[KDE 4.4 Beta2] Plasma desktop crashes when adding a second Folder View widget to desktop

[Untitled No. 4]

Binary package hint: kdebase-workspace

plasma-desktop crashes every time when doing the following:
* Make sure you have one Folder View widget on your desktop
* Right click on desktop
* Select Add Widgets...
* Enter "folder" in search terms
* Double click or drag/drop on Folder View to add it to the desktop
The widget is added to the desktop and after a second or two plasma desktop
crashes. Most times I have to run "kstart plasma-desktop" to bring back my
desktop.

I have reported the bug to KDE (https://bugs.kde.org/show_bug.cgi?id=219664) and their reply is that this is a Qt 4.6.0 bug. It is fixed in 4.6.1 and kde-qt.

 -- Backtrace:
Application: Plasma Workspace (plasma-desktop), signal: Segmentation fault
[Current thread is 1 (Thread 0xb7709760 (LWP 3799))]

Thread 2 (Thread 0xaaf1fb70 (LWP 3802)):
#0 0x00dfc422 in __kernel_vsyscall ()
#1 0x00e06e05 in pthread_cond_wait@@GLIBC_2.3.2 () from
/lib/tls/i686/cmov/libpthread.so.0
#2 0x006478dd in pthread_cond_wait () from /lib/tls/i686/cmov/libc.so.6
#3 0x062da2e7 in QWaitConditionPrivate::wait (this=0x941d988, mutex=0x941d984,
time=4294967295) at thread/qwaitcondition_unix.cpp:87
#4 QWaitCondition::wait (this=0x941d988, mutex=0x941d984, time=4294967295) at
thread/qwaitcondition_unix.cpp:159
#5 0x0564be82 in QHostInfoAgent::run (this=0x941d978) at
kernel/qhostinfo.cpp:252
#6 0x062d938e in QThreadPrivate::start (arg=0x941d978) at
thread/qthread_unix.cpp:244
#7 0x00e0280e in start_thread () from /lib/tls/i686/cmov/libpthread.so.0
#8 0x0063a93e in clone () from /lib/tls/i686/cmov/libc.so.6

Thread 1 (Thread 0xb7709760 (LWP 3799)):
[KCrash Handler]
#6 QGraphicsScenePrivate::processDirtyItemsRecursive (this=0x8cbf7d0,
item=0x9be52a8, dirtyAncestorContainsChildren=false, parentOpacity=1) at
graphicsview/qgraphicsscene.cpp:4895
#7 0x02601f0d in QGraphicsScenePrivate::_q_processDirtyItems (this=0x8cbf7d0)
at graphicsview/qgraphicsscene.cpp:466
#8 0x02602516 in QGraphicsScene::qt_metacall (this=0x8cbeb08,
_c=QMetaObject::InvokeMetaMethod, _id=14, _a=0x9b28f08) at
.moc/release-shared/moc_qgraphicsscene.cpp:130
#9 0x001db88a in Plasma::Corona::qt_metacall (this=0x8cbeb08,
_c=QMetaObject::InvokeMetaMethod, _id=18, _a=0x9b28f08) at ./corona.moc:107
#10 0x00f5327a in ?? () from /usr/lib/libkdeinit4_plasma-desktop.so
#11 0x063df95a in QMetaObject::metacall (object=0x8cbeb08,
cl=QMetaObject::InvokeMetaMethod, idx=18, argv=0x0) at
kernel/qmetaobject.cpp:237
#12 0x063ea096 in QMetaCallEvent::placeMetaCall (this=0x9be0630,
object=0x8cbeb08) at kernel/qobject.cpp:574
#13 0x063eb0ee in QObject::event (this=0x8cbeb08, e=0x9be0630) at
kernel/qobject.cpp:1260
#14 0x025fe1e4 in QGraphicsScene::event (this=0x8cbeb08, event=0x9be0630) at
graphicsview/qgraphicsscene.cpp:3450
#15 0x01f591dc in QApplicationPrivate::notify_helper (this=0x8bffa88,
receiver=0x8cbeb08, e=0x9be0630) at kernel/qapplication.cpp:4242
#16 0x01f5fe37 in QApplication::notify (this=0x8bf2e58, receiver=0x8cbeb08,
e=0x9be0630) at kernel/qapplication.cpp:3661
#17 0x011612fa in KApplication::notify (this=0x8bf2e58, receiver=0x8cbeb08,
event=0x9be0630) at ../../kdeui/kernel/kapplication.cpp:302
#18 0x063da6fb in QCoreApplication::notifyInternal (this=0x8bf2e58,
receiver=0x8cbeb08, event=0x9be0630) at kernel/qcoreapplication.cpp:704
#19 0x063dd133 in QCoreApplication::sendEvent (receiver=0x0, event_type=0,
data=0x8be3418) at
../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:215
#20 QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0,
data=0x8be3418) at kernel/qcoreapplication.cpp:1345
#21 0x063dd29d in QCoreApplication::sendPostedEvents (receiver=0x0,
event_type=0) at kernel/qcoreapplication.cpp:1238
#22 0x064068ff in QCoreApplication::sendPostedEvents (s=0x8c02458) at
../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:220
#23 postEventSourceDispatch (s=0x8c02458) at
kernel/qeventdispatcher_glib.cpp:276
#24 0x05c81fd8 in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#25 0x05c85880 in ?? () from /lib/libglib-2.0.so.0
#26 0x05c859b3 in g_main_context_iteration () from /lib/libglib-2.0.so.0
#27 0x064063f5 in QEventDispatcherGlib::processEvents (this=0x8bff328,
flags=...) at kernel/qeventdispatcher_glib.cpp:407
#28 0x02016ba5 in QGuiEventDispatcherGlib::processEvents (this=0x8bff328,
flags=...) at kernel/qguieventdispatcher_glib.cpp:202
#29 0x063d8d19 in QEventLoop::processEvents (this=0xbfc449f4, flags=) at
kernel/qeventloop.cpp:149
#30 0x063d916a in QEventLoop::exec (this=0xbfc449f4, flags=...) at
kernel/qeventloop.cpp:201
#31 0x063dd35f in QCoreApplication::exec () at kernel/qcoreapplication.cpp:981
#32 0x01f59277 in QApplication::exec () at kernel/qapplication.cpp:3570
#33 0x00f5b0de in kdemain () from /usr/lib/libkdeinit4_plasma-desktop.so
#34 0x080485cb in _start ()

