FYI, we noticed the below changes on

commit ad46cb533d586fdb256855437af876617c6cf609 ("drm/i915: Prevent recursive deadlock on releasing a busy userptr")


       v3.17-rc4  ad46cb533d586fdb256855437a  testbox/testcase/testparams
----------------  --------------------------  ---------------------------
       fail:runs  %reproduction    fail:runs
           |             |             |    
           :5          100%           5:5     lkp-t410/piglit/performance-igt-002
           :5          100%           5:5     TOTAL piglit.igt/gem_userptr_blits/coherency-sync.crash

       v3.17-rc4  ad46cb533d586fdb256855437a  
----------------  --------------------------  
           :5          100%           5:5     lkp-t410/piglit/performance-igt-002
           :5          100%           5:5     TOTAL dmesg.Out_of_memory:Kill_process



<6>[   16.764414] BTRFS: device fsid 8886adc6-3306-411a-bbf8-6638ebb74746 devid 1 transid 57 /dev/sda6
<6>[   18.558946] intel ips 0000:00:1f.6: i915 driver attached, reenabling gpu turbo
<6>[   69.352751] Purging GPU memory, 0 bytes freed, 12288 bytes still pinned.
<4>[   69.363044] gem_userptr_bli invoked oom-killer: gfp_mask=0xa00d2, order=0, oom_score_adj=1000
<6>[   69.373682] gem_userptr_bli cpuset=/ mems_allowed=0
<4>[   69.380617] CPU: 1 PID: 3058 Comm: gem_userptr_bli Not tainted 3.17.0-dirty #1
<4>[   69.390574] Hardware name: LENOVO 25222AU/25222AU, BIOS 6IET52WW (1.12 ) 02/16/2010
<4>[   69.399759]  0000000000000000 ffff8800749d37d8 ffffffff81870560 ffff880074a00000
<4>[   69.409950]  ffff8800749d3840 ffffffff8186d528 ffff880000000015 0000000000000000
<4>[   69.419535]  00000000ffffffff ffff880076ffe0c0 0000000000000206 ffffffff81cf5440
<4>[   69.429544] Call Trace:
<4>[   69.435415]  [<ffffffff81870560>] dump_stack+0x4d/0x66
<4>[   69.442549]  [<ffffffff8186d528>] dump_header+0x9e/0x225
<4>[   69.448393]  [<ffffffff81163bed>] oom_kill_process+0x20d/0x380
<4>[   69.451840]  [<ffffffff81388a65>] ? security_capable_noaudit+0x15/0x20
<4>[   69.456166]  [<ffffffff81164419>] out_of_memory+0x4f9/0x540
<4>[   69.459434]  [<ffffffff8116ad58>] __alloc_pages_nodemask+0xab8/0xb00
<4>[   69.463816]  [<ffffffff811b130f>] alloc_pages_vma+0xaf/0x1c0
<4>[   69.467235]  [<ffffffff8117847f>] shmem_alloc_page+0x5f/0x90
<4>[   69.470444]  [<ffffffff81194cd9>] ? __vm_enough_memory+0x29/0x150
<4>[   69.474756]  [<ffffffff8117b490>] shmem_getpage_gfp+0x550/0x8e0
<4>[   69.478142]  [<ffffffff8117c371>] shmem_read_mapping_page_gfp+0x31/0x60
<4>[   69.481728]  [<ffffffffa01e830c>] i915_gem_object_get_pages_gtt+0x2dc/0x3b0 [i915]
<4>[   69.486341]  [<ffffffff811badec>] ? kmem_cache_alloc_trace+0x4c/0x210
<4>[   69.490795]  [<ffffffffa00d20da>] ? drm_vma_node_allow+0x2a/0xe0 [drm]
<4>[   69.494314]  [<ffffffffa01e3ca0>] i915_gem_object_get_pages+0x50/0xb0 [i915]
<4>[   69.498890]  [<ffffffffa01ea789>] i915_gem_pwrite_ioctl+0x369/0x800 [i915]
<4>[   69.503486]  [<ffffffffa01e5d28>] ? i915_gem_create+0x58/0xe0 [i915]
<4>[   69.508875]  [<ffffffffa00b9df7>] drm_ioctl+0x197/0x680 [drm]
<4>[   69.513217]  [<ffffffff810a0928>] ? __enqueue_entity+0x78/0x80
<4>[   69.517707]  [<ffffffff810a2745>] ? set_next_entity+0x95/0xb0
<4>[   69.521943]  [<ffffffff811ed620>] do_vfs_ioctl+0x2f0/0x4f0
<4>[   69.527080]  [<ffffffff8138e7c6>] ? file_has_perm+0x86/0xa0
<4>[   69.531373]  [<ffffffff811ed8a1>] SyS_ioctl+0x81/0xa0
<4>[   69.535560]  [<ffffffff81879229>] system_call_fastpath+0x16/0x1b
<4>[   69.539938] Mem-Info:
<4>[   69.543345] Node 0 DMA per-cpu:
<4>[   69.547209] CPU    0: hi:    0, btch:   1 usd:   0


	--yliu