panic: sbfree: m 0xfffff80012b09600 !M_NOTREADY
cpuid = 0
time = 1552864696
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x47/frame 0xfffffe00212a94c0
vpanic() at vpanic+0x1e0/frame 0xfffffe00212a9520
panic() at panic+0x43/frame 0xfffffe00212a9580
sbfree() at sbfree+0x1f4/frame 0xfffffe00212a95c0
sbcut_internal() at sbcut_internal+0xf0/frame 0xfffffe00212a9610
sbrelease_internal() at sbrelease_internal+0x9c/frame 0xfffffe00212a9650
sofree() at sofree+0x492/frame 0xfffffe00212a96b0
soclose() at soclose+0x5b3/frame 0xfffffe00212a9730
_fdrop() at _fdrop+0x3a/frame 0xfffffe00212a9760
closef() at closef+0x27d/frame 0xfffffe00212a97f0
fdescfree_fds() at fdescfree_fds+0xbd/frame 0xfffffe00212a9840
fdescfree() at fdescfree+0x58a/frame 0xfffffe00212a9900
exit1() at exit1+0x780/frame 0xfffffe00212a9970
sys_sys_exit() at sys_sys_exit+0xd/frame 0xfffffe00212a9980
amd64_syscall() at amd64_syscall+0x436/frame 0xfffffe00212a9ab0
fast_syscall_common() at fast_syscall_common+0x101/frame 0xfffffe00212a9ab0
--- syscall (1, FreeBSD ELF64, sys_sys_exit), rip = 0x44f30a, rsp = 0x7fffffffec58, rbp = 0 ---
KDB: enter: panic
[ thread pid 913 tid 100182 ]
Stopped at      kdb_enter+0x6a: movq    $0,kdb_why