System Environment:
--------------------------
Arch:             x86_64
Platform:         Ivybridge/Haswell
Kernel:      (drm-intel-next-queued)798183c54799fbe1e5a5bfabb3a8c0505ffd2149

Bug detailed description:
---------------------------
It causes system hang with -queued kernel. It fails on -fixes and -nightly kernel(bug 72507)

Bisect on -fixes kernel, commit a415d355645ca5e8797235a76026ca2622ceefdb fixed it.
commit a415d355645ca5e8797235a76026ca2622ceefdb
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Tue Nov 26 11:23:15 2013 +0000

    drm/i915: Pin relocations for the duration of constructing the execbuffer

    As the execbuffer dispatch grows ever more complex and involves multiple
    stages of moving objects into the aperture, we need to take greater care
    that we do not evict our execbuffer objects prior to dispatch. This is
    relatively simple as we can just keep the objects pinned for not just
    the relocation but until we are finished.

    One such example is the possibility of the context switch causing an
    eviction or hitting the shrinker in order to fit its object into the
    aperture.

    Link: http://lists.freedesktop.org/archives/intel-gfx/2013-November/036166.h                                                                                                 tml
    Reported-by: "Siluvery, Arun" <arun.siluvery@intel.com>
    Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
    Cc: Ben Widawsky <benjamin.widawsky@intel.com>
    Cc: Daniel Vetter <daniel@ffwll.ch>
    Cc: stable@vger.kernel.org


output:
trying buffer count 521599
trying buffer count 521598
trying buffer count 521597
trying buffer count 521596

Reproduce steps:
-------------------------
1. ./gem_ctx_exec --run-subtest eviction