Bug 449350

Summary: DrmGpu::findWorkingCombination failed to find any functional combinations
Product: [Plasma] kwin Reporter: Mateusz Warzynski <mathew.warzynski>
Component: platform-drmAssignee: KWin default assignee <kwin-bugs-null>
Status: RESOLVED FIXED    
Severity: crash CC: nate, xaver.hugl
Priority: NOR    
Version First Reported In: 5.23.5   
Target Milestone: ---   
Platform: Arch Linux   
OS: Linux   
Latest Commit: Version Fixed/Implemented In: 5.24
Sentry Crash Report:
Attachments: debug log output

Description Mateusz Warzynski 2022-01-30 01:58:01 UTC 
Created attachment 146060 [details]
debug log output

Possibly related to https://bugs.kde.org/show_bug.cgi?id=438789.
However, fix proposed in the comments were pushed to 5.22 and I observe a similar issue at 5.23.

SUMMARY
While having KDE running, when I connect an external monitor to the dock the `kwin_wayland` crashes. It works fine if I start KDE with the external monitor already connected.
`kwin_wayland_drm` seems to be unable to find a functional combination after a new external monitor via dock is connected.


STEPS TO REPRODUCE
1. Disconnect external monitor (or dock),
2. Start KDE with Wayland (`XDG_SESSION_TYPE=wayland dbus-run-session startplasma-wayland`),
3. Connect external monitor (or dock),
4. -- crash --

OBSERVED RESULT
KDE exits to tty, loads up again (from scratch) with external monitor working fine.
Since the whole KDE exits it also closes all working GUI applications (like web browser), so that I have to open all of them once again.

EXPECTED RESULT
KDE should not crash. KDE should use the new monitor.


SOFTWARE/OS VERSIONS
OS: ArchLinux
```
~ uname -a
Linux mia 5.16.3-arch1-1 #1 SMP PREEMPT Thu, 27 Jan 2022 14:18:25 +0000 x86_64 GNU/Linux
```

KDE Plasma Version: 5.23.5
KDE Frameworks Version: 5.90.0
Qt Version: 5.15.2
Graphics Platform: Wayland

ADDITIONAL INFORMATION
Interesting logs from "debug log output":
```
kwin_wayland_drm: DrmGpu::findWorkingCombination failed to find any functional combinations! Reverting to the old configuration!
kwin_wayland_drm: Could not set cursor: Bad file descriptor
kwin_wayland_drm: Could not set cursor: Bad file descriptor
kwin_wayland_drm: Could not set cursor: Bad file descriptor
kwin_wayland_drm: Failed to update cursor on output "eDP-1"
kwin_wayland_drm: Could not set cursor: Bad file descriptor
kwin_wayland_drm: New gpu found: ""
kwin_wayland_drm: failed to open drm device at ""
kwin_wayland_drm: Received change event for monitored drm device "/dev/dri/card0"
The Wayland connection broke. Did the Wayland compositor die?
The Wayland connection broke. Did the Wayland compositor die?
kdeinit5: PID 76335 terminated.
(EE) failed to read Wayland events: Broken pipe
kdeinit5_wrapper: Warning: connect(/run/user/1000/kdeinit5__13) failed: : No such file or directory
Error: Can not contact kdeinit5!
startplasma-waylandsession: Starting up...startplasma-waylandsession: Shutting down...
startplasma-waylandsession: Done.
```
(I pasted full log as an attachment as context might be helpful.)

Crash backtrace:
```
(gdb) bt
#0  0x00007f57303271ea in QVector<KWin::DrmConnector::Mode>::clear() (this=<optimized out>) at /usr/include/qt/QtCore/qvector.h:442
#1  KWin::DrmConnector::updateModes() (this=0x18) at /usr/src/debug/kwin-5.23.5/src/plugins/platforms/drm/drm_object_connector.cpp:319
#2  0x00007f573032f28c in KWin::DrmOutput::updateModes() (this=this@entry=0x5624de19cc40) at /usr/src/debug/kwin-5.23.5/src/plugins/platforms/drm/drm_output.cpp:331
#3  0x00007f5730337f3d in KWin::DrmGpu::updateOutputs() (this=this@entry=0x5624dd95cac0) at /usr/src/debug/kwin-5.23.5/src/plugins/platforms/drm/drm_gpu.cpp:222
#4  0x00007f573031f101 in KWin::DrmBackend::updateOutputs() (this=0x5624dd93d6d0) at /usr/src/debug/kwin-5.23.5/src/plugins/platforms/drm/drm_backend.cpp:356
#5  0x00007f5730320763 in KWin::DrmBackend::handleUdevEvent() (this=0x5624dd93d6d0) at /usr/src/debug/kwin-5.23.5/src/plugins/platforms/drm/drm_backend.cpp:259
#6  0x00007f57373c1da3 in  () at /usr/lib/libQt5Core.so.5
#7  0x00007f57373c3a64 in QSocketNotifier::activated(QSocketDescriptor, QSocketNotifier::Type, QSocketNotifier::QPrivateSignal) () at /usr/lib/libQt5Core.so.5
#8  0x00007f57373c3baf in QSocketNotifier::event(QEvent*) () at /usr/lib/libQt5Core.so.5
#9  0x00007f5737fad1a6 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5
#10 0x00007f573739117a in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at /usr/lib/libQt5Core.so.5
#11 0x00007f57373db0f4 in QEventDispatcherUNIXPrivate::activateSocketNotifiers() () at /usr/lib/libQt5Core.so.5
#12 0x00007f57373dc065 in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#13 0x00005624dcc58a42 in QUnixEventDispatcherQPA::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
#14 0x00007f573738945b in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#15 0x00007f5737394ba7 in QCoreApplication::exec() () at /usr/lib/libQt5Core.so.5
#16 0x00005624dcbf48cb in main(int, char**) (argc=<optimized out>, argv=<optimized out>) at /usr/src/debug/kwin-5.23.5/src/main_wayland.cpp:745
```

