Bug 483243

Summary: kwin_wayland segfault when taking screenshot when locked and/or without a screen
Product: [Plasma] kwin Reporter: andy <andy>
Component: wayland-genericAssignee: KWin default assignee <kwin-bugs-null>
Status: RESOLVED FIXED    
Severity: crash CC: dashonwwIII, meven29, nate
Priority: NOR Keywords: qt6
Version First Reported In: 6.0.2   
Target Milestone: ---   
Platform: Arch Linux   
OS: Linux   
Latest Commit: Version Fixed In:
Sentry Crash Report:

Description andy 2024-03-11 14:19:26 UTC 
SUMMARY

STEPS TO REPRODUCE
1. At night: lock screen, turn off monitors (mix of DP and HDMI).
2. In morning: turn on monitors, unlock screen

OBSERVED RESULT
The desktop is from a replaced kwin_wayland instance (apps closed, etc.). The journal shows a segfault coinciding with the time of turning on the monitors.

EXPECTED RESULT
No crash

SOFTWARE/OS VERSIONS
Operating System: Arch Linux rolling
KDE Plasma Version: 6.0.1
KDE Frameworks Version: 6.0.0
Qt Version: 6.6.2
Kernel Version: 6.7.8-arch1-1 (64-bit)
Graphics Platform: Wayland
Processors: 16 × Intel® Core™ i9-9900K CPU @ 3.60GHz
Memory: 62.6 GiB of RAM
Graphics Processor: AMD Radeon RX 6600

ADDITIONAL INFORMATION

It didn't crash with plasma 5.
A USB hub in one of the monitors connects the mouse, keyboard, and an audio interface, so those are connected when turning the monitors on too. 


journalctl output

Mar 11 06:45:09 fractal systemd-coredump[521944]: [🡕] Process 2635 (kwin_wayland) of user 1000 dumped core.
                                                  
                                                  Stack trace of thread 2635:
                                                  #0  0x00005a39fb8aa812 n/a (kwin_wayland + 0xc9812)
                                                  #1  0x00007db44dcbcca9 n/a (libQt6Core.so.6 + 0x190ca9)
                                                  #2  0x00007db44dcbcca9 n/a (libQt6Core.so.6 + 0x190ca9)
                                                  #3  0x00007db44ddd8b24 _ZN18QFutureWatcherBase5eventEP6QEvent (libQt6Core.so.6 + 0x2acb24)
                                                  #4  0x00007db44ec6138b _ZN19QApplicationPrivate13notify_helperEP7QObjectP6QEvent (libQt6Widgets.so.6 + 0xf438b)
                                                  #5  0x00007db44dc65818 _ZN16QCoreApplication15notifyInternal2EP7QObjectP6QEvent (libQt6Core.so.6 + 0x139818)
                                                  #6  0x00007db44dc65b9b _ZN23QCoreApplicationPrivate16sendPostedEventsEP7QObjectiP11QThreadData (libQt6Core.so.6 + 0x139b9b)
                                                  #7  0x00007db44ddcb18f _ZN20QEventDispatcherUNIX13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt6Core.so.6 + 0x29f18f)
                                                  #8  0x00007db44e6b46e2 _ZN23QUnixEventDispatcherQPA13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt6Gui.so.6 + 0x5b26e2)
                                                  #9  0x00007db44dc6fd6e _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt6Core.so.6 + 0x143d6e)
                                                  #10 0x00007db44dc682b8 _ZN16QCoreApplication4execEv (libQt6Core.so.6 + 0x13c2b8)
                                                  #11 0x00005a39fb81ddee n/a (kwin_wayland + 0x3cdee)
                                                  #12 0x00007db44d608cd0 n/a (libc.so.6 + 0x25cd0)
                                                  #13 0x00007db44d608d8a __libc_start_main (libc.so.6 + 0x25d8a)
                                                  #14 0x00005a39fb824425 n/a (kwin_wayland + 0x43425)
                                                  
                                                  Stack trace of thread 2670:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66d750 pthread_cond_wait (libc.so.6 + 0x8a750)
                                                  #2  0x00007db444f7781c n/a (radeonsi_dri.so + 0x8681c)
                                                  #3  0x00007db444f8f7ec n/a (radeonsi_dri.so + 0x9e7ec)
                                                  #4  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #5  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 2672:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66d750 pthread_cond_wait (libc.so.6 + 0x8a750)
                                                  #2  0x00007db444f7781c n/a (radeonsi_dri.so + 0x8681c)
                                                  #3  0x00007db444f8f7ec n/a (radeonsi_dri.so + 0x9e7ec)
                                                  #4  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #5  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 2702:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66d750 pthread_cond_wait (libc.so.6 + 0x8a750)
                                                  #2  0x00007db444f7781c n/a (radeonsi_dri.so + 0x8681c)
                                                  #3  0x00007db444f8f7ec n/a (radeonsi_dri.so + 0x9e7ec)
                                                  #4  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #5  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 2701:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66d750 pthread_cond_wait (libc.so.6 + 0x8a750)
                                                  #2  0x00007db444f7781c n/a (radeonsi_dri.so + 0x8681c)
                                                  #3  0x00007db444f8f7ec n/a (radeonsi_dri.so + 0x9e7ec)
                                                  #4  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #5  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 2675:
                                                  #0  0x00007db44d6de0bf __poll (libc.so.6 + 0xfb0bf)
                                                  #1  0x00007db44c6352f6 n/a (libglib-2.0.so.0 + 0xb82f6)
                                                  #2  0x00007db44c5d5162 g_main_context_iteration (libglib-2.0.so.0 + 0x58162)
                                                  #3  0x00007db44de9f9c4 _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt6Core.so.6 + 0x3739c4)
                                                  #4  0x00007db44dc6fd6e _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt6Core.so.6 + 0x143d6e)
                                                  #5  0x00007db44dd4d16f _ZN7QThread3runEv (libQt6Core.so.6 + 0x22116f)
                                                  #6  0x00007db44ddccbd3 n/a (libQt6Core.so.6 + 0x2a0bd3)
                                                  #7  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #8  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)

