 25 Jan 2018 at 21:39:22 +0100, Thomas Renard wrote:
> I downgraded libgjs0g to 1.50.2-2 and the whole desktop is stable again.
> 
> Bug seems to depend on bug #887082 and #881301

The changes I merged from upstream in 1.50.2-3 to address #881301 were
intended to make gnome-shell *more* robust/less likely to crash, by
turning potential segfaults into warnings, so I'm quite surprised we're
seeing the opposite effect here.

I'm fairly sure #887082 is a pre-existing bug that was made visible by
the changes in 1.50.2-3: previously, accessing a previously destroyed
object would have failed silently, but now gjs makes more noise about it
(which will hopefully help us to track down and fix it). I get the
same backtrace reported in the Journal that you do (#887082), quite
frequently, but my gnome-shell isn't crashing...

I don't see any gnome-shell crashes (or even unsuccessful exits) in the
journalctl output that you attached, but your log seems to end at the
point where you log in to gdm. Can you provide further log entries from
after you've logged in?

Would you be able to install systemd-coredump, upgrade libgjs0g to the
broken version, let gnome-shell crash a few times, downgrade back to
1.50.2-2 so you can get back into a working GUI, and report what was
logged about the crashes?

Also, if you use 1.50.2-3, do you get the same crashing behaviour as
with 1.50.3-1?

If gjs is hitting an "unrecoverable exception" I would expect to see
something like this in the Journal, similar to #888052:

Jan 23 12:34:56 yourmachine gnome-session[1234]: gnome-session-binary[1234]:
WARNING: App 'org.gnome.Shell.desktop' exited with code 1

and if gnome-shell is crashing, I'd expect to see that logged too.

It seems odd that this version is working fine for me (and presumably
for upstream GNOME maintainers) but crashing so repeatably for you. Are
you using any gnome-shell extensions or other special configuration?

Am I right in thinking that the gdm "greeter" (the login screen), which
is actually just GNOME Shell in a special mode, is working correctly for
you, and it's only the copy of GNOME Shell that runs *after* you log in
that is crashing? If so, that's useful information.

https://gitlab.gnome.org/GNOME/gjs/issues/38 might be related: it's
reported to be a regression caused by the same changes that arrived in
1.50.2-3 (and upstream in 1.50.3).

Thanks,
    smcv