Seems like I wasn't right. I can launch kmail standalone, but it crahes whenever I try to browse my mails.

backtrace is similar to the above as I can tell:


Application: KMail (kmail), signal: Illegal instruction
[Current thread is 1 (Thread 0x7fc0e3ac6760 (LWP 13788))]

Thread 5 (Thread 0x7fc0c67c0700 (LWP 13793)):
#0  pthread_cond_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x00007fc0d5312034 in scavengerThread (this=0x7fc0d5cf8100) at wtf/FastMalloc.cpp:2495
#2  WTF::TCMalloc_PageHeap::runScavengerThread (context=0x7fc0d5cf8100) at wtf/FastMalloc.cpp:1618
#3  0x00007fc0debe3dbc in start_thread (arg=0x7fc0c67c0700) at pthread_create.c:301
#4  0x00007fc0e0d80ded in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:115

Thread 4 (Thread 0x7fc0c5ebf700 (LWP 13794)):
#0  0x00007fc0e0d77fb3 in *__GI___poll (fds=<optimized out>, nfds=<optimized out>, timeout=<optimized out>) at ../sysdeps/unix/sysv/linux/poll.c:87
#1  0x00007fc0d974c554 in g_main_context_poll (n_fds=1, fds=0x7fc0c0000f30, timeout=-1, context=0x1e77060, priority=<optimized out>) at gmain.c:3402
#2  g_main_context_iterate (context=0x1e77060, block=1, dispatch=1, self=<optimized out>) at gmain.c:3084
#3  0x00007fc0d974c9bf in g_main_context_iteration (context=0x1e77060, may_block=1) at gmain.c:3152
#4  0x00007fc0e170bf96 in QEventDispatcherGlib::processEvents (this=0x1e07bd0, flags=<optimized out>) at kernel/qeventdispatcher_glib.cpp:426
#5  0x00007fc0e16dbcf2 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#6  0x00007fc0e16dbfe5 in QEventLoop::exec (this=0x7fc0c5ebee20, flags=...) at kernel/qeventloop.cpp:204
#7  0x00007fc0e15d9888 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:501
#8  0x00007fc0e15dbf67 in QThreadPrivate::start (arg=0x1e3b610) at thread/qthread_unix.cpp:298
#9  0x00007fc0debe3dbc in start_thread (arg=0x7fc0c5ebf700) at pthread_create.c:301
#10 0x00007fc0e0d80ded in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:115

Thread 3 (Thread 0x7fc07f5a2700 (LWP 14196)):
#0  pthread_cond_timedwait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:216
#1  0x00007fc0e15dcd7e in wait (time=30000, this=0x1d15210) at thread/qwaitcondition_unix.cpp:84
#2  QWaitCondition::wait (this=<optimized out>, mutex=0x1d15188, time=30000) at thread/qwaitcondition_unix.cpp:158
#3  0x00007fc0e15d03ff in QThreadPoolThread::run (this=0x1e5e7c0) at concurrent/qthreadpool.cpp:141
#4  0x00007fc0e15dbf67 in QThreadPrivate::start (arg=0x1e5e7c0) at thread/qthread_unix.cpp:298
#5  0x00007fc0debe3dbc in start_thread (arg=0x7fc07f5a2700) at pthread_create.c:301
#6  0x00007fc0e0d80ded in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:115

Thread 2 (Thread 0x7fc0c4a1d700 (LWP 14204)):
#0  pthread_cond_timedwait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:216
#1  0x00007fc0e15dcd7e in wait (time=30000, this=0x3d1b330) at thread/qwaitcondition_unix.cpp:84
#2  QWaitCondition::wait (this=<optimized out>, mutex=0x3d26748, time=30000) at thread/qwaitcondition_unix.cpp:158
#3  0x00007fc0e15d03ff in QThreadPoolThread::run (this=0x3d1ad80) at concurrent/qthreadpool.cpp:141
#4  0x00007fc0e15dbf67 in QThreadPrivate::start (arg=0x3d1ad80) at thread/qthread_unix.cpp:298
#5  0x00007fc0debe3dbc in start_thread (arg=0x7fc0c4a1d700) at pthread_create.c:301
#6  0x00007fc0e0d80ded in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:115

