Bug 288897

Summary:	kwin crash on second (and subsequent) login
Product:	[Plasma] kwin	Reporter:	Robert Chalmas <rc_kde>
Component:	compositing	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED UPSTREAM
Severity:	crash
Priority:	NOR
Version:	4.7.2
Target Milestone:	---
Platform:	Ubuntu
OS:	Linux
Latest Commit:		Version Fixed In:

Description Robert Chalmas 2011-12-13 15:12:48 UTC

Version: 4.7.2 (using KDE 4.7.2)
OS: Linux

At boot time, the KDE session always opens successfully. If I log out and try to log in again, kwin crashes immediatly after entering my password and pressing enter, without displaying KDE desktop, instead I'm back to the login screen. The next attempt is always successful and the KDE session opens, but with the desktop effects disabled.

After opening System Settings, then Desktop Effects, I can see the message "OpenGL compositing (the default) has crashed KWin in the past." If I re-enable the desktop effects and log out, then try to log in again, the crash repeats as described above. This is 100% reproductible.

The only two ways to be able to log in without crash when the desktop effects are enabled are rebooting or killing the X-server.

Reproducible: Always

Steps to Reproduce:
Log in; make sure the desktop effects are enabled (OpenGL or XRender give similar results); log out; try to log in again.

Actual Results:
The login fails and I'm returned almost immediatly to the login window (as if the password was wrong, but it isn't).

Expected Results:
I would expect my login to succeed and the KDE desktop to appear.

This happens with kubuntu 11.10 (on a fresh install but also with all updates) and 12.04 alpha1, but this did not happen with kubuntu 11.04 (using KDE 4.6.x), so it seems to be specific to KDE 4.7.x.

This happens with both 32 bit and 64 bit versions of kubuntu.

This is 100% reproductible and was verified on several machines from different models and brands.

I found no way to get a backtrace. As the crash happens before the KDE desktop appears, I get no DrKonqi window. I tried the method described here:
https://bugs.kde.org/show_bug.cgi?id=203793#c10
but the only result was I could no more login at all.

I will be glad to provide any useful information.

Comment 1 Thomas Lübking 2011-12-13 15:24:05 UTC

(In reply to comment #0)
> If I log out and try to log in again, kwin crashes immediatly after entering 
> my password and pressing enter, without displaying KDE desktop, instead I'm 
> back to the login screen.

That means the X11 server crashed, most likely due to a driver bug (nouveau or fglrx?)
Information about the crash can usually be found in /var/log/Xorg.0.log

It's not a KDE bug, you can file it at the freedesktop.org bugtracker (ensure to provide information about your graphics hardware & driver versions - usually the mentioned log is sufficient)

Comment 2 Robert Chalmas 2011-12-15 19:20:32 UTC

Many thanks for your quick answer and your advice!
As you suggested, I filed this bug here:
https://bugs.freedesktop.org/show_bug.cgi?id=43853
and a solution was found using an experimental version of the xorg drivers.