Bug 360408

Summary: Another deadlock with Qt 5.6 git
Product: [Frameworks and Libraries] frameworks-kded Reporter: Jan Kundrát <jkt>
Component: generalAssignee: Alex Fiestas <afiestas>
Status: RESOLVED UPSTREAM    
Severity: major CC: eugene.shalygin+bugzilla.kde, faure, hrvoje.senjan, kdelibs-bugs, kv, rdieter, thiago
Priority: NOR    
Version: unspecified   
Target Milestone: ---   
Platform: Other   
OS: Linux   
See Also: https://bugs.kde.org/show_bug.cgi?id=359611
Latest Commit: Version Fixed In:
Sentry Crash Report:

Description Jan Kundrát 2016-03-11 12:19:05 UTC 
This is with Qt from the 5.6 branch (not 5.6.0, the 5.6 branch) from git (e69e69519661954716d59bfa5bbd0626515cfda9, about three days old), a recent kded (e0781c3963fc2d3569f442d10e2a2d07a4dd9724), and powerdevil from dc76062a0616d1b64b516e4132cf9613d306770d (February):

#0  pthread_cond_wait () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007ffff5b97e93 in wait (time=18446744073709551615, this=0x555555bc7240)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/thread/qwaitcondition_unix.cpp:136
#2  QWaitCondition::wait (this=this@entry=0x555555bbb180, mutex=mutex@entry=0x555555bbb178, time=time@entry=18446744073709551615)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/thread/qwaitcondition_unix.cpp:208
#3  0x00007ffff7f9b57b in QDBusPendingCallPrivate::waitForFinished (this=this@entry=0x555555bbb140)
    at /var/tmp/portage/dev-qt/qtdbus-5.6.9999/work/qtdbus-5.6.9999/src/dbus/qdbuspendingcall.cpp:234
#4  0x00007ffff7f550f9 in QDBusConnectionPrivate::sendWithReply (this=0x7fffdc011080, message=..., sendMode=1, timeout=-1)
    at /var/tmp/portage/dev-qt/qtdbus-5.6.9999/work/qtdbus-5.6.9999/src/dbus/qdbusintegrator.cpp:1955
#5  0x00007ffff7f4002b in QDBusConnection::call (this=this@entry=0x7fffdc014450, message=..., mode=mode@entry=QDBus::Block, 
    timeout=<optimized out>) at /var/tmp/portage/dev-qt/qtdbus-5.6.9999/work/qtdbus-5.6.9999/src/dbus/qdbusconnection.cpp:682
#6  0x00007ffff7f61a2b in QDBusAbstractInterface::callWithArgumentList (this=0x7fffdc014370, mode=QDBus::Block, 
    mode@entry=QDBus::AutoDetect, method=..., args=...)
    at /var/tmp/portage/dev-qt/qtdbus-5.6.9999/work/qtdbus-5.6.9999/src/dbus/qdbusabstractinterface.cpp:488
#7  0x00007ffff7f6242f in QDBusAbstractInterface::internalConstCall (this=<optimized out>, mode=mode@entry=QDBus::AutoDetect, 
    method=..., args=...) at /var/tmp/portage/dev-qt/qtdbus-5.6.9999/work/qtdbus-5.6.9999/src/dbus/qdbusabstractinterface.cpp:843
#8  0x00007ffff7f46108 in QDBusConnectionInterface::isServiceRegistered (this=<optimized out>, serviceName=...)