coredump info
```
           PID: 75999 (kwin_wayland)
           UID: 1000 (mwarzynski)
           GID: 1000 (mwarzynski)
        Signal: 11 (SEGV)
     Timestamp: Sun 2022-01-30 02:17:48 CET (10min ago)
  Command Line: /usr/bin/kwin_wayland --wayland_fd 5 --socket wayland-0 --xwayland-fd 7 --xwayland-fd 6 --xwayland-display :13 --xwayland-xauthority /run/user/1000/xauth_UkRjbm --xwayland /usr/lib/startplasma-waylandsession
    Executable: /usr/bin/kwin_wayland
 Control Group: /user.slice/user-1000.slice/session-1.scope
          Unit: session-1.scope
         Slice: user-1000.slice
       Session: 1
     Owner UID: 1000 (mwarzynski)
       Boot ID: 193f064636b3431cbcd6cdbdc1a17c74
    Machine ID: 4fa290243f6a492fa8fbd786b758cf66
      Hostname: mia
       Storage: /var/lib/systemd/coredump/core.kwin_wayland.1000.193f064636b3431cbcd6cdbdc1a17c74.75999.1643505468000000.zst (present)
     Disk Size: 4.2M
       Message: Process 75999 (kwin_wayland) of user 1000 dumped core.

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                Module libQt5Qml.so.5 with build-id 212307572d9d92b0cb4d236fda1fe3f354b01093
                Module libQt5Quick.so.5 with build-id 2dca83de5d1ef02b8ef03fef5f18b531a2457e42
                Module libKF5Service.so.5 with build-id d1b849804483cf5e5d045fb60432203206c2ed38
                Module libwayland-server.so.0 with build-id 645526447334b85a6f4bf5a8b37737b27696365f
                Module libKF5Activities.so.5 with build-id b500ac9d9db8af60bf0d5223c830887b1503612c
                Module liblcms2.so.2 with build-id 92d69ecb51e7b4dee5a17936b6ac947a2a2042a5
                Module libxkbcommon.so.0 with build-id 1f1bc7527e57c886c3df5803068122e1971d4724
                Module libudev.so.1 with build-id e7bd18780bd5753c14f8561be78e4e78ae0266ee
                Module libinput.so.10 with build-id 956df35c2a15681d4aa87253ed15a5c18a339183
                Module libxcb-sync.so.1 with build-id dda14591103b01b1311906053bf1ca9e82ade35c
                Module libxcb-shm.so.0 with build-id fb797f299a446f559a95afcc168227482cc800d1
                Module libxcb-shape.so.0 with build-id f1b3376c4534fab0469feb1cd19f022ff98df533
                Module libxcb-render.so.0 with build-id a37bdb37744b508be9dd29fd9ccb9bb0170d43e5
                Module libxcb-randr.so.0 with build-id b6c1c7d4b28863b55ade251813db7f246b7ffe8b
                Module libxcb-keysyms.so.1 with build-id 333e5eb4075795f947c924a2085f17e2e2ae7147
                Module libxcb-icccm.so.4 with build-id 73f1e12d76af383aa969a60279ed5ed922045f47
                Module libxcb-glx.so.0 with build-id 8ad115382ad874165523dc5b4488c99d73bbc3c4
                Module libxcb-damage.so.0 with build-id 14ba8de82d16adadd150a1d0ae3e8ac2119ccc8a
                Module libxcb-cursor.so.0 with build-id 69d87b342ff51e520334e5fda3dd33bcf09c1483
                Module libxcb-composite.so.0 with build-id 94fff40466ef37eb5973997211aa68f9beb81d15
                Module libKScreenLocker.so.5 with build-id e41887d51747be992fe9dc2498b9794785889994
                Module libkdecorations2private.so.9 with build-id 822f79e2c74a010056323c4e2eb160ba8c72c696
                Module libkdecorations2.so.5 with build-id 684b26b757edf543097bfa3d97fececaf9bf16c2
                Module libKF5Plasma.so.5 with build-id 7ac5e2f353ba47c4dff42030a193726be02d88da
                Module libdbus-1.so.3 with build-id 74f2ab9c60512f3a93c932c3f627564d42e0b11e
                Module libbrotlidec.so.1 with build-id 45defc036e918e0140a72f1fbce6e7692d38241d
                Module libharfbuzz.so.0 with build-id 1d9dee49dd99162c3f83eb3259c3c88c6b4cd7fe
                Module libpng16.so.16 with build-id 2dc0bce07f199bf983c07a05fb95a6f4af83a9b3
                Module libbz2.so.1.0 with build-id 919597c477c9b2cb9cdbb7745ed6494ac0e6da60
                Module libz.so.1 with build-id 0c1459c56513efd5d53eb3868290e9afee6a6a26
                Module libexpat.so.1 with build-id 64e977cfebfe7539f428dec3b388f5d0498b3108
                Module libQt5X11Extras.so.5 with build-id e41614d2e35852f913bf00633d635cfbf5a90dce
                Module libX11.so.6 with build-id 5ba5798d193c0065014b8c6252a0678671c8d478
                Module libc.so.6 with build-id 4b406737057708c0e4c642345a703c47a61c73dc
                Module libstdc++.so.6 with build-id 9b5eeeb149bf3c4efe787fb398b44f00507aec87
                Module libpipewire-0.3.so.0 with build-id 8f52458089af917ee6586a4c375a339ea0ae15ff
                Module libpthread.so.0 with build-id 07c8f95b4f3251d08550217ad8a1f31066229996
                Module libepoxy.so.0 with build-id b6357fc6b748c512f90339433d74502b9d0621dc
