(gdb) bt
#0  0x023baf27 in ?? () from /usr/lib/dri/nouveau_dri.so
#1  0x0237b4b8 in ?? () from /usr/lib/dri/nouveau_dri.so
#2  0x0279218f in nouveau_pushbuf_flush () from /usr/lib/libdrm_nouveau.so.1
#3  0x0237b44f in ?? () from /usr/lib/dri/nouveau_dri.so
#4  0x024696a2 in ?? () from /usr/lib/dri/nouveau_dri.so
#5  0x024696e1 in ?? () from /usr/lib/dri/nouveau_dri.so
#6  0x023d0031 in ?? () from /usr/lib/dri/nouveau_dri.so
#7  0x023d076d in ?? () from /usr/lib/dri/nouveau_dri.so
#8  0x46529d02 in glFlush () from /usr/lib/libGL.so.1
#9  0x464fc669 in glXSwapBuffers () from /usr/lib/libGL.so.1
#10 0x021cb9c0 in QGLXContext::swapBuffers (this=0x80cb3e0, surface=0x80531e0) at qglxintegration.cpp:107
#11 0x0195401e in QOpenGLContext::swapBuffers (this=0x80cdf58, surface=0x80975c8) at kernel/qopenglcontext.cpp:310
#12 0x010c587a in QGLContext::swapBuffers (this=0x808f498) at qgl_qpa.cpp:231
#13 0x01083006 in QGLWidget::swapBuffers (this=0xbfffee58) at qgl.cpp:3666
#14 0x010a13fe in QGLWidgetGLPaintDevice::endPaint (this=0x807d528) at qglpaintdevice.cpp:182
#15 0x010baad7 in QGL2PaintEngineEx::end (this=0x815aa78) at gl2paintengineex/qpaintengineex_opengl2.cpp:2022
#16 0x01b14d72 in QPainter::end (this=0xbfffdbcc) at painting/qpainter.cpp:1907
#17 0x01b1389e in QPainter::~QPainter (this=0xbfffdbcc, __in_chrg=<optimized out>) at painting/qpainter.cpp:1483
#18 0x0804d83e in QWidgetCompositor::paintEvent (this=0xbfffee58) at main.cpp:216
#19 0x0124d1da in QWidget::event (this=0xbfffee58, event=0xbfffe304) at kernel/qwidget.cpp:7998
#20 0x010c5cec in QGLWidget::event (this=0xbfffee58, e=0xbfffe304) at qgl_qpa.cpp:346
#21 0x011fc198 in QApplicationPrivate::notify_helper (this=0x805c148, receiver=0xbfffee58, e=0xbfffe304) at kernel/qapplication.cpp:4054
#22 0x011fbed9 in QApplication::notify (this=0xbfffeee8, receiver=0xbfffee58, e=0xbfffe304) at kernel/qapplication.cpp:4019
#23 0x01ef220f in QCoreApplication::notifyInternal (this=0xbfffeee8, receiver=0xbfffee58, event=0xbfffe304) at kernel/qcoreapplication.cpp:805
#24 0x011fdf27 in QCoreApplication::sendSpontaneousEvent (receiver=0xbfffee58, event=0xbfffe304) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:213
#25 0x01245ad5 in QWidgetPrivate::drawWidget (this=0x807d408, pdev=0xbfffee60, rgn=..., offset=..., flags=3, sharedPainter=0x0, backingStore=0x0) at kernel/qwidget.cpp:5152
#26 0x0120a72e in QWidgetPrivate::repaint_sys (this=0x807d408, rgn=...) at kernel/qwidgetbackingstore.cpp:1381
#27 0x0123d0cf in QWidgetPrivate::syncBackingStore (this=0x807d408) at kernel/qwidget.cpp:1685
#28 0x0124d6a8 in QWidget::event (this=0xbfffee58, event=0x8228e40) at kernel/qwidget.cpp:8141
#29 0x010c5cec in QGLWidget::event (this=0xbfffee58, e=0x8228e40) at qgl_qpa.cpp:346
#30 0x011fc198 in QApplicationPrivate::notify_helper (this=0x805c148, receiver=0xbfffee58, e=0x8228e40) at kernel/qapplication.cpp:4054
#31 0x011fbed9 in QApplication::notify (this=0xbfffeee8, receiver=0xbfffee58, e=0x8228e40) at kernel/qapplication.cpp:4019
#32 0x01ef220f in QCoreApplication::notifyInternal (this=0xbfffeee8, receiver=0xbfffee58, event=0x8228e40) at kernel/qcoreapplication.cpp:805
#33 0x01ef5941 in QCoreApplication::sendEvent (receiver=0xbfffee58, event=0x8228e40) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:210
#34 0x01ef3103 in QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0, data=0x805c218) at kernel/qcoreapplication.cpp:1447
#35 0x01ef2dab in QCoreApplication::sendPostedEvents (receiver=0x0, event_type=0) at kernel/qcoreapplication.cpp:1308
#36 0x01f455f8 in QCoreApplication::sendPostedEvents () at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:215
#37 0x01f44786 in postEventSourceDispatch (s=0x8069860) at kernel/qeventdispatcher_glib.cpp:279
#38 0x432f55bf in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#39 0x432f5d00 in ?? () from /lib/libglib-2.0.so.0
#40 0x432f5faf in g_main_context_iteration () from /lib/libglib-2.0.so.0
#41 0x01f44f22 in QEventDispatcherGlib::processEvents (this=0x8064420, flags=...) at kernel/qeventdispatcher_glib.cpp:424
#42 0x01eefcbd in QEventLoop::processEvents (this=0xbfffedec, flags=...) at kernel/qeventloop.cpp:149
#43 0x01eeff1e in QEventLoop::exec (this=0xbfffedec, flags=...) at kernel/qeventloop.cpp:225
#44 0x01ef286e in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1063
#45 0x0195bfbb in QGuiApplication::exec () at kernel/qguiapplication.cpp:521
#46 0x011f97d4 in QApplication::exec () at kernel/qapplication.cpp:3355
#47 0x0804bf5f in main (argc=1, argv=0xbfffef94) at main.cpp:396