** Also affects: gnome-shell via
https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/4597
Importance: Unknown
Status: Unknown
** Changed in: gnome-shell (Ubuntu)
Status: Incomplete => New
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https://bugs.launchpad.net/bugs/1937958
Title:
gnome-shell gdb instructions cause immediate "Oh no" crash
Status in GNOME Shell:
Unknown
Status in gnome-shell package in Ubuntu:
New
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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