Many examples in CI system, starting from RO_CI_DRM_649 on 2015-07-08, on one specific machine (ro-bdw-i7-5600u). Failure looks like this:

Stdout 	

IGT-Version: 1.15-ge28120d (x86_64) (Linux: 4.7.0-rc6-gfxbench-RO_CI_DRM_649+ x86_64)
vebox completed 28672 cycles: 350.539 us
render completed 23552 cycles: 428.201 us
bsd completed 29696 cycles: 366.052 us
blt completed 24576 cycles: 443.494 us
Stack trace:
  #0 [__igt_fail_assert+0x101]
  #1 [store_ring+0x57b]
  #2 [__real_main692+0x46c]
  #3 [main+0x23]
  #4 [__libc_start_main+0xf0]
  #5 [_start+0x29]
  #6 [<unknown>+0x29]
Subtest basic-store-each: FAIL (10.907s)

Stderr 	

(gem_sync:5914) CRITICAL: Test assertion failure function store_ring, file gem_sync.c:281:
(gem_sync:5914) CRITICAL: Failed assertion: intel_detect_and_clear_missed_interrupts(fd) == 0
(gem_sync:5914) CRITICAL: error: 6 != 0
Subtest basic-store-each failed.
**** DEBUG ****
(gem_sync:5914) CRITICAL: Test assertion failure function store_ring, file gem_sync.c:281:
(gem_sync:5914) CRITICAL: Failed assertion: intel_detect_and_clear_missed_interrupts(fd) == 0
(gem_sync:5914) CRITICAL: error: 6 != 0
****  END  ****