Comment 6 for bug 1300411

I ran into this when debugging laney's webapp issue.

==6587== Thread 21 Chrome_InProcGpuThread:
==6587== Invalid write of size 8
==6587== at 0x1C033982: pushbuf_validate (in /usr/lib/x86_64-linux-gnu/libdrm_nouveau.so.2.0.0)
==6587== by 0x1B751A4A: nvc0_m2mf_transfer_rect (nvc0_transfer.c:37)
==6587== by 0x1B7525C0: nvc0_miptree_transfer_unmap (nvc0_transfer.c:489)
==6587== by 0x1B5BAB24: st_texture_image_unmap (u_inlines.h:481)
==6587== by 0x1B53D612: store_texsubimage (texstore.c:4108)
==6587== by 0x1B594439: st_TexSubImage (st_cb_texture.c:787)
==6587== by 0x1B594EC2: st_TexImage (st_cb_texture.c:811)
==6587== by 0x1B52AD48: teximage (teximage.c:3250)
==6587== by 0x1B52C06F: _mesa_TexImage2D (teximage.c:3289)
==6587== by 0x2B40723C: ??? (in /usr/lib/x86_64-linux-gnu/libOxideQtCore.so.0)
==6587== by 0x2B407291: ??? (in /usr/lib/x86_64-linux-gnu/libOxideQtCore.so.0)
==6587== by 0x2B39AAA8: ??? (in /usr/lib/x86_64-linux-gnu/libOxideQtCore.so.0)
==6587== Address 0x24462bc8 is 8 bytes inside a block of size 112 free'd
==6587== at 0x4C2BDEC: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==6587== by 0x1C033DAD: nouveau_bufctx_del (in /usr/lib/x86_64-linux-gnu/libdrm_nouveau.so.2.0.0)
==6587== by 0x1B741DE9: nvc0_destroy (nvc0_context.c:65)
==6587== by 0x1B595F01: st_destroy_context (st_context.c:341)
==6587== by 0x1B6618EE: dri_destroy_context (dri_context.c:192)
==6587== by 0x1B476912: driDestroyContext (dri_util.c:486)
==6587== by 0x96A1A5E: dri2_destroy_context (dri2_glx.c:132)
==6587== by 0x967B288: glXDestroyContext (glxcmds.c:473)
==6587== by 0xE3A8CA5: ??? (in /usr/lib/x86_64-linux-gnu/qt5/plugins/platforms/libqxcb.so)
==6587== by 0xE3A8CC8: ??? (in /usr/lib/x86_64-linux-gnu/qt5/plugins/platforms/libqxcb.so)
==6587== by 0x63A31A2: QOpenGLContext::destroy() (in /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5.2.1)
==6587== by 0x63A3406: QOpenGLContext::~QOpenGLContext() (in /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5.2.1)
==6587== block was alloc'd at
==6587== at 0x4C2CC70: calloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==6587== by 0x1C033C90: nouveau_bufctx_new (in /usr/lib/x86_64-linux-gnu/libdrm_nouveau.so.2.0.0)
==6587== by 0x1B7421F4: nvc0_create (nvc0_context.c:242)
==6587== by 0x1B5B1081: st_api_create_context (st_manager.c:615)
==6587== by 0x1B6616F2: dri_create_context (dri_context.c:130)
==6587== by 0x1B476C33: driCreateContextAttribs (dri_util.c:434)
==6587== by 0x96A18C4: dri2_create_context_attribs (dri2_glx.c:320)
==6587== by 0x9679A01: glXCreateContextAttribsARB (create_context.c:78)
==6587== by 0xE3A9BD1: ??? (in /usr/lib/x86_64-linux-gnu/qt5/plugins/platforms/libqxcb.so)
==6587== by 0xE38C3F3: ??? (in /usr/lib/x86_64-linux-gnu/qt5/plugins/platforms/libqxcb.so)
==6587== by 0x63A3362: QOpenGLContext::create() (in /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5.2.1)
==6587== by 0xE3AA203: ??? (in /usr/lib/x86_64-linux-gnu/qt5/plugins/platforms/libqxcb.so)