KWin from yesterday's Plasma 6 git master.


STEPS TO REPRODUCE
1. Do an in-place upgrade of the system that includes a new version of PipeWire
2. Do something light on the machine that does *not* involve showing KPipeWire-provided Task Manager thumbnails

OBSERVED RESULT
kwin_wayland crashed in suspiciously in PipeWire code:

#0  spa_list_insert (elem=0x3b2e6c0, list=0x800000007000000) at ../spa/include/spa/utils/list.h:44
#1  create_mix (data=data@entry=0x3057288, port=port@entry=0x3e0e200, mix_id=mix_id@entry=4294967295, 
    peer_id=peer_id@entry=4294967295) at ../src/modules/module-client-node/remote-node.c:189
#2  0x00007fd836d3864d in do_node_init (data=0x3057288)
    at ../src/modules/module-client-node/remote-node.c:964
#3  node_export (core=<optimized out>, object=<optimized out>, do_free=<optimized out>, 
    user_data_size=<optimized out>) at ../src/modules/module-client-node/remote-node.c:1250
#4  0x00007fd8740eba69 in pw_core_export (core=0x41099a0, 
    type=0x7fd874146259 "PipeWire:Interface:Node", props=0x0, object=0x3e0dca0, user_data_size=0)
    at ../src/pipewire/core.c:279
#5  0x00007fd874130f2e in pw_stream_connect (stream=0x40cb6d0, direction=SPA_DIRECTION_OUTPUT, 
    target_id=<optimized out>, flags=<optimized out>, params=<optimized out>, 
    n_params=<optimized out>) at ../src/pipewire/stream.c:2112
#6  0x00007fd8741cb2b8 in KWin::ScreenCastStream::createStream (this=this@entry=0x39cf710)
    at /usr/include/qt6/QtCore/qarraydatapointer.h:104
#7  0x00007fd8741cb909 in KWin::ScreenCastStream::init (this=this@entry=0x39cf710)
    at /home/nate/kde/src/kwin/src/plugins/screencast/screencaststream.cpp:357
#8  0x00007fd8741c2a6e in KWin::ScreencastManager::integrateStreams (this=<optimized out>, 
    waylandStream=0x34e75a0, stream=0x39cf710)
    at /home/nate/kde/src/kwin/src/plugins/screencast/screencastmanager.cpp:219
#9  0x00007fd897fde394 in QtPrivate::QSlotObjectBase::call (a=0x7ffe5dd836b0, r=0x1b2f600, 
    this=0x21bf560)
    at /usr/src/debug/qt6-qtbase-6.5.2-1.fc38.x86_64/src/corelib/kernel/qobjectdefs_impl.h:363
#10 doActivate<false> (sender=0x21be8f0, signal_index=5, argv=0x7ffe5dd836b0)
    at /usr/src/debug/qt6-qtbase-6.5.2-1.fc38.x86_64/src/corelib/kernel/qobject.cpp:3992
#11 0x00007fd897fd4e17 in QMetaObject::activate (sender=<optimized out>, 
    m=m@entry=0x7fd89b96b160 <KWaylandServer::ScreencastV1Interface::staticMetaObject>, 
    local_signal_index=local_signal_index@entry=2, argv=argv@entry=0x7ffe5dd836b0)
    at /usr/src/debug/qt6-qtbase-6.5.2-1.fc38.x86_64/src/corelib/kernel/qobject.cpp:4052
#12 0x00007fd89b6d8c65 in KWaylandServer::ScreencastV1Interface::windowScreencastRequested (
    this=<optimized out>, _t1=<optimized out>, _t2=..., _t3=<optimized out>)
    at /home/nate/kde/build6/kwin/src/kwin_autogen/include/moc_screencast_v1_interface.cpp:459
#13 0x00007fd89b7b72d3 in QtWaylandServer::zkde_screencast_unstable_v1::handle_stream_window (
    client=<optimized out>, resource=<optimized out>, stream=370, 
    window_uuid=0x3ea3980 "{5d9f5314-f2c4-46d7-9a49-b260fd34c7fe}", pointer=1)
    at /home/nate/kde/build6/kwin/src/wayland/qwayland-server-zkde-screencast-unstable-v1.cpp:262
#14 0x00007fd897496be6 in ffi_call_unix64 () at ../src/x86/unix64.S:104
#15 0x00007fd8974934bf in ffi_call_int (cif=cif@entry=0x7ffe5dd83930, fn=<optimized out>, 
    rvalue=<optimized out>, avalue=<optimized out>, closure=closure@entry=0x0)
    at ../src/x86/ffi64.c:673
#16 0x00007fd89749618e in ffi_call (cif=cif@entry=0x7ffe5dd83930, fn=<optimized out>, 
    rvalue=rvalue@entry=0x0, avalue=avalue@entry=0x7ffe5dd83a00) at ../src/x86/ffi64.c:710
#17 0x00007fd89affe521 in wl_closure_invoke (closure=0x3ea38a0, flags=<optimized out>, 
    target=<optimized out>, opcode=1, data=<optimized out>) at ../../src/wayland/src/connection.c:1025
#18 0x00007fd89aff9a92 in wl_client_connection_data (fd=<optimized out>, mask=<optimized out>, 