                                                  Stack trace of thread 2700:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66d750 pthread_cond_wait (libc.so.6 + 0x8a750)
                                                  #2  0x00007db444f7781c n/a (radeonsi_dri.so + 0x8681c)
                                                  #3  0x00007db444f8f7ec n/a (radeonsi_dri.so + 0x9e7ec)
                                                  #4  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #5  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 2709:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66d750 pthread_cond_wait (libc.so.6 + 0x8a750)
                                                  #2  0x00007db44d98ae11 __gthread_cond_wait (libstdc++.so.6 + 0xd9e11)
                                                  #3  0x00007db4504e72a0 n/a (libkwin.so.6 + 0x3cf2a0)
                                                  #4  0x00007db4504e25bd n/a (libkwin.so.6 + 0x3ca5bd)
                                                  #5  0x00007db44d6736af n/a (libc.so.6 + 0x906af)
                                                  #6  0x00007db4504e296f n/a (libkwin.so.6 + 0x3ca96f)
                                                  #7  0x00007db44dd44555 n/a (libQt6Core.so.6 + 0x218555)
                                                  #8  0x00007db44ddccbd3 n/a (libQt6Core.so.6 + 0x2a0bd3)
                                                  #9  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #10 0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 2705:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66dd35 pthread_cond_clockwait (libc.so.6 + 0x8ad35)
                                                  #2  0x00007db4504e6fa1 n/a (libkwin.so.6 + 0x3cefa1)
                                                  #3  0x00007db4504e25bd n/a (libkwin.so.6 + 0x3ca5bd)
                                                  #4  0x00007db44d6736af n/a (libc.so.6 + 0x906af)
                                                  #5  0x00007db4504e296f n/a (libkwin.so.6 + 0x3ca96f)
                                                  #6  0x00007db44dd44555 n/a (libQt6Core.so.6 + 0x218555)
                                                  #7  0x00007db44ddccbd3 n/a (libQt6Core.so.6 + 0x2a0bd3)
                                                  #8  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #9  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 2713:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66d750 pthread_cond_wait (libc.so.6 + 0x8a750)
                                                  #2  0x00007db44d98ae11 __gthread_cond_wait (libstdc++.so.6 + 0xd9e11)
                                                  #3  0x00007db4504e72a0 n/a (libkwin.so.6 + 0x3cf2a0)
                                                  #4  0x00007db4504e25bd n/a (libkwin.so.6 + 0x3ca5bd)
                                                  #5  0x00007db44d6736af n/a (libc.so.6 + 0x906af)
                                                  #6  0x00007db4504e296f n/a (libkwin.so.6 + 0x3ca96f)
                                                  #7  0x00007db44dd44555 n/a (libQt6Core.so.6 + 0x218555)
                                                  #8  0x00007db44ddccbd3 n/a (libQt6Core.so.6 + 0x2a0bd3)
                                                  #9  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #10 0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 2730:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66d750 pthread_cond_wait (libc.so.6 + 0x8a750)
                                                  #2  0x00007db444f7781c n/a (radeonsi_dri.so + 0x8681c)
                                                  #3  0x00007db444f8f7ec n/a (radeonsi_dri.so + 0x9e7ec)
                                                  #4  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #5  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 2729:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66d750 pthread_cond_wait (libc.so.6 + 0x8a750)
                                                  #2  0x00007db444f7781c n/a (radeonsi_dri.so + 0x8681c)
                                                  #3  0x00007db444f8f7ec n/a (radeonsi_dri.so + 0x9e7ec)
                                                  #4  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #5  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                         Stack trace of thread 39722:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66da65 pthread_cond_timedwait (libc.so.6 + 0x8aa65)
                                                  #2  0x00007db44ddcfba4 _ZN14QWaitCondition4waitEP6QMutex14QDeadlineTimer (libQt6Core.so.6 + 0x2a3ba4)
                                                  #3  0x00007db44ddd24aa n/a (libQt6Core.so.6 + 0x2a64aa)
                                                  #4  0x00007db44ddccbd3 n/a (libQt6Core.so.6 + 0x2a0bd3)
                                                  #5  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #6  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 2697:
                                                  #0  0x00007db44d6ebe66 epoll_wait (libc.so.6 + 0x108e66)
                                                  #1  0x00007db436828bd9 n/a (libspa-support.so + 0x16bd9)
                                                  #2  0x00007db43681a58d n/a (libspa-support.so + 0x858d)
                                                  #3  0x00007db435d61db2 n/a (libpipewire-0.3.so.0 + 0x45db2)
                                                  #4  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #5  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 2661:
                                                  #0  0x00007db44d6de0bf __poll (libc.so.6 + 0xfb0bf)
                                                  #1  0x00007db44c6352f6 n/a (libglib-2.0.so.0 + 0xb82f6)
                                                  #2  0x00007db44c5d5162 g_main_context_iteration (libglib-2.0.so.0 + 0x58162)
                                                  #3  0x00007db44de9f9c4 _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt6Core.so.6 + 0x3739c4)
                                                  #4  0x00007db44dc6fd6e _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt6Core.so.6 + 0x143d6e)
                                                  #5  0x00007db44dd4d06f _ZN7QThread4execEv (libQt6Core.so.6 + 0x22106f)
                                                  #6  0x00007db44e9489df n/a (libQt6DBus.so.6 + 0x299df)
                                                  #7  0x00007db44ddccbd3 n/a (libQt6Core.so.6 + 0x2a0bd3)
                                                  #8  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #9  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 2667:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66d750 pthread_cond_wait (libc.so.6 + 0x8a750)
                                                  #2  0x00007db444f7781c n/a (radeonsi_dri.so + 0x8681c)
                                                  #3  0x00007db444f8f7ec n/a (radeonsi_dri.so + 0x9e7ec)
                                                  #4  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #5  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 2731:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66da65 pthread_cond_timedwait (libc.so.6 + 0x8aa65)
                                                  #2  0x00007db44ddcfba4 _ZN14QWaitCondition4waitEP6QMutex14QDeadlineTimer (libQt6Core.so.6 + 0x2a3ba4)
                                                  #3  0x00007db44ddd24aa n/a (libQt6Core.so.6 + 0x2a64aa)
                                                  #4  0x00007db44ddccbd3 n/a (libQt6Core.so.6 + 0x2a0bd3)
                                                  #5  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #6  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 8215:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66d750 pthread_cond_wait (libc.so.6 + 0x8a750)
                                                  #2  0x00007db444f7781c n/a (radeonsi_dri.so + 0x8681c)
                                                  #3  0x00007db444f8f7ec n/a (radeonsi_dri.so + 0x9e7ec)
                                                  #4  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #5  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                Stack trace of thread 2669:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66d750 pthread_cond_wait (libc.so.6 + 0x8a750)
                                                  #2  0x00007db444f7781c n/a (radeonsi_dri.so + 0x8681c)
                                                  #3  0x00007db444f8f7ec n/a (radeonsi_dri.so + 0x9e7ec)
                                                  #4  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #5  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 39721:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66da65 pthread_cond_timedwait (libc.so.6 + 0x8aa65)
                                                  #2  0x00007db44ddcfba4 _ZN14QWaitCondition4waitEP6QMutex14QDeadlineTimer (libQt6Core.so.6 + 0x2a3ba4)
                                                  #3  0x00007db44ddd24aa n/a (libQt6Core.so.6 + 0x2a64aa)
                                                  #4  0x00007db44ddccbd3 n/a (libQt6Core.so.6 + 0x2a0bd3)
                                                  #5  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #6  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 2703:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66d750 pthread_cond_wait (libc.so.6 + 0x8a750)
                                                  #2  0x00007db44d98ae11 __gthread_cond_wait (libstdc++.so.6 + 0xd9e11)
                                                  #3  0x00007db4504e72a0 n/a (libkwin.so.6 + 0x3cf2a0)
                                                  #4  0x00007db4504e25bd n/a (libkwin.so.6 + 0x3ca5bd)
                                                  #5  0x00007db44d6736af n/a (libc.so.6 + 0x906af)
                                                  #6  0x00007db4504e296f n/a (libkwin.so.6 + 0x3ca96f)
                                                  #7  0x00007db44dd44555 n/a (libQt6Core.so.6 + 0x218555)
                                                  #8  0x00007db44ddccbd3 n/a (libQt6Core.so.6 + 0x2a0bd3)
                                                  #9  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #10 0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 5106:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66da65 pthread_cond_timedwait (libc.so.6 + 0x8aa65)
                                                  #2  0x00007db44ddcfba4 _ZN14QWaitCondition4waitEP6QMutex14QDeadlineTimer (libQt6Core.so.6 + 0x2a3ba4)
                                                  #3  0x00007db44ddd24aa n/a (libQt6Core.so.6 + 0x2a64aa)
                                                  #4  0x00007db44ddccbd3 n/a (libQt6Core.so.6 + 0x2a0bd3)
                                                  #5  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #6  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 39716:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66da65 pthread_cond_timedwait (libc.so.6 + 0x8aa65)
                                                  #2  0x00007db44ddcfba4 _ZN14QWaitCondition4waitEP6QMutex14QDeadlineTimer (libQt6Core.so.6 + 0x2a3ba4)
                                                  #3  0x00007db44ddd24aa n/a (libQt6Core.so.6 + 0x2a64aa)
                                                  #4  0x00007db44ddccbd3 n/a (libQt6Core.so.6 + 0x2a0bd3)
                                                  #5  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #6  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 2668:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66d750 pthread_cond_wait (libc.so.6 + 0x8a750)
                                                  #2  0x00007db444f7781c n/a (radeonsi_dri.so + 0x8681c)
                                                  #3  0x00007db444f8f7ec n/a (radeonsi_dri.so + 0x9e7ec)
                                                  #4  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #5  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 5105:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66da65 pthread_cond_timedwait (libc.so.6 + 0x8aa65)
                                                  #2  0x00007db44ddcfba4 _ZN14QWaitCondition4waitEP6QMutex14QDeadlineTimer (libQt6Core.so.6 + 0x2a3ba4)
                                                  #3  0x00007db44ddd24aa n/a (libQt6Core.so.6 + 0x2a64aa)
                                                  #4  0x00007db44ddccbd3 n/a (libQt6Core.so.6 + 0x2a0bd3)
                                                  #5  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #6  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)

