If you can reproduce the crash at will, may you read http://techbase.kde.org/Development/Tutorials/Debugging/How_to_create_useful_crash_reports and post a complete backtrace here? 
You need to install the "kdegraphics-dbg" package.
Thanks

I have installed the last package of gwenview from debian unstable and it consistently crashes.

Steps to reproduce:

Browse a directory with images.
double click on a image to open the view of the image.
Resize this image.
Go to next image
resize the image
continue until you have 10 images resized pending for saving
Go to the 11th image
click save all

I have installed kdegraphics-dbg and libglib2.0-0-dbg from debian repositories to get a usable backtrace

Application: Gwenview (gwenview), signal SIGSEGV
0xb67472fc in nanosleep () from /lib/libc.so.6
[Current thread is 0 (LWP 5263)]

Thread 2 (Thread 0xb44acb90 (LWP 5264)):
#0  0xb5eb68d0 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#1  0xb67887bd in pthread_cond_wait () from /lib/libc.so.6
#2  0xb794d822 in QWaitCondition::wait (this=0x8e8da88, mutex=0x8e8da84, time=4294967295) at thread/qwaitcondition_unix.cpp:87
#3  0xb7e4009f in Gwenview::SemanticInfoThread::run (this=0x8e8da78) at ../../../gwenview/lib/semanticinfo/nepomuksemanticinfobackend.cpp:135
#4  0xb794c80e in QThreadPrivate::start (arg=0x8e8da78) at thread/qthread_unix.cpp:189
#5  0xb5eb2f50 in start_thread () from /lib/libpthread.so.0
#6  0xb677c69e in clone () from /lib/libc.so.6

