I am also seeing this with Linux 4.18-rc5+ on a MSI MS-7A37/B3=
50M MORTAR.

```
19.940: [    0.072004] ACPI BIOS Error (bug): Failure creating [\_SB.SMIC],
AE_ALREADY_EXISTS (20180531/dswload2-316)
19.939: [    0.080004] ACPI Error: AE_ALREADY_EXISTS, During name
lookup/catalog (20180531/psobject-221)
19.939: [    0.092000] ACPI Error: Ignore error and continue table load
(20180531/psobject-604)
19.939: [    0.096021] ACPI BIOS Error (bug): Failure creating [\_SB.SMIB],
AE_ALREADY_EXISTS (20180531/dsfield-594)
20.044: [    0.205797] AMD-Vi: Unable to write to IOMMU perf counter.
20.104: <ff>[    1.077147] ata9.00: failed to set xfermode (err_mask=
=3D0x40)
54.879: [   35.052403] sp5100-tco sp5100-tco: Watchdog hardware is disabled
54.924: [   35.104108] Error: Driver 'pcspkr' is already registered,
aborting...
55.061: [   35.246972] kvm: disabled by bios
55.077: [   35.265941] kfd kfd: kgd2kfd_probe failed
55.344: [   35.537445] general protection fault: 0000 [#1] SMP NOPTI
55.344: [   35.543209] CPU: 0 PID: 367 Comm: systemd-udevd Not tainted
4.18.0-rc5+ #1
55.345: [   35.550371] Hardware name: MSI MS-7A37/B350M MORTAR (MS-7A37), B=
IOS
1.G1 05/17/2018
55.345: [   35.558562] RIP: 0010:prefetch_freepointer+0x10/0x20
55.346: [   35.563881] Code: 89 d3 e8 c3 fe 4a 00 85 c0 0f 85 31 75 00 00 4=
8 83
c4 08 5b 5d 41 5c 41 5d c3 0f 1f 44 00 00 48 85 f6 74 13 8b 47 20 48 01 c6 =
<48>
33 36 48 33 b7 38 01 00 00 0f 18 0e c3 66 90 0f 1f 44 00 00 48=20
55.347: [   35.584215] RSP: 0018:ffff9c3181f77560 EFLAGS: 00010202
55.347: [   35.589849] RAX: 0000000000000000 RBX: 4b2c8be0a60f6ab9 RCX:
0000000000000ccc
55.348: [   35.597492] RDX: 0000000000000ccb RSI: 4b2c8be0a60f6ab9 RDI:
ffff8d5b1e406e80
55.349: [   35.605166] RBP: ffff8d5b1e406e80 R08: ffff8d5b1e824f00 R09:
ffffffffc0a45423
55.349: [   35.612808] R10: fffff1b60fff64c0 R11: ffff9c3181f77520 R12:
00000000006080c0
55.350: [   35.620451] R13: 0000000000000230 R14: ffff8d5b1e406e80 R15:
ffff8d5b0c304400
55.350: [   35.628116] FS:  00007fb194e4b8c0(0000) GS:ffff8d5b1e800000(0000)
knlGS:0000000000000000
55.351: [   35.636771] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
55.351: [   35.642931] CR2: 000055c0661d60d0 CR3: 000000040b9ee000 CR4:
00000000003406f0
55.352: [   35.650566] Call Trace:
55.352: [   35.653198]  kmem_cache_alloc_trace+0xb5/0x1c0
55.352: [   35.658077]  ? dal_ddc_service_create+0x38/0x110 [amdgpu]
55.353: [   35.663962]  dal_ddc_service_create+0x38/0x110 [amdgpu]
55.353: [   35.669656]  ? dal_gpio_create_irq+0x19/0x30 [amdgpu]
55.354: [   35.675155]  ? dal_gpio_service_create_irq+0x48/0x70 [amdgpu]
55.354: [   35.681413]  ? get_hpd_gpio+0x63/0x90 [amdgpu]
55.355: [   35.686281]  construct+0x201/0x640 [amdgpu]
55.355: [   35.690838]  link_create+0x33/0x50 [amdgpu]
55.356: [   35.695400]  dc_create+0x2d3/0x640 [amdgpu]
55.356: [   35.699980]  dm_hw_init+0xc8/0x130 [amdgpu]
55.356: [   35.704568]  amdgpu_device_init.cold.28+0x1043/0x11ee [amdgpu]
55.357: [   35.710923]  amdgpu_driver_load_kms+0x86/0x2c0 [amdgpu]