    data=0x2df0a30) at ../../src/wayland/src/wayland-server.c:438
#19 0x00007fd89affc652 in wl_event_loop_dispatch (loop=0x1ad85a0, timeout=<optimized out>)
    at ../../src/wayland/src/event-loop.c:1104
#20 0x00007fd89b698c64 in KWaylandServer::Display::dispatchEvents (this=<optimized out>)
    at /home/nate/kde/src/kwin/src/wayland/display.cpp:113
#21 0x00007fd897fde394 in QtPrivate::QSlotObjectBase::call (a=0x7ffe5dd83eb0, r=0x1b6bf40, 
    this=0x1e7d5a0)
    at /usr/src/debug/qt6-qtbase-6.5.2-1.fc38.x86_64/src/corelib/kernel/qobjectdefs_impl.h:363
#22 doActivate<false> (sender=0x1b5d340, signal_index=3, argv=0x7ffe5dd83eb0)
    at /usr/src/debug/qt6-qtbase-6.5.2-1.fc38.x86_64/src/corelib/kernel/qobject.cpp:3992
#23 0x00007fd897fd4e17 in QMetaObject::activate (sender=sender@entry=0x1b5d340, 
    m=m@entry=0x7fd89840a0a0, local_signal_index=local_signal_index@entry=0, 
    argv=argv@entry=0x7ffe5dd83eb0)
    at /usr/src/debug/qt6-qtbase-6.5.2-1.fc38.x86_64/src/corelib/kernel/qobject.cpp:4052
#24 0x00007fd897feebfd in QSocketNotifier::activated (this=this@entry=0x1b5d340, _t1=..., 
    _t2=<optimized out>, _t3=...)
    at /usr/src/debug/qt6-qtbase-6.5.2-1.fc38.x86_64/redhat-linux-build/src/corelib/Core_autogen/include/moc_qsocketnotifier.cpp:231
#25 0x00007fd897fef3fb in QSocketNotifier::event (this=0x1b5d340, e=<optimized out>)
    at /usr/src/debug/qt6-qtbase-6.5.2-1.fc38.x86_64/src/corelib/kernel/qsocketnotifier.cpp:326
#26 0x00007fd8993c0af8 in QApplicationPrivate::notify_helper (this=<optimized out>, 
    receiver=0x1b5d340, e=0x7ffe5dd84000)
    at /usr/src/debug/qt6-qtbase-6.5.2-1.fc38.x86_64/src/widgets/kernel/qapplication.cpp:3287
#27 0x00007fd897f7cdb8 in QCoreApplication::notifyInternal2 (receiver=0x1b5d340, event=0x7ffe5dd84000)
    at /usr/src/debug/qt6-qtbase-6.5.2-1.fc38.x86_64/src/corelib/kernel/qcoreapplication.cpp:1118
#28 0x00007fd897f7cfbd in QCoreApplication::sendEvent (receiver=<optimized out>, 
    event=<optimized out>)
    at /usr/src/debug/qt6-qtbase-6.5.2-1.fc38.x86_64/src/corelib/kernel/qcoreapplication.cpp:1536
#29 0x00007fd8980fe10e in QEventDispatcherUNIXPrivate::activateSocketNotifiers (
    this=this@entry=0x1b5a0b0)
    at /usr/src/debug/qt6-qtbase-6.5.2-1.fc38.x86_64/src/corelib/kernel/qeventdispatcher_unix.cpp:268
#30 0x00007fd8980fea37 in QEventDispatcherUNIX::processEvents (this=<optimized out>, flags=...)
    at /usr/src/debug/qt6-qtbase-6.5.2-1.fc38.x86_64/src/corelib/kernel/qeventdispatcher_unix.cpp:477
#31 0x00007fd898d40092 in QUnixEventDispatcherQPA::processEvents (this=<optimized out>, flags=...)
    at /usr/src/debug/qt6-qtbase-6.5.2-1.fc38.x86_64/src/gui/platform/unix/qunixeventdispatcher.cpp:27
#32 0x00007fd897f899f3 in QEventLoop::exec (this=this@entry=0x7ffe5dd841c0, flags=..., 
    flags@entry=...) at /usr/src/debug/qt6-qtbase-6.5.2-1.fc38.x86_64/src/corelib/global/qflags.h:34
#33 0x00007fd897f8569d in QCoreApplication::exec ()
    at /usr/src/debug/qt6-qtbase-6.5.2-1.fc38.x86_64/src/corelib/global/qflags.h:74
#34 0x00007fd8987f917d in QGuiApplication::exec ()
    at /usr/src/debug/qt6-qtbase-6.5.2-1.fc38.x86_64/src/gui/kernel/qguiapplication.cpp:1908
#35 0x00007fd8993c0a69 in QApplication::exec ()
    at /usr/src/debug/qt6-qtbase-6.5.2-1.fc38.x86_64/src/widgets/kernel/qapplication.cpp:2566
#36 0x00000000004308e8 in main (argc=<optimized out>, argv=<optimized out>)
    at /home/nate/kde/src/kwin/src/main_wayland.cpp:613

Normally I do offline upgrades, but Discover is somewhat broken in Plasma 6 right now, so I have been doing `sudo dnf update` instead recently.

I can't be sure that the in-place upgrade triggered this, but the timing seems suspicious to me. I was not doing anything that should have triggered any pipewire-related code to be run, though. And it's clearly not ideal for kwin_wayland to crash when performing in-place upgrades. :)