panic: pmap_demote_pde: page table page for a wired mapping is missing
cpuid = 0
time = 1552804140
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x47/frame 0xfffffe001fa276b0
vpanic() at vpanic+0x1e0/frame 0xfffffe001fa27710
panic() at panic+0x43/frame 0xfffffe001fa27770
pmap_demote_pde_locked() at pmap_demote_pde_locked+0x1288/frame 0xfffffe001fa27840
pmap_remove() at pmap_remove+0x5c8/frame 0xfffffe001fa278d0
vm_map_protect() at vm_map_protect+0x666/frame 0xfffffe001fa27940
sys_mprotect() at sys_mprotect+0xcc/frame 0xfffffe001fa27980
amd64_syscall() at amd64_syscall+0x436/frame 0xfffffe001fa27ab0
fast_syscall_common() at fast_syscall_common+0x101/frame 0xfffffe001fa27ab0
--- syscall (0, FreeBSD ELF64, nosys), rip = 0x4574fa, rsp = 0x7fffdffdcf88, rbp = 0x6b5a00 ---
KDB: enter: panic
[ thread pid 759 tid 100101 ]
Stopped at      kdb_enter+0x6a: movq    $0,kdb_why