Comment 31 for bug 926379

Forwarding this bug from Ubuntu that multiple people are hitting:
http://bugs.launchpad.net/ubuntu/+source/mesa/+bug/926379

[Problem]
compiz crash in intel_miptree_release() at intel_mipmap_tree.c:290 called by intel_process_dri2_buffer_with_separate_stencil()

Occurs right after a fresh boot on an otherwise vanilla laptop (no external displays). Others indicate their crashes occur post-boot in compiz while switching desktops, minimizing windows, etc. but we don't have stack traces for these other cases so I can't be 100% certain.

[Description]
Since moving to mesa 8.x, we've had scattered reports where compiz crashes with stacktraces terminating in intel_miptree_release().

We thought updating to 8.0.1 would resolve these crashes (and perhaps they did; the frequency of reports seems lower than before). However we've still gotten a handful of people hitting it. I don't know what graphics these other folk were running; could well be Sandybridge. I have not been able to reproduce this on my own (non-Sandybridge, non-Ironlake) hardware.

[Stacktrace top]
Thread 1 (Thread 0x7f80c961c780 (LWP 2324)):
#0 intel_miptree_release (mt=0x220) at intel_mipmap_tree.c:290
        __FUNCTION__ = "intel_miptree_release"
#1 0x00007f80c0468421 in intel_process_dri2_buffer_with_separate_stencil (buffer_name=0x7f80c04f0d90 "dri2 hiz buffer", rb=0x3487cb0, buffer=<optimized out>, intel=0x1ce7bf0, drawable=<optimized out>) at intel_context.c:1267
        buffer_width = <optimized out>
        buffer_height = <optimized out>
        region = 0x0
        mt = <optimized out>
#2 intel_update_renderbuffers (context=<optimized out>, drawable=0x26669e0) at intel_context.c:361
        fb = 0x4343720
        rb = 0x3487cb0
        intel = 0x1ce7bf0
        buffers = <optimized out>
        attachments = <optimized out>
        i = <optimized out>
        count = 5
        region_name = 0x7f80c04f0d90 "dri2 hiz buffer"
        try_separate_stencil = true
        __func__ = "intel_update_renderbuffers"
#3 0x00007f80c04758bd in intelSetTexBuffer2 (pDRICtx=0x1ce1ae0, target=3553, texture_format=8410, dPriv=0x26669e0) at intel_tex_image.c:335
        fb = 0x4343720
        intel = 0x1ce7bf0
        ctx = 0x1ce7bf0
        rb = 0x1ce1ae0
        texObj = 0x3f86920
        texImage = <optimized out>
        texFormat = <optimized out>

[lspci]
00:02.0 0300: 8086:0126 (rev 09) (prog-if 00 [VGA controller])