                                                  Stack trace of thread 2671:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66d750 pthread_cond_wait (libc.so.6 + 0x8a750)
                                                  #2  0x00007db444f7781c n/a (radeonsi_dri.so + 0x8681c)
                                                  #3  0x00007db444f8f7ec n/a (radeonsi_dri.so + 0x9e7ec)
                                                  #4  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #5  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 2696:
                                                  #0  0x00007db44d6de0bf __poll (libc.so.6 + 0xfb0bf)
                                                  #1  0x00007db44c6352f6 n/a (libglib-2.0.so.0 + 0xb82f6)
                                                  #2  0x00007db44c5d5162 g_main_context_iteration (libglib-2.0.so.0 + 0x58162)
                                                  #3  0x00007db44de9f9c4 _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt6Core.so.6 + 0x3739c4)
                                                  #4  0x00007db44dc6fd6e _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt6Core.so.6 + 0x143d6e)
                                                  #5  0x00007db44dd4d16f _ZN7QThread3runEv (libQt6Core.so.6 + 0x22116f)
                                                  #6  0x00007db44ddccbd3 n/a (libQt6Core.so.6 + 0x2a0bd3)
                                                  #7  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #8  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 8216:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66d750 pthread_cond_wait (libc.so.6 + 0x8a750)
                                                  #2  0x00007db444f7781c n/a (radeonsi_dri.so + 0x8681c)
                                                  #3  0x00007db444f8f7ec n/a (radeonsi_dri.so + 0x9e7ec)
                                                  #4  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #5  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 424086:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66d750 pthread_cond_wait (libc.so.6 + 0x8a750)
                                                  #2  0x00007db444f7781c n/a (radeonsi_dri.so + 0x8681c)
                                                  #3  0x00007db444f8f7ec n/a (radeonsi_dri.so + 0x9e7ec)
                                                  #4  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #5  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 2699:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66d750 pthread_cond_wait (libc.so.6 + 0x8a750)
                                                  #2  0x00007db444f7781c n/a (radeonsi_dri.so + 0x8681c)
                                                  #3  0x00007db444f8f7ec n/a (radeonsi_dri.so + 0x9e7ec)
                                                  #4  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #5  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 2732:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66d750 pthread_cond_wait (libc.so.6 + 0x8a750)
                                                  #2  0x00007db444f7781c n/a (radeonsi_dri.so + 0x8681c)
                                                  #3  0x00007db444f8f7ec n/a (radeonsi_dri.so + 0x9e7ec)
                                                  #4  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #5  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  
                                                  Stack trace of thread 39720:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66da65 pthread_cond_timedwait (libc.so.6 + 0x8aa65)
                                                  #2  0x00007db44ddcfba4 _ZN14QWaitCondition4waitEP6QMutex14QDeadlineTimer (libQt6Core.so.6 + 0x2a3ba4)
                                                  #3  0x00007db44ddd24aa n/a (libQt6Core.so.6 + 0x2a64aa)
                                                  #4  0x00007db44ddccbd3 n/a (libQt6Core.so.6 + 0x2a0bd3)
                                                  #5  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #6  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)

                                                  Stack trace of thread 39719:
                                                  #0  0x00007db44d66aebe n/a (libc.so.6 + 0x87ebe)
                                                  #1  0x00007db44d66da65 pthread_cond_timedwait (libc.so.6 + 0x8aa65)
                                                  #2  0x00007db44ddcfba4 _ZN14QWaitCondition4waitEP6QMutex14QDeadlineTimer (libQt6Core.so.6 + 0x2a3ba4)
                                                  #3  0x00007db44ddd24aa n/a (libQt6Core.so.6 + 0x2a64aa)
                                                  #4  0x00007db44ddccbd3 n/a (libQt6Core.so.6 + 0x2a0bd3)
                                                  #5  0x00007db44d66e55a n/a (libc.so.6 + 0x8b55a)
                                                  #6  0x00007db44d6eba3c n/a (libc.so.6 + 0x108a3c)
                                                  ELF object binary architecture: AMD x86-64


