syzbot

login: panic: Can't clear local locks with F_UNLCKSYS
cpuid = 1
time = 1552712050
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x47/frame 0xfffffe001fa04520
vpanic() at vpanic+0x1e0/frame 0xfffffe001fa04580
panic() at panic+0x43/frame 0xfffffe001fa045e0
lf_advlockasync() at lf_advlockasync+0x14dd/frame 0xfffffe001fa046a0
lf_advlock() at lf_advlock+0x5e/frame 0xfffffe001fa04710
vop_stdadvlock() at vop_stdadvlock+0xf2/frame 0xfffffe001fa04810
VOP_ADVLOCK_APV() at VOP_ADVLOCK_APV+0xc5/frame 0xfffffe001fa04840
kern_fcntl() at kern_fcntl+0xfd1/frame 0xfffffe001fa048f0
kern_fcntl_freebsd() at kern_fcntl_freebsd+0x14f/frame 0xfffffe001fa04980
amd64_syscall() at amd64_syscall+0x436/frame 0xfffffe001fa04ab0
fast_syscall_common() at fast_syscall_common+0x101/frame 0xfffffe001fa04ab0
--- syscall (0, FreeBSD ELF64, nosys), rip = 0x41c31a, rsp = 0x7fffffffeae8, rbp = 0x7fffffffeb40 ---
KDB: enter: panic
[ thread pid 759 tid 100094 ]
Stopped at      kdb_enter+0x6a: movq    $0,kdb_why