    at /var/tmp/portage/dev-qt/qtdbus-5.6.9999/work/qtdbus-5.6.9999/src/dbus/qdbusconnectioninterface.cpp:202
#9  0x00007fffd01831c0 in KDEDPowerDevil::init (this=0x555555cbf300)
    at /var/tmp/portage/kde-plasma/powerdevil-9999/work/powerdevil-9999/daemon/kdedpowerdevil.cpp:70
#10 0x00007ffff5da7b3a in QObject::event (this=0x555555cbf300, e=<optimized out>)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qobject.cpp:1256
#11 0x00007ffff725fe54 in QApplicationPrivate::notify_helper (this=<optimized out>, receiver=0x555555cbf300, e=0x555555c8cda0)
    at /var/tmp/portage/dev-qt/qtwidgets-5.6.9999/work/qtwidgets-5.6.9999/src/widgets/kernel/qapplication.cpp:3771
#12 0x00007ffff7264c9e in QApplication::notify (this=0x7fffffffd750, receiver=0x555555cbf300, e=0x555555c8cda0)
    at /var/tmp/portage/dev-qt/qtwidgets-5.6.9999/work/qtwidgets-5.6.9999/src/widgets/kernel/qapplication.cpp:3528
#13 0x00007ffff5d766d8 in QCoreApplication::notifyInternal2 (receiver=0x555555cbf300, event=event@entry=0x555555c8cda0)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.cpp:1016
#14 0x00007ffff5d79287 in sendEvent (event=0x555555c8cda0, receiver=<optimized out>)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.h:227
#15 QCoreApplicationPrivate::sendPostedEvents (receiver=receiver@entry=0x0, event_type=event_type@entry=0, data=0x555555756db0)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.cpp:1651
#16 0x00007ffff5d7989e in QCoreApplication::sendPostedEvents (receiver=receiver@entry=0x0, event_type=event_type@entry=0)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.cpp:1509
#17 0x00007ffff5dd1139 in postEventSourceDispatch (s=0x555555784af0)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qeventdispatcher_glib.cpp:270
#18 0x00007ffff2d0f08c in g_main_dispatch (context=0x7fffe4002450)
    at /var/tmp/portage/dev-libs/glib-2.44.1-r1/work/glib-2.44.1/glib/gmain.c:3122
#19 g_main_context_dispatch (context=context@entry=0x7fffe4002450)
    at /var/tmp/portage/dev-libs/glib-2.44.1-r1/work/glib-2.44.1/glib/gmain.c:3737
#20 0x00007ffff2d0f398 in g_main_context_iterate (context=context@entry=0x7fffe4002450, block=block@entry=1, 
    dispatch=dispatch@entry=1, self=<optimized out>)
    at /var/tmp/portage/dev-libs/glib-2.44.1-r1/work/glib-2.44.1/glib/gmain.c:3808
#21 0x00007ffff2d0f4a1 in g_main_context_iteration (context=0x7fffe4002450, may_block=1)
    at /var/tmp/portage/dev-libs/glib-2.44.1-r1/work/glib-2.44.1/glib/gmain.c:3869
#22 0x00007ffff5dd11ed in QEventDispatcherGlib::processEvents (this=0x555555799020, flags=...)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qeventdispatcher_glib.cpp:417
#23 0x00007ffff5d74b5a in QEventLoop::exec (this=this@entry=0x7fffffffd620, flags=..., flags@entry=...)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qeventloop.cpp:204
#24 0x00007ffff5d7db96 in QCoreApplication::exec ()
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.cpp:1286
#25 0x00007ffff65ceeda in QGuiApplication::exec ()
    at /var/tmp/portage/dev-qt/qtgui-5.6.9999/work/qtgui-5.6.9999/src/gui/kernel/qguiapplication.cpp:1601
#26 0x00007ffff725c30b in QApplication::exec ()
    at /var/tmp/portage/dev-qt/qtwidgets-5.6.9999/work/qtwidgets-5.6.9999/src/widgets/kernel/qapplication.cpp:2974
#27 0x00007ffff7bd11e7 in kdemain (argc=1, argv=<optimized out>)
    at /var/tmp/portage/kde-frameworks/kded-9999/work/kded-9999/src/kded.cpp:767
#28 0x00007ffff783a9e4 in __libc_start_main (main=0x5555555548b0 <main(int, char**)>, argc=1, argv=0x7fffffffd918, 
    init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffffffd908) at libc-start.c:297
#29 0x0000555555554919 in _start ()

plasmashell won't even show its panels of course.
