Application: kwin (4.9.4)
KDE Platform Version: 4.9.4
Qt Version: 4.8.3
Operating System: Linux 3.5.0-23-generic x86_64
Distribution: Ubuntu 12.10

-- Information about the crash:
- What I was doing when the application crashed:
Large number of windows open, tried to send mail from kmail client.
Laptop with wireless disabled, using ethernet.

The crash can be reproduced some of the time.

-- Backtrace:
Application: KWin (kwin), signal: Segmentation fault
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Current thread is 1 (Thread 0x7fe8b96ef780 (LWP 6049))]

Thread 3 (Thread 0x7fe8b134a700 (LWP 6053)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x00007fe8c8f06cd7 in ?? () from /usr/lib/x86_64-linux-gnu/libQtScript.so.4
#2  0x00007fe8c8f06d09 in ?? () from /usr/lib/x86_64-linux-gnu/libQtScript.so.4
#3  0x00007fe8c1067e9a in start_thread (arg=0x7fe8b134a700) at pthread_create.c:308
#4  0x00007fe8cbfddcbd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#5  0x0000000000000000 in ?? ()

Thread 2 (Thread 0x7fe8abd97700 (LWP 6054)):
#0  0x00007fe8cbfd7023 in select () at ../sysdeps/unix/syscall-template.S:82
#1  0x00007fe8c7ce2023 in qt_safe_select (nfds=17, fdread=0x7fe8a4000ac8, fdwrite=0x7fe8a4000d60, fdexcept=0x7fe8a4000ff8, orig_timeout=0x0) at kernel/qcore_unix.cpp:83
#2  0x00007fe8c7ce69e4 in QEventDispatcherUNIXPrivate::doSelect (this=this@entry=0x7fe8a4000910, flags=..., timeout=0x0) at kernel/qeventdispatcher_unix.cpp:223
#3  0x00007fe8c7ce7572 in QEventDispatcherUNIX::processEvents (this=0x7fe8a40008f0, flags=...) at kernel/qeventdispatcher_unix.cpp:926
#4  0x00007fe8c7cb52bf in QEventLoop::processEvents (this=this@entry=0x7fe8abd96dd0, flags=...) at kernel/qeventloop.cpp:149
#5  0x00007fe8c7cb5548 in QEventLoop::exec (this=0x7fe8abd96dd0, flags=...) at kernel/qeventloop.cpp:204
#6  0x00007fe8c7bb6b10 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:501
#7  0x00007fe8c7c959af in QInotifyFileSystemWatcherEngine::run (this=0x11c9730) at io/qfilesystemwatcher_inotify.cpp:248
#8  0x00007fe8c7bb9aec in QThreadPrivate::start (arg=0x11c9730) at thread/qthread_unix.cpp:338
#9  0x00007fe8c1067e9a in start_thread (arg=0x7fe8abd97700) at pthread_create.c:308
#10 0x00007fe8cbfddcbd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#11 0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7fe8b96ef780 (LWP 6049)):
[KCrash Handler]
#6  0x00007fe8cc2a2c48 in main_arena () from /lib/x86_64-linux-gnu/libc.so.6
#7  0x00007fe8cc306f15 in KWin::Workspace::constrainedStackingOrder (this=this@entry=0x10bcd20) at ../../kwin/layers.cpp:541
#8  0x00007fe8cc3075db in updateStackingOrder (propagate_new_clients=true, this=0x10bcd20) at ../../kwin/layers.cpp:118
#9  KWin::Workspace::updateStackingOrder (this=0x10bcd20, propagate_new_clients=<optimized out>) at ../../kwin/layers.cpp:111
#10 0x00007fe8cc307770 in blockStackingUpdates (this=<optimized out>, block=<optimized out>) at ../../kwin/layers.cpp:648
#11 KWin::Workspace::blockStackingUpdates (this=<optimized out>, block=<optimized out>) at ../../kwin/layers.cpp:640
#12 0x00007fe8cc2fe199 in ~StackingUpdatesBlocker (this=<synthetic pointer>, __in_chrg=<optimized out>) at ../../kwin/workspace.h:965
#13 KWin::Client::releaseWindow (this=0x1cfe500, on_shutdown=<optimized out>) at ../../kwin/client.cpp:303
#14 0x00007fe8cc31664b in KWin::Client::windowEvent (this=0x1cfe500, e=0x7fff40464a60) at ../../kwin/events.cpp:583
#15 0x00007fe8cc317483 in KWin::Workspace::workspaceEvent (this=0x10bcd20, e=0x7fff40464a60) at ../../kwin/events.cpp:294
#16 0x00007fe8cc309848 in KWin::Application::x11EventFilter (this=0x7fff40464fc0, e=0x7fff40464a60) at ../../kwin/main.cpp:362
#17 0x00007fe8c70ca7bc in qt_x11EventFilter (ev=0x7fff40464a60) at kernel/qapplication_x11.cpp:441
#18 qt_x11EventFilter (ev=0x7fff40464a60) at kernel/qapplication_x11.cpp:429
#19 0x00007fe8c70da7f0 in QApplication::x11ProcessEvent (this=0x7fff40464fc0, event=0x7fff40464a60) at kernel/qapplication_x11.cpp:3449
#20 0x00007fe8c71039d9 in QEventDispatcherX11::processEvents (this=0xf5aad0, flags=...) at kernel/qeventdispatcher_x11.cpp:132
#21 0x00007fe8c7cb52bf in QEventLoop::processEvents (this=this@entry=0x7fff40464cd0, flags=...) at kernel/qeventloop.cpp:149
#22 0x00007fe8c7cb5548 in QEventLoop::exec (this=0x7fff40464cd0, flags=...) at kernel/qeventloop.cpp:204
#23 0x00007fe8c7cba708 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1187
#24 0x00007fe8cc30bed4 in kdemain (argc=3, argv=0x7fff40465108) at ../../kwin/main.cpp:545
#25 0x00007fe8cbf0b76d in __libc_start_main (main=0x4006a0 <main(int, char**)>, argc=3, ubp_av=0x7fff40465108, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fff404650f8) at libc-start.c:226
#26 0x00000000004006d1 in _start ()

Reported using DrKonqi