Bug 515156

Summary: KWin crashed in KWin::Item::sortedChildItems while interacting with QtCreator
Product: [Plasma] kwin Reporter: Daniel Schulte <trilader+kdebugs>
Component: generalAssignee: KWin default assignee <kwin-bugs-null>
Status: REOPENED ---    
Severity: crash CC: kde, kdedev
Priority: NOR Keywords: drkonqi
Version First Reported In: 6.5.5   
Target Milestone: ---   
Platform: Arch Linux   
OS: Linux   
See Also: https://bugs.kde.org/show_bug.cgi?id=515123
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: New crash information added by DrKonqi

Description Daniel Schulte 2026-01-27 15:17:32 UTC
Application: kwin_wayland (6.5.5)

ApplicationNotResponding [ANR]: false
Qt Version: 6.10.1
Frameworks Version: 6.22.0
Operating System: Linux 6.18.6-arch1-1 x86_64
Windowing System: Wayland
Distribution: "Arch Linux"
DrKonqi: 6.5.5 [CoredumpBackend]

-- Information about the crash:
I was interacting with a QtCreator window when KWin crashed and automatically restarted. I didn't notice notice/do anything specific, I used this QtCreator window earlier today as well. I'm pretty sure it's the same as 515123 which I reported yesterday (where KWin crashed when starting a game).

The reporter is unsure if this crash is reproducible.

-- Backtrace (Reduced):
#5  KWin::Item::sortedChildItems (this=0x0) at /usr/include/c++/15.2.1/optional:562
#6  0x00007ffacd5341dd in KWin::ItemRendererOpenGL::createRenderNode (this=this@entry=0x556a718eab90, item=item@entry=0x0, context=context@entry=0x7ffc7edacaf0, filter=..., holeFilter=...) at /usr/src/debug/kwin/kwin-6.5.5/src/scene/itemrenderer_opengl.cpp:133
#7  0x00007ffacd5396df in KWin::ItemRendererOpenGL::renderItem (this=this@entry=0x556a718eab90, renderTarget=..., viewport=..., item=0x0, mask=mask@entry=4, region=..., data=..., filter=..., holeFilter=...) at /usr/src/debug/kwin/kwin-6.5.5/src/scene/itemrenderer_opengl.cpp:349
#8  0x00007ffaaaa3a251 in KWin::WindowScreenCastSource::render (this=this@entry=0x556a72479620, target=0x556a7290b430, bufferDamage=...) at /usr/src/debug/kwin/kwin-6.5.5/src/plugins/screencast/windowscreencastsource.cpp:132
#9  0x00007ffaaaa38a70 in KWin::ScreenCastStream::record (this=0x556a73338c50, contents=...) at /usr/include/c++/15.2.1/bits/unique_ptr.h:192
#10 0x00007ffaaaa38c64 in operator() (__closure=0x556a731eb770) at /usr/src/debug/kwin/kwin-6.5.5/src/plugins/screencast/screencaststream.cpp:353
#11 operator() (__closure=<optimized out>) at /usr/include/qt6/QtCore/qobjectdefs_impl.h:116
#15 QtPrivate::QCallableObject<KWin::ScreenCastStream::ScreenCastStream(KWin::ScreenCastSource*, std::shared_ptr<KWin::PipeWireCore>, QObject*)::<lambda()>, QtPrivate::List<>, void>::impl(int, QtPrivate::QSlotObjectBase *, QObject *, void **, bool *) (which=<optimized out>, this_=0x556a731eb760, r=<optimized out>, a=<optimized out>, ret=<optimized out>) at /usr/include/qt6/QtCore/qobjectdefs_impl.h:547
#16 0x00007ffacabd734f in QtPrivate::QSlotObjectBase::call (this=<optimized out>, r=<optimized out>, a=<optimized out>, this=<optimized out>, r=<optimized out>, a=<optimized out>) at /usr/src/debug/qt6-base/qtbase/src/corelib/kernel/qobjectdefs_impl.h:461
#17 doActivate<false> (sender=<optimized out>, signal_index=<optimized out>, argv=<optimized out>) at /usr/src/debug/qt6-base/qtbase/src/corelib/kernel/qobject.cpp:4257
[...]
#19 QTimer::timeout (this=<optimized out>, _t1=...) at /usr/src/debug/qt6-base/build/src/corelib/Core_autogen/include/moc_qtimer.cpp:182
#20 QTimer::timerEvent (e=<optimized out>, this=<optimized out>) at /usr/src/debug/qt6-base/qtbase/src/corelib/kernel/qtimer.cpp:331
#21 QTimer::timerEvent (this=<optimized out>, e=<optimized out>) at /usr/src/debug/qt6-base/qtbase/src/corelib/kernel/qtimer.cpp:325
#22 0x00007ffacabc4936 in QObject::event (this=<optimized out>, e=<optimized out>) at /usr/src/debug/qt6-base/qtbase/src/corelib/kernel/qobject.cpp:1388
#23 0x00007ffacbd021c0 in QApplicationPrivate::notify_helper (this=<optimized out>, receiver=0x556a73338e10, e=0x7ffc7edad250) at /usr/src/debug/qt6-base/qtbase/src/widgets/kernel/qapplication.cpp:3305
#24 0x00007ffacab6a958 in QCoreApplication::notifyInternal2 (receiver=0x556a73338e10, event=0x7ffc7edad250) at /usr/src/debug/qt6-base/qtbase/src/corelib/kernel/qcoreapplication.cpp:1109