Comment 1 Jan Kundrát 2016-03-11 12:24:37 UTC 
...while the other thread is stuck on this:

Thread 3 (Thread 0x7fffe21bf700 (LWP 44964)):
#0  pthread_cond_wait () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007ffff5b97e93 in wait (time=18446744073709551615, this=0x7fffdc014870)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/thread/qwaitcondition_unix.cpp:136
#2  QWaitCondition::wait (this=this@entry=0x7fffdc010138, mutex=mutex@entry=0x7fffdc010130, time=time@entry=18446744073709551615)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/thread/qwaitcondition_unix.cpp:208
#3  0x00007ffff5b90343 in QSemaphore::acquire (this=this@entry=0x7fffe21be8f0, n=n@entry=1)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/thread/qsemaphore.cpp:137
#4  0x00007ffff7f52c8f in QDBusConnectionPrivate::handleObjectCall (this=0x7fffdc0030f0, msg=...)
    at /var/tmp/portage/dev-qt/qtdbus-5.6.9999/work/qtdbus-5.6.9999/src/dbus/qdbusintegrator.cpp:1506
#5  0x00007ffff5da7b3a in QObject::event (this=0x7fffdc0030f0, e=<optimized out>)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qobject.cpp:1256
#6  0x00007ffff5d764f5 in doNotify (receiver=<optimized out>, event=<optimized out>)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.cpp:1091
#7  0x00007ffff5d76678 in notify (event=<optimized out>, receiver=<optimized out>, this=<optimized out>)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.cpp:1077
#8  QCoreApplication::notifyInternal2 (receiver=0x7fffdc0030f0, event=event@entry=0x555555b5a280)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.cpp:1016
#9  0x00007ffff5d79287 in sendEvent (event=0x555555b5a280, receiver=<optimized out>)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.h:227
#10 QCoreApplicationPrivate::sendPostedEvents (receiver=receiver@entry=0x0, event_type=event_type@entry=0, data=0x55555579e180)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.cpp:1651
#11 0x00007ffff5d7989e in QCoreApplication::sendPostedEvents (receiver=receiver@entry=0x0, event_type=event_type@entry=0)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.cpp:1509
#12 0x00007ffff5dd1139 in postEventSourceDispatch (s=0x7fffdc0012d0)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qeventdispatcher_glib.cpp:270
#13 0x00007ffff2d0f08c in g_main_dispatch (context=0x7fffdc000990)
    at /var/tmp/portage/dev-libs/glib-2.44.1-r1/work/glib-2.44.1/glib/gmain.c:3122
#14 g_main_context_dispatch (context=context@entry=0x7fffdc000990)
    at /var/tmp/portage/dev-libs/glib-2.44.1-r1/work/glib-2.44.1/glib/gmain.c:3737
#15 0x00007ffff2d0f398 in g_main_context_iterate (context=context@entry=0x7fffdc000990, block=block@entry=1, 
    dispatch=dispatch@entry=1, self=<optimized out>)
    at /var/tmp/portage/dev-libs/glib-2.44.1-r1/work/glib-2.44.1/glib/gmain.c:3808
#16 0x00007ffff2d0f4a1 in g_main_context_iteration (context=0x7fffdc000990, may_block=1)
    at /var/tmp/portage/dev-libs/glib-2.44.1-r1/work/glib-2.44.1/glib/gmain.c:3869
#17 0x00007ffff5dd1204 in QEventDispatcherGlib::processEvents (this=0x7fffdc0008c0, flags=...)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qeventdispatcher_glib.cpp:417
---Type <return> to continue, or q <return> to quit---
#18 0x00007ffff5d74b5a in QEventLoop::exec (this=this@entry=0x7fffe21bede0, flags=..., flags@entry=...)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qeventloop.cpp:204
#19 0x00007ffff5b91ded in QThread::exec (this=this@entry=
    0x7ffff7fb71c0 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/thread/qthread.cpp:503
#20 0x00007ffff7f3f315 in QDBusConnectionManager::run (this=
