When executing the IGT test igt@i915_module_load@reload-no-display which unloads then reload the i915 driver, the following BUG happened:

<6> [253.036198] [IGT] i915_module_load: executing
<6> [253.065705] [IGT] i915_module_load: starting subtest reload-no-display
<3> [253.200845] snd_hda_codec_analog hdaudioC0D0: out of range cmd 0:6b6b:f09:0
<3> [253.200996] snd_hda_codec_analog hdaudioC0D0: out of range cmd 0:6b6b:f09:0
<3> [253.201040] snd_hda_codec_analog hdaudioC0D0: out of range cmd 0:6b6b:f09:0
<3> [253.201083] snd_hda_codec_analog hdaudioC0D0: out of range cmd 0:6b6b:f09:0
<1> [253.201133] BUG: unable to handle kernel NULL pointer dereference at 0000000000000a00
<1> [253.201151] #PF error: [normal kernel read fault]
<6> [253.201163] PGD 0 P4D 0 
<4> [253.201174] Oops: 0000 [#1] PREEMPT SMP PTI
<4> [253.201187] CPU: 1 PID: 256 Comm: kworker/1:3 Tainted: G     U            5.0.0-rc3-CI-CI_DRM_5458+ #1
<4> [253.201206] Hardware name: Dell Inc.                 OptiPlex 745                 /0GW726, BIOS 2.3.1  05/21/2007
<4> [253.201238] Workqueue: events snd_hdac_bus_process_unsol_events [snd_hda_core]
<4> [253.201262] RIP: 0010:call_update_outputs+0xc/0x50 [snd_hda_codec_generic]
<4> [253.201280] Code: 83 3c 09 00 00 5b 5d e9 62 fd ff ff 5b 5d c3 0f 1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 00 55 53 48 89 fb 48 8b af 68 05 00 00 <48> 8b 85 00 0a 00 00 48 85 c0 74 31 e8 e3 f6 b2 e1 f6 85 3d 09 00
<4> [253.201319] RSP: 0018:ffffc90000333e08 EFLAGS: 00010246
<4> [253.201333] RAX: 0000000000000120 RBX: ffff88803b685698 RCX: 0000000000000000
<4> [253.201350] RDX: 0000000000000002 RSI: 00000000ffffffff RDI: ffff88803b685698
<4> [253.201367] RBP: 0000000000000000 R08: 0000000007d8d437 R09: 0000000000000000
<4> [253.201384] R10: 0000000000006b6b R11: 0000000000000000 R12: ffff88803b685698
<4> [253.201401] R13: 0000000008000000 R14: 0000000000000000 R15: 0000000000000001
<4> [253.201419] FS:  0000000000000000(0000) GS:ffff88803e040000(0000) knlGS:0000000000000000
<4> [253.201439] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
<4> [253.201454] CR2: 0000000000000a00 CR3: 000000003a7b2000 CR4: 00000000000006e0
<4> [253.201471] Call Trace:
<4> [253.201493]  call_jack_callback+0x2f/0xc0 [snd_hda_codec]
<4> [253.201515]  snd_hda_jack_unsol_event+0x5e/0x70 [snd_hda_codec]
<4> [253.201535]  snd_hdac_bus_process_unsol_events+0x5d/0x70 [snd_hda_core]
<4> [253.201555]  process_one_work+0x245/0x610
<4> [253.201572]  worker_thread+0x37/0x380
<4> [253.201586]  ? process_one_work+0x610/0x610
<4> [253.201599]  kthread+0x119/0x130
<4> [253.201610]  ? kthread_park+0x80/0x80
<4> [253.201625]  ret_from_fork+0x3a/0x50
<4> [253.201641] Modules linked in: snd_hda_intel i915 vgem coretemp snd_hda_codec_analog snd_hda_codec_generic i2c_i801 snd_hda_codec lpc_ich snd_hwdep snd_hda_core snd_pcm tg3 prime_numbers [last unloaded: i915]

All the information about this failure can be found at: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_5458/fi-bwr-2160/igt@i915_module_load@reload-no-display.html

Boot kernel logs: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_5458/fi-bwr-2160/boot0.log

Kernel logs during the execution of our testing: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_5458/fi-bwr-2160/dmesg0.log

Machine: https://intel-gfx-ci.01.org/hardware.html#fi-bwr-2160