gdb bt full

#0  0x00005a39fb8aa812 in ??? ()
#1  0x00007db44dcbcca9 in QtPrivate::QSlotObjectBase::call (a=0x7ffe1e9779e8, r=0x5a39fe477c20, this=0x5a39fd24aee0, this=<optimized out>, r=<optimized out>, a=<optimized out>) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/kernel/qobjectdefs_impl.h:433
#2  doActivate<false> (sender=0x5a39fe6ee750, signal_index=4, argv=0x7ffe1e9779e8) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/kernel/qobject.cpp:4039
        obj = {m_slotObject = std::unique_ptr<class QtPrivate::QSlotObjectBase> = {get() = 0x5a39fd24aee0}}
        receiver = 0x5a39fe477c20
        td = <optimized out>
        receiverInSameThread = <optimized out>
        senderData = {previous = 0x0, receiver = 0x5a39fe477c20, sender = 0x5a39fe6ee750, signal = 4}
        c = 0x5a39fe7990b0
        connections = {d = 0x5a39feb6fb80}
        list = <optimized out>
        inSenderThread = <optimized out>
        highestConnectionId = <optimized out>
        signalVector = <optimized out>
        currentThreadId = <optimized out>
        sp = <optimized out>
        signal_spy_set = 0x0
        empty_argv = {0x0}
        senderDeleted = false
#3  0x00007db44dcbcca9 in QtPrivate::QSlotObjectBase::call (a=0x7ffe1e977ac8, r=0x5a39fe6ee750, this=0x5a39fd772dd0, this=<optimized out>, r=<optimized out>, a=<optimized out>) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/kernel/qobjectdefs_impl.h:433
#4  doActivate<false> (sender=0x5a39fd772ef0, signal_index=4, argv=0x7ffe1e977ac8) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/kernel/qobject.cpp:4039
        obj = {m_slotObject = std::unique_ptr<class QtPrivate::QSlotObjectBase> = {get() = 0x5a39fd772dd0}}
        receiver = 0x5a39fe6ee750
        td = <optimized out>
        receiverInSameThread = <optimized out>
        senderData = {previous = 0x0, receiver = 0x5a39fe6ee750, sender = 0x5a39fd772ef0, signal = 4}
        c = 0x5a39fe8d4ef0
        connections = {d = 0x5a39feb6f8a0}
        list = <optimized out>
        inSenderThread = <optimized out>
        highestConnectionId = <optimized out>
        signalVector = <optimized out>
        currentThreadId = <optimized out>
        sp = <optimized out>
        signal_spy_set = 0x0
        empty_argv = {0x0}
        senderDeleted = false
#5  0x00007db44ddd8b24 in QFutureWatcherBase::finished (this=0x5a39fd772ef0) at /usr/src/debug/qt6-base/build/src/corelib/Core_autogen/include/moc_qfuturewatcher.cpp:454
#6  QFutureWatcherBasePrivate::sendCallOutEvent (event=0x5a39fe5ad4e0, this=0x5a39fe78bc90) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/thread/qfuturewatcher.cpp:493
        q = 0x5a39fd772ef0
        q = <optimized out>
        beginIndex = <optimized out>
        endIndex = <optimized out>
        i = <optimized out>
#7  QFutureWatcherBase::event (this=<optimized out>, event=0x5a39fe5ad4e0) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/thread/qfuturewatcher.cpp:392
        callOutEvent = 0x5a39fe5ad4e0
        d = 0x5a39fe78bc90
#8  0x00007db44ec6138b in QApplicationPrivate::notify_helper (this=<optimized out>, receiver=0x5a39fd772ef0, e=0x5a39fe5ad4e0) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/widgets/kernel/qapplication.cpp:3296
        consumed = false
        filtered = false
#9  0x00007db44dc65818 in QCoreApplication::notifyInternal2 (receiver=0x5a39fd772ef0, event=event@entry=0x5a39fe5ad4e0) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/kernel/qcoreapplication.cpp:1121
        selfRequired = <optimized out>
        result = false
        cbdata = {0x5a39fd772ef0, 0x5a39fe5ad4e0, 0x7ffe1e977bcf}
        d = <optimized out>
        threadData = 0x5a39fccc3430
        scopeLevelCounter = {threadData = 0x5a39fccc3430}
#10 0x00007db44dc65b9b in QCoreApplication::sendEvent (event=0x5a39fe5ad4e0, receiver=<optimized out>) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/kernel/qcoreapplication.cpp:1539
#11 QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0, data=0x5a39fccc3430) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/kernel/qcoreapplication.cpp:1901
        e = 0x5a39fe5ad4e0
        pe = <optimized out>
        r = <optimized out>
        relocker = {m_func = {__locker = <optimized out>}, m_invoke = <optimized out>}
        event_deleter = {d = 0x5a39fe5ad4e0}
        locker = {_M_device = 0x5a39fccc3488, _M_owns = false}
        startOffset = 0
        i = @0x5a39fccc3478: 117
        cleanup = {receiver = <optimized out>, event_type = <optimized out>, data = <optimized out>, exceptionCaught = <optimized out>}
#12 0x00007db44ddcb18f in QEventDispatcherUNIX::processEvents (this=0x5a39fcd560b0, flags=flags@entry=...) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/kernel/qeventdispatcher_unix.cpp:431
        d = 0x5a39fccd5b00
        threadData = 0x5a39fccc3430
        include_timers = <optimized out>
        include_notifiers = <optimized out>
        wait_for_events = <optimized out>
        canWait = <optimized out>
        tm = <optimized out>
        wait_tm = {tv_sec = -344, tv_nsec = 22}
        nevents = <optimized out>
#13 0x00007db44e6b46e2 in QUnixEventDispatcherQPA::processEvents (this=<optimized out>, flags=...) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/gui/platform/unix/qunixeventdispatcher.cpp:27
        didSendEvents = <optimized out>
#14 0x00007db44dc6fd6e in QEventLoop::processEvents (flags=..., this=0x7ffe1e977e60) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/kernel/qeventloop.cpp:100
        d = <optimized out>
        threadData = <optimized out>
#15 QEventLoop::exec (this=0x7ffe1e977e60, flags=...) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/kernel/qeventloop.cpp:182
        d = 0x5a39fd504270
        threadData = <optimized out>
        locker = {m_mutex = <optimized out>, m_isLocked = false}
        ref = {d = <optimized out>, locker = <optimized out>, exceptionCaught = <optimized out>}
        app = 0x7ffe1e9781d0
#16 0x00007db44dc682b8 in QCoreApplication::exec () at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/global/qflags.h:74
        threadData = 0x5a39fccc3430
        eventLoop = {<QObject> = {_vptr.QObject = 0x7db44e0ec3b8 <vtable for QEventLoop+16>, static staticMetaObject = {d = {superdata = {direct = 0x0}, stringdata = 0x7db44df317e0 <_ZN12_GLOBAL__N_1L39qt_meta_stringdata_CLASSQObjectENDCLASSE.lto_priv.0>, data = 0x7db44df316a0 <_ZL33qt_meta_data_CLASSQObjectENDCLASS.lto_priv.0>, static_metacall = 0x7db44dcb3080 <QObject::qt_static_metacall(QObject*, QMetaObject::Call, int, void**)>, relatedMetaObjects = 0x0, metaTypes = 0x7db44e0eaa20 <_Z27qt_incomplete_metaTypeArrayIN12_GLOBAL__N_141qt_meta_stringdata_CLASSQObjectENDCLASS_tEJN9QtPrivate20TypeAndForceCompleteI7QStringSt17integral_constantIbLb1EEEENS3_I7QObjectS6_EENS3_IvS5_IbLb0EEEENS3_IPS8_SA_EESB_SB_NS3_IRKS4_SA_EESB_SB_NS3_IPvSA_EESD_EE.lto_priv.0>, extradata = 0x0}}, d_ptr = {d = 0x5a39fd504270}}, static staticMetaObject = {d = {superdata = {direct = 0x7db44e0eaaa0 <QObject::staticMetaObject>}, stringdata = 0x7db44df30be0 <_ZN12_GLOBAL__N_1L42qt_meta_stringdata_CLASSQEventLoopENDCLASSE.lto_priv.0>, data = 0x7db44df30ae0 <_ZL36qt_meta_data_CLASSQEventLoopENDCLASS.lto_priv.0>, static_metacall = 0x7db44dc6d3e0 <QEventLoop::qt_static_metacall(QObject*, QMetaObject::Call, int, void**)>, relatedMetaObjects = 0x0, metaTypes = 0x7db44e0ea520 <_Z27qt_incomplete_metaTypeArrayIN12_GLOBAL__N_144qt_meta_stringdata_CLASSQEventLoopENDCLASS_tEJN9QtPrivate20TypeAndForceCompleteI6QFlagsIN10QEventLoop17ProcessEventsFlagEESt17integral_constantIbLb1EEEENS3_IS5_S9_EENS3_IvS8_IbLb0EEEENS3_IiSC_EESD_SD_EE.lto_priv.0>, extradata = 0x0}}}
        returnCode = <optimized out>
#17 0x00005a39fb81ddee in ??? ()
#18 0x00007db44d608cd0 in __libc_start_call_main (main=main@entry=0x5a39fb81bec0, argc=argc@entry=14, argv=argv@entry=0x7ffe1e9784e8) at ../sysdeps/nptl/libc_start_call_main.h:58
        self = <optimized out>
        result = <optimized out>
        unwind_buf = {cancel_jmp_buf = {{jmp_buf = {140729411667176, 4625612548147429806, 0, 140729411667296, 138213399851008, 99205080559640, -4625962945401667154, -4946675480293097042}, mask_was_saved = 0}}, priv = {pad = {0x0, 0x0, 0x7ffe1e978560, 0x7db45099f000 <_rtld_global>}, data = {prev = 0x0, cleanup = 0x0, canceltype = 513246560}}}
        not_first_call = <optimized out>
#19 0x00007db44d608d8a in __libc_start_main_impl (main=0x5a39fb81bec0, argc=14, argv=0x7ffe1e9784e8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffe1e9784d8) at ../csu/libc-start.c:360
#20 0x00005a39fb824425 in ??? ()
Comment 1 andy 2024-03-16 19:41:18 UTC 
Still happening in 6.0.2. Here's another backtrace.