                Module libQt5Core.so.5 with build-id b1ac453e8b3748ea2e73b0c967572c7554cb6aa7
                Module libQt5Gui.so.5 with build-id cf297530c359dd9cdb6c22fd191d57dcb4f4c429
                Module libxcb.so.1 with build-id 0d1ef11740a5daad2ee331e812a51aa6574af222
                Module libxcb-xfixes.so.0 with build-id a6b197ace5b9b59f913f5969eb419a88d1194f47
                Module libKWaylandServer.so.5 with build-id 8f56d56f8fce558576756f0606fb98889a1e5c4c
                Module libQt5Widgets.so.5 with build-id 9d23b10eb82cdeacf3b47f677077fc2abdc4e2cd
                Module libKF5I18n.so.5 with build-id 141662ef754d2d992a1a32082b2f2ddb830676b8
                Module libKF5CoreAddons.so.5 with build-id 42164ce0f5987f623e5285b1ecd65ceeb0bfce2e
                Module libKF5ConfigCore.so.5 with build-id c58e94e4adb85b1097f065447c2af4cc585906ff
                Module libKF5IdleTime.so.5 with build-id 54b299ba2e4803832eae5160b2e973021e950dbf
                Module libKF5WindowSystem.so.5 with build-id 10d0f0de888eb46a1fddcb91ef4ea4dcb3f117f2
                Module libKF5Notifications.so.5 with build-id cf776e57e2e8be19d6ccaec217f91db22751d115
                Module libKF5WaylandClient.so.5 with build-id 62d9d21d32df6ff25802eeef87b59e7b0895af39
                Module libKF5QuickAddons.so.5 with build-id fd00c054198847ab6d9e6c1142e512d53ec4cdbc
                Module libKF5GlobalAccelPrivate.so.5 with build-id 0494e001b0fcf80c92d46eb125bca973b22afe7b
                Module libkwinglutils.so.13 with build-id 382d270888e2f141e3aa8953ba253edb073b0dcb
                Module libkwineffects.so.13 with build-id 38ef3002d48af27c6edbfb5f902a483d71de1b72
                Module libkwin4_effect_builtins.so.1 with build-id 4836bfb272b1622dbd5db6a581eb8cc560085c8f
                Module libkwin.so.5 with build-id dcb3967ea55a6c3a02888a1839b5f7dd32ab88bc
                Module libQt5DBus.so.5 with build-id 2e76850f86958307f5d749c780f9f2587e14c9ff
                Module libfreetype.so.6 with build-id 26c5f833068ff72660d1975cbc2074c3eb47fad8
                Module libfontconfig.so.1 with build-id 1103a641395c7d3b42e49b793d3a9ea927c77bf6
                Module libcap.so.2 with build-id c86eeb29471e24e4dcce8bdba133919582424cef
                Module libKF5Crash.so.5 with build-id bb5c5cd905cfdd34bd246bed989f3989ec8bde08
                Module kwin_wayland with build-id c3ca03e1132283cca0ec080b6d257f9eeed8a11e
                Stack trace of thread 75999:
                #0  0x00007f57303271ea _ZN7QVectorIN4KWin12DrmConnector4ModeEE5clearEv (KWinWaylandDrmBackend.so + 0x261ea)
                #1  0x00007f573032f28c _ZN4KWin9DrmOutput11updateModesEv (KWinWaylandDrmBackend.so + 0x2e28c)
                #2  0x00007f5730337f3d _ZN4KWin6DrmGpu13updateOutputsEv (KWinWaylandDrmBackend.so + 0x36f3d)
                #3  0x00007f573031f101 _ZN4KWin10DrmBackend13updateOutputsEv (KWinWaylandDrmBackend.so + 0x1e101)
                #4  0x00007f5730320763 _ZN4KWin10DrmBackend15handleUdevEventEv (KWinWaylandDrmBackend.so + 0x1f763)
                #5  0x00007f57373c1da3 n/a (libQt5Core.so.5 + 0x2bcda3)
                #6  0x00007f57373c3a64 _ZN15QSocketNotifier9activatedE17QSocketDescriptorNS_4TypeENS_14QPrivateSignalE (libQt5Core.so.5 + 0x2bea64)
                #7  0x00007f57373c3baf _ZN15QSocketNotifier5eventEP6QEvent (libQt5Core.so.5 + 0x2bebaf)
                #8  0x00007f5737fad1a6 _ZN19QApplicationPrivate13notify_helperEP7QObjectP6QEvent (libQt5Widgets.so.5 + 0x1791a6)
                #9  0x00007f573739117a _ZN16QCoreApplication15notifyInternal2EP7QObjectP6QEvent (libQt5Core.so.5 + 0x28c17a)
                #10 0x00007f57373db0f4 _ZN27QEventDispatcherUNIXPrivate23activateSocketNotifiersEv (libQt5Core.so.5 + 0x2d60f4)
                #11 0x00007f57373dc065 _ZN20QEventDispatcherUNIX13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt5Core.so.5 + 0x2d7065)
                #12 0x00005624dcc58a42 _ZN23QUnixEventDispatcherQPA13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (kwin_wayland + 0x8ea42)
                #13 0x00007f573738945b _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt5Core.so.5 + 0x28445b)
                #14 0x00007f5737394ba7 _ZN16QCoreApplication4execEv (libQt5Core.so.5 + 0x28fba7)
                #15 0x00005624dcbf48cb main (kwin_wayland + 0x2a8cb)
                #16 0x00007f5736b1eb25 __libc_start_main (libc.so.6 + 0x27b25)
                #17 0x00005624dcbf52ce _start (kwin_wayland + 0x2b2ce)

                Stack trace of thread 76002:
                #0  0x00007f5736fc58ca __futex_abstimed_wait_common64 (libpthread.so.0 + 0x158ca)
                #1  0x00007f5736fbf270 pthread_cond_wait@@GLIBC_2.3.2 (libpthread.so.0 + 0xf270)