55.357: [   35.716535]  drm_dev_register+0x109/0x140 [drm]
55.358: [   35.721468]  amdgpu_pci_probe+0x13c/0x1c0 [amdgpu]
55.358: [   35.726612]  local_pci_probe+0x41/0x90
55.358: [   35.730628]  pci_device_probe+0x189/0x1a0
55.359: [   35.734952]  driver_probe_device+0x2b9/0x460
55.359: [   35.739544]  __driver_attach+0xdd/0x110
55.359: [   35.743633]  ? driver_probe_device+0x460/0x460
55.360: [   35.748383]  bus_for_each_dev+0x76/0xc0
55.360: [   35.752480]  ? klist_add_tail+0x3b/0x70
55.360: [   35.756574]  bus_add_driver+0x152/0x230
55.361: [   35.760692]  ? 0xffffffffc0c37000
55.361: [   35.764255]  driver_register+0x6b/0xb0
55.361: [   35.768265]  ? 0xffffffffc0c37000
55.361: [   35.771814]  do_one_initcall+0x46/0x1c3
55.362: [   35.775944]  ? _cond_resched+0x15/0x30
55.362: [   35.779940]  ? kmem_cache_alloc_trace+0x15c/0x1c0
55.362: [   35.784982]  ? do_init_module+0x22/0x210
55.362: [   35.789172]  do_init_module+0x5a/0x210
55.363: [   35.793227]  load_module+0x2124/0x2500
55.363: [   35.797250]  ? vfs_read+0x110/0x140
55.363: [   35.800985]  ? __do_sys_finit_module+0xa8/0x110
55.364: [   35.805837]  __do_sys_finit_module+0xa8/0x110
55.364: [   35.810516]  do_syscall_64+0x55/0xe0
55.364: [   35.814358]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
55.365: [   35.819768] RIP: 0033:0x7fb195ea8a79
55.365: [   35.823607] Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 4=
0 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 df 43 0c 00 f7 d8 64 89 01 48=20
55.366: [   35.843819] RSP: 002b:00007ffec10a9518 EFLAGS: 00000246 ORIG_RAX:
0000000000000139
55.367: [   35.851960] RAX: ffffffffffffffda RBX: 00005561d3488730 RCX:
00007fb195ea8a79
55.367: [   35.859595] RDX: 0000000000000000 RSI: 00007fb195bb00ed RDI:
0000000000000013
55.368: [   35.867206] RBP: 00007fb195bb00ed R08: 0000000000000000 R09:
0000000000000000
55.368: [   35.874824] R10: 0000000000000013 R11: 0000000000000246 R12:
0000000000000000
55.369: [   35.882477] R13: 00005561d3478500 R14: 0000000000020000 R15:
00005561d3488730
55.370: [   35.890099] Modules linked in: amdkfd edac_mce_amd nls_ascii ppd=
ev
ccp wmi_bmof rng_core nls_cp437 vfat fat kvm amdgpu(+) irqbypass
snd_hda_codec_realtek snd_hda_codec_generic chash gpu_sched snd_hda_codec_h=
dmi
ttm efi_pstore crct10dif_pclmul crc32_pclmul drm_kms_helper ghash_clmulni_i=
ntel
snd_hda_intel snd_hda_codec drm pcspkr efivars snd_hda_core sp5100_tco k10t=
emp
snd_hwdep snd_pcm r8169 snd_timer snd sg i2c_piix4 soundcore i2c_algo_bit m=
ii
parport_pc wmi parport video button acpi_cpufreq efivarfs ip_tables x_tables
autofs4 ext4 crc16 mbcache jbd2 fscrypto dm_crypt dm_mod raid10 raid456
libcrc32c crc32c_generic async_raid6_recov async_memcpy async_pq async_xor =
xor
async_tx raid6_pq raid1 raid0 multipath linear md_mod sd_mod evdev hid_gene=
ric
usbhid hid crc32c_intel aesni_intel aes_x86_64 crypto_simd
55.375: [   35.966200]  xhci_pci cryptd glue_helper ahci libahci xhci_hcd
libata usbcore scsi_mod gpio_amdpt gpio_generic
55.375: [   35.976975] ---[ end trace a9eb7c09b06a0207 ]---
```