Thread 1 (Thread 0x7fc0e3ac6760 (LWP 13788)):
[KCrash Handler]
#6  WTF::StringImpl::find (this=0x7fc0c5f8fea0, matchString=<optimized out>, index=36) at wtf/text/StringImpl.cpp:641
#7  0x00007fc0d532667a in WTF::StringImpl::endsWith (this=<optimized out>, matchString=<optimized out>, caseSensitive=<optimized out>) at wtf/text/StringImpl.cpp:767
#8  0x00007fc0d51f1cc7 in endsWith (caseSensitive=true, s=<optimized out>, this=0x7fc0c5f22ac0) at ../JavaScriptCore/wtf/text/WTFString.h:206
#9  WebCore::CSSImportRule::setCSSStyleSheet (this=0x7fc0c5f1a240, href=..., baseURL=..., charset=..., sheet=0x7fc0c5f22a80) at css/CSSImportRule.cpp:93
#10 0x00007fc0d4da4e1e in WebCore::CachedCSSStyleSheet::checkNotify (this=0x7fc0c5f22a80) at loader/cache/CachedCSSStyleSheet.cpp:116
#11 0x00007fc0d4da5036 in WebCore::CachedCSSStyleSheet::data (this=0x7fc0c5f22a80, data=<optimized out>, allDataReceived=<optimized out>) at loader/cache/CachedCSSStyleSheet.cpp:104
#12 0x00007fc0d526857c in WebCore::CachedResourceRequest::didFinishLoading (this=0x7fc0c5f230f0, loader=0x7fc0c5f19900) at loader/cache/CachedResourceRequest.cpp:166
#13 0x00007fc0d4df7cbf in WebCore::SubresourceLoader::didFinishLoading (this=0x7fc0c5f19900, finishTime=0) at loader/SubresourceLoader.cpp:196
#14 0x00007fc0d4fef262 in WebCore::QNetworkReplyHandler::finish (this=0x38a9c20) at platform/network/qt/QNetworkReplyHandler.cpp:454
#15 0x00007fc0d4feed68 in WebCore::QNetworkReplyHandlerCallQueue::flush (this=0x38a9c58) at platform/network/qt/QNetworkReplyHandler.cpp:195
#16 0x00007fc0d4feee65 in WebCore::QNetworkReplyHandlerCallQueue::push (this=0x38a9c58, method=(void (WebCore::QNetworkReplyHandler::*)(WebCore::QNetworkReplyHandler * const)) 0x7fc0d4feee70 <WebCore::QNetworkReplyHandler::finish()>) at platform/network/qt/QNetworkReplyHandler.cpp:164
#17 0x00007fc0d4fef8bc in WebCore::QNetworkReplyWrapper::didReceiveFinished (this=0x39c43e0) at platform/network/qt/QNetworkReplyHandler.cpp:349
#18 0x00007fc0e16f26c2 in QMetaObject::activate (sender=0x2224a70, m=<optimized out>, local_signal_index=<optimized out>, argv=0x0) at kernel/qobject.cpp:3547
#19 0x00007fc0ddaa61fb in KDEPrivate::AccessManagerReply::slotResult (this=0x2224a70, kJob=0x1f012a0) at /var/tmp/portage/kde-base/kdelibs-4.7.97/work/kdelibs-4.7.97/kio/kio/accessmanagerreply_p.cpp:386
#20 0x00007fc0e16f26c2 in QMetaObject::activate (sender=0x1f012a0, m=<optimized out>, local_signal_index=<optimized out>, argv=0x7fff32f69ba0) at kernel/qobject.cpp:3547
#21 0x00007fc0e2ec31b2 in KJob::result (this=<optimized out>, _t1=0x1f012a0) at /var/tmp/portage/kde-base/kdelibs-4.7.97/work/kdelibs-4.7.97_build/kdecore/kjob.moc:208
#22 0x00007fc0e2ec31f0 in KJob::emitResult (this=0x1f012a0) at /var/tmp/portage/kde-base/kdelibs-4.7.97/work/kdelibs-4.7.97/kdecore/jobs/kjob.cpp:318
#23 0x00007fc0ddade5cd in KIO::SimpleJob::slotFinished (this=0x1f012a0) at /var/tmp/portage/kde-base/kdelibs-4.7.97/work/kdelibs-4.7.97/kio/kio/job.cpp:494
#24 0x00007fc0ddae24ce in KIO::TransferJob::slotFinished (this=0x1f012a0) at /var/tmp/portage/kde-base/kdelibs-4.7.97/work/kdelibs-4.7.97/kio/kio/job.cpp:1081
#25 0x00007fc0e16f26c2 in QMetaObject::activate (sender=0x38da3d0, m=<optimized out>, local_signal_index=<optimized out>, argv=0x0) at kernel/qobject.cpp:3547
#26 0x00007fc0ddb8a709 in KIO::SlaveInterface::dispatch (this=<optimized out>, _cmd=104, rawdata=...) at /var/tmp/portage/kde-base/kdelibs-4.7.97/work/kdelibs-4.7.97/kio/kio/slaveinterface.cpp:172
