Application: kwin_x11 (5.12.7) Qt Version: 5.9.5 Frameworks Version: 5.44.0 Operating System: Linux 4.15.0-54-generic x86_64 Distribution: Ubuntu 18.04.2 LTS -- Information about the crash: - What I was doing when the application crashed: Alt+TABbing regularly causes kwin_x11 to crash Notes: - What seems to mitigate the frequency of the occurance by about 1:10 was switching to the 'compact' task switcher as opposed to the 'cover flip', or one of the other presumeably more resource intensive ones - This has happened a lot, like through the lifetime of my 18.04 Kubuntu installation it's probably in the triple digits, but this was the first time the crash handler caught it The crash can be reproduced sometimes. -- Backtrace: Application: KWin (kwin_x11), signal: Segmentation fault Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". [Current thread is 1 (Thread 0x7fdaf5a9cd00 (LWP 1471))] Thread 6 (Thread 0x7fda377dd700 (LWP 2205)): #0 0x00007fdaee4809f3 in futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0x55aaf6c79de4) at ../sysdeps/unix/sysv/linux/futex-internal.h:88 #1 0x00007fdaee4809f3 in __pthread_cond_wait_common (abstime=0x0, mutex=0x55aaf6c79d90, cond=0x55aaf6c79db8) at pthread_cond_wait.c:502 #2 0x00007fdaee4809f3 in __pthread_cond_wait (cond=0x55aaf6c79db8, mutex=0x55aaf6c79d90) at pthread_cond_wait.c:655 #3 0x00007fdaf25e459b in QWaitCondition::wait(QMutex*, unsigned long) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #4 0x00007fdaed6546a8 in () at /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5 #5 0x00007fdaed654b0a in () at /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5 #6 0x00007fdaf25e316d in () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #7 0x00007fdaee47a6db in start_thread (arg=0x7fda377dd700) at pthread_create.c:463 #8 0x00007fdaf542188f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 5 (Thread 0x7fdad19b1700 (LWP 2204)): #0 0x00007fdaee4809f3 in futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0x55aaf6a2a3f4) at ../sysdeps/unix/sysv/linux/futex-internal.h:88 #1 0x00007fdaee4809f3 in __pthread_cond_wait_common (abstime=0x0, mutex=0x55aaf6a2a3a0, cond=0x55aaf6a2a3c8) at pthread_cond_wait.c:502 #2 0x00007fdaee4809f3 in __pthread_cond_wait (cond=0x55aaf6a2a3c8, mutex=0x55aaf6a2a3a0) at pthread_cond_wait.c:655 #3 0x00007fdaf25e459b in QWaitCondition::wait(QMutex*, unsigned long) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #4 0x00007fdaed6546a8 in () at /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5 #5 0x00007fdaed654b0a in () at /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5 #6 0x00007fdaf25e316d in () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #7 0x00007fdaee47a6db in start_thread (arg=0x7fdad19b1700) at pthread_create.c:463 #8 0x00007fdaf542188f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 4 (Thread 0x7fdac2def700 (LWP 1622)): #0 0x00007fdaee4809f3 in futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0x7fdaf1a17fb8) at ../sysdeps/unix/sysv/linux/futex-internal.h:88 #1 0x00007fdaee4809f3 in __pthread_cond_wait_common (abstime=0x0, mutex=0x7fdaf1a17f68, cond=0x7fdaf1a17f90) at pthread_cond_wait.c:502 #2 0x00007fdaee4809f3 in __pthread_cond_wait (cond=0x7fdaf1a17f90, mutex=0x7fdaf1a17f68) at pthread_cond_wait.c:655 #3 0x00007fdaf17215f4 in () at /usr/lib/x86_64-linux-gnu/libQt5Script.so.5 #4 0x00007fdaf1721639 in () at /usr/lib/x86_64-linux-gnu/libQt5Script.so.5 #5 0x00007fdaee47a6db in start_thread (arg=0x7fdac2def700) at pthread_create.c:463 #6 0x00007fdaf542188f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 3 (Thread 0x7fdad0d51700 (LWP 1620)): #0 0x00007fdaf5414cf6 in __GI_ppoll (fds=0x7fdac8000d48, nfds=1, timeout=<optimized out>, sigmask=0x0) at ../sysdeps/unix/sysv/linux/ppoll.c:39 #1 0x00007fdaf28165c1 in qt_safe_poll(pollfd*, unsigned long, timespec const*) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #2 0x00007fdaf2817cde in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #3 