panic: Duplicate alloc of 0xfffff80003aaef60 from zone 0xfffff8007ffdc900(16) slab 0xfffff80003aaef90(492)

cpuid = 0
time = 1495898827
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe007bcf9060
vpanic() at vpanic+0x19c/frame 0xfffffe007bcf90e0
panic() at panic+0x43/frame 0xfffffe007bcf9140
uma_dbg_alloc() at uma_dbg_alloc+0x174/frame 0xfffffe007bcf9170
uma_zalloc_arg() at uma_zalloc_arg+0x588/frame 0xfffffe007bcf91d0
malloc() at malloc+0x1e0/frame 0xfffffe007bcf9220
dtrace_probe_create() at dtrace_probe_create+0x272/frame 0xfffffe007bcf9290
dtvirt_probe_create() at dtvirt_probe_create+0x25b/frame 0xfffffe007bcf9450
dtrace_ioctl() at dtrace_ioctl+0x27b1/frame 0xfffffe007bcf9550
devfs_ioctl() at devfs_ioctl+0xc0/frame 0xfffffe007bcf95a0
VOP_IOCTL_APV() at VOP_IOCTL_APV+0xe0/frame 0xfffffe007bcf95d0
vn_ioctl() at vn_ioctl+0x124/frame 0xfffffe007bcf96d0
devfs_ioctl_f() at devfs_ioctl_f+0x1f/frame 0xfffffe007bcf96f0
kern_ioctl() at kern