Bug 510541

Summary: KWin segfault in libQt6Qml.so.6.10.0 during window drag with Wobbly Windows effect
Product: [Plasma] kwin Reporter: TheBearKing <kde.headstand443>
Component: wayland-genericAssignee: KWin default assignee <kwin-bugs-null>
Status: RESOLVED DOWNSTREAM    
Severity: crash CC: kde
Priority: NOR    
Version First Reported In: git master   
Target Milestone: ---   
Platform: Arch Linux   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: KWin system configuration, active effects, compositor state, and kernel crash signature at time of segfault

Description TheBearKing 2025-10-12 21:35:44 UTC 
Created attachment 185720 [details]
KWin system configuration, active effects, compositor state, and kernel crash signature at time of segfault

STEPS TO REPRODUCE
1. Enable Wobbly Windows effect (System Settings → Desktop Effects)
2. Drag a window or screenshot between positions
3. Crash occurs intermittently during drag operation

OBSERVED RESULT
kwin_wayland[74757]: segfault at 35 ip 00007f057a456a26 sp 00007ffd0f623310 error 4 
in libQt6Qml.so.6.10.0[456a26,7f057a08c000+3f5000] likely on CPU 4

EXPECTED RESULT
Window should drag smoothly without crash.

SOFTWARE/OS VERSIONS
- Distribution: Garuda Linux Dr460nized (Arch-based)
- KWin Version: 6.4.5
- Qt Version: 6.10.0
- Plasma: 6.4.5
- GPU: NVIDIA GeForce RTX 3080 Ti (Driver: 580.95.05)
- Display: Single 2560x1440 @ 165Hz
- Session: Wayland

ADDITIONAL INFORMATION
Active effects at crash: wobblywindows, kwin4_effect_shapecorners, forceblur, slidingpopups

Workaround: Disabling Wobbly Windows effect prevents the crash.

CRASH DETECTION & DATA COLLECTION
This crash was automatically detected using the KWin/Plasma Crash Monitor:
https://codeberg.org/thebearking/kwin-crash-monitor

Complete system state captured at crash time for diagnosis.
Comment 2 Bug Janitor Service 2025-10-28 03:47:35 UTC 
🐛🧹 ⚠️ This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information, then set the bug status to REPORTED. If there is no change for at least 30 days, it will be automatically closed as RESOLVED WORKSFORME.

For more information about our bug triaging procedures, please read https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging.

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Comment 3 TheBearKing 2025-10-28 22:40:54 UTC 
Update: I was attempting to provide diagnostic data for this crash, but my capture system had a problem during cascade failures. I've fixed that in v2.2.7.
I still haven't been able to reproduce this KWin issue reliably. If anyone hits it, I have a proper capture tool now that will get the right coredump. I am also on new hardware here, so reproducing is very unlikely. Should this be closed out?
Comment 4 TheBearKing 2025-10-28 22:43:11 UTC 
After investigation, I believe this crash was actually caused by the screenshot tool, not KWin. This is a known issue in that component.
I developed a crash monitoring tool to help track KWin stability issues. If the actual KWin crash recurs, I have a better capture system now that can provide accurate diagnostics.