0x00007fdaf27bf9ea in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #4 0x00007fdaf25de22a in QThread::exec() () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #5 0x00007fdaecf666f5 in () at /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5 #6 0x00007fdaf25e316d in () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #7 0x00007fdaee47a6db in start_thread (arg=0x7fdad0d51700) at pthread_create.c:463 #8 0x00007fdaf542188f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 2 (Thread 0x7fdad2c2d700 (LWP 1586)): #0 0x00007fdaf5414cf6 in __GI_ppoll (fds=0x7fdacc00b368, nfds=1, timeout=<optimized out>, sigmask=0x0) at ../sysdeps/unix/sysv/linux/ppoll.c:39 #1 0x00007fdaf28165c1 in qt_safe_poll(pollfd*, unsigned long, timespec const*) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #2 0x00007fdaf2817cde in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #3 0x00007fdaf27bf9ea in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #4 0x00007fdaf25de22a in QThread::exec() () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #5 0x00007fdaebe3fd45 in () at /usr/lib/x86_64-linux-gnu/libQt5DBus.so.5 #6 0x00007fdaf25e316d in () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #7 0x00007fdaee47a6db in start_thread (arg=0x7fdad2c2d700) at pthread_create.c:463 #8 0x00007fdaf542188f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 1 (Thread 0x7fdaf5a9cd00 (LWP 1471)): [KCrash Handler] #6 0x000055aaf6fd19e0 in () #7 0x00007fdaf4f0cd6d in KWin::Workspace::constrainedStackingOrder() () at /usr/lib/x86_64-linux-gnu/libkwin.so.5 #8 0x00007fdaf4f0d538 in KWin::Workspace::updateStackingOrder(bool) () at /usr/lib/x86_64-linux-gnu/libkwin.so.5 #9 0x00007fdaf4f0dac0 in KWin::Workspace::blockStackingUpdates(bool) () at /usr/lib/x86_64-linux-gnu/libkwin.so.5 #10 0x00007fdaf4eb8870 in KWin::Client::destroyClient() () at /usr/lib/x86_64-linux-gnu/libkwin.so.5 #11 0x00007fdaf4f18769 in KWin::Client::unmapNotifyEvent(xcb_unmap_notify_event_t*) () at /usr/lib/x86_64-linux-gnu/libkwin.so.5 #12 0x00007fdaf4f1be6b in KWin::Client::windowEvent(xcb_generic_event_t*) () at /usr/lib/x86_64-linux-gnu/libkwin.so.5 #13 0x00007fdaf4f1c7f5 in KWin::Workspace::workspaceEvent(xcb_generic_event_t*) () at /usr/lib/x86_64-linux-gnu/libkwin.so.5 #14 0x00007fdaf27be58f in QAbstractEventDispatcher::filterNativeEvent(QByteArray const&, void*, long*) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #15 0x00007fdada253820 in QXcbConnection::handleXcbEvent(xcb_generic_event_t*) () at /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5 #16 0x00007fdada2544ac in QXcbConnection::processXcbEvents() () at /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5 #17 0x00007fdaf27f1122 in QObject::event(QEvent*) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #18 0x00007fdaf353f82c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #19 0x00007fdaf35470f4 in QApplication::notify(QObject*, QEvent*) () at /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #20 0x00007fdaf27c19a8 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #21 0x00007fdaf27c411d in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #22 0x00007fdaf2817af4 in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #23 0x00007fdada2b55cd in () at /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5 #24 0x00007fdaf27bf9ea in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #25 0x00007fdaf27c8a84 in QCoreApplication::exec() () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #26 0x00007fdaf56f9dbb in kdemain () at /usr/lib/x86_64-linux-gnu/libkdeinit5_kwin_x11.so #27 0x00007fdaf5321b97 in __libc_start_main (main=0x55aaf5379730, argc=1, argv=0x7ffccd6d1a48, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffccd6d1a38) at ../csu/libc-start.c:310 #28 0x000055aaf537976a in _start () Reported using DrKonqi
Please post output of qdbus org.kde.KWin /KWin supportInformation Can you recall if any window were closed during alt-tabbing?
