Bug 432317 - Can't logout session - it restarts immediately
Summary: Can't logout session - it restarts immediately
Status: RESOLVED WORKSFORME
Alias: None
Product: kwin
Classification: Plasma
Component: general (show other bugs)
Version: git master
Platform: Compiled Sources Linux
: NOR crash
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2021-01-30 16:33 UTC by Andrey
Modified: 2021-02-04 22:28 UTC (History)
0 users

See Also:
Latest Commit:
Version Fixed In:
butirsky: Wayland+
butirsky: X11-

Attachments
Backtrace of the crash on logout (860 bytes, text/plain)
2021-01-30 16:33 UTC, Andrey 		Details
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Description Andrey 2021-01-30 16:33:19 UTC 
Created attachment 135305 [details]
Backtrace of the crash on logout

SUMMARY
On logout, session restarts instead of returning to Display Manager.
Also, KWin crashes on the logout, which presumably is the reason of the restarting.

STEPS TO REPRODUCE
1. Logout by any means, even Ctrl+Alt+Backspace suits

OBSERVED RESULT
Session restarts

EXPECTED RESULT
Display Manager should appear

SOFTWARE/OS VERSIONS
Operating System: Fedora 33
KDE Plasma Version: 5.21.80
KDE Frameworks Version: 5.79.0
Qt Version: 5.15.2
Kernel Version: 5.9.11-200.fc33.x86_64
OS Type: 64-bit
Processors: 2 × Intel® Celeron® CPU 847 @ 1.10GHz
Graphics Processor: Mesa DRI Intel® HD Graphics 2000

ADDITIONAL INFORMATION
Backtrace attached
Comment 1 Andrey 2021-02-01 14:26:32 UTC 
I don't know what exactly solved it for me, but I can't reproduce it any more.
I rebuilt ~70 modules occasionally, maybe that helped..
Comment 2 Andrey 2021-02-01 16:42:05 UTC 
Unfortunately, this problem returned.
Seems we have a crash here which is not always reproducible :(
Comment 3 Andrey 2021-02-01 17:22:57 UTC 
Also can be reproduced with:

qdbus org.kde.KWin /Session org.kde.KWin.Session.quit
Comment 4 Andrey 2021-02-04 22:28:40 UTC 
Bisecting KWin lead to this:
```
commit a0c7f997d4714ae89ed8ff5ee2bb353ab4b0de60 (HEAD, refs/bisect/bad)
Author: Jonathan Riddell <jr@jriddell.org>
Date:   Thu Jan 21 12:07:20 2021 +0000

    Update version number for 5.20.90
    GIT_SILENT

commit e370fcb218ab5ef63928564bd7124fa17acac63f (refs/bisect/good-e370fcb218ab5ef63928564bd7124fa17acac63f)
Author: Vlad Zahorodnii <vlad.zahorodnii@kde.org>
Date:   Thu Jan 21 09:04:58 2021 +0200

    Simplify Toplevel::addRepaintFull()
    
    This avoids mapping the visible rect between the window local
    coordinates and the global coordinates back and forth.
```

So just bumping the version provoked the crash.
kwayland-server was on e1e3a4a commit.

Bad thing I can't reproduce it any more on clean Plasma reinstall.

My conclusion: the installation system is very fragile.
There is no guarantee next build won't screw you installation up.
We can't protect ourselves from it in any way currently.
The only thing we can do is reinstall from scratch as frequent as possible. Which doesn't feel too satisfiable.