Comment 2 for bug 2062146

#0 0x0000ffff7721ad7c in v3d_load_utile (gpu_stride=16, gpu=0xffff2840e000,
    cpu_stride=4096, cpu=0xffff1e880f90)
    at ../src/broadcom/common/v3d_cpu_tiling.h:108
#1 v3d_move_pixels_general_percpp (gpu=0xffff28126000, cpu=0xffff1e800010,
    cpu_stride=4096, cpp=4, image_h=768, box=0xaaaaf986a674,
    get_pixel_offset=0xffff7721a930 <v3d_get_uif_xor_pixel_offset>,
    is_load=true, gpu_stride=<optimized out>)
    at ../src/broadcom/common/v3d_tiling.c:289
#2 0x0000ffff771dc420 in v3d_resource_transfer_map (pctx=<optimized out>,
    prsc=0xaaaaf9963be0, level=<optimized out>, usage=<optimized out>,
    box=<optimized out>, pptrans=<optimized out>)
    at ../src/gallium/drivers/v3d/v3d_resource.c:327
#3 0x0000ffff762fcb40 in pipe_texture_map (transfer=0xffffc86d4490, h=730,
    w=1024, y=0, x=0, access=1, layer=0, level=0, resource=<optimized out>,
    context=0xaaaaf98e8c40) at ../src/gallium/auxiliary/util/u_inlines.h:557
#4 dri2_map_image (context=0xaaaaf9964910, image=0xaaaaf985df70, x0=0, y0=0,
    width=1024, height=730, flags=1, stride=0xffffc86d459c,
    data=0xffffc86d45a0) at ../src/gallium/frontends/dri/dri2.c:1964
#5 0x0000ffff847a46a8 in gbm_dri_bo_map (_bo=0xaaaaf9872e20, x=0, y=0,
    width=1024, height=730, flags=1, stride=0xffffc86d459c,
    map_data=0xffffc86d45a0) at ../src/gbm/backends/dri/gbm_dri.c:1122
#6 0x0000ffff89d7f644 in WebKit::AcceleratedBackingStoreDMABuf::BufferGBM::didUpdateContents ()
    at /usr/src/webkit2gtk-2.44.0-2/Source/WebKit/UIProcess/gtk/AcceleratedBackingStoreDMABuf.cpp:368
#7 0x0000ffff89d809fc in WebKit::AcceleratedBackingStoreDMABuf::frame ()
    at /usr/src/webkit2gtk-2.44.0-2/Source/WebKit/UIProcess/gtk/AcceleratedBackingStoreDMABuf.cpp:531