(In reply to Vlad Zahorodnii from comment #1) > Please post output of > qdbus org.kde.KWin /KWin supportInformation > > Can you recall if any window were closed during alt-tabbing? First the output of 'qdbus org.kde.KWin /KWin support information: ========================== Version ======= KWin version: 5.12.7 Qt Version: 5.9.5 Qt compile version: 5.9.5 XCB compile version: 1.13 Operation Mode: X11 only Build Options ============= KWIN_BUILD_DECORATIONS: yes KWIN_BUILD_TABBOX: yes KWIN_BUILD_ACTIVITIES: yes HAVE_INPUT: yes HAVE_DRM: yes HAVE_GBM: yes HAVE_X11_XCB: yes HAVE_EPOXY_GLX: yes HAVE_WAYLAND_EGL: yes X11 === Vendor: The X.Org Foundation Vendor Release: 11906000 Protocol Version/Revision: 11/0 SHAPE: yes; Version: 0x11 RANDR: yes; Version: 0x14 DAMAGE: yes; Version: 0x11 Composite: yes; Version: 0x4 RENDER: yes; Version: 0xb XFIXES: yes; Version: 0x50 SYNC: yes; Version: 0x31 GLX: yes; Version: 0x0 Decoration ========== Plugin: org.kde.breeze Theme: Blur: 0 onAllDesktopsAvailable: true alphaChannelSupported: false closeOnDoubleClickOnMenu: false decorationButtonsLeft: 0, 2 decorationButtonsRight: 6, 3, 4, 5 borderSize: 3 gridUnit: 10 font: Noto Sans,10,-1,0,50,0,0,0,0,0,Regular smallSpacing: 2 largeSpacing: 10 Platform ========== Name: KWin::X11StandalonePlatform Options ======= focusPolicy: 0 nextFocusPrefersMouse: false clickRaise: true autoRaise: false autoRaiseInterval: 0 delayFocusInterval: 0 shadeHover: false shadeHoverInterval: 250 separateScreenFocus: false placement: 4 focusPolicyIsReasonable: true borderSnapZone: 10 windowSnapZone: 10 centerSnapZone: 0 snapOnlyWhenOverlapping: false rollOverDesktops: true focusStealingPreventionLevel: 1 legacyFullscreenSupport: false operationTitlebarDblClick: 5000 operationMaxButtonLeftClick: 5000 operationMaxButtonMiddleClick: 5015 operationMaxButtonRightClick: 5014 commandActiveTitlebar1: 0 commandActiveTitlebar2: 30 commandActiveTitlebar3: 2 commandInactiveTitlebar1: 4 commandInactiveTitlebar2: 30 commandInactiveTitlebar3: 2 commandWindow1: 7 commandWindow2: 8 commandWindow3: 8 commandWindowWheel: 31 commandAll1: 10 commandAll2: 3 commandAll3: 14 keyCmdAllModKey: 16777251 showGeometryTip: false condensedTitle: false electricBorderMaximize: true electricBorderTiling: true electricBorderCornerRatio: 0.25 borderlessMaximizedWindows: false killPingTimeout: 5000 hideUtilityWindowsForInactive: true inactiveTabsSkipTaskbar: false autogroupSimilarWindows: false autogroupInForeground: true compositingMode: 1 useCompositing: false compositingInitialized: false hiddenPreviews: 1 glSmoothScale: 2 xrenderSmoothScale: false maxFpsInterval: 16666666 refreshRate: 0 vBlankTime: 6000000 glStrictBinding: true glStrictBindingFollowsDriver: true glCoreProfile: false glPreferBufferSwap: 97 glPlatformInterface: 1 windowsBlockCompositing: true Screen Edges ============ desktopSwitching: false desktopSwitchingMovingClients: false cursorPushBackDistance: 1x1 timeThreshold: 150 reActivateThreshold: 350 actionTopLeft: 0 actionTop: 0 actionTopRight: 0 actionRight: 0 actionBottomRight: 0 actionBottom: 0 actionBottomLeft: 0 actionLeft: 0 Screens ======= Multi-Head: no Active screen follows mouse: no Number of Screens: 2 Screen 0: --------- Name: LVDS-0 Geometry: 1920,0,1366x768 Scale: 1 Refresh Rate: 59.9939 Screen 1: --------- Name: VGA-0 Geometry: 0,0,1920x1080 Scale: 1 Refresh Rate: 60 Compositing =========== Compositing is not active =============================== Secondly: Regarding whether I could remember whether a window was closed: That actually makes the crash reproducible every time. If the task switcher is open and the window which closes happens to be selected kwin crashes. It survives if the window which closes is not selected so that hunch was on the money.
That's a known bug. I fixed it quite recently but I can't recall if the fix was backported to 5.12 branch. In either case, you can work around the bug by just enabling compositing.
I backported the fix to 5.12 branch. The fix will be available in 5.12.9, which is released on 9/10/2019. *** This bug has been marked as a duplicate of bug 406784 ***
In any case thank you very much for providing me an workaround and pointing me towards a fix! Much appreciated! Sent with ProtonMail Secure Email. ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ On Monday, July 15, 2019 3:53 PM, Vlad Zahorodnii <bugzilla_noreply@kde.org> wrote: > https://bugs.kde.org/show_bug.cgi?id=409815 > > --- Comment #3 from Vlad Zahorodnii vladzzag@gmail.com --- > > That's a known bug. I fixed it quite recently but I can't recall if the fix was > backported to 5.12 branch. > > In either case, you can work around the bug by just enabling compositing. > > -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- > > You are receiving this mail because: > You reported the bug.