panic: vm_object_vndeallocate: bad object reference count
cpuid = 0
time = 1557782405
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x47/frame 0xfffffe001f5b66f0
vpanic() at vpanic+0x1e0/frame 0xfffffe001f5b6750
panic() at panic+0x43/frame 0xfffffe001f5b67b0
vm_object_collapse() at vm_object_collapse/frame 0xfffffe001f5b6810
vn_mmap() at vn_mmap+0x2e3/frame 0xfffffe001f5b6890
kern_mmap() at kern_mmap+0x8a8/frame 0xfffffe001f5b6950
sys_mmap() at sys_mmap+0x38/frame 0xfffffe001f5b6980
amd64_syscall() at amd64_syscall+0x436/frame 0xfffffe001f5b6ab0
fast_syscall_common() at fast_syscall_common+0x101/frame 0xfffffe001f5b6ab0
--- syscall (0, FreeBSD ELF64, nosys), rip = 0x41c34a, rsp = 0x7fffffffead8, rbp = 0x7fffffffeb40 ---
KDB: enter: panic
[ thread pid 761 tid 100079 ]
Stopped at      kdb_enter+0x6a: movq    $0,kdb_why