#0  0x00005b4e77246722 in QtPrivate::ResultIteratorBase::pointer<QImage> (this=<optimized out>) at /usr/include/qt6/QtCore/qresultstore.h:81
#1  QtPrivate::ResultIteratorBase::pointer<QImage> (this=<optimized out>) at /usr/include/qt6/QtCore/qresultstore.h:74
        p = <optimized out>
        p = <optimized out>
#2  QtPrivate::ResultIteratorBase::value<QImage> (this=<optimized out>) at /usr/include/qt6/QtCore/qresultstore.h:68
#3  QFutureInterface<QImage>::resultReference (index=0, this=0x5b4e7938e8b0) at /usr/include/qt6/QtCore/qfutureinterface.h:388
        locker = {m_mutex = <optimized out>, m_isLocked = true}
        locker = {m_mutex = <optimized out>, m_isLocked = <optimized out>}
#4  QFuture<QImage>::result<QImage, void> (this=<optimized out>) at /usr/include/qt6/QtCore/qfuture.h:308
#5  KWin::ScreenShotSource2::marshal (sink=0x76b5f4014420, this=0x5b4e7938e8a0) at /usr/src/debug/kwin/kwin-6.0.2/src/plugins/screenshot/screenshotdbusinterface2.cpp:244
#6  operator() (__closure=0x5b4e7a96eaa0) at /usr/src/debug/kwin/kwin-6.0.2/src/plugins/screenshot/screenshotdbusinterface2.cpp:588
        source = 0x5b4e7938e8a0
        sink = 0x76b5f4014420
        source = <optimized out>
        sink = <optimized out>
#7  QtPrivate::FunctorCall<QtPrivate::IndexesList<>, QtPrivate::List<>, void, KWin::ScreenShotDBusInterface2::bind(KWin::ScreenShotSinkPipe2*, KWin::ScreenShotSource2*)::<lambda()> >::call (arg=<optimized out>, f=...) at /usr/include/qt6/QtCore/qobjectdefs_impl.h:137
#8  QtPrivate::Functor<KWin::ScreenShotDBusInterface2::bind(KWin::ScreenShotSinkPipe2*, KWin::ScreenShotSource2*)::<lambda()>, 0>::call<QtPrivate::List<>, void> (arg=<optimized out>, f=...) at /usr/include/qt6/QtCore/qobjectdefs_impl.h:339
#9  QtPrivate::QCallableObject<KWin::ScreenShotDBusInterface2::bind(KWin::ScreenShotSinkPipe2*, KWin::ScreenShotSource2*)::<lambda()>, QtPrivate::List<>, void>::impl(int, QtPrivate::QSlotObjectBase *, QObject *, void **, bool *) (which=<optimized out>, this_=0x5b4e7a96ea90, r=<optimized out>, a=<optimized out>, ret=<optimized out>) at /usr/include/qt6/QtCore/qobjectdefs_impl.h:522
        that = 0x5b4e7a96ea90
#10 0x000076b600e9bca9 in QtPrivate::QSlotObjectBase::call (a=0x7ffebf2511f8, r=0x76b5f4014420, this=0x5b4e7a96ea90, this=<optimized out>, r=<optimized out>, a=<optimized out>) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/kernel/qobjectdefs_impl.h:433
#11 doActivate<false> (sender=0x5b4e7938e8a0, signal_index=4, argv=0x7ffebf2511f8) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/kernel/qobject.cpp:4039
        obj = {m_slotObject = std::unique_ptr<QtPrivate::QSlotObjectBase> = {get() = 0x5b4e7a96ea90}}
        receiver = 0x76b5f4014420
        td = <optimized out>
        receiverInSameThread = <optimized out>
        senderData = {previous = 0x0, receiver = 0x76b5f4014420, sender = 0x5b4e7938e8a0, signal = 4}
        c = 0x5b4e7a6d3ca0
        connections = {d = 0x5b4e79563650}
        list = <optimized out>
        inSenderThread = <optimized out>
        highestConnectionId = <optimized out>
        signalVector = <optimized out>
        currentThreadId = <optimized out>
        sp = <optimized out>
        signal_spy_set = 0x0
        empty_argv = {0x0}
        senderDeleted = false
#12 0x000076b600e9bca9 in QtPrivate::QSlotObjectBase::call (a=0x7ffebf2512d8, r=0x5b4e7938e8a0, this=0x5b4e79563190, this=<optimized out>, r=<optimized out>, a=<optimized out>) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/kernel/qobjectdefs_impl.h:433
#13 doActivate<false> (sender=0x5b4e79563300, signal_index=4, argv=0x7ffebf2512d8) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/kernel/qobject.cpp:4039
        obj = {m_slotObject = std::unique_ptr<QtPrivate::QSlotObjectBase> = {get() = 0x5b4e79563190}}
        receiver = 0x5b4e7938e8a0
        td = <optimized out>
        receiverInSameThread = <optimized out>
        senderData = {previous = 0x0, receiver = 0x5b4e7938e8a0, sender = 0x5b4e79563300, signal = 4}
        c = 0x5b4e79c008f0
        connections = {d = 0x5b4e795635a0}
        list = <optimized out>
        inSenderThread = <optimized out>
        highestConnectionId = <optimized out>
        signalVector = <optimized out>
        currentThreadId = <optimized out>
        sp = <optimized out>
        signal_spy_set = 0x0
        empty_argv = {0x0}
        senderDeleted = false
#14 0x000076b600fb7b24 in QFutureWatcherBase::finished (this=0x5b4e79563300) at /usr/src/debug/qt6-base/build/src/corelib/Core_autogen/include/moc_qfuturewatcher.cpp:454
#15 QFutureWatcherBasePrivate::sendCallOutEvent (event=0x5b4e7ac98a50, this=0x5b4e79b38070) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/thread/qfuturewatcher.cpp:493
        q = 0x5b4e79563300
        q = <optimized out>
        beginIndex = <optimized out>
        endIndex = <optimized out>
        i = <optimized out>
#16 QFutureWatcherBase::event (this=<optimized out>, event=0x5b4e7ac98a50) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/thread/qfuturewatcher.cpp:392
        callOutEvent = 0x5b4e7ac98a50
        d = 0x5b4e79b38070
#17 0x000076b601e4038b in QApplicationPrivate::notify_helper (this=<optimized out>, receiver=0x5b4e79563300, e=0x5b4e7ac98a50) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/widgets/kernel/qapplication.cpp:3296
        consumed = false
        filtered = false
#18 0x000076b600e44818 in QCoreApplication::notifyInternal2 (receiver=0x5b4e79563300, event=event@entry=0x5b4e7ac98a50) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/kernel/qcoreapplication.cpp:1121
        selfRequired = <optimized out>
        result = false
        cbdata = {0x5b4e79563300, 0x5b4e7ac98a50, 0x7ffebf2513df}
        d = <optimized out>
        threadData = 0x5b4e790c8430
        scopeLevelCounter = {threadData = 0x5b4e790c8430}
#19 0x000076b600e44b9b in QCoreApplication::sendEvent (event=0x5b4e7ac98a50, receiver=<optimized out>) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/kernel/qcoreapplication.cpp:1539
#20 QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0, data=0x5b4e790c8430) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/kernel/qcoreapplication.cpp:1901
        e = 0x5b4e7ac98a50
        pe = <optimized out>
        r = <optimized out>
        relocker = {m_func = {__locker = <optimized out>}, m_invoke = <optimized out>}
        event_deleter = {d = 0x5b4e7ac98a50}
        locker = {_M_device = 0x5b4e790c8488, _M_owns = false}
        startOffset = 0
        i = @0x5b4e790c8478: 168
        cleanup = {receiver = <optimized out>, event_type = <optimized out>, data = <optimized out>, exceptionCaught = <optimized out>}
#21 0x000076b600faa18f in QEventDispatcherUNIX::processEvents (this=0x5b4e7911b2c0, flags=flags@entry=...) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/kernel/qeventdispatcher_unix.cpp:431
        d = 0x5b4e790d8eb0
        threadData = 0x5b4e790c8430
        include_timers = <optimized out>
        include_notifiers = <optimized out>
        wait_for_events = <optimized out>
        canWait = <optimized out>
        tm = <optimized out>
        wait_tm = {tv_sec = -344, tv_nsec = 22}
        nevents = <optimized out>
#22 0x000076b6018936e2 in QUnixEventDispatcherQPA::processEvents (this=<optimized out>, flags=...) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/gui/platform/unix/qunixeventdispatcher.cpp:27
        didSendEvents = <optimized out>
#23 0x000076b600e4ed6e in QEventLoop::processEvents (flags=..., this=0x7ffebf251670) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/kernel/qeventloop.cpp:100
        d = <optimized out>
        threadData = <optimized out>
#24 QEventLoop::exec (this=0x7ffebf251670, flags=...) at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/kernel/qeventloop.cpp:182
        d = 0x5b4e799597c0
        threadData = <optimized out>
        locker = {m_mutex = <optimized out>, m_isLocked = false}
        ref = {d = <optimized out>, locker = <optimized out>, exceptionCaught = <optimized out>}
        app = 0x7ffebf2519e0
#25 0x000076b600e472b8 in QCoreApplication::exec () at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/corelib/global/qflags.h:74
        threadData = 0x5b4e790c8430
        eventLoop = {<QObject> = {_vptr.QObject = 0x76b6012cb3b8 <vtable for QEventLoop+16>, static staticMetaObject = {d = {superdata = {direct = 0x0}, stringdata = 0x76b6011107e0 <_ZN12_GLOBAL__N_1L39qt_meta_stringdata_CLASSQObjectENDCLASSE.lto_priv.0>, data = 0x76b6011106a0 <_ZL33qt_meta_data_CLASSQObjectENDCLASS.lto_priv.0>, static_metacall = 0x76b600e92080 <QObject::qt_static_metacall(QObject*, QMetaObject::Call, int, void**)>, relatedMetaObjects = 0x0, metaTypes = 0x76b6012c9a20 <_Z27qt_incomplete_metaTypeArrayIN12_GLOBAL__N_141qt_meta_stringdata_CLASSQObjectENDCLASS_tEJN9QtPrivate20TypeAndForceCompleteI7QStringSt17integral_constantIbLb1EEEENS3_I7QObjectS6_EENS3_IvS5_IbLb0EEEENS3_IPS8_SA_EESB_SB_NS3_IRKS4_SA_EESB_SB_NS3_IPvSA_EESD_EE.lto_priv.0>, extradata = 0x0}}, d_ptr = {d = 0x5b4e799597c0}}, static staticMetaObject = {d = {superdata = {direct = 0x76b6012c9aa0 <QObject::staticMetaObject>}, stringdata = 0x76b60110fbe0 <_ZN12_GLOBAL__N_1L42qt_meta_stringdata_CLASSQEventLoopENDCLASSE.lto_priv.0>, data = 0x76b60110fae0 <_ZL36qt_meta_data_CLASSQEventLoopENDCLASS.lto_priv.0>, static_metacall = 0x76b600e4c3e0 <QEventLoop::qt_static_metacall(QObject*, QMetaObject::Call, int, void**)>, relatedMetaObjects = 0x0, metaTypes = 0x76b6012c9520 <_Z27qt_incomplete_metaTypeArrayIN12_GLOBAL__N_144qt_meta_stringdata_CLASSQEventLoopENDCLASS_tEJN9QtPrivate20TypeAndForceCompleteI6QFlagsIN10QEventLoop17ProcessEventsFlagEESt17integral_constantIbLb1EEEENS3_IS5_S9_EENS3_IvS8_IbLb0EEEENS3_IiSC_EESD_SD_EE.lto_priv.0>, extradata = 0x0}}}
        returnCode = <optimized out>
#26 0x000076b601e3cf0a in QApplication::exec () at /usr/src/debug/qt6-base/qtbase-everywhere-src-6.6.2/src/widgets/kernel/qapplication.cpp:2574
