100% reproducible for me; just hover over a Task Manager task: #11 QString::QString (this=0x7ffc13c4d9c0, other=...) at /usr/include/qt6/QtCore/qstring.h:1186 #12 KWin::Window::desktopFileName (this=0x31a257e0) at /home/nate/kde/src/kwin/src/window.h:1241 #13 KWin::ScreencastManager::streamWindow (this=0x3070f150, waylandStream=0x31253aa0, winid=<optimized out>, mode=KWin::ScreencastV1Interface::Hidden) at /home/nate/kde/src/kwin/src/plugins/screencast/screencastmanager.cpp:50 `git bisect` says it was this commit: 0d7bca07b920319a18007aa6a599f664236b3cc6 is the first bad commit commit 0d7bca07b920319a18007aa6a599f664236b3cc6 Author: Marco Martin <notmart@gmail.com> Date: Mon Oct 21 17:13:03 2024 +0200 Double buffer m_tile Add a new m_requestedTile member that gets set immediately with either requestTile() or setQuickTileMode(), at XdgToplevelWindow::handleStatesAcknowledged() Window::commitTile() will be called and m_tile will be actually set only on that step Going back to 649b3df296cbcae2dce21fbb555ee3796e4e543e (the immediately preceding commit) makes the crash go away.
Full backtrace: #0 __pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=11, no_tid=no_tid@entry=0) at pthread_kill.c:44 #1 0x00007fedea0a86d3 in __pthread_kill_internal (threadid=<optimized out>, signo=11) at pthread_kill.c:78 #2 0x00007fedea04fc4e in __GI_raise (sig=11) at ../sysdeps/posix/raise.c:26 #3 0x00007fedee4c55ab in KCrash::defaultCrashHandler (sig=11) at /home/nate/kde/src/kcrash/src/kcrash.cpp:596 #4 0x00007fedea04fd00 in <signal handler called> () at /lib64/libc.so.6 #5 std::__atomic_base<int>::fetch_add (this=0x8000000000000000, __i=1, __m=std::memory_order::acq_rel) at /usr/include/c++/14/bits/atomic_base.h:629 #6 QAtomicOps<int>::ref<int> (_q_value=<error reading variable: Cannot access memory at address 0x8000000000000000>) at /usr/include/qt6/QtCore/qatomic_cxx11.h:259 #7 QBasicAtomicInteger<int>::ref (this=0x8000000000000000) at /usr/include/qt6/QtCore/qbasicatomic.h:47 #8 QArrayData::ref (this=0x8000000000000000) at /usr/include/qt6/QtCore/qarraydata.h:58 #9 QArrayDataPointer<char16_t>::ref (this=0x7ffc13c4d9c0) at /usr/include/qt6/QtCore/qarraydatapointer.h:438 #10 QArrayDataPointer<char16_t>::QArrayDataPointer (this=0x7ffc13c4d9c0, other=...) at /usr/include/qt6/QtCore/qarraydatapointer.h:40 #11 QString::QString (this=0x7ffc13c4d9c0, other=...) at /usr/include/qt6/QtCore/qstring.h:1186 #12 KWin::Window::desktopFileName (this=0x31a257e0) at /home/nate/kde/src/kwin/src/window.h:1241 #13 KWin::ScreencastManager::streamWindow (this=0x3070f150, waylandStream=0x31253aa0, winid=<optimized out>, mode=KWin::ScreencastV1Interface::Hidden) at /home/nate/kde/src/kwin/src/plugins/screencast/screencastmanager.cpp:50 #14 0x00007fedea7fc8f2 in QtPrivate::QSlotObjectBase::call (this=0x3075aad0, r=<optimized out>, a=0x7ffc13c4db10) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/corelib/kernel/qobjectdefs_impl.h:469 #15 doActivate<false> (sender=0x30706830, signal_index=5, argv=0x7ffc13c4db10) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/corelib/kernel/qobject.cpp:4086 #16 0x00007fedea7f2bc7 in QMetaObject::activate (sender=<optimized out>, m=m@entry=0x7fedee093ee0 <KWin::ScreencastV1Interface::staticMetaObject>, local_signal_index=local_signal_index@entry=2, argv=argv@entry=0x7ffc13c4db10) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/corelib/kernel/qobject.cpp:4146 #17 0x00007fededd99f85 in KWin::ScreencastV1Interface::windowScreencastRequested (this=<optimized out>, _t1=<optimized out>, _t2=<optimized out>, _t3=<optimized out>) at /home/nate/kde/build/kwin/src/kwin_autogen/include/moc_screencast_v1.cpp:371 #18 0x00007fedede89d01 in QtWaylandServer::zkde_screencast_unstable_v1::handle_stream_window (client=<optimized out>, resource=<optimized out>, stream=107, window_uuid=0x31665a20 "{47e65496-0bde-43b5-ae21-e2919ba39fc1}", pointer=1) at /home/nate/kde/build/kwin/src/wayland/qwayland-server-zkde-screencast-unstable-v1.cpp:262 #19 0x00007fede9901056 in ffi_call_unix64 () at ../src/x86/unix64.S:104 #20 0x00007fede98fd6a0 