panic: vm_object_vndeallocate: bad object reference count
cpuid = 0
time = 1557770838
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x47/frame 0xfffffe00212776f0
vpanic() at vpanic+0x1e0/frame 0xfffffe0021277750
panic() at panic+0x43/frame 0xfffffe00212777b0
vm_object_collapse() at vm_object_collapse/frame 0xfffffe0021277810
vn_mmap() at vn_mmap+0x2e3/frame 0xfffffe0021277890
kern_mmap() at kern_mmap+0x8a8/frame 0xfffffe0021277950
sys_mmap() at sys_mmap+0x38/frame 0xfffffe0021277980
amd64_syscall() at amd64_syscall+0x436/frame 0xfffffe0021277ab0
fast_syscall_common() at fast_syscall_common+0x101/frame 0xfffffe0021277ab0
--- syscall (198, FreeBSD ELF64, nosys), rip = 0x41309a, rsp = 0x7fffdfffdf38, rbp = 0x6 ---
KDB: enter: panic
[ thread pid 1114 tid 100457 ]
Stopped at      kdb_enter+0x6a: movq    $0,kdb_why