zposnull: calling stock drm_atomic_normalize_zpos (expect NULL-deref panic)
Fatal user address access from kernel mode from kldload at ffffffff8260c81b


Fatal trap 12: page fault while in kernel mode
cpuid = 3; lapic id = 3
fault virtual address	= 0xa
fault code		= supervisor write data, page not present
instruction pointer	= 0x8:0xffffffff8260c81b
stack pointer	        = 0x10:0xfffff8011836b748
frame pointer	        = 0x10:0xfffff8011836b798
code segment		= base 0x0, limit 0xfffff, type 0x1b
			= DPL 0, pres 1, long 0, def32 0, gran 1
processor eflags	= interrupt enabled, resume, IOPL = 0
current process		= 1627
current thread          = pri 6 
kernel: type 12 trap, code=2

CPU3 stopping CPUs: 0x00000037
 stopped
Stopped at      drm_atomic_normalize_zpos+0x6b: orb     $0x10,0xa(%rax)
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