    0x7ffff7fb71c0 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>)
    at /var/tmp/portage/dev-qt/qtdbus-5.6.9999/work/qtdbus-5.6.9999/src/dbus/qdbusconnection.cpp:181
#21 0x00007ffff5b976d2 in QThreadPrivate::start (
    arg=0x7ffff7fb71c0 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/thread/qthread_unix.cpp:340
#22 0x00007ffff55a04dc in start_thread (arg=0x7fffe21bf700) at pthread_create.c:333
#23 0x00007ffff790e8cd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109
Comment 2 Jan Kundrát 2016-03-11 12:50:37 UTC 
And just FYI, after this fugly patch to powerdevil, the problem only moves to other services:

--- a/daemon/kdedpowerdevil.cpp
+++ b/daemon/kdedpowerdevil.cpp
@@ -45,7 +45,7 @@ KDEDPowerDevil::KDEDPowerDevil(QObject* parent, const QVariantList &)
     : KDEDModule(parent)
     , m_core(Q_NULLPTR)
 {
-    QTimer::singleShot(0, this, SLOT(init()));
+    QTimer::singleShot(3000, this, SLOT(init()));


For example, I now get this from the touchpad module:

Thread 3 (Thread 0x7fffe21bf700 (LWP 94561)):
#0  pthread_cond_wait () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007ffff5b97e93 in wait (time=18446744073709551615, this=0x7fffdc014b80)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/thread/qwaitcondition_unix.cpp:136
#2  QWaitCondition::wait (this=this@entry=0x7fffdc003028, mutex=mutex@entry=0x7fffdc003020, time=time@entry=18446744073709551615)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/thread/qwaitcondition_unix.cpp:208
#3  0x00007ffff5b90343 in QSemaphore::acquire (this=this@entry=0x7fffe21be8f0, n=n@entry=1)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/thread/qsemaphore.cpp:137
#4  0x00007ffff7f52c8f in QDBusConnectionPrivate::handleObjectCall (this=0x7fffdc0030f0, msg=...)
    at /var/tmp/portage/dev-qt/qtdbus-5.6.9999/work/qtdbus-5.6.9999/src/dbus/qdbusintegrator.cpp:1506
#5  0x00007ffff5da7b3a in QObject::event (this=0x7fffdc0030f0, e=<optimized out>)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qobject.cpp:1256
#6  0x00007ffff5d764f5 in doNotify (receiver=<optimized out>, event=<optimized out>)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.cpp:1091
#7  0x00007ffff5d76678 in notify (event=<optimized out>, receiver=<optimized out>, this=<optimized out>)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.cpp:1077
#8  QCoreApplication::notifyInternal2 (receiver=0x7fffdc0030f0, event=event@entry=0x555555b94540)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.cpp:1016
#9  0x00007ffff5d79287 in sendEvent (event=0x555555b94540, receiver=<optimized out>)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.h:227
#10 QCoreApplicationPrivate::sendPostedEvents (receiver=receiver@entry=0x0, event_type=event_type@entry=0, data=0x5555557ba7d0)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.cpp:1651
#11 0x00007ffff5d7989e in QCoreApplication::sendPostedEvents (receiver=receiver@entry=0x0, event_type=event_type@entry=0)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.cpp:1509
#12 0x00007ffff5dd1139 in postEventSourceDispatch (s=0x7fffdc0012d0)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qeventdispatcher_glib.cpp:270
#13 0x00007ffff2d0f08c in g_main_dispatch (context=0x7fffdc000990)
    at /var/tmp/portage/dev-libs/glib-2.44.1-r1/work/glib-2.44.1/glib/gmain.c:3122
#14 g_main_context_dispatch (context=context@entry=0x7fffdc000990)
    at /var/tmp/portage/dev-libs/glib-2.44.1-r1/work/glib-2.44.1/glib/gmain.c:3737
#15 0x00007ffff2d0f398 in g_main_context_iterate (context=context@entry=0x7fffdc000990, block=block@entry=1, 
    dispatch=dispatch@entry=1, self=<optimized out>)
