Created attachment 16939 [details]
dmesg log after X crashed

X crashed when run rendercheck

Reproduce steps:
1, modprobe drm debug=1
2, modprobe i915 modeset=1
3, X &
4, xterm &
5, rendercheck -t fill

My platform: Intel Q35

source:
xserver - master tip commit 26e7e69ab893d1f2b35213250ada40ec90944f62
drm - modesetting-101 03bf1fba67413f381d2a548fe08bd634a48fcc48
xf86-video-intel - intel-kernelmode 95fb4ac2ea326ee67f472e33ba4202942f246df1

Backtrace info:
Program received signal SIGSEGV, Segmentation fault.
exaGetPixmapFirstPixel (pPixmap=0x83d2dd0) at exa_unaccel.c:396
396             pixel = *(CARD32 *)fb;
(gdb) bt
#0  exaGetPixmapFirstPixel (pPixmap=0x83d2dd0) at exa_unaccel.c:396
#1  0xb79dad3e in exaComposite (op=1 '\001', pSrc=0x83f1c28, pMask=0x0,
    pDst=0x83f4268, xSrc=0, ySrc=0, xMask=0, yMask=0, xDst=0, yDst=0,
    width=40, height=40) at exa_render.c:285
#2  0x0817c381 in damageComposite (op=1 '\001', pSrc=0x83f1c28, pMask=0x0,
    pDst=0x83f4268, xSrc=0, ySrc=0, xMask=0, yMask=0, xDst=0, yDst=0,
    width=40, height=40) at damage.c:576
#3  0x081628f0 in CompositePicture (op=1 '\001', pSrc=0x83f1c28, pMask=0x0,
    pDst=0x83f4268, xSrc=0, ySrc=0, xMask=0, yMask=0, xDst=0, yDst=0,
    width=40, height=40) at picture.c:1661
#4  0x0816707f in ProcRenderComposite (client=0x83f45d0) at render.c:729
#5  0x081643b5 in ProcRenderDispatch (client=0x0) at render.c:2086
#6  0x0808c404 in Dispatch () at dispatch.c:448
#7  0x080718f5 in main (argc=1, argv=0xbfb47db4, envp=Cannot access memory at address 0x8
) at main.c:415