Reported using DrKonqi
Comment 1 Daniel Schulte 2026-01-27 15:17:33 UTC
Created attachment 188949 [details]
New crash information added by DrKonqi

DrKonqi auto-attaching complete backtrace.
Comment 2 Daniel Schulte 2026-01-27 15:26:39 UTC
I've had a log at the system journal. It shows that qtcreator crashed just before kwin_wayland did:

```
Jan 27 16:10:25 eldingar kernel: qtcreator[30091]: segfault at 100000014 ip 00007f1756b2905f sp 00007fffe3b5f468 error 4 in libQt6Gui.so.6.10.1[12905f,7f1756ae4000+6c8000] likely on CPU 8 (core 8>
Jan 27 16:10:25 eldingar kernel: Code: 18 f3 0f 7e 50 04 66 0f 14 c0 f3 0f e6 ca 66 0f 5e c8 66 0f 28 c1 66 0f 15 c9 c3 f3 0f 1e fa 48 8b 57 10 31 c0 48 85 d2 74 04 <48> 8b 42 10 c3 90 66 66 2e 0>
Jan 27 16:10:25 eldingar systemd-coredump[311081]: Process 30091 (qtcreator) of user 1000 terminated abnormally with signal 11/SEGV, processing...
Jan 27 16:10:25 eldingar systemd[1]: Started Process Core Dump (PID 311081/UID 0).
Jan 27 16:10:25 eldingar systemd[1]: Started Pass systemd-coredump journal entries to relevant user for potential DrKonqi handling.
Jan 27 16:10:28 eldingar kwin_wayland_wrapper[135076]: KCrash: Application 'kwin_wayland' crashing... crashRecursionCounter = 2
Jan 27 16:10:28 eldingar systemd-coredump[311126]: Process 135076 (kwin_wayland) of user 1000 terminated abnormally with signal 11/SEGV, processing...
Jan 27 16:10:28 eldingar systemd[1]: Started Process Core Dump (PID 311126/UID 0).
Jan 27 16:10:28 eldingar systemd[1]: Started Pass systemd-coredump journal entries to relevant user for potential DrKonqi handling.
```
Comment 3 David Edmundson 2026-01-28 09:17:18 UTC

*** This bug has been marked as a duplicate of bug 510781 ***
Comment 4 Daniel Schulte 2026-01-28 11:46:36 UTC
I'm unsure if this really is a duplicate of 510781 (which itself is marked as a duplicate of 509690) as both of them are marked as resolved since 2025-10-14 and this has happened for me again. If this really is a duplicate maybe one of them should also be re-opened?
Comment 5 TraceyC 2026-01-29 10:53:57 UTC
I had a look at those other two bugs, and their backtraces look subtly different. Also, they were supposed to be fixed with 6.5.0 and you're running 6.5.5. Let's keep those other bugs closed for now, and use this one for this backtrace.

I also took a look at bug 515123 and while the backtrace also shares some similarities with this one, they are sufficiently different for me not to mark them as duplicates.