This crash occurred when running media/video-initially-hidden-volume-slider-up.html, but it's very rare so I doubt you'll be able to reproduce it. The crash is deep in mesa. Not updating expectations because the crash seems random. We should consider running tests under GDK_SYNCHRONIZE. Thread 1 (Thread 0x7fc082ff5700 (LWP 9490)): #0 _g_log_abort () at /home/slave/webkitgtk/gtk-linux-64-release-tests/build/WebKitBuild/DependenciesGTK/Source/glib-2.54.2/glib/gmessages.c:554 #1 0x00007fc112364691 in g_log_writer_default () at /home/slave/webkitgtk/gtk-linux-64-release-tests/build/WebKitBuild/DependenciesGTK/Source/glib-2.54.2/glib/gmessages.c:2628 #2 0x00007fc112362d0c in g_log_structured_array () at /home/slave/webkitgtk/gtk-linux-64-release-tests/build/WebKitBuild/DependenciesGTK/Source/glib-2.54.2/glib/gmessages.c:1941 #3 0x00007fc112362ff8 in g_log_structured () at /home/slave/webkitgtk/gtk-linux-64-release-tests/build/WebKitBuild/DependenciesGTK/Source/glib-2.54.2/glib/gmessages.c:1768 #4 0x00007fc1103f0525 in _gdk_x11_display_error_event () at /home/slave/webkitgtk/gtk-linux-64-release-tests/build/WebKitBuild/DependenciesGTK/Source/gtk+-3.22.11/gdk/x11/gdkdisplay-x11.c:2579 #5 0x00007fc1103fd223 in gdk_x_error () at /home/slave/webkitgtk/gtk-linux-64-release-tests/build/WebKitBuild/DependenciesGTK/Source/gtk+-3.22.11/gdk/x11/gdkmain-x11.c:307 #6 0x00007fc11169122d in _XError () from /usr/lib/x86_64-linux-gnu/libX11.so.6 #7 0x00007fc11168e157 in ?? () from /usr/lib/x86_64-linux-gnu/libX11.so.6 #8 0x00007fc11168e215 in ?? () from /usr/lib/x86_64-linux-gnu/libX11.so.6 #9 0x00007fc11168f128 in _XReply () from /usr/lib/x86_64-linux-gnu/libX11.so.6 #10 0x00007fc111673c4e in XGetGeometry () from /usr/lib/x86_64-linux-gnu/libX11.so.6 #11 0x00007fc11abaa759 in swrastGetDrawableInfo () at /home/slave/webkitgtk/gtk-linux-64-release-tests/build/WebKitBuild/DependenciesGTK/Source/Mesa/src/glx/drisw_glx.c:108 #12 0x00007fc096011609 in get_drawable_info () at /home/slave/webkitgtk/gtk-linux-64-release-tests/build/WebKitBuild/DependenciesGTK/Source/Mesa/src/gallium/state_trackers/dri/drisw.c:61 #13 drisw_update_drawable_info () at /home/slave/webkitgtk/gtk-linux-64-release-tests/build/WebKitBuild/DependenciesGTK/Source/Mesa/src/gallium/state_trackers/dri/drisw.c:121 #14 0x00007fc09600f955 in dri_st_framebuffer_validate () at /home/slave/webkitgtk/gtk-linux-64-release-tests/build/WebKitBuild/DependenciesGTK/Source/Mesa/src/gallium/state_trackers/dri/dri_drawable.c:83 #15 0x00007fc095ed01e0 in st_framebuffer_validate () at /home/slave/webkitgtk/gtk-linux-64-release-tests/build/WebKitBuild/DependenciesGTK/Source/Mesa/src/mesa/state_tracker/st_manager.c:197 #16 0x00007fc095ed1a51 in st_manager_validate_framebuffers () at /home/slave/webkitgtk/gtk-linux-64-release-tests/build/WebKitBuild/DependenciesGTK/Source/Mesa/src/mesa/state_tracker/st_manager.c:1065 #17 0x00007fc095e922e5 in st_validate_state () at /home/slave/webkitgtk/gtk-linux-64-release-tests/build/WebKitBuild/DependenciesGTK/Source/Mesa/src/mesa/state_tracker/st_atom.c:202 #18 0x00007fc095e9a133 in st_Clear () at /home/slave/webkitgtk/gtk-linux-64-release-tests/build/WebKitBuild/DependenciesGTK/Source/Mesa/src/mesa/state_tracker/st_cb_clear.c:411 #19 0x00007fc1188d1526 in _ZN6WebKit24CoordinatedGraphicsScene23paintToCurrentGLContextERKN7WebCore20TransformationMatrixEfRKNS1_9FloatRectERKNS1_5ColorEbRKNS1_10FloatPointEj () from /home/slave/webkitgtk/gtk-linux-64-release/build/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37 #20 0x00007fc1188db369 in _ZN6WebKit18ThreadedCompositor15renderLayerTreeEv () from /home/slave/webkitgtk/gtk-linux-64-release/build/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37 #21 0x00007fc1188d9ec1 in _ZN6WebKit18CompositingRunLoop16updateTimerFiredEv () from /home/slave/webkitgtk/gtk-linux-64-release/build/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37 #22 0x00007fc1167bce93 in _ZZN3WTF7RunLoop9TimerBaseC4ERS0_ENUlPvE_4_FUNES3_ () from /home/slave/webkitgtk/gtk-linux-64-release/build/WebKitBuild/Release/lib/libjavascriptcoregtk-4.0.so.18 #23 0x00007fc11235c81a in g_main_dispatch () at /home/slave/webkitgtk/gtk-linux-64-release-tests/build/WebKitBuild/DependenciesGTK/Source/glib-2.54.2/glib/gmain.c:3148 #24 g_main_context_dispatch () at /home/slave/webkitgtk/gtk-linux-64-release-tests/build/WebKitBuild/DependenciesGTK/Source/glib-2.54.2/glib/gmain.c:3813 #25 0x00007fc11235cba8 in g_main_context_iterate () at /home/slave/webkitgtk/gtk-linux-64-release-tests/build/WebKitBuild/DependenciesGTK/Source/glib-2.54.2/glib/gmain.c:3886 #26 0x00007fc11235cec2 in g_main_loop_run () at /home/slave/webkitgtk/gtk-linux-64-release-tests/build/WebKitBuild/DependenciesGTK/Source/glib-2.54.2/glib/gmain.c:4082 #27 0x00007fc1167bd2c0 in _ZN3WTF7RunLoop3runEv () from /home/slave/webkitgtk/gtk-linux-64-release/build/WebKitBuild/Release/lib/libjavascriptcoregtk-4.0.so.18 #28 0x00007fc11678771b in _ZN3WTF6Thread10entryPointEPNS0_16NewThreadContextE () from /home/slave/webkitgtk/gtk-linux-64-release/build/WebKitBuild/Release/lib/libjavascriptcoregtk-4.0.so.18 #29 0x00007fc1167bb699 in _ZN3WTFL19wtfThreadEntryPointEPv () from /home/slave/webkitgtk/gtk-linux-64-release/build/WebKitBuild/Release/lib/libjavascriptcoregtk-4.0.so.18 #30 0x00007fc113b15494 in start_thread (arg=0x7fc082ff5700) at pthread_create.c:333 #31 0x00007fc10f5ab93f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:97 STDERR: STDERR: warning: core file may not match specified executable file. STDERR: STDERR: (WebKitWebProcess:9430): Gdk-ERROR **: The program 'WebKitWebProcess' received an X Window System error. STDERR: This probably reflects a bug in the program. STDERR: The error was 'BadAccess (attempt to access private resource denied)'. STDERR: (Details: serial 1446 error_code 10 request_code 130 (MIT-SHM) minor_code 1) STDERR: (Note to programmers: normally, X errors are reported asynchronously; STDERR: that is, you will receive the error a while after causing it. STDERR: To debug your program, run it with the GDK_SYNCHRONIZE environment STDERR: variable to change this behavior. You can then get a meaningful STDERR: backtrace from your debugger if you break on the gdk_x_error() function.)