                #2  0x00007f572a50edfc n/a (iris_dri.so + 0x1dbdfc)
                #3  0x00007f572a507aac n/a (iris_dri.so + 0x1d4aac)
                #4  0x00007f5736fb9259 start_thread (libpthread.so.0 + 0x9259)
                #5  0x00007f5736bf55e3 __clone (libc.so.6 + 0xfe5e3)

                Stack trace of thread 76000:
                #0  0x00007f5736beab2f __poll (libc.so.6 + 0xf3b2f)
                #1  0x00007f5734e39066 n/a (libglib-2.0.so.0 + 0xab066)
                #2  0x00007f5734de0485 g_main_context_iteration (libglib-2.0.so.0 + 0x52485)
                #3  0x00007f57373dc45a _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt5Core.so.5 + 0x2d745a)
                #4  0x00007f573738945b _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt5Core.so.5 + 0x28445b)
                #5  0x00007f57371ecac6 _ZN7QThread4execEv (libQt5Core.so.5 + 0xe7ac6)
                #6  0x00007f5738d5c3c9 n/a (libQt5DBus.so.5 + 0x233c9)
                #7  0x00007f57371e988c n/a (libQt5Core.so.5 + 0xe488c)
                #8  0x00007f5736fb9259 start_thread (libpthread.so.0 + 0x9259)
                #9  0x00007f5736bf55e3 __clone (libc.so.6 + 0xfe5e3)

                Stack trace of thread 76003:
                #0  0x00007f5736fc58ca __futex_abstimed_wait_common64 (libpthread.so.0 + 0x158ca)
                #1  0x00007f5736fbf270 pthread_cond_wait@@GLIBC_2.3.2 (libpthread.so.0 + 0xf270)
                #2  0x00007f572a50edfc n/a (iris_dri.so + 0x1dbdfc)
                #3  0x00007f572a507aac n/a (iris_dri.so + 0x1d4aac)
                #4  0x00007f5736fb9259 start_thread (libpthread.so.0 + 0x9259)
                #5  0x00007f5736bf55e3 __clone (libc.so.6 + 0xfe5e3)

                Stack trace of thread 76004:
                #0  0x00007f5736fc58ca __futex_abstimed_wait_common64 (libpthread.so.0 + 0x158ca)
                #1  0x00007f5736fbf270 pthread_cond_wait@@GLIBC_2.3.2 (libpthread.so.0 + 0xf270)
                #2  0x00007f572a50edfc n/a (iris_dri.so + 0x1dbdfc)
                #3  0x00007f572a507aac n/a (iris_dri.so + 0x1d4aac)
                #4  0x00007f5736fb9259 start_thread (libpthread.so.0 + 0x9259)
                #5  0x00007f5736bf55e3 __clone (libc.so.6 + 0xfe5e3)

                Stack trace of thread 76007:
                #0  0x00007f5736fc58ca __futex_abstimed_wait_common64 (libpthread.so.0 + 0x158ca)
                #1  0x00007f5736fbf270 pthread_cond_wait@@GLIBC_2.3.2 (libpthread.so.0 + 0xf270)
                #2  0x00007f572a50edfc n/a (iris_dri.so + 0x1dbdfc)
                #3  0x00007f572a507aac n/a (iris_dri.so + 0x1d4aac)
                #4  0x00007f5736fb9259 start_thread (libpthread.so.0 + 0x9259)
                #5  0x00007f5736bf55e3 __clone (libc.so.6 + 0xfe5e3)

                Stack trace of thread 76015:
                #0  0x00007f5736fc58ca __futex_abstimed_wait_common64 (libpthread.so.0 + 0x158ca)
                #1  0x00007f5736fbf574 pthread_cond_timedwait@@GLIBC_2.3.2 (libpthread.so.0 + 0xf574)
                #2  0x00007f57371f0c84 _ZN14QWaitCondition4waitEP6QMutex14QDeadlineTimer (libQt5Core.so.5 + 0xebc84)
                #3  0x00007f57371edb47 n/a (libQt5Core.so.5 + 0xe8b47)
                #4  0x00007f57371e988c n/a (libQt5Core.so.5 + 0xe488c)
                #5  0x00007f5736fb9259 start_thread (libpthread.so.0 + 0x9259)
                #6  0x00007f5736bf55e3 __clone (libc.so.6 + 0xfe5e3)

                Stack trace of thread 76010:
                #0  0x00007f5736fc58ca __futex_abstimed_wait_common64 (libpthread.so.0 + 0x158ca)
                #1  0x00007f5736fbf270 pthread_cond_wait@@GLIBC_2.3.2 (libpthread.so.0 + 0xf270)
                #2  0x00007f572a50edfc n/a (iris_dri.so + 0x1dbdfc)
                #3  0x00007f572a507aac n/a (iris_dri.so + 0x1d4aac)
                #4  0x00007f5736fb9259 start_thread (libpthread.so.0 + 0x9259)
                #5  0x00007f5736bf55e3 __clone (libc.so.6 + 0xfe5e3)

                Stack trace of thread 76011:
                #0  0x00007f5736fc58ca __futex_abstimed_wait_common64 (libpthread.so.0 + 0x158ca)
                #1  0x00007f5736fbf270 pthread_cond_wait@@GLIBC_2.3.2 (libpthread.so.0 + 0xf270)
                #2  0x00007f572a50edfc n/a (iris_dri.so + 0x1dbdfc)
                #3  0x00007f572a507aac n/a (iris_dri.so + 0x1d4aac)
                #4  0x00007f5736fb9259 start_thread (libpthread.so.0 + 0x9259)
                #5  0x00007f5736bf55e3 __clone (libc.so.6 + 0xfe5e3)

                Stack trace of thread 76012:
                #0  0x00007f5736fc58ca __futex_abstimed_wait_common64 (libpthread.so.0 + 0x158ca)
                #1  0x00007f5736fbf574 pthread_cond_timedwait@@GLIBC_2.3.2 (libpthread.so.0 + 0xf574)
