Created attachment 99056 [details]
dmesg

system Environment:
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Platform: Broadwell
Kernel:(drm-intel-nightly)c74cad3c2599b47438b168ca5629fbb00ab63f95

Bug detailed description:
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Run some gem_reset_stats subcases, GPU HANG reports in dmesg. It happens on  Broadwell with -nightly, queued and -fixes kernel.
Run earlier kernel, this issue still exists.

run  ./gem_reset_stats --run-subtest ban-blt
output:
IGT-Version: 1.6-g351e7d3 (x86_64) (Linux: 3.15.0-rc3_drm-intel-nightly_c74cad_20140515+ x86_64)
Subtest ban-blt: SUCCESS

dmesg -r | egrep "<[1-6]>" |grep drm
<6>[  106.713869] [drm] stuck on blitter ring
<6>[  106.715357] [drm] GPU HANG: ecode 2:0xe77ffff2, in gem_reset_stats [4470], reason: Ring hung, action: reset
<6>[  106.715360] [drm] GPU hangs can indicate a bug anywhere in the entire gfx stack, including userspace.
<6>[  106.715362] [drm] Please file a _new_ bug report on bugs.freedesktop.org against DRI -> DRM/Intel
<6>[  106.715366] [drm] drm/i915 developers can then reassign to the right component if it's not a kernel issue.
<6>[  106.715370] [drm] The gpu crash dump is required to analyze gpu hangs, so please always attach it.
<6>[  106.715371] [drm] GPU crash dump saved to /sys/class/drm/card0/error
<6>[  106.716771] [drm] Simulated gpu hang, resetting stop_rings
<6>[  112.711645] [drm] stuck on blitter ring
<6>[  112.712839] [drm] GPU HANG: ecode 2:0xe77ffff2, in gem_reset_stats [4470], reason: Ring hung, action: reset
<6>[  112.714606] [drm] Simulated gpu hang, resetting stop_rings

Reproduce steps:
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1. ./gem_reset_stats --run-subtest ban-blt