With linux-next-2017-12-14, I get a crash when nouveau is loaded by
systemd-udevd.

[   12.050625] Unable to handle kernel NULL pointer dereference at virtual
address 00000058
[   12.050627] Mem abort info:
[   12.050628]   ESR = 0x96000004
[   12.050630]   Exception class = DABT (current EL), IL = 32 bits
[   12.050631]   SET = 0, FnV = 0
[   12.050632]   EA = 0, S1PTW = 0
[   12.050633] Data abort info:
[   12.050634]   ISV = 0, ISS = 0x00000004
[   12.050635]   CM = 0, WnR = 0
[   12.050637] user pgtable: 4k pages, 48-bit VAs, pgd = 00000000af2ac1b1
[   12.050639] [0000000000000058] *pgd=0000000000000000
[   12.050643] Internal error: Oops: 96000004 [#1] SMP
[   12.050644] Modules linked in: dwmac_dwc_qos_eth(+) stmmac_platform
stmmac ptp nouveau(+) tegra_drm(+) i2c_algo_bit ttm gpio_keys
drm_kms_helper drm drm_panel_orientation_quirks(P) syscopy
area sysfillrect sysimgblt fb_sys_fops pps_core host1x
[   12.050665] CPU: 0 PID: 261 Comm: systemd-udevd Tainted: P S
  4.15.0-rc3-next-20171214-ARCH-AEDEN+ #3
[   12.050666] Hardware name: NVIDIA Tegra186 P2771-0000 Development Board
(DT)
[   12.050668] pstate: 80000005 (Nzcv daif -PAN -UAO)
[   12.050675] pc : mutex_lock+0x28/0x58
[   12.050676] lr : mutex_lock+0x1c/0x58
[   12.050677] sp : ffff00000a33b970
[   12.050679] x29: ffff00000a33b970 x28: ffff000009527a20
[   12.050682] x27: ffff8001c5089c00 x26: ffffffffffffffff
[   12.050684] x25: 0000000000000001 x24: 0000000000000001
[   12.050686] x23: 0000000000000000 x22: 0000000000000000
[   12.050689] x21: ffff8001c8c5af80 x20: 0000000000000058
[   12.050691] x19: 0000000000000058 x18: 0000000000000230
[   12.050693] x17: fffffffffffffff0 x16: ffff7e00071fb300
[   12.050695] x15: 0000000000000000 x14: ffffffffffffffff
[   12.050697] x13: 0000000000000038 x12: 0000000000000018
[   12.050700] x11: 0101010101010101 x10: 7f7f7f7f7f7f7f7f
[   12.050702] x9 : 0000000000000000 x8 : ffff8001c8c5b000
[   12.050704] x7 : 0000000000000000 x6 : 000000000000003f
[   12.050706] x5 : 0000000000000040 x4 : 0000000000000000
[   12.050708] x3 : 0000000000000004 x2 : 0000000000000000
[   12.050710] x1 : ffff8001c915b800 x0 : 0000000000000000
[   12.050713] Process systemd-udevd (pid: 261, stack limit =
0x00000000247b2b64)
[   12.050714] Call trace:
[   12.050717]  mutex_lock+0x28/0x58
[   12.050721]  iommu_attach_device+0xac/0xf8
[   12.050948]  nvkm_device_tegra_new+0x260/0x510 [nouveau]
[   12.051166]  nouveau_platform_device_create+0x48/0xa8 [nouveau]
[   12.051364]  nouveau_platform_probe+0x34/0x80 [nouveau]
[   12.051368]  platform_drv_probe+0x60/0xc0
[   12.051372]  driver_probe_device+0x33c/0x4a0
[   12.051375]  __driver_attach+0xdc/0x128
[   12.051377]  bus_for_each_dev+0x5c/0xa8
[   12.051379]  driver_attach+0x30/0x40
[   12.051381]  bus_add_driver+0x218/0x2b8
[   12.051384]  driver_register+0x6c/0x118
[   12.051385]  __platform_driver_register+0x54/0x60
[   12.051578]  nouveau_drm_init+0x164/0x1000 [nouveau]
[   12.051584]  do_one_initcall+0x44/0x138
[   12.051588]  do_init_module+0x64/0x1dc
[   12.051590]  load_module+0x12f4/0x14b8
[   12.051592]  SyS_finit_module+0xd8/0xf0
[   12.051594]  el0_svc_naked+0x20/0x24
[   12.051597] Code: 97fffa1e d2800000 d5384101 f9800271 (c85ffe62)
[   12.051600] ---[ end trace 7e15532ee457d321 ]---
[   12.346156] iommu: Adding device 15220000.display to group 1
[   12.360735] tegra-dpaux 15040000.dpaux: 15040000.dpaux supply vdd not
found, using dummy regulator
[   12.372895] tegra-dpaux 155c0000.dpaux: 155c0000.dpaux supply vdd not
found, using dummy regulator
[   12.384763] tegra-sor 15580000.sor: failed to probe output: -517
[   12.391830] tegra-sor 15580000.sor: failed to probe output: -517

Here's the trace with files and line numbers (via addr2line -pfi):

__cmpxchg_case_acq_8 at arch/arm64/include/asm/atomic_ll_sc.h:284
 (inlined by) __cmpxchg_acq at arch/arm64/include/asm/cmpxchg.h:140
 (inlined by) __mutex_trylock_fast at kernel/locking/mutex.c:143
 (inlined by) mutex_lock at kernel/locking/mutex.c:240
iommu_group_device_count at drivers/iommu/iommu.c:673
 (inlined by) iommu_attach_device at drivers/iommu/iommu.c:1312
clk_prepare_enable at include/linux/clk.h:646
 (inlined by) nvkm_device_tegra_power_up at
drivers/gpu/drm/nouveau/nvkm/engine/device/tegra.c:37
 (inlined by) nvkm_device_tegra_new at
drivers/gpu/drm/nouveau/nvkm/engine/device/tegra.c:319
nouveau_platform_device_create at drivers/gpu/drm/nouveau/nouveau_drm.c:1193
nouveau_platform_probe at drivers/gpu/drm/nouveau/nouveau_platform.c:44
platform_drv_probe at drivers/base/platform.c:577
really_probe at drivers/base/dd.c:423
 (inlined by) driver_probe_device at drivers/base/dd.c:565
__driver_attach at drivers/base/dd.c:799
bus_for_each_dev at drivers/base/bus.c:311
driver_attach at drivers/base/dd.c:819
bus_add_driver at drivers/base/bus.c:668
driver_register at drivers/base/driver.c:166
__platform_driver_register at drivers/base/platform.c:636
nouveau_drm_init at drivers/gpu/drm/nouveau/nouveau_drm.c:1212
do_one_initcall at init/main.c:833
do_init_module at kernel/module.c:3451
load_module at kernel/module.c:3775
SYSC_finit_module at kernel/module.c:3874
 (inlined by) SyS_finit_module at kernel/module.c:3850
el0_svc_naked at arch/arm64/kernel/entry.S:937

Serial output is attached which includes rest of dmesg.

Thanks,
-Anthony