Version:            (using KDE KDE 3.5.2)
Installed from:    Slackware Packages
Compiler:          gcc 3.4.6
 
OS:                Linux

Hello,

I stumbled on an interesting bug in kdesktop some times ago, but now I managed to reproduce it reliably and take backtraces :)

Here is how I reliably made kdesktop and kopete freeze:
- I started konqueror from a little superkaramba applet
- My start page is quite resource consuming, so while konqueror is consuming CPU starting itself and processing the web page:
- I repeatedly right/left clicked on a mount point icon on my desktop and on the desktop itself (yay that's quite far fetched - I clicked that badly because I was in a hurry the day I first triggered it). Usually, three well paced mischievous clicks are sufficient.

And then, kdesktop froze. Interestingly enough, Kopete too. May the bug come from a strange interaction between them ?

Here is my setup:
KDE 3.5.2/Kopete 0.11.1 running on Slackware-current
custom linux 2.6.16.16 SMP kernel
Pentium4 with HT enabled
Memory recently checked with memcheck86 ;)

I took backtraces by attaching gdb in text mode, here they are:

KDESKTOP:
------------------------8<----------------------------------

0xa6a0622e in __read_nocancel () from /lib/tls/libpthread.so.0
#0  0xa6a0622e in __read_nocancel () from /lib/tls/libpthread.so.0
#1  0xa74c8dce in _kde_IceTransFreeConnInfo () from /opt/kde/lib/libDCOP.so.4
#2  0xa74c921f in _kde_IceTransRead () from /opt/kde/lib/libDCOP.so.4
#3  0xa74c1abc in _kde_IceRead () from /opt/kde/lib/libDCOP.so.4
#4  0xa74c20e7 in KDE_IceProcessMessages () from /opt/kde/lib/libDCOP.so.4
#5  0xa74b1020 in DCOPClient::callInternal () from /opt/kde/lib/libDCOP.so.4
#6  0xa74b1611 in DCOPClient::callInternal () from /opt/kde/lib/libDCOP.so.4
#7  0xa74b5f5c in DCOPClient::call () from /opt/kde/lib/libDCOP.so.4
#8  0xa74b5fc8 in DCOPClient::call () from /opt/kde/lib/libDCOP.so.4
#9  0xa5ebefad in KIMIface_stub::fileTransferContacts () from /opt/kde/lib/libkimproxy.so.0
#10 0xa5eb98ba in KIMProxy::fileTransferContacts () from /opt/kde/lib/libkimproxy.so.0
#11 0xa60e3f8d in KMetaMenu::KMetaMenu () from /opt/kde/lib/kde3/libkuickplugin.so
#12 0xa60df1ed in KTestMenu::slotPrepareMenu () from /opt/kde/lib/kde3/libkuickplugin.so
#13 0xa60df950 in KTestMenu::qt_invoke () from /opt/kde/lib/kde3/libkuickplugin.so
#14 0xa6f7dd34 in QObject::activate_signal () from /usr/lib/qt/lib/libqt-mt.so.3
#15 0xa6f7e4cc in QObject::activate_signal () from /usr/lib/qt/lib/libqt-mt.so.3
#16 0xa72d3a9c in QPopupMenu::aboutToShow () from /usr/lib/qt/lib/libqt-mt.so.3
#17 0xa7091039 in QPopupMenu::popup () from /usr/lib/qt/lib/libqt-mt.so.3
#18 0xa709445f in QPopupMenu::exec () from /usr/lib/qt/lib/libqt-mt.so.3
#19 0xa7f1ae9c in KDIconView::popupMenu () from /opt/kde/lib/libkdeinit_kdesktop.so
#20 0xa7f1b05a in KDIconView::slotContextMenuRequested () from /opt/kde/lib/libkdeinit_kdesktop.so
#21 0xa7f1e617 in KDIconView::qt_invoke () from /opt/kde/lib/libkdeinit_kdesktop.so
#22 0xa6f7dd34 in QObject::activate_signal () from /usr/lib/qt/lib/libqt-mt.so.3
#23 0xa72ead69 in QIconView::contextMenuRequested () from /usr/lib/qt/lib/libqt-mt.so.3
#24 0xa715ac55 in QIconView::contentsContextMenuEvent () from /usr/lib/qt/lib/libqt-mt.so.3
#25 0xa709d2e5 in QScrollView::viewportContextMenuEvent () from /usr/lib/qt/lib/libqt-mt.so.3
#26 0xa709f319 in QScrollView::eventFilter () from /usr/lib/qt/lib/libqt-mt.so.3
#27 0xa71527ef in QIconView::eventFilter () from /usr/lib/qt/lib/libqt-mt.so.3
#28 0xa6f7b0bf in QObject::activate_filters () from /usr/lib/qt/lib/libqt-mt.so.3
#29 0xa6f7b194 in QObject::event () from /usr/lib/qt/lib/libqt-mt.so.3
#30 0xa6fb750f in QWidget::event () from /usr/lib/qt/lib/libqt-mt.so.3
#31 0xa6f1922f in QApplication::internalNotify () from /usr/lib/qt/lib/libqt-mt.so.3
#32 0xa6f1968e in QApplication::notify () from /usr/lib/qt/lib/libqt-mt.so.3
#33 0xa7588965 in KApplication::notify () from /opt/kde/lib/libkdecore.so.4
#34 0xa6eb37a2 in QETWidget::translateMouseEvent () from /usr/lib/qt/lib/libqt-mt.so.3
#35 0xa6eb1821 in QApplication::x11ProcessEvent () from /usr/lib/qt/lib/libqt-mt.so.3
#36 0xa6ec4f25 in QEventLoop::processEvents () from /usr/lib/qt/lib/libqt-mt.so.3
#37 0xa6f2f951 in QEventLoop::enterLoop () from /usr/lib/qt/lib/libqt-mt.so.3
#38 0xa6f2f8a6 in QEventLoop::exec () from /usr/lib/qt/lib/libqt-mt.so.3
#39 0xa6f1838f in QApplication::exec () from /usr/lib/qt/lib/libqt-mt.so.3
#40 0xa7f0e29b in kdemain () from /opt/kde/lib/libkdeinit_kdesktop.so
#41 0x0804872e in ?? ()
#42 0x00000001 in ?? ()
#43 0xaf885734 in ?? ()
#44 0x08049838 in ?? ()
#45 0xa68d4ffc in ?? () from /lib/tls/libc.so.6
#46 0x00000000 in ?? ()