    at /var/tmp/portage/dev-libs/glib-2.44.1-r1/work/glib-2.44.1/glib/gmain.c:3808
#16 0x00007ffff2d0f4a1 in g_main_context_iteration (context=0x7fffdc000990, may_block=1)
    at /var/tmp/portage/dev-libs/glib-2.44.1-r1/work/glib-2.44.1/glib/gmain.c:3869
#17 0x00007ffff5dd1204 in QEventDispatcherGlib::processEvents (this=0x7fffdc0008c0, flags=...)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qeventdispatcher_glib.cpp:417
---Type <return> to continue, or q <return> to quit---
#18 0x00007ffff5d74b5a in QEventLoop::exec (this=this@entry=0x7fffe21bede0, flags=..., flags@entry=...)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qeventloop.cpp:204
#19 0x00007ffff5b91ded in QThread::exec (this=this@entry=
    0x7ffff7fb71c0 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/thread/qthread.cpp:503
#20 0x00007ffff7f3f315 in QDBusConnectionManager::run (this=
    0x7ffff7fb71c0 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>)
    at /var/tmp/portage/dev-qt/qtdbus-5.6.9999/work/qtdbus-5.6.9999/src/dbus/qdbusconnection.cpp:181
#21 0x00007ffff5b976d2 in QThreadPrivate::start (
    arg=0x7ffff7fb71c0 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/thread/qthread_unix.cpp:340
#22 0x00007ffff55a04dc in start_thread (arg=0x7fffe21bf700) at pthread_create.c:333
#23 0x00007ffff790e8cd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 1 (Thread 0x7ffff7e9a780 (LWP 94041)):
#0  pthread_cond_wait () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007ffff5b97e93 in wait (time=18446744073709551615, this=0x555555bb3970)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/thread/qwaitcondition_unix.cpp:136
#2  QWaitCondition::wait (this=this@entry=0x555555dad5d8, mutex=mutex@entry=0x555555dad5d0, time=time@entry=18446744073709551615)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/thread/qwaitcondition_unix.cpp:208
#3  0x00007ffff5b90343 in QSemaphore::acquire (this=this@entry=0x7fffffffcaf0, n=n@entry=1)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/thread/qsemaphore.cpp:137
#4  0x00007ffff5da65f2 in QMetaObject::activate (sender=sender@entry=0x7fffdc0030f0, signalOffset=<optimized out>, 
    local_signal_index=local_signal_index@entry=5, argv=argv@entry=0x7fffffffcb80)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qobject.cpp:3698
#5  0x00007ffff5da6fa5 in QMetaObject::activate (sender=sender@entry=0x7fffdc0030f0, 
    m=m@entry=0x7ffff7fb6d40 <QDBusConnectionPrivate::staticMetaObject>, local_signal_index=local_signal_index@entry=5, 
    argv=argv@entry=0x7fffffffcb80)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qobject.cpp:3595
#6  0x00007ffff7f9f52f in QDBusConnectionPrivate::signalNeedsDisconnecting (this=this@entry=0x7fffdc0030f0, _t1=..., _t2=...)
    at .moc/moc_qdbusconnection_p.cpp:345
#7  0x00007ffff7f4b883 in QDBusConnectionPrivate::disconnectSignal (this=this@entry=0x7fffdc0030f0, service=..., path=..., 
    interface=..., name=..., argumentMatch=..., signature=..., receiver=0x55555596bf48, 
    slot=0x7ffff7fa2c00 "1_q_serviceOwnerChanged(QString,QString,QString)")
    at /var/tmp/portage/dev-qt/qtdbus-5.6.9999/work/qtdbus-5.6.9999/src/dbus/qdbusintegrator.cpp:2188
#8  0x00007ffff7f4ba6f in QDBusConnectionPrivate::unwatchService (this=0x7fffdc0030f0, service=..., mode=..., 
    obj=<optimized out>, member=member@entry=0x7ffff7fa2c00 "1_q_serviceOwnerChanged(QString,QString,QString)")
    at /var/tmp/portage/dev-qt/qtdbus-5.6.9999/work/qtdbus-5.6.9999/src/dbus/qdbusintegrator.cpp:2383
#9  0x00007ffff7f9ce0e in QDBusServiceWatcherPrivate::removeService (this=this@entry=0x555555bc5670, service=...)
