At boot time, we got the following issue on our CFL machine (https://intel-gfx-ci.01.org/hardware.html#fi-cfl-8700k):

<4>[    4.185379] sysfs: cannot create duplicate filename '/devices/pci0000:00/0000:00:1f.3/sound/card0/input9'
<4>[    4.185383] CPU: 7 PID: 364 Comm: systemd-udevd Not tainted 4.20.0-rc7-g9373de80d37b-drmtip_175+ #1
<4>[    4.185386] Hardware name: Micro-Star International Co., Ltd. MS-7B54/Z370M MORTAR (MS-7B54), BIOS 1.00 10/31/2017
<4>[    4.185389] Call Trace:
<4>[    4.185394]  dump_stack+0x67/0x9b
<4>[    4.185399]  sysfs_warn_dup+0x51/0x60
<4>[    4.185402]  sysfs_create_dir_ns+0xa9/0xc0
<4>[    4.185406]  kobject_add_internal+0xac/0x2d0
<4>[    4.185410]  kobject_add+0x71/0xd0
<4>[    4.185417]  device_add+0x110/0x670
<4>[    4.185421]  ? rcu_read_lock_sched_held+0x6f/0x80
<4>[    4.185425]  ? __kmalloc+0x262/0x2e0
<4>[    4.185430]  input_register_device+0x182/0x4f0
<4>[    4.185434]  snd_jack_dev_register+0x94/0xc0
<4>[    4.185437]  __snd_device_register.part.0+0x16/0x30
<4>[    4.185440]  snd_device_register_all+0x33/0x50
<4>[    4.185443]  snd_card_register+0x5f/0x1d0
<4>[    4.185449]  ? snd_hda_codec_build_controls+0xac/0x200 [snd_hda_codec]
<4>[    4.185482]  ? hda_codec_driver_probe+0x120/0x140 [snd_hda_codec]
<4>[    4.185485]  hda_codec_driver_probe+0x120/0x140 [snd_hda_codec]
<4>[    4.185488]  really_probe+0xf3/0x3e0
<4>[    4.185492]  driver_probe_device+0x10a/0x120
<4>[    4.185495]  __driver_attach+0xdb/0x100
<4>[    4.185497]  ? driver_probe_device+0x120/0x120
<4>[    4.185499]  ? driver_probe_device+0x120/0x120
<4>[    4.185501]  bus_for_each_dev+0x74/0xc0
<4>[    4.185505]  bus_add_driver+0x15f/0x250
<4>[    4.185507]  ? 0xffffffffc0489000
<4>[    4.185510]  driver_register+0x56/0xe0
<4>[    4.185511]  ? 0xffffffffc0489000
<4>[    4.185513]  do_one_initcall+0x58/0x2e0
<4>[    4.185516]  ? do_init_module+0x1d/0x1ea
<4>[    4.185518]  ? rcu_read_lock_sched_held+0x6f/0x80
<4>[    4.185520]  ? kmem_cache_alloc_trace+0x264/0x290
<4>[    4.185524]  do_init_module+0x56/0x1ea
<4>[    4.185527]  load_module+0x227a/0x29c0
<4>[    4.185541]  ? __se_sys_finit_module+0xd3/0xf0
<4>[    4.185542]  __se_sys_finit_module+0xd3/0xf0
<4>[    4.185550]  do_syscall_64+0x55/0x190
<4>[    4.185553]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
<4>[    4.185554] RIP: 0033:0x7fe5b78c2839
<4>[    4.185556] Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 1f f6 2c 00 f7 d8 64 89 01 48
<4>[    4.185557] RSP: 002b:00007ffc6e3b5bb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
<4>[    4.185559] RAX: ffffffffffffffda RBX: 000055dc6653e690 RCX: 00007fe5b78c2839
<4>[    4.185560] RDX: 0000000000000000 RSI: 00007fe5b75a1145 RDI: 0000000000000007
<4>[    4.185561] RBP: 00007fe5b75a1145 R08: 0000000000000000 R09: 00007ffc6e3b5cd0
<4>[    4.185562] R10: 0000000000000007 R11: 0000000000000246 R12: 0000000000000000
<4>[    4.185563] R13: 000055dc6651dc00 R14: 0000000000020000 R15: 000055dc6653e690
<3>[    4.185574] kobject_add_internal failed for input9 with -EEXIST, don't try to register things with the same name in the same directory.
<1>[    4.185628] BUG: unable to handle kernel NULL pointer dereference at 0000000000000048