------------------------8<----------------------------------

KOPETE 0.11.1
------------------------8<----------------------------------

0xa6353251 in __read_nocancel () from /lib/tls/libpthread.so.0
#0  0xa6353251 in __read_nocancel () from /lib/tls/libpthread.so.0
#1  0xa6deddce in _kde_IceTransFreeConnInfo () from /opt/kde/lib/libDCOP.so.4
#2  0xa6dee21f in _kde_IceTransRead () from /opt/kde/lib/libDCOP.so.4
#3  0xa6de6abc in _kde_IceRead () from /opt/kde/lib/libDCOP.so.4
#4  0xa6de70e7 in KDE_IceProcessMessages () from /opt/kde/lib/libDCOP.so.4
#5  0xa6dd6020 in DCOPClient::callInternal () from /opt/kde/lib/libDCOP.so.4
#6  0xa6dd6611 in DCOPClient::callInternal () from /opt/kde/lib/libDCOP.so.4
#7  0xa6ddaf5c in DCOPClient::call () from /opt/kde/lib/libDCOP.so.4
#8  0xa6dd0f01 in DCOPRef::callInternal () from /opt/kde/lib/libDCOP.so.4
#9  0xa6dd101d in DCOPRef::callInternal () from /opt/kde/lib/libDCOP.so.4
#10 0xa7e7e265 in Kopete::Away::slotTimerTimeout () from /opt/kde/lib/libkopete.so.1
#11 0xa7e7e4fc in Kopete::Away::qt_invoke () from /opt/kde/lib/libkopete.so.1
#12 0xa68c6d34 in QObject::activate_signal () from /usr/lib/qt/lib/libqt-mt.so.3
#13 0xa68c74cc in QObject::activate_signal () from /usr/lib/qt/lib/libqt-mt.so.3
#14 0xa6c089e9 in QTimer::timeout () from /usr/lib/qt/lib/libqt-mt.so.3
#15 0xa68e900f in QTimer::event () from /usr/lib/qt/lib/libqt-mt.so.3
#16 0xa686222f in QApplication::internalNotify () from /usr/lib/qt/lib/libqt-mt.so.3
#17 0xa68623cc in QApplication::notify () from /usr/lib/qt/lib/libqt-mt.so.3
#18 0xa6ead965 in KApplication::notify () from /opt/kde/lib/libkdecore.so.4
#19 0xa685578c in QEventLoop::activateTimers () from /usr/lib/qt/lib/libqt-mt.so.3
#20 0xa680e4d1 in QEventLoop::processEvents () from /usr/lib/qt/lib/libqt-mt.so.3
#21 0xa6878951 in QEventLoop::enterLoop () from /usr/lib/qt/lib/libqt-mt.so.3
#22 0xa68788a6 in QEventLoop::exec () from /usr/lib/qt/lib/libqt-mt.so.3
#23 0xa686138f in QApplication::exec () from /usr/lib/qt/lib/libqt-mt.so.3

------------------------8<----------------------------------

I also took a backtrace of the dcopserver but it appeared to work as usual:

DCOPSERVER
------------------------8<----------------------------------

0xa69d1fe8 in ___newselect_nocancel () from /lib/tls/libc.so.6
#0  0xa69d1fe8 in ___newselect_nocancel () from /lib/tls/libc.so.6
#1  0xa702a16a in QEventLoop::processEvents () from /usr/lib/qt/lib/libqt-mt.so.3
#2  0xa7094951 in QEventLoop::enterLoop () from /usr/lib/qt/lib/libqt-mt.so.3
#3  0xa70948a6 in QEventLoop::exec () from /usr/lib/qt/lib/libqt-mt.so.3
#4  0xa707d38f in QApplication::exec () from /usr/lib/qt/lib/libqt-mt.so.3
#5  0xa75f3cdd in kdemain () from /opt/kde/lib/libkdeinit_dcopserver.so
#6  0xa75ff6f4 in kdeinitmain () from /opt/kde/lib/kde3/dcopserver.so

------------------------8<----------------------------------

Anyway, this bug might become nasty when you play with it, the third time I repeated it my keystrokes got ignored and the left click went weird. For example, I right clicked on the superkaramba systray icon and then on the Quit entry, but I was unable to confirm quitting - my left click on the Quit button was ignored. Already launched windows in the background could not be brought to the foreground by clicking on them as well, though I could drag them around. Weird :) I had to use ssh to kill kdesktop and all went fine after that.

Thank you for reading this, and have a nice day :)

PS: oh, I don't know if it can be useful, but as I tried to repeated it, I once got a messagebox from kdesktop about dcop, and the following message was printed on stderr:
"Very strange ! Got a DCOPReply opcode, but we were not waiting for a reply !"

Best regards.