https://intel-gfx-ci.01.org/tree/drm-tip/drmtip_19/fi-cfl-u/igt@kms_atomic_transition@1x-modeset-transitions-nonblocking-fencing.html

run.log:
running: igt/kms_atomic_transition/1x-modeset-transitions-nonblocking-fencing

[66/76] skip: 16, pass: 50 -                                                 
owatch: TIMEOUT!

dmesg:
<1>[  331.145300] BUG: unable to handle kernel NULL pointer dereference at 00000000000005e0
<1>[  331.145341] IP: intel_psr_flush+0x61/0x150 [i915]
<6>[  331.145344] PGD 0 P4D 0 
<4>[  331.145349] Oops: 0000 [#1] PREEMPT SMP PTI
<0>[  331.145352] Dumping ftrace buffer:
<0>[  331.145355] ---------------------------------
<0>[  331.145401] CPU:2 [LOST 93795 EVENTS]
                  gem_exec-1378    2d.s2 242338279us : __i915_request_submit: rcs0 fence 549:135385 -> global=135385, current 135384
<0>[  331.145444] gem_exec-1378    2..s1 242338281us : execlists_submission_tasklet: rcs0 in[0]:  ctx=2.2, global=135385 (fence 549:135385) (current 135384), prio=0
...
<0>[  331.176216] perf_pmu-2655    7.... 326980843us : reset_all_global_seqno.part.5: vcs0 seqno 0 (current 0) -> 0
<0>[  331.176243] perf_pmu-2655    7.... 326980880us : reset_all_global_seqno.part.5: vecs0 seqno 0 (current 0) -> 0
<0>[  331.176246] ---------------------------------
<4>[  331.176248] Modules linked in: vgem snd_hda_codec_hdmi i915 x86_pkg_temp_thermal intel_powerclamp coretemp snd_hda_intel crct10dif_pclmul crc32_pclmul ghash_clmulni_intel snd_hda_codec snd_hwdep snd_hda_core e1000e snd_pcm mei_me mei prime_numbers
<4>[  331.176265] CPU: 0 PID: 59 Comm: kworker/0:1 Tainted: G     U           4.16.0-rc7-gdc857e9d853d-drmtip_19+ #1
<4>[  331.176266] Hardware name: Intel Corporation CoffeeLake Client Platform/CoffeeLake U DDR4 RVP, BIOS CNLSFWR1.R00.X124.B01.1802051324 02/05/2018
<4>[  331.176290] Workqueue: events i915_clflush_work [i915]
<4>[  331.176321] RIP: 0010:intel_psr_flush+0x61/0x150 [i915]
<4>[  331.176323] RSP: 0018:ffffb065802a7dd0 EFLAGS: 00010282
<4>[  331.176325] RAX: 0000000000000000 RBX: ffff9d3c4bbfa5d8 RCX: 0000000000000000
<4>[  331.176327] RDX: 0000000080000001 RSI: ffffffffffffffff RDI: 00000000ffffffff
<4>[  331.176328] RBP: 0000000000000001 R08: ffff9d3c58a1b148 R09: 00000000c610cb46
<4>[  331.176330] R10: ffffb065802a7dd0 R11: ffff9d3c58a1a840 R12: ffff9d3c4bbf0000
<4>[  331.176331] R13: 0000000000000001 R14: 0000000000000001 R15: ffff9d3c4622c568
<4>[  331.176333] FS:  0000000000000000(0000) GS:ffff9d3c6bc00000(0000) knlGS:0000000000000000
<4>[  331.176334] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
<4>[  331.176336] CR2: 00000000000005e0 CR3: 0000000282210006 CR4: 00000000003606f0
<4>[  331.176337] Call Trace:
<4>[  331.176370]  intel_frontbuffer_flush+0x6a/0x80 [i915]
<4>[  331.176395]  i915_clflush_work+0x73/0x1c0 [i915]
<4>[  331.176398]  process_one_work+0x21a/0x640
<4>[  331.176402]  worker_thread+0x48/0x3a0
<4>[  331.176406]  kthread+0xfb/0x130
<4>[  331.176408]  ? process_one_work+0x640/0x640
<4>[  331.176410]  ? _kthread_create_on_node+0x60/0x60
<4>[  331.176414]  ret_from_fork+0x3a/0x50
<4>[  331.176418] Code: d8 a5 00 00 89 f5 31 f6 48 89 df e8 6a 76 4a d2 49 8b 84 24 60 a6 00 00 48 85 c0 74 7d 48 8b 80 48 ff ff ff 48 c7 c6 ff ff ff ff <48> 63 90 e0 05 00 00 b8 01 00 00 00 8d 0c d5 00 00 00 00 48 d3 
<1>[  331.176487] RIP: intel_psr_flush+0x61/0x150 [i915] RSP: ffffb065802a7dd0
<4>[  331.176489] CR2: 00000000000005e0
<4>[  331.176491] ---[ end trace f61ac999ea445f85 ]---
<3>[  331.423860] BUG: sleeping function called from invalid context at ./include/linux/percpu-rwsem.h:34
<3>[  331.423865] in_atomic(): 0, irqs_disabled(): 1, pid: 59, name: kworker/0:1
<4>[  331.423867] INFO: lockdep is turned off.
<4>[  331.423868] irq event stamp: 9892118
<4>[  331.423875] hardirqs last  enabled at (9892117): [<000000000ae2345c>] restore_regs_and_return_to_kernel+0x0/0x1f
<4>[  331.423878] hardirqs last disabled at (9892118): [<00000000d33c694a>] error_entry+0x78/0xf0
<4>[  331.423880] softirqs last  enabled at (9892116): [<00000000d2bea887>] __do_softirq+0x3a1/0x4aa
<4>[  331.423883] softirqs last disabled at (9892109): [<00000000e64713e4>] irq_exit+0xa4/0xb0
<4>[  331.423886] CPU: 0 PID: 59 Comm: kworker/0:1 Tainted: G     UD          4.16.0-rc7-gdc857e9d853d-drmtip_19+ #1
<4>[  331.423888] Hardware name: Intel Corporation CoffeeLake Client Platform/CoffeeLake U DDR4 RVP, BIOS CNLSFWR1.R00.X124.B01.1802051324 02/05/2018
<4>[  331.423923] Workqueue: events i915_clflush_work [i915]
<4>[  331.423925] Call Trace:
<4>[  331.423929]  dump_stack+0x5f/0x86
<4>[  331.423931]  ___might_sleep+0x1d9/0x240
<4>[  331.423934]  exit_signals+0x2b/0x2d0
<4>[  331.423936]  do_exit+0xa3/0xd30
<4>[  331.423939]  ? kthread+0xfb/0x130
<4>[  331.423941]  rewind_stack_do_exit+0x17/0x20
<7>[  334.146536] [IGT] kms_atomic_transition: exiting, ret=99

then there is backtrace in pstore of the softdog execution.