<6>[    4.185629] PGD 0 P4D 0 
<4>[    4.185631] Oops: 0000 [#1] PREEMPT SMP PTI
<4>[    4.185633] CPU: 11 PID: 245 Comm: kworker/11:1 Not tainted 4.20.0-rc7-g9373de80d37b-drmtip_175+ #1
<4>[    4.185633] Hardware name: Micro-Star International Co., Ltd. MS-7B54/Z370M MORTAR (MS-7B54), BIOS 1.00 10/31/2017
<4>[    4.185636] Workqueue: events azx_probe_work [snd_hda_intel]
<4>[    4.185638] RIP: 0010:klist_add_tail+0x29/0x80
<4>[    4.185639] Code: a9 41 56 41 55 41 54 4c 8d 67 08 55 53 48 89 f3 48 89 37 83 e6 01 4c 89 67 08 48 89 fd 4c 89 67 10 c7 47 18 01 00 00 00 75 53 <48> 8b 43 48 48 85 c0 74 08 48 89 ef e8 16 6a 2a 00 48 89 df 4c 8d
<4>[    4.185640] RSP: 0018:ffff9fa080837c48 EFLAGS: 00010246
<4>[    4.185641] RAX: ffff912792c33098 RBX: 0000000000000000 RCX: 0000000000000006
<4>[    4.185642] RDX: 0000000000000006 RSI: 0000000000000000 RDI: ffff912792c330f0
<4>[    4.185643] RBP: ffff912792c330f0 R08: 0000000000000000 R09: 0000000000000000
<4>[    4.185644] R10: 0000000000000000 R11: 0000000000000000 R12: ffff912792c330f8
<4>[    4.185644] R13: ffff91279bdce7e0 R14: 0000000000000000 R15: 0000000000000000
<4>[    4.185645] FS:  0000000000000000(0000) GS:ffff9127a6ac0000(0000) knlGS:0000000000000000
<4>[    4.185646] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
<4>[    4.185647] CR2: 0000000000000048 CR3: 00000002643f8005 CR4: 00000000003606e0
<4>[    4.185648] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
<4>[    4.185649] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
<4>[    4.185649] Call Trace:
<4>[    4.185652]  device_add+0x444/0x670
<4>[    4.185655]  cdev_device_add+0x43/0x70
<4>[    4.185656]  ? cdev_init+0x4b/0x60
<4>[    4.185658]  evdev_connect+0x195/0x1e0
<4>[    4.185660]  input_attach_handler+0x73/0xb0
<4>[    4.185662]  input_register_device+0x447/0x4f0
<4>[    4.185664]  snd_jack_dev_register+0x94/0xc0
<4>[    4.185665]  __snd_device_register.part.0+0x16/0x30
<4>[    4.185667]  snd_device_register_all+0x33/0x50
<4>[    4.185668]  snd_card_register+0x5f/0x1d0
<4>[    4.185672]  ? snd_hdac_device_register+0x19/0x40 [snd_hda_core]
<4>[    4.185675]  ? azx_probe_work+0x564/0x970 [snd_hda_intel]
<4>[    4.185676]  azx_probe_work+0x564/0x970 [snd_hda_intel]
<4>[    4.185679]  process_one_work+0x262/0x630
<4>[    4.185682]  worker_thread+0x37/0x380
<4>[    4.185684]  ? process_one_work+0x630/0x630
<4>[    4.185686]  kthread+0x119/0x130
<4>[    4.185687]  ? kthread_park+0x80/0x80
<4>[    4.185689]  ret_from_fork+0x3a/0x50
<4>[    4.185692] Modules linked in: snd_hda_codec_hdmi(+) snd_hda_codec_realtek snd_hda_codec_generic i915 x86_pkg_temp_thermal coretemp snd_hda_intel snd_hda_codec crct10dif_pclmul crc32_pclmul snd_hwdep snd_hda_core ghash_clmulni_intel snd_pcm e1000e i2c_i801 mei_me mei prime_numbers
<4>[    4.185699] CR2: 0000000000000048
<4>[    4.185700] ---[ end trace a7d98d770f9af7e6 ]---

Here are the full kernel logs: https://intel-gfx-ci.01.org/tree/drm-tip/drmtip_175/fi-cfl-8700k/boot5.log

This bug has been seen once and might be related to https://bugzilla.kernel.org/show_bug.cgi?id=202107, which also happened only on this machine too.