https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_5097/shard-apl5/igt@gem_userptr_blits@stress-mm-invalidate-close-overlap.html

<4> [821.766372] stack segment: 0000 [#1] PREEMPT SMP NOPTI
<4> [821.766397] CPU: 1 PID: 157 Comm: kworker/1:3 Tainted: G     U  W         4.20.0-rc1-CI-CI_DRM_5097+ #1
<4> [821.766417] Hardware name:  /NUC6CAYB, BIOS AYAPLCEL.86A.0050.2018.0521.1533 05/21/2018
<4> [821.766440] Workqueue: events free_obj_work
<4> [821.766454] RIP: 0010:free_obj_work+0x143/0x210
<4> [821.766466] Code: dd 00 00 00 49 bd 00 01 00 00 00 00 ad de 49 bc 00 02 00 00 00 00 ad de 48 89 43 08 4c 89 2e 4c 89 66 08 e8 3f 0e d6 ff eb 16 <48> 89 45 08 48 89 de 4c 89 2b 4c 89 63 08 48 89 eb e8 27 0e d6 ff
<4> [821.766499] RSP: 0018:ffffc90000233e30 EFLAGS: 00010202
<4> [821.766512] RAX: ffffc90000233e30 RBX: ffff88014f22d610 RCX: 0000000000000000
<4> [821.766527] RDX: 0000000000000002 RSI: 0000000000000000 RDI: ffff880276816a80
<4> [821.766542] RBP: 6b6b6b6b6b6b6b6b R08: 0000000000000000 R09: 0000000000000000
<4> [821.766556] R10: 0000000000000000 R11: 0000000000000178 R12: dead000000000200
<4> [821.766571] R13: dead000000000100 R14: 0000000000000000 R15: 0000000000000000
<4> [821.766586] FS:  0000000000000000(0000) GS:ffff880277a80000(0000) knlGS:0000000000000000
<4> [821.766603] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
<4> [821.766616] CR2: 00007fa8241cd100 CR3: 00000002709aa000 CR4: 00000000003406e0
<4> [821.766630] Call Trace:
<4> [821.766647]  process_one_work+0x262/0x630
<4> [821.766663]  worker_thread+0x37/0x380
<4> [821.766676]  ? process_one_work+0x630/0x630
<4> [821.766687]  kthread+0x119/0x130
<4> [821.766698]  ? kthread_park+0x80/0x80
<4> [821.766711]  ret_from_fork+0x3a/0x50
<4> [821.766727] Modules linked in: vgem snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic x86_pkg_temp_thermal coretemp crct10dif_pclmul crc32_pclmul ghash_clmulni_intel i915 lpc_ich r8169 snd_hda_intel snd_hda_codec snd_hwdep snd_hda_core snd_pcm mei_me mei pinctrl_broxton pinctrl_intel prime_numbers