Thread 1 (Thread 0xb5aae710 (LWP 5263)):
[KCrash Handler]
#5  QUrl::path (this=0xbfe10c8c) at ../../include/QtCore/../../src/corelib/arch/qatomic_i386.h:120
#6  0xb73a053f in KUrl::path (this=0xbfe10c8c, trailing=KUrl::LeaveTrailingSlash) at ../../kdecore/io/kurl.cpp:859
#7  0xb73a4d19 in KUrl::cleanPath (this=0xbfe10c8c, options=@0xbfe10c48) at ../../kdecore/io/kurl.cpp:742
#8  0xb7c30a8e in cleanupUrl (url=<value optimized out>) at ../../kio/kio/kdirmodel.cpp:43
#9  0xb7c32675 in KDirModelPrivate::nodeForUrl (this=0x8e96b50, _url=@0x93c0744) at ../../kio/kio/kdirmodel.cpp:187
#10 0xb7c3442f in KDirModel::indexForUrl (this=0x8e8fcf8, url=@0x93c0744) at ../../kio/kio/kdirmodel.cpp:898
#11 0xb7e17099 in Gwenview::SortedDirModel::indexForUrl (this=0x8e94cd8, url=@0x93c0744) at ../../../gwenview/lib/semanticinfo/sorteddirmodel.cpp:155
#12 0x0807edab in Gwenview::MainWindow::generateThumbnailForUrl (this=0x8e6e4c0, url=@0x93c0744) at ../../../gwenview/app/mainwindow.cpp:1153
#13 0x080841c9 in Gwenview::MainWindow::qt_metacall (this=0x8e6e4c0, _c=QMetaObject::InvokeMetaMethod, _id=30, _a=0xbfe10e5c) at ./mainwindow.moc:154
#14 0xb7a55b98 in QMetaObject::activate (sender=0xb7e557a8, from_signal_index=5, to_signal_index=5, argv=0xbfe10e5c) at kernel/qobject.cpp:3120
#15 0xb7a56822 in QMetaObject::activate (sender=0xb7e557a8, m=0xb7e51628, local_signal_index=1, argv=0xbfe10e5c) at kernel/qobject.cpp:3194
#16 0xb7de8393 in Gwenview::DocumentFactory::documentChanged (this=0xb7e557a8, _t1=@0x93c0744) at ./documentfactory.moc:97
#17 0xb7de8c75 in Gwenview::DocumentFactory::slotSaved (this=0xb7e557a8, url=@0x93c0744) at ../../../gwenview/lib/document/documentfactory.cpp:200
#18 0xb7de8d2a in Gwenview::DocumentFactory::qt_metacall (this=0xb7e557a8, _c=QMetaObject::InvokeMetaMethod, _id=3, _a=0xbfe10f7c) at ./documentfactory.moc:78
#19 0xb7a55b98 in QMetaObject::activate (sender=0x9370620, from_signal_index=10, to_signal_index=10, argv=0xbfe10f7c) at kernel/qobject.cpp:3120
#20 0xb7a56822 in QMetaObject::activate (sender=0x9370620, m=0xb7e515ac, local_signal_index=6, argv=0xbfe10f7c) at kernel/qobject.cpp:3194
#21 0xb7de68f3 in Gwenview::Document::saved (this=0x9370620, _t1=@0x93c0744) at ./document.moc:156
#22 0xb7de694a in Gwenview::Document::slotCleanChanged (this=0xbfe10bd8, clean=true) at ../../../gwenview/lib/document/document.cpp:392
#23 0xb7de6cf5 in Gwenview::Document::qt_metacall (this=0x9370620, _c=QMetaObject::InvokeMetaMethod, _id=13, _a=0x91132f0) at ./document.moc:103
#24 0xb7a4e7eb in QMetaCallEvent::placeMetaCall (this=0x9786ea8, object=0x9370620) at kernel/qobject.cpp:489
#25 0xb7a50290 in QObject::event (this=0x9370620, e=0x9786ea8) at kernel/qobject.cpp:1118
#26 0xb6a247bc in QApplicationPrivate::notify_helper (this=0x8e18c30, receiver=0x9370620, e=0x9786ea8) at kernel/qapplication.cpp:4057
#27 0xb6a2cace in QApplication::notify (this=0xbfe116b0, receiver=0x9370620, e=0x9786ea8) at kernel/qapplication.cpp:3604
#28 0xb76cc5ed in KApplication::notify (this=0xbfe116b0, receiver=0x9370620, event=0x9786ea8) at ../../kdeui/kernel/kapplication.cpp:307
#29 0xb7a3fa2b in QCoreApplication::notifyInternal (this=0xbfe116b0, receiver=0x9370620, event=0x9786ea8) at kernel/qcoreapplication.cpp:610
#30 0xb7a40685 in QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0, data=0x8e03d10) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:213
#31 0xb7a4087d in QCoreApplication::sendPostedEvents (receiver=0x0, event_type=0) at kernel/qcoreapplication.cpp:1140
#32 0xb7a6b74f in postEventSourceDispatch (s=0x8e1a790) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:218
#33 0xb5efe848 in IA__g_main_context_dispatch (context=0x8e1a710) at /build/buildd-glib2.0_2.20.1-2-i386-hGzT8z/glib2.0-2.20.1/glib/gmain.c:1814
#34 0xb5f01dab in g_main_context_iterate (context=0x8e1a710, block=1, dispatch=1, self=0x8e18e00) at /build/buildd-glib2.0_2.20.1-2-i386-hGzT8z/glib2.0-2.20.1/glib/gmain.c:2448
#35 0xb5f01f28 in IA__g_main_context_iteration (context=0x8e1a710, may_block=1) at /build/buildd-glib2.0_2.20.1-2-i386-hGzT8z/glib2.0-2.20.1/glib/gmain.c:2511
#36 0xb7a6b398 in QEventDispatcherGlib::processEvents (this=0x8e06ac8, flags={i = -1075767912}) at kernel/qeventdispatcher_glib.cpp:324
#37 0xb6ac50e5 in QGuiEventDispatcherGlib::processEvents (this=0x8e06ac8, flags={i = -1075767864}) at kernel/qguieventdispatcher_glib.cpp:202
#38 0xb7a3e05a in QEventLoop::processEvents (this=0xbfe11640, flags={i = -1075767800}) at kernel/qeventloop.cpp:149
#39 0xb7a3e49a in QEventLoop::exec (this=0xbfe11640, flags={i = -1075767736}) at kernel/qeventloop.cpp:200
#40 0xb7a40949 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#41 0xb6a24637 in QApplication::exec () at kernel/qapplication.cpp:3526
#42 0x0807e91d in main (argc=1, argv=0xbfe11804) at ../../../gwenview/app/main.cpp:95

I wonder if this could be related to bug 189992. Thanks

Yes, the symptoms are just the same, the pictures are all resized before the crash. I do not know if the backtraces agree.

@Aurelien: what do you think?

(In reply to comment #6)
> @Aurelien: what do you think?

I agree it's most likely a duplicate of bug 189992.

The way you reproduce that one is interesting: does it only crash if there is at least 11 images modified?

Thanks to your detailed reproduction steps, I was able to reproduce and fix this bug, which is indeed the same as 189992.

*** This bug has been marked as a duplicate of bug 189992 ***