    at /var/tmp/portage/dev-qt/qtdbus-5.6.9999/work/qtdbus-5.6.9999/src/dbus/qdbusservicewatcher.cpp:107
#10 0x00007ffff7f9d888 in QDBusServiceWatcher::removeWatchedService (this=this@entry=0x55555596bf48, service=...)
    at /var/tmp/portage/dev-qt/qtdbus-5.6.9999/work/qtdbus-5.6.9999/src/dbus/qdbusservicewatcher.cpp:296
#11 0x00007fffc31ef72c in TouchpadDisabler::serviceRegistered (this=this@entry=0x55555596bee0, service=...)
---Type <return> to continue, or q <return> to quit---
    at /var/tmp/portage/kde-plasma/plasma-desktop-9999/work/plasma-desktop-9999/kcms/touchpad/src/kded/kded.cpp:35
#12 0x00007fffc31efadf in TouchpadDisabler::serviceNameFetchFinished (this=0x55555596bee0, callWatcher=<optimized out>)
    at /var/tmp/portage/kde-plasma/plasma-desktop-9999/work/plasma-desktop-9999/kcms/touchpad/src/kded/kded.cpp:98
#13 0x00007fffc31ff4bc in TouchpadDisabler::qt_static_metacall (_o=<optimized out>, _c=<optimized out>, _id=<optimized out>, 
    _a=<optimized out>)
    at /var/tmp/portage/kde-plasma/plasma-desktop-9999/work/plasma-desktop-9999_build/kcms/touchpad/src/moc_kded.cpp:161
#14 0x00007ffff5da6365 in QMetaObject::activate (sender=0x555555dad450, signalOffset=<optimized out>, 
    local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x7fffffffd020)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qobject.cpp:3730
#15 0x00007ffff5da6fa5 in QMetaObject::activate (sender=<optimized out>, 
    m=m@entry=0x7ffff7fb6840 <QDBusPendingCallWatcher::staticMetaObject>, local_signal_index=local_signal_index@entry=0, 
    argv=argv@entry=0x7fffffffd020)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qobject.cpp:3595
#16 0x00007ffff7f9a69c in QDBusPendingCallWatcher::finished (this=<optimized out>, _t1=0x555555dad450)
    at .moc/moc_qdbuspendingcall.cpp:152
#17 0x00007ffff7f9a7b0 in _q_finished (this=<optimized out>)
    at /var/tmp/portage/dev-qt/qtdbus-5.6.9999/work/qtdbus-5.6.9999/src/dbus/qdbuspendingcall.cpp:488
#18 QDBusPendingCallWatcher::qt_static_metacall (_o=<optimized out>, _c=<optimized out>, _id=<optimized out>, _a=<optimized out>)
    at .moc/moc_qdbuspendingcall.cpp:83
#19 0x00007ffff5da7b3a in QObject::event (this=0x555555dad450, e=<optimized out>)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qobject.cpp:1256
#20 0x00007ffff725fe54 in QApplicationPrivate::notify_helper (this=<optimized out>, receiver=0x555555dad450, e=0x7fffdc053750)
    at /var/tmp/portage/dev-qt/qtwidgets-5.6.9999/work/qtwidgets-5.6.9999/src/widgets/kernel/qapplication.cpp:3771
#21 0x00007ffff7264c9e in QApplication::notify (this=0x7fffffffd750, receiver=0x555555dad450, e=0x7fffdc053750)
    at /var/tmp/portage/dev-qt/qtwidgets-5.6.9999/work/qtwidgets-5.6.9999/src/widgets/kernel/qapplication.cpp:3528
#22 0x00007ffff5d766d8 in QCoreApplication::notifyInternal2 (receiver=0x555555dad450, event=event@entry=0x7fffdc053750)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.cpp:1016
#23 0x00007ffff5d79287 in sendEvent (event=0x7fffdc053750, receiver=<optimized out>)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.h:227
