That wiki is not owned by Ubuntu so we can't fix the instructions it
gives. As for any and all crashes in Ubuntu, please follow these
instructions:
1. Look in /var/crash for crash files and if found run:
ubuntu-bug YOURFILE.crash
Then tell us the ID of the newly-created bug.
2. If step 1 failed then look at https://errors.ubuntu.com/user/ID where
ID is the content of file /var/lib/whoopsie/whoopsie-id on the machine.
Do you find any links to recent problems on that page? If so then please
send the links to us.
3. If step 2 also failed then apply the workaround from bug 994921,
reboot, reproduce the crash, and retry step 1.
Please take care to avoid attaching .crash files to bugs as we are
unable to process them as file attachments. It would also be a security
risk for yourself.
** Changed in: gnome-shell (Ubuntu)
Status: New => Incomplete
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https://bugs.launchpad.net/bugs/1937958
Title:
gnome-shell gdb instructions cause immediate "Oh no" crash
Status in gnome-shell package in Ubuntu:
Incomplete
Bug description:
I wanted to report a gnome-shell bug with a backtrace, so tried to use
the instructions in
https://wiki.gnome.org/Projects/GnomeShell/Debugging
which say to do the following in an ssh login or separate VT:
gnome_session=$(pgrep -u $USER gnome-session)
eval export $(sed 's/\o000/\n/g;' < /proc/$gnome_session/environ | grep
DISPLAY)
eval export $(sed 's/\o000/\n/g;' < /proc/$gnome_session/environ | grep
XAUTHORITY)
eval export $(sed 's/\o000/\n/g;' < /proc/$gnome_session/environ | grep
DBUS_SESSION_BUS_ADDRESS)
gdb
...etc...
However three problems came up, two minor (wrong instructions), the
other major:
(1) There is more than one gnome-session process, and so the shell
variable $gnome_session gets set to a list of several PIDs, which in
turn causes syntax errors when using the expression
"/proc/$gnome_session/environ".
In Ubuntu 21.04 I have three gnome-session processes immediately after
rebooting and logging in (I have auto-login enabled, so the login
happens by itself, in case that matters):
$ ps -F $(pgrep -u $USER gnome-session|perl -p -e 's/(\d+)/-p $1/')
UID PID PPID C SZ RSS PSR STIME TTY TIME CMD
jima 9743 9725 0 55216 16084 2 13:41 tty3 00:00:00
/usr/libexec/gnome-session-binary --systemd --session=ubuntu
jima 9828 8066 0 24031 6148 8 13:41 ? 00:00:00
/usr/libexec/gnome-session-ctl --monitor
jima 9838 8066 0 129272 18176 7 13:41 ? 00:00:00
/usr/libexec/gnome-session-binary --systemd-service --session=ubuntu
(2) The instructions specify this gdb command:
call gjs_dumpstack ()
However that results in an error and the call is not made:
'gjs_dumpstack' has unknown return type; cast the call to its declared
return type
(3) Most importantly, a crash: Immediately upon starting the new
gnome-shell process (with option --replace) a white screen appears
with "Oh No... something went wrong..." forcing me log out.
The crash happens whether using an independent VT or an ssh login.
Afterwards I typed Control-C to get control in gdb, and produced the
attached backtraces but they don't seem useful (see attached
typescript file).
/var/syslog might be useful. I will attach the portion beginning just
before starting the new gnome-shell
The attached typescript file shows what I did to circumvent the buggy
instructions at https://wiki.gnome.org/Projects/GnomeShell/Debugging
P.S. The original crash I wanted to report was that opening any .jpg
in gimp and selecting part of the image and then doing Select->Invert
instantly freezes the system. The only recovery is to use a separate
VT to kill the gimp process, after which gnome-shell restarts. A
system error dialog appears saying gnome-session [correction: gnome-
shell] got a segfault somewhere; thus the desire to get a backtrace.
But this bug report is _not_ about that bug, but is about how using
the debug instructions in the wiki are incorrect and when fixed seem
to cause a crash on their own.
ProblemType: Bug
DistroRelease: Ubuntu 21.04
Package: gnome-shell 3.38.4-1ubuntu3~21.04.1
ProcVersionSignature: Ubuntu 5.11.0-25.27-generic 5.11.22
Uname: Linux 5.11.0-25-generic x86_64
ApportVersion: 2.20.11-0ubuntu65.1
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: GNOME
Date: Sun Jul 25 13:41:54 2021
DisplayManager: gdm3
InstallationDate: Installed on 2021-07-20 (5 days ago)
InstallationMedia: Ubuntu-Server 21.04 "Hirsute Hippo" - Release amd64
(20210421)
RelatedPackageVersions: mutter-common 3.38.4-1ubuntu2
SourcePackage: gnome-shell
UpgradeStatus: No upgrade log present (probably fresh install)
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