ProblemType: Bug
Architecture: i386
Date: Tue Dec 22 13:39:37 2009
DistroRelease: Ubuntu 10.04
InstallationMedia: Kubuntu 10.04 "Lucid Lynx" - Alpha i386 (20091210)
Package: plasma-desktop 4:4.3.85-0ubuntu1
ProcEnviron:
 LANGUAGE=
 LANG=C
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.32-9.13-generic
SourcePackage: kdebase-workspace
Tags: lucid
Uname: Linux 2.6.32-9-generic i686

[Jonathan Thomas (echidnaman)]

As you said, a fix has been committed for Qt 4.6.1.

[Chris Samuel (chris-csamuel)]

I just got this crash in KDE 4.4 RC2 on AMD64 when sending an email reply - the window with the reply closing was enough to trigger the crash.

Any chance of getting commit 705880f0045ac39140f980d69aec68869213e379 backported to the QT 4.6.0 that's in the Kubuntu beta PPA please ?

[Sami Nieminen (sami-nieminen)]

The qt bug fix is important for those who are running KDE 4.4. Is there such a qt package available somewhere on ppa repositories?

Here KDE and Qt developers are saying that distributions should provide the patched Qt if they provide KDE 4.4 packages: http://old.nabble.com/KDE-4.4-Qt-version-td27120421.html

[Sami Nieminen (sami-nieminen)]

I forgot to mention that I am running karmic and using the KDE 4.4 RC2 frm the Kubuntu beta PPA.

[Chris Samuel (chris-csamuel)]

Aaron Siego wrote in his blog:

Original KDE bug is https://bugs.kde.org/show_bug.cgi?id=210146

http://aseigo.blogspot.com/2010/01/qt-460-kde-sc-44-configchanged.html

# As a heads up to everyone out there: we're getting a lot of bug reports,
# particularly crashes, from people using Qt 4.6.0. That version of Qt has
# a handful of crashes in it that some KDE apps trigger all too reliably. A
# patch release of Qt, v4.6.1, has been released that addresses a number
# of these issues. Qt 4.6.2 that's upcoming will be even better, and I
# understand that some distributions have been backporting some of these
# critical fixes. If you are having a hard time with the 4.4 release candidates,
# please check your Qt version first.

Any chance of getting the fix for at least the cause of these crashes, commit http://qt.gitorious.org/+kde-developers/qt/kde-qt/commit/705880f0045ac39140f980d69aec68869213e379 backported to the QT 4.6.0 that's in the Kubuntu beta PPA please ?

[Jonathan Thomas (echidnaman)]

Fix released to Kubuntu 10.04. It will also be available with the KDE 4.4.0 packages for 9.10.