                #2  0x00007f57371f0c84 _ZN14QWaitCondition4waitEP6QMutex14QDeadlineTimer (libQt5Core.so.5 + 0xebc84)
                #3  0x00007f57371edb47 n/a (libQt5Core.so.5 + 0xe8b47)
                #4  0x00007f57371e988c n/a (libQt5Core.so.5 + 0xe488c)
                #5  0x00007f5736fb9259 start_thread (libpthread.so.0 + 0x9259)
                #6  0x00007f5736bf55e3 __clone (libc.so.6 + 0xfe5e3)

                Stack trace of thread 76006:
                #0  0x00007f5736fc58ca __futex_abstimed_wait_common64 (libpthread.so.0 + 0x158ca)
                #1  0x00007f5736fbf270 pthread_cond_wait@@GLIBC_2.3.2 (libpthread.so.0 + 0xf270)
                #2  0x00007f572a50edfc n/a (iris_dri.so + 0x1dbdfc)
                #3  0x00007f572a507aac n/a (iris_dri.so + 0x1d4aac)
                #4  0x00007f5736fb9259 start_thread (libpthread.so.0 + 0x9259)
                #5  0x00007f5736bf55e3 __clone (libc.so.6 + 0xfe5e3)

                Stack trace of thread 76008:
                #0  0x00007f5736beab2f __poll (libc.so.6 + 0xf3b2f)
                #1  0x00007f5734e39066 n/a (libglib-2.0.so.0 + 0xab066)
                #2  0x00007f5734de0485 g_main_context_iteration (libglib-2.0.so.0 + 0x52485)
                #3  0x00007f57373dc45a _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt5Core.so.5 + 0x2d745a)
                #4  0x00007f573738945b _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt5Core.so.5 + 0x28445b)
                #5  0x00007f57371ecac6 _ZN7QThread4execEv (libQt5Core.so.5 + 0xe7ac6)
                #6  0x00007f57371e988c n/a (libQt5Core.so.5 + 0xe488c)
                #7  0x00007f5736fb9259 start_thread (libpthread.so.0 + 0x9259)
                #8  0x00007f5736bf55e3 __clone (libc.so.6 + 0xfe5e3)

                Stack trace of thread 76005:
                #0  0x00007f5736fc58ca __futex_abstimed_wait_common64 (libpthread.so.0 + 0x158ca)
                #1  0x00007f5736fbf270 pthread_cond_wait@@GLIBC_2.3.2 (libpthread.so.0 + 0xf270)
                #2  0x00007f572a50edfc n/a (iris_dri.so + 0x1dbdfc)
                #3  0x00007f572a507aac n/a (iris_dri.so + 0x1d4aac)
                #4  0x00007f5736fb9259 start_thread (libpthread.so.0 + 0x9259)
                #5  0x00007f5736bf55e3 __clone (libc.so.6 + 0xfe5e3)

                Stack trace of thread 76013:
                #0  0x00007f5736beab2f __poll (libc.so.6 + 0xf3b2f)
                #1  0x00007f5734e39066 n/a (libglib-2.0.so.0 + 0xab066)
                #2  0x00007f5734de0485 g_main_context_iteration (libglib-2.0.so.0 + 0x52485)
                #3  0x00007f57373dc45a _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt5Core.so.5 + 0x2d745a)
                #4  0x00007f573738945b _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt5Core.so.5 + 0x28445b)
                #5  0x00007f57371ecac6 _ZN7QThread4execEv (libQt5Core.so.5 + 0xe7ac6)
                #6  0x00007f5735dde4b0 n/a (libQt5Qml.so.5 + 0x2c64b0)
                #7  0x00007f57371e988c n/a (libQt5Core.so.5 + 0xe488c)
                #8  0x00007f5736fb9259 start_thread (libpthread.so.0 + 0x9259)
                #9  0x00007f5736bf55e3 __clone (libc.so.6 + 0xfe5e3)

                Stack trace of thread 76001:
                #0  0x00007f5736fc58ca __futex_abstimed_wait_common64 (libpthread.so.0 + 0x158ca)
                #1  0x00007f5736fbf270 pthread_cond_wait@@GLIBC_2.3.2 (libpthread.so.0 + 0xf270)
                #2  0x00007f572a50edfc n/a (iris_dri.so + 0x1dbdfc)
                #3  0x00007f572a507aac n/a (iris_dri.so + 0x1d4aac)
                #4  0x00007f5736fb9259 start_thread (libpthread.so.0 + 0x9259)
                #5  0x00007f5736bf55e3 __clone (libc.so.6 + 0xfe5e3)

                Stack trace of thread 76009:
                #0  0x00007f5736beab2f __poll (libc.so.6 + 0xf3b2f)
                #1  0x00007f5734e39066 n/a (libglib-2.0.so.0 + 0xab066)
                #2  0x00007f5734de0485 g_main_context_iteration (libglib-2.0.so.0 + 0x52485)
                #3  0x00007f57373dc45a _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt5Core.so.5 + 0x2d745a)
                #4  0x00007f573738945b _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt5Core.so.5 + 0x28445b)
                #5  0x00007f57371ecac6 _ZN7QThread4execEv (libQt5Core.so.5 + 0xe7ac6)
                #6  0x00007f57371e988c n/a (libQt5Core.so.5 + 0xe488c)
                #7  0x00007f5736fb9259 start_thread (libpthread.so.0 + 0x9259)
                #8  0x00007f5736bf55e3 __clone (libc.so.6 + 0xfe5e3)
                ELF object binary architecture: AMD x86-64
```
Comment 1 Mateusz Warzynski 2022-01-30 02:16:46 UTC 
In addition, this crash might be caused by different parts of the code. I reproduced it once again and this time it crashed with ABRT.