in ffi_call_int (cif=cif@entry=0x7ffc13c4dd80, fn=<optimized out>, rvalue=<optimized out>, avalue=<optimized out>, closure=closure@entry=0x0) at ../src/x86/ffi64.c:673 --Type <RET> for more, q to quit, c to continue without paging--c #21 0x00007fede99004ee in ffi_call (cif=cif@entry=0x7ffc13c4dd80, fn=<optimized out>, rvalue=rvalue@entry=0x0, avalue=avalue@entry=0x7ffc13c4de50) at ../src/x86/ffi64.c:710 #22 0x00007fedee4b6b21 in wl_closure_invoke (closure=0x31665940, flags=<optimized out>, target=<optimized out>, opcode=1, data=<optimized out>) at ../../src/wayland/src/connection.c:1236 #23 0x00007fedee4b1aa2 in wl_client_connection_data (fd=<optimized out>, mask=<optimized out>, data=0x3132f2f0) at ../../src/wayland/src/wayland-server.c:460 #24 0x00007fedee4b46d2 in wl_event_loop_dispatch (loop=0x301e8210, timeout=<optimized out>) at ../../src/wayland/src/event-loop.c:1106 #25 0x00007fededd52574 in KWin::Display::dispatchEvents (this=<optimized out>) at /home/nate/kde/src/kwin/src/wayland/display.cpp:121 #26 0x00007fedea7fc8f2 in QtPrivate::QSlotObjectBase::call (this=0x306d3ce0, r=<optimized out>, a=0x7ffc13c4e2f0) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/corelib/kernel/qobjectdefs_impl.h:469 #27 doActivate<false> (sender=0x304ce530, signal_index=3, argv=0x7ffc13c4e2f0) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/corelib/kernel/qobject.cpp:4086 #28 0x00007fedea7f2bc7 in QMetaObject::activate (sender=sender@entry=0x304ce530, m=m@entry=0x7fedeac8afa0, local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x7ffc13c4e2f0) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/corelib/kernel/qobject.cpp:4146 #29 0x00007fedea80a54d in QSocketNotifier::activated (this=this@entry=0x304ce530, _t1=..., _t2=<optimized out>, _t3=...) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/redhat-linux-build/src/corelib/Core_autogen/include/moc_qsocketnotifier.cpp:195 #30 0x00007fedea80ad5b in QSocketNotifier::event (this=0x304ce530, e=<optimized out>) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/corelib/kernel/qsocketnotifier.cpp:327 #31 0x00007fedebb8b218 in QApplicationPrivate::notify_helper (this=<optimized out>, receiver=0x304ce530, e=0x7ffc13c4e440) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/widgets/kernel/qapplication.cpp:3287 #32 0x00007fedea796e88 in QCoreApplication::notifyInternal2 (receiver=0x304ce530, event=0x7ffc13c4e440) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/corelib/kernel/qcoreapplication.cpp:1142 #33 0x00007fedea7970ed in QCoreApplication::sendEvent (receiver=<optimized out>, event=<optimized out>) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/corelib/kernel/qcoreapplication.cpp:1583 #34 0x00007fedea9569c6 in QEventDispatcherUNIXPrivate::activateSocketNotifiers (this=this@entry=0x3015a6d0) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/corelib/kernel/qeventdispatcher_unix.cpp:251 #35 0x00007fedea9572d4 in QEventDispatcherUNIX::processEvents (this=<optimized out>, flags=...) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/corelib/kernel/qeventdispatcher_unix.cpp:467 #36 0x00007fedeb563492 in QUnixEventDispatcherQPA::processEvents (this=<optimized out>, flags=...) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/gui/platform/unix/qunixeventdispatcher.cpp:27 #37 0x00007fedea7a3bc3 in QEventLoop::exec (this=this@entry=0x7ffc13c4e600, flags=..., flags@entry=...) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/corelib/global/qflags.h:34 #38 0x00007fedea79fa7c in QCoreApplication::exec () at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/corelib/global/qflags.h:74 #39 0x00007fedeafd66ed in QGuiApplication::exec () at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/gui/kernel/qguiapplication.cpp:1926 #40 0x00007fedebb8b189 in QApplication::exec () at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/widgets/kernel/qapplication.cpp:2555 #41 0x000000000043665c in main (argc=<optimized out>, argv=<optimized out>) at /home/nate/kde/src/kwin/src/main_wayland.cpp:626
*** This bug has been marked as a duplicate of bug 495250 ***