#27 0x00007fc0ddb8774c in KIO::SlaveInterface::dispatch (this=<optimized out>) at /var/tmp/portage/kde-base/kdelibs-4.7.97/work/kdelibs-4.7.97/kio/kio/slaveinterface.cpp:88
#28 0x00007fc0ddb7a9b6 in KIO::Slave::gotInput (this=0x38da3d0) at /var/tmp/portage/kde-base/kdelibs-4.7.97/work/kdelibs-4.7.97/kio/kio/slave.cpp:344
#29 0x00007fc0e16f26c2 in QMetaObject::activate (sender=0x3cad1f0, m=<optimized out>, local_signal_index=<optimized out>, argv=0x0) at kernel/qobject.cpp:3547
#30 0x00007fc0ddaaf30d in KIO::ConnectionPrivate::dequeue (this=0x388f250) at /var/tmp/portage/kde-base/kdelibs-4.7.97/work/kdelibs-4.7.97/kio/kio/connection.cpp:82
#31 0x00007fc0e16f1abe in QObject::event (this=0x3cad1f0, e=<optimized out>) at kernel/qobject.cpp:1195
#32 0x00007fc0e1c19d3c in QApplicationPrivate::notify_helper (this=0x18dc3e0, receiver=0x3cad1f0, e=0x3c65db0) at kernel/qapplication.cpp:4550
#33 0x00007fc0e1c1e92f in QApplication::notify (this=<optimized out>, receiver=0x3cad1f0, e=0x3c65db0) at kernel/qapplication.cpp:4411
#34 0x00007fc0e34cf208 in KApplication::notify (this=0x7fff32f6b070, receiver=0x3cad1f0, event=0x3c65db0) at /var/tmp/portage/kde-base/kdelibs-4.7.97/work/kdelibs-4.7.97/kdeui/kernel/kapplication.cpp:311
#35 0x00007fc0e16dcd4b in QCoreApplication::notifyInternal (this=0x7fff32f6b070, receiver=0x3cad1f0, event=0x3c65db0) at kernel/qcoreapplication.cpp:876
#36 0x00007fc0e16e0347 in sendEvent (event=0x3c65db0, receiver=0x3cad1f0) at kernel/qcoreapplication.h:231
#37 QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0, data=0x15cf7b0) at kernel/qcoreapplication.cpp:1500
#38 0x00007fc0e170bdf3 in sendPostedEvents () at kernel/qcoreapplication.h:236
#39 postEventSourceDispatch (s=<optimized out>) at kernel/qeventdispatcher_glib.cpp:279
#40 0x00007fc0d974c01a in g_main_dispatch (context=0x18dece0) at gmain.c:2441
#41 g_main_context_dispatch (context=0x18dece0) at gmain.c:3011
#42 0x00007fc0d974c828 in g_main_context_iterate (context=0x18dece0, block=1, dispatch=1, self=<optimized out>) at gmain.c:3089
#43 0x00007fc0d974c9bf in g_main_context_iteration (context=0x18dece0, may_block=1) at gmain.c:3152
#44 0x00007fc0e170bf5a in QEventDispatcherGlib::processEvents (this=0x15cf060, flags=<optimized out>) at kernel/qeventdispatcher_glib.cpp:424
#45 0x00007fc0e1cbffe6 in QGuiEventDispatcherGlib::processEvents (this=<optimized out>, flags=<optimized out>) at kernel/qguieventdispatcher_glib.cpp:204
#46 0x00007fc0e16dbcf2 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#47 0x00007fc0e16dbfe5 in QEventLoop::exec (this=0x7fff32f6af40, flags=...) at kernel/qeventloop.cpp:204
#48 0x00007fc0e16e07db in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1148
#49 0x00000000004033d2 in main (argc=<optimized out>, argv=<optimized out>) at /var/tmp/portage/kde-base/kmail-4.7.97/work/kmail-4.7.97/kmail/main.cpp:145

Cannot reproduce this and the crash is upstream in QtWebKit. Since you are using Gentoo may I inquire what compiler flags you are using when compiling Qt and hence QtWebKit ?

I have these in make.conf, no special configurations made for qt-webkit.

CFLAGS="-O2 -pipe -march=amdfam10 -msse4.1 -ggdb"
CXXFLAGS="${CFLAGS}"

Considering #284777 and #273561 it seems I have run into some really weird machine specific problems, because on my laptop I cannot reproduce those bugs as well. I will try to file upstream bug, then.

Upstream bug: https://bugs.webkit.org/show_bug.cgi?id=76136

(In reply to comment #4)
> Upstream bug: https://bugs.webkit.org/show_bug.cgi?id=76136

Thanks for the update.