Created attachment 131739 [details]
crash report

SUMMARY

I have the top left corner of my screen set to "Present Windows - All Desktops". Frequently, starting this trigger (or hitting it again to close the "present windows" mode) will crash the compositor. 

At least, I'm pretty sure it's the compositor, because after this has happened a few times in a session KDE will drop into a safe mode that disables compositing, and going into the settings to uncheck and check "enable compositor" fixes this. 


STEPS TO REPRODUCE
1. Set the top-left corner trigger to "Present Windows - All Desktops"
2. Trigger present windows with the mouse.
3. Hit the trigger again to return to the normal desktop.

OBSERVED RESULT

KWin frequently crashes and restarts, eventually disabling the compositor.

EXPECTED RESULT

KWin doesn't crash.


SOFTWARE/OS VERSIONS
Linux: 5.8.5-arch1-1
KDE Plasma Version: 5.19.5
KDE Frameworks Version: 5.73.0
Qt Version: 5.15.1

ADDITIONAL INFORMATION

One thing I've noticed is that it's vastly more likely to hang and crash when I have a lot of windows open, especially across multiple workspaces. (A lot meaning 20-40.) 

Clicking on a grouped icon in the Icons-Only Task Manager to expose all the windows from that program / group has never crashed for me, even though (I assume) this uses basically the same code.

I expect this problem might be hardware-specific. Some details:

 * Intel i7-2630QM
 * Intel HD Graphics 3000
 * Compositor rendering backend: OpenGL 3.1
 * I'm using kwin_x11, not Wayland.

I've included a crash dump, but the bug reporter rates it "not useful".

If there's anything I do to capture more useful debugging information without having to completely recompile my KDE packages, let me know.