coredump info:
>            PID: 76934 (kwin_wayland)
>            UID: 1000 (mwarzynski)
>            GID: 1000 (mwarzynski)
>         Signal: 6 (ABRT)
>      Timestamp: Sun 2022-01-30 02:39:11 CET (31min ago)
>   Command Line: /usr/bin/kwin_wayland --wayland_fd 5 --socket wayland-0 --xwayland-fd 7 --xwayland-fd 6 --xwayland-display :14 --xwayland-xauthority /run/user/1000/xauth_aKwnFp --xwayland /usr/lib/startplasma-way>
>     Executable: /usr/bin/kwin_wayland
>  Control Group: /user.slice/user-1000.slice/session-1.scope
>           Unit: session-1.scope
>          Slice: user-1000.slice
>        Session: 1
>      Owner UID: 1000 (mwarzynski)
>        Boot ID: 193f064636b3431cbcd6cdbdc1a17c74
>     Machine ID: 4fa290243f6a492fa8fbd786b758cf66
>       Hostname: mia
>        Storage: /var/lib/systemd/coredump/core.kwin_wayland.1000.193f064636b3431cbcd6cdbdc1a17c74.76934.1643506751000000.zst (present)
>      Disk Size: 4.4M
>        Message: Process 76934 (kwin_wayland) of user 1000 dumped core.
>                 Stack trace of thread 76934:
>                 #0  0x00007fa1eb29cd22 raise (libc.so.6 + 0x3cd22)
>                 #1  0x00007fa1eb28690e abort (libc.so.6 + 0x2690e)
>                 #2  0x00007fa1eb2ded28 __libc_message (libc.so.6 + 0x7ed28)
>                 #3  0x00007fa1eb2e692a malloc_printerr (libc.so.6 + 0x8692a)
>                 #4  0x00007fa1eb2e9f4c _int_malloc (libc.so.6 + 0x89f4c)
>                 #5  0x00007fa1eb2eb4e1 malloc (libc.so.6 + 0x8b4e1)
>                 #6  0x00007fa1eb4d244d _Znwm (libstdc++.so.6 + 0xa644d)
>                 #7  0x00007fa1ec12f9db _ZNK18QRasterPaintEngine11createStateEP13QPainterState (libQt5Gui.so.5 + 0x3a39db)
>                 #8  0x00007fa1ec144cca _ZN8QPainter5beginEP12QPaintDevice (libQt5Gui.so.5 + 0x3b8cca)
>                 #9  0x00007fa1e4a9892b _ZN4KWin9DrmOutput12updateCursorEv (KWinWaylandDrmBackend.so + 0x2e92b)
>                 #10 0x00007fa1e4a89077 _ZN4KWin10DrmBackend12updateCursorEv (KWinWaylandDrmBackend.so + 0x1f077)
>                 #11 0x00007fa1e4a8976c _ZN4KWin10DrmBackend15handleUdevEventEv (KWinWaylandDrmBackend.so + 0x1f76c)
>                 #12 0x00007fa1ebb2ada3 n/a (libQt5Core.so.5 + 0x2bcda3)
>                 #13 0x00007fa1ebb2ca64 _ZN15QSocketNotifier9activatedE17QSocketDescriptorNS_4TypeENS_14QPrivateSignalE (libQt5Core.so.5 + 0x2bea64)
>                 #14 0x00007fa1ebb2cbaf _ZN15QSocketNotifier5eventEP6QEvent (libQt5Core.so.5 + 0x2bebaf)
>                 #15 0x00007fa1ec7161a6 _ZN19QApplicationPrivate13notify_helperEP7QObjectP6QEvent (libQt5Widgets.so.5 + 0x1791a6)
>                 #16 0x00007fa1ebafa17a _ZN16QCoreApplication15notifyInternal2EP7QObjectP6QEvent (libQt5Core.so.5 + 0x28c17a)
>                 #17 0x00007fa1ebb440f4 _ZN27QEventDispatcherUNIXPrivate23activateSocketNotifiersEv (libQt5Core.so.5 + 0x2d60f4)
>                 #18 0x00007fa1ebb45065 _ZN20QEventDispatcherUNIX13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt5Core.so.5 + 0x2d7065)
>                 #19 0x00005620fd55aa42 _ZN23QUnixEventDispatcherQPA13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (kwin_wayland + 0x8ea42)
>                 #20 0x00007fa1ebaf245b _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt5Core.so.5 + 0x28445b)
>                 #21 0x00007fa1ebafdba7 _ZN16QCoreApplication4execEv (libQt5Core.so.5 + 0x28fba7)
>                 #22 0x00005620fd4f68cb main (kwin_wayland + 0x2a8cb)
>                 #23 0x00007fa1eb287b25 __libc_start_main (libc.so.6 + 0x27b25)
>                 #24 0x00005620fd4f72ce _start (kwin_wayland + 0x2b2ce)