#27 0x00005b4e771b9dee in main (argc=<optimized out>, argv=<optimized out>) at /usr/src/debug/kwin/kwin-6.0.2/src/main_wayland.cpp:609
        environment = {d = {d = 0x5b4e790d5450}}
        a = {<KWin::Application> = {<QApplication> = {<QGuiApplication> = {<QCoreApplication> = {<QObject> = {_vptr.QObject = 0x5b4e77300e68 <vtable for KWin::ApplicationWayland+16>, static staticMetaObject = {d = {superdata = {direct = 0x0}, stringdata = 0x76b6011107e0 <_ZN12_GLOBAL__N_1L39qt_meta_stringdata_CLASSQObjectENDCLASSE.lto_priv.0>, data = 0x76b6011106a0 <_ZL33qt_meta_data_CLASSQObjectENDCLASS.lto_priv.0>, static_metacall = 0x76b600e92080 <QObject::qt_static_metacall(QObject*, QMetaObject::Call, int, void**)>, relatedMetaObjects = 0x0, metaTypes = 0x76b6012c9a20 <_Z27qt_incomplete_metaTypeArrayIN12_GLOBAL__N_141qt_meta_stringdata_CLASSQObjectENDCLASS_tEJN9QtPrivate20TypeAndForceCompleteI7QStringSt17integral_constantIbLb1EEEENS3_I7QObjectS6_EENS3_IvS5_IbLb0EEEENS3_IPS8_SA_EESB_SB_NS3_IRKS4_SA_EESB_SB_NS3_IPvSA_EESD_EE.lto_priv.0>, extradata = 0x0}}, d_ptr = {d = 0x5b4e790d7190}}, static staticMetaObject = {d = {superdata = {direct = 0x76b6012c9aa0 <QObject::staticMetaObject>}, stringdata = 0x76b60110fee0 <_ZN12_GLOBAL__N_1L48qt_meta_stringdata_CLASSQCoreApplicationENDCLASSE.lto_priv.0>, data = 0x76b60110fd40 <_ZL42qt_meta_data_CLASSQCoreApplicationENDCLASS.lto_priv.0>, static_metacall = 0x76b600e4ddf0 <QCoreApplication::qt_static_metacall(QObject*, QMetaObject::Call, int, void**)>, relatedMetaObjects = 0x0, metaTypes = 0x76b6012c95a0 <_Z27qt_incomplete_metaTypeArrayIN12_GLOBAL__N_150qt_meta_stringdata_CLASSQCoreApplicationENDCLASS_tEJN9QtPrivate20TypeAndForceCompleteI7QStringSt17integral_constantIbLb1EEEES7_S7_S7_NS3_IbS6_EENS3_I16QCoreApplicationS6_EENS3_IvS5_IbLb0EEEESC_SC_SC_SC_SC_SC_NS3_IiSB_EESC_EE.lto_priv.0>, extradata = 0x0}}, static self = 0x7ffebf2519e0}, static staticMetaObject = {d = {superdata = {direct = 0x76b6012c9620 <QCoreApplication::staticMetaObject>}, stringdata = 0x76b6019a0940 <_ZN12_GLOBAL__N_1L47qt_meta_stringdata_CLASSQGuiApplicationENDCLASSE.lto_priv.0>, data = 0x76b6019a0640 <_ZL41qt_meta_data_CLASSQGuiApplicationENDCLASS.lto_priv.0>, static_metacall = 0x76b601460420 <QGuiApplication::qt_static_metacall(QObject*, QMetaObject::Call, int, void**)>, relatedMetaObjects = 0x0, metaTypes = 0x76b601ad6600 <_Z27qt_incomplete_metaTypeArrayIN12_GLOBAL__N_149qt_meta_stringdata_CLASSQGuiApplicationENDCLASS_tEJN9QtPrivate20TypeAndForceCompleteI5QIconSt17integral_constantIbLb1EEEENS3_I7QStringS6_EES9_NS3_IN2Qt15LayoutDirectionES6_EES9_NS3_IbS6_EENS3_IP7QScreenS6_EENS3_I15QGuiApplicationS6_EENS3_IvS5_IbLb0EEEESK_NS3_ISF_SJ_EESK_SL_SK_SL_SK_SK_NS3_IP7QObjectSJ_EESK_NS3_IP7QWindowSJ_EESK_NS3_INSA_16ApplicationStateESJ_EESK_NS3_ISB_SJ_EESK_NS3_IR15QSessionManagerSJ_EESK_SX_SK_SK_NS3_IRK8QPaletteSJ_EESK_NS3_IRK5QFontSJ_EESK_NS3_IxSJ_EESK_SO_EE.lto_priv.0>, extradata = 0x0}}}, static staticMetaObject = {d = {superdata = {direct = 0x76b601ad6a00 <QGuiApplication::staticMetaObject>}, stringdata = 0x76b6022ac7c0 <_ZN12_GLOBAL__N_1L44qt_meta_stringdata_CLASSQApplicationENDCLASSE.lto_priv.0>, data = 0x76b6022ac620 <_ZL38qt_meta_data_CLASSQApplicationENDCLASS.lto_priv.0>, static_metacall = 0x76b601e4bc10 <QApplication::qt_static_metacall(QObject*, QMetaObject::Call, int, void**)>, relatedMetaObjects = 0x0, metaTypes = 0x76b6023f8460 <_Z27qt_incomplete_metaTypeArrayIN12_GLOBAL__N_146qt_meta_stringdata_CLASSQApplicationENDCLASS_tEJN9QtPrivate20TypeAndForceCompleteIiSt17integral_constantIbLb1EEEES6_S6_S6_S6_S6_NS3_I7QStringS5_EENS3_IbS5_EENS3_I12QApplicationS5_EENS3_IvS4_IbLb0EEEENS3_IP7QWidgetSC_EESG_SD_NS3_IRKS7_SC_EESD_NS3_IKbSC_EESD_SD_EE.lto_priv.0>, extradata = 0x0}}}, static staticMetaObject = {d = {superdata = {direct = 0x76b6023f8b40 <QApplication::staticMetaObject>}, stringdata = 0x76b6038de980 <_ZN12_GLOBAL__N_1L52qt_meta_stringdata_CLASSKWinSCOPEApplicationENDCLASSE.lto_priv.0>, data = 0x76b6038de800 <_ZL46qt_meta_data_CLASSKWinSCOPEApplicationENDCLASS.lto_priv.0>, static_metacall = 0x76b603543c50 <KWin::Application::qt_static_metacall(QObject*, QMetaObject::Call, int, void**)>, relatedMetaObjects = 0x0, metaTypes = 0x76b603a0a9c0 <_Z27qt_incomplete_metaTypeArrayIN12_GLOBAL__N_154qt_meta_stringdata_CLASSKWinSCOPEApplicationENDCLASS_tEJN9QtPrivate20TypeAndForceCompleteIjSt17integral_constantIbLb1EEEES6_NS3_IPvS5_EENS3_I28QExplicitlySharedDataPointerI13KSharedConfigES5_EESC_NS3_IN4KWin11Application13OperationModeES5_EENS3_ISE_S5_EENS3_IvS4_IbLb0EEEESJ_SJ_SJ_SJ_SJ_EE.lto_priv.0>, extradata = 0x0}}, static crashes = 0, m_eventFilters = {<QListSpecialMethods<QPointer<KWin::X11EventFilterContainer> >> = {<QListSpecialMethodsBase<QPointer<KWin::X11EventFilterContainer> >> = {<No data fields>}, <No data fields>}, d = {d = 0x5b4e7a649590, ptr = 0x5b4e7a6495a0, size = 4}}, m_genericEventFilters = {<QListSpecialMethods<QPointer<KWin::X11EventFilterContainer> >> = {<QListSpecialMethodsBase<QPointer<KWin::X11EventFilterContainer> >> = {<No data fields>}, <No data fields>}, d = {d = 0x0, ptr = 0x0, size = 0}}, m_eventFilter = std::unique_ptr<KWin::XcbEventFilter> = {get() = 0x5b4e791bfcf0}, m_followLocale1 = false, m_configLock = false, m_config = {d = 0x5b4e79151220}, m_kxkbConfig = {d = 0x5b4e791b33b0}, m_inputConfig = {d = 0x5b4e791b33d0}, m_operationMode = KWin::Application::OperationModeXwayland, m_x11Time = 63105646, m_rootWindow = 1046, m_compositeWindow = 0, m_connection = 0x5b4e7a66a110, m_useKActivities = true, m_session = std::unique_ptr<KWin::Session> = {get() = 0x5b4e791c3010}, m_outputBackend = std::unique_ptr<KWin::OutputBackend> = {get() = 0x76b5f40099b0}, m_terminating = false, m_xwaylandScale = 1, m_processEnvironment = {d = {d = 0x5b4e79b596a0}}, m_pluginManager = std::unique_ptr<KWin::PluginManager> = {get() = 0x5b4e797d8550}, m_inputMethod = std::unique_ptr<KWin::InputMethod> = {get() = 0x5b4e7937a390}, m_colorManager = std::unique_ptr<KWin::ColorManager> = {get() = 0x5b4e797d6860}, m_tabletModeManager = std::unique_ptr<KWin::TabletModeManager> = {get() = 0x5b4e795eda80}, m_screenLockerWatcher = std::unique_ptr<KWin::ScreenLockerWatcher> = {get() = 0x5b4e791d1df0}, m_platformCursor = std::unique_ptr<KWin::Cursor> = {get() = 0x5b4e79494140}}, static staticMetaObject = {d = {superdata = {direct = 0x76b603a0ab40 <KWin::Application::staticMetaObject>}, stringdata = 0x5b4e772a9fe0 <(anonymous namespace)::qt_meta_stringdata_CLASSKWinSCOPEApplicationWaylandENDCLASS>, data = 0x5b4e772a9820 <qt_meta_data_CLASSKWinSCOPEApplicationWaylandENDCLASS>, static_metacall = 0x5b4e771c0530 <KWin::ApplicationWayland::qt_static_metacall(QObject*, QMetaObject::Call, int, void**)>, relatedMetaObjects = 0x0, metaTypes = 0x5b4e772ff0a8 <qt_incomplete_metaTypeArray<(anonymous namespace)::qt_meta_stringdata_CLASSKWinSCOPEApplicationWaylandENDCLASS_t, QtPrivate::TypeAndForceComplete<KWin::ApplicationWayland, std::integral_constant<bool, true> > >>, extradata = 0x0}}, m_startXWayland = true, m_applicationsToStart = {<QListSpecialMethods<QString>> = {<QListSpecialMethodsBase<QString>> = {<No data fields>}, <No data fields>}, d = {d = 0x0, ptr = 0x0, size = 0}}, m_inputMethodServerToStart = {d = {d = 0x0, ptr = 0x0, size = 0}, static _empty = 0 u'\000'}, m_sessionArgument = {d = {d = 0x0, ptr = 0x0, size = 0}, static _empty = 0 u'\000'}, m_xwayland = std::unique_ptr<KWin::Xwl::Xwayland> = {get() = 0x5b4e796b9000}, m_xwaylandListenFds = {<QListSpecialMethods<int>> = {<QListSpecialMethodsBase<int>> = {<No data fields>}, <No data fields>}, d = {d = 0x5b4e790ccdc0, ptr = 0x5b4e790ccdd0, size = 2}}, m_xwaylandDisplay = {d = {d = 0x5b4e791b5b90, ptr = 0x5b4e791b5ba0 u":0", size = 2}, static _empty = 0 u'\000'}, m_xwaylandXauthority = {d = {d = 0x5b4e791287d0, ptr = 0x5b4e791287e0 u"/run/user/1000/xauth_fwpFAb", size = 27}, static _empty = 0 u'\000'}, m_settingsWatcher = {value = 0x5b4e791b0150, d = 0x5b4e7912e300}}
        xwaylandOption = {d = {d = 0x5b4e791a70d0}}
        waylandSocketOption = {d = {d = 0x5b4e791a7150}}
        x11DisplayOption = {d = {d = 0x5b4e791a7230}}
        waylandDisplayOption = {d = {d = 0x5b4e791a73e0}}
        virtualFbOption = {d = {d = 0x5b4e791a74f0}}
        widthOption = {d = {d = 0x5b4e791cf700}}
        heightOption = {d = {d = 0x5b4e791cf7d0}}
        scaleOption = {d = {d = 0x5b4e791cf920}}
        outputCountOption = {d = {d = 0x5b4e791bfaa0}}
        waylandSocketFdOption = {d = {d = 0x5b4e791bfb20}}
        xwaylandListenFdOption = {d = {d = 0x5b4e791bfbf0}}
        xwaylandDisplayOption = {d = {d = 0x5b4e791bfc70}}
        xwaylandXAuthorityOption = {d = {d = 0x5b4e791c4810}}
        replaceOption = {d = {d = 0x5b4e791cfb30}}
        drmOption = {d = {d = 0x5b4e791cfc50}}
        locale1Option = {d = {d = 0x5b4e791a81c0}}
        parser = {d = 0x5b4e791a8240}
        inputMethodOption = {d = {d = 0x5b4e791a9500}}
        screenLockerOption = {d = {d = 0x5b4e791ba400}}
        noScreenLockerOption = {d = {d = 0x5b4e791ba5a0}}
        noGlobalShortcutsOption = {d = {d = 0x5b4e791ba670}}
        noActivitiesOption = {d = {d = 0x5b4e791ba750}}
        exitWithSessionOption = {d = {d = 0x5b4e791ba880}}
        backendType = <optimized out>
        pluginName = {d = {d = 0x0, ptr = 0x0, size = 0}, static _empty = 0 u'\000'}
        initialWindowSize = {wd = <optimized out>, ht = <optimized out>}
        outputCount = <optimized out>
        outputScale = 1
        ok = true
        width = <optimized out>
        height = <optimized out>
        scale = <optimized out>
        count = <optimized out>
        server = <optimized out>
        flags = {i = <optimized out>}
        socketName = {d = {d = 0x5b4e791baa70, ptr = 0x5b4e791baa80 u"wayland-0", size = 9}, static _empty = 0 u'\000'}
Comment 2 andy 2024-03-16 20:59:19 UTC 
possibly related https://bugs.kde.org/show_bug.cgi?id=483008
Comment 3 Méven Car 2024-03-18 16:22:59 UTC 
(In reply to andy from comment #2)
> possibly related https://bugs.kde.org/show_bug.cgi?id=483008
Unrelated.

