NULL pointer dereference BUG in check_preempt_wakeup

[Sowadski. Craig]

Hello,

I have been having random lockups with my new Ryzen build. I have
finally setup a serial console and received the Oops info below. I
have had the problem with 4.10, 4.11, 4.11.2, and 4.11.3, but this is
the only trap of info I have so I do not know that all my lockups are
of the same nature. I'm not sure what to investigate to further help
debug this. Please let me know if there is anything I can provide.

Thanks,

Craig Sowadski (sowadski@xxxxxxxxxxxxx)


[391216.417126] BUG: unable to handle kernel NULL pointer dereference at 0000000
[391216.464610] IP: check_preempt_wakeup+0xcb/0x230
[391216.492253] PGD 401fd0067
[391216.492254] PUD 407e88067
[391216.508969] PMD 0
[391216.525685]
[391216.547658] Oops: 0000 [#1] SMP
[391216.566975] Modules linked in: iptable_filter ip_tables x_tables
cdc_acm nlswmi sparse_keymap video irqbypass crct10dif_pclmul
crc32_pclmul ghash_clmulni_ind snd_seq glue_helper cryptd
snd_hda_codec_hdmi snd_hda_intel snd_hda_codec snd_are_core mac_hid
parport_pc ppdev lp parport autofs4 btrfs xor raid6_pq dm_mirro
[391216.990926]  ttm drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fop
[391217.070692] CPU: 1 PID: 2 Comm: kthreadd Not tainted 4.11.3-041103-generic #
[391217.119686] Hardware name: System manufacturer System Product Name/PRIME B35
[391217.175985] task: ffff98010ce11680 task.stack: ffffc043818c0000
[391217.211969] RIP: 0010:check_preempt_wakeup+0xcb/0x230
[391217.242746] RSP: 0018:ffffc043818c3d70 EFLAGS: 00010006
[391217.274566] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000000000000
[391217.317843] RDX: 0000000000000000 RSI: ffff9801071b1680 RDI: ffff98011ec1b22
[391217.361118] RBP: ffffc043818c3da8 R08: 0000000000000000 R09: 000000000000000
[391217.404392] R10: ffffc043818c3d20 R11: 0000000000800711 R12: 000000000000000
[391217.447667] R13: 0000000000000008 R14: ffff980104149680 R15: 000000000000000
[391217.490940] FS:  0000000000000000(0000) GS:ffff98011ec40000(0000) knlGS:0000
[391217.539937] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[391217.574880] CR2: 0000000000000150 CR3: 000000040b13b000 CR4: 00000000003406e
[391217.618156] Call Trace:
[391217.633311]  check_preempt_curr+0x79/0x90
[391217.657839]  wake_up_new_task+0x12d/0x240
[391217.682367]  _do_fork+0x131/0x390
[391217.702726]  kernel_thread+0x29/0x30
[391217.724648]  kthreadd+0x29f/0x2f0
[391217.745012]  ? kthread_create_on_cpu+0xc0/0xc0
[391217.772138]  ret_from_fork+0x2c/0x40
[391217.794060] Code: 00 00 39 c2 75 f2 48 8b bb 50 01 00 00 49 39 bc
24 50 01 085 ff
[391217.907685] RIP: check_preempt_wakeup+0xcb/0x230 RSP: ffffc043818c3d70
[391217.947311] CR2: 0000000000000150
[391217.979880] ---[ end trace a770376e6c998367 ]---