backtrace:
> (gdb) bt
> #0  0x00007fa1eb29cd22 in raise () at /usr/lib/libc.so.6
> #1  0x00007fa1eb28690e in abort () at /usr/lib/libc.so.6
> #2  0x00007fa1eb2ded28 in __libc_message () at /usr/lib/libc.so.6
> #3  0x00007fa1eb2e692a in  () at /usr/lib/libc.so.6
> #4  0x00007fa1eb2e9f4c in _int_malloc () at /usr/lib/libc.so.6
> #5  0x00007fa1eb2eb4e1 in malloc () at /usr/lib/libc.so.6
> #6  0x00007fa1eb4d244d in operator new(unsigned long) (sz=1040) at /build/gcc/src/gcc/libstdc++-v3/libsupc++/new_op.cc:50
> #7  0x00007fa1ec12f9db in QRasterPaintEngine::createState(QPainterState*) const () at /usr/lib/libQt5Gui.so.5
> #8  0x00007fa1ec144cca in QPainter::begin(QPaintDevice*) () at /usr/lib/libQt5Gui.so.5
> #9  0x00007fa1e4a9892b in KWin::DrmOutput::updateCursor() (this=0x5620ff0c95e0) at /usr/src/debug/kwin-5.23.5/src/plugins/platforms/drm/drm_output.cpp:150
> #10 0x00007fa1e4a89077 in KWin::DrmBackend::updateCursor() (this=0x5620fe87cfb0) at /usr/src/debug/kwin-5.23.5/src/plugins/platforms/drm/drm_backend.cpp:572
> #11 0x00007fa1e4a8976c in KWin::DrmBackend::handleUdevEvent() (this=0x5620fe87cfb0) at /usr/src/debug/kwin-5.23.5/src/plugins/platforms/drm/drm_backend.cpp:260
> #12 0x00007fa1ebb2ada3 in  () at /usr/lib/libQt5Core.so.5
> #13 0x00007fa1ebb2ca64 in QSocketNotifier::activated(QSocketDescriptor, QSocketNotifier::Type, QSocketNotifier::QPrivateSignal) () at /usr/lib/libQt5Core.so.5
> #14 0x00007fa1ebb2cbaf in QSocketNotifier::event(QEvent*) () at /usr/lib/libQt5Core.so.5
> #15 0x00007fa1ec7161a6 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5
> #16 0x00007fa1ebafa17a in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at /usr/lib/libQt5Core.so.5
> #17 0x00007fa1ebb440f4 in QEventDispatcherUNIXPrivate::activateSocketNotifiers() () at /usr/lib/libQt5Core.so.5
> #18 0x00007fa1ebb45065 in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
> #19 0x00005620fd55aa42 in QUnixEventDispatcherQPA::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
> #20 0x00007fa1ebaf245b in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
> #21 0x00007fa1ebafdba7 in QCoreApplication::exec() () at /usr/lib/libQt5Core.so.5
> #22 0x00005620fd4f68cb in main(int, char**) (argc=<optimized out>, argv=<optimized out>) at /usr/src/debug/kwin-5.23.5/src/main_wayland.cpp:745
Comment 2 Zamundaaa 2022-02-05 14:24:55 UTC 
As 5.23 is end of life and the relevant code received quite a bit of attention with 5.24, could you try the beta or git master with a live boot, to see if it's still happening?
Comment 3 Mateusz Warzynski 2022-02-05 14:26:52 UTC 
(In reply to Zamundaaa from comment #2)
> As 5.23 is end of life and the relevant code received quite a bit of
> attention with 5.24, could you try the beta or git master with a live boot,
> to see if it's still happening?