#24 QCoreApplicationPrivate::sendPostedEvents (receiver=receiver@entry=0x0, event_type=event_type@entry=0, data=0x555555756db0)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.cpp:1651
#25 0x00007ffff5d7989e in QCoreApplication::sendPostedEvents (receiver=receiver@entry=0x0, event_type=event_type@entry=0)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.cpp:1509
#26 0x00007ffff5dd1139 in postEventSourceDispatch (s=0x55555579b190)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qeventdispatcher_glib.cpp:270
#27 0x00007ffff2d0f08c in g_main_dispatch (context=0x7fffe4002450)
    at /var/tmp/portage/dev-libs/glib-2.44.1-r1/work/glib-2.44.1/glib/gmain.c:3122
#28 g_main_context_dispatch (context=context@entry=0x7fffe4002450)
    at /var/tmp/portage/dev-libs/glib-2.44.1-r1/work/glib-2.44.1/glib/gmain.c:3737
#29 0x00007ffff2d0f398 in g_main_context_iterate (context=context@entry=0x7fffe4002450, block=block@entry=1, 
    dispatch=dispatch@entry=1, self=<optimized out>)
    at /var/tmp/portage/dev-libs/glib-2.44.1-r1/work/glib-2.44.1/glib/gmain.c:3808
#30 0x00007ffff2d0f4a1 in g_main_context_iteration (context=0x7fffe4002450, may_block=1)
    at /var/tmp/portage/dev-libs/glib-2.44.1-r1/work/glib-2.44.1/glib/gmain.c:3869
#31 0x00007ffff5dd11ed in QEventDispatcherGlib::processEvents (this=0x5555557a19f0, flags=...)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qeventdispatcher_glib.cpp:417
#32 0x00007ffff5d74b5a in QEventLoop::exec (this=this@entry=0x7fffffffd620, flags=..., flags@entry=...)
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qeventloop.cpp:204
#33 0x00007ffff5d7db96 in QCoreApplication::exec ()
    at /var/tmp/portage/dev-qt/qtcore-5.6.9999/work/qtcore-5.6.9999/src/corelib/kernel/qcoreapplication.cpp:1286
#34 0x00007ffff65ceeda in QGuiApplication::exec ()
    at /var/tmp/portage/dev-qt/qtgui-5.6.9999/work/qtgui-5.6.9999/src/gui/kernel/qguiapplication.cpp:1601
#35 0x00007ffff725c30b in QApplication::exec ()
    at /var/tmp/portage/dev-qt/qtwidgets-5.6.9999/work/qtwidgets-5.6.9999/src/widgets/kernel/qapplication.cpp:2974
#36 0x00007ffff7bd11e7 in kdemain (argc=1, argv=<optimized out>)
    at /var/tmp/portage/kde-frameworks/kded-9999/work/kded-9999/src/kded.cpp:767
#37 0x00007ffff783a9e4 in __libc_start_main (main=0x5555555548b0 <main(int, char**)>, argc=1, argv=0x7fffffffd918, 
    init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffffffd908) at libc-start.c:297
#38 0x0000555555554919 in _start ()
Comment 3 Thiago Macieira 2016-03-11 16:26:32 UTC 
Might be https://bugreports.qt.io/browse/QTBUG-51676
Comment 4 Jan Kundrát 2016-03-11 17:38:44 UTC 
Thanks, Thiago -- the patch linked patch (https://codereview.qt-project.org/#/c/151459/3) fixes the problem for me.
Comment 5 Jan Kundrát 2016-03-21 03:14:05 UTC 
The patch is in upstream's 5.6 branch and will be released with the 5.6.1 release.
Comment 6 Christoph Feck 2016-06-16 08:46:17 UTC 
*** Bug 363488 has been marked as a duplicate of this bug. ***