Relevant part:

#0  0x00005b4e77246722 in QtPrivate::ResultIteratorBase::pointer<QImage> (this=<optimized out>) at /usr/include/qt6/QtCore/qresultstore.h:81
#1  QtPrivate::ResultIteratorBase::pointer<QImage> (this=<optimized out>) at /usr/include/qt6/QtCore/qresultstore.h:74
        p = <optimized out>
        p = <optimized out>
#2  QtPrivate::ResultIteratorBase::value<QImage> (this=<optimized out>) at /usr/include/qt6/QtCore/qresultstore.h:68
#3  QFutureInterface<QImage>::resultReference (index=0, this=0x5b4e7938e8b0) at /usr/include/qt6/QtCore/qfutureinterface.h:388
        locker = {m_mutex = <optimized out>, m_isLocked = true}
        locker = {m_mutex = <optimized out>, m_isLocked = <optimized out>}
#4  QFuture<QImage>::result<QImage, void> (this=<optimized out>) at /usr/include/qt6/QtCore/qfuture.h:308
#5  KWin::ScreenShotSource2::marshal (sink=0x76b5f4014420, this=0x5b4e7938e8a0) at /usr/src/debug/kwin/kwin-6.0.2/src/plugins/screenshot/screenshotdbusinterface2.cpp:244
#6  operator() (__closure=0x5b4e7a96eaa0) at /usr/src/debug/kwin/kwin-6.0.2/src/plugins/screenshot/screenshotdbusinterface2.cpp:588
        source = 0x5b4e7938e8a0
        sink = 0x76b5f4014420
        source = <optimized out>
        sink = <optimized out>
#7  QtPrivate::FunctorCall<QtPrivate::IndexesList<>, QtPrivate::List<>, void, KWin::ScreenShotDBusInterface2::bind(KWin::ScreenShotSinkPipe2*, KWin::ScreenShotSource2*)::<lambda()> >::call (arg=<optimized out>, f=...) at /usr/include/qt6/QtCore/qobjectdefs_impl.h:137