Of, I will check it out.
Thanks for the reply!
Comment 4 Nate Graham 2022-02-05 15:09:18 UTC 
.
Comment 5 Mateusz Warzynski 2022-02-05 16:09:01 UTC 
(In reply to Zamundaaa from comment #2)
> As 5.23 is end of life and the relevant code received quite a bit of
> attention with 5.24, could you try the beta or git master with a live boot,
> to see if it's still happening?

TLDR, it works with KDE Plasma Version: 5.23.90. (It does not work with KDE Plasma Version 5.23.5.)

---

Thanks for the suggestion.

Firstly, I've used the `neon-testing-20220201-1820.iso` as this is the most recent iso I could find at https://neon.kde.org/download.
It worked fine on Wayland (and Xorg too). I found that KDE Plasma Version in this ISO is 5.23.90. (To be honest, I thought it will be 5.24 or newer -- as you suggested this version to check.)

The next step was to check the same version of KDE Plasma on my normal day-to-day system.
This particular version is available for ArchLinux at `kde-unstable` repository: https://wiki.archlinux.org/title/Official_repositories#kde-unstable. I've added this repository to pacman configuration and upgraded KDE (including Plasma):
> sudo pacman -S $(pacman -Sl kde-unstable | grep installed | awk '{print $2}')
double check:
> pacman -Ss plasma | grep kde-unstable | grep installed
> kde-unstable/plasma-desktop 5.23.90-1 (plasma) [installed]
So, at this point, I have the same Plasma version as I had with the KDE Testing ISO.

I tested it a few times by disconnecting and connecting the dock or just the external monitor (HDMI). It didn't crash.

I am satisfied with the current result. Should we mark this bug as resolved?
Comment 6 Zamundaaa 2022-02-06 00:21:03 UTC 
Thanks for testing!
> I found that KDE Plasma Version in this ISO is 5.23.90. (To be honest, I thought it will be 5.24 or newer -- as you suggested this version to check
That's just our naming - *.90 is the beta for the next version.

> I am satisfied with the current result. Should we mark this bug as resolved?
Yes, we can mark it as fixed.