Two strange things: 
 - a screenshot future that get activated on unlock
 - consequently, a finished future that has a nullptr result, here QImage
 
The watcher might work properly.

@andy, did you use spectacle or other screenshot application in your session previous to the crash ?
Comment 4 andy 2024-03-18 16:47:06 UTC 
(In reply to Méven Car from comment #3)
> @andy, did you use spectacle or other screenshot application in your session
> previous to the crash ?

I do have a script that periodically takes screenshots with spectacle. I'll try disabling that overnight tonight to see if it makes a difference. In my first comment in the backtrace there was no QImage mention so I wonder if it's unrelated. Given so many threads in the core dump log, which does `gdb bt full` show?
Comment 5 Méven Car 2024-03-18 17:01:31 UTC 
(In reply to andy from comment #4)
> (In reply to Méven Car from comment #3)
> > @andy, did you use spectacle or other screenshot application in your session
> > previous to the crash ?
> 
> I do have a script that periodically takes screenshots with spectacle.
> I'll try disabling that overnight tonight to see if it makes a difference.

I am about 95% sure that it will.
You can try disabling it as you lock you session.

>  In my first comment in the backtrace there was no QImage mention so I wonder if
> it's unrelated. Given so many threads in the core dump log, which does `gdb
> bt full` show?

The first trace ends with `#0  0x00005a39fb8aa812 in ??? ()` i.e couldn't display more information, 
Meaning it could end in the same place as before, we had the mention of `QFutureWatcherBase::finished` which hints that way.
Between the two traces you must have installed better debug symbols that allowed to read that.
Comment 6 andy 2024-03-19 23:03:07 UTC 
I wrapped my screenshot operations around checking `dbus-send --session --dest=org.freedesktop.ScreenSaver --type=method_call --print-reply /org/freedesktop/ScreenSaver org.freedesktop.ScreenSaver.GetActive`. It seems to have done the trick, no crash this morning.

Maybe this is still relevant to fix for the sake of kwin shouldn't be able to get segfaulted by a screenshot program.
Comment 7 Méven Car 2024-03-20 09:43:34 UTC 
(In reply to andy from comment #6)
> I wrapped my screenshot operations around checking `dbus-send --session
> --dest=org.freedesktop.ScreenSaver --type=method_call --print-reply
> /org/freedesktop/ScreenSaver org.freedesktop.ScreenSaver.GetActive`. It
> seems to have done the trick, no crash this morning.
> 
> Maybe this is still relevant to fix for the sake of kwin shouldn't be able
> to get segfaulted by a screenshot program.

Yes indeed.
Comment 8 Vlad Zahorodnii 2024-05-31 11:40:54 UTC 
It should be fixed by https://invent.kde.org/plasma/kwin/-/commit/8bf1f9203b4016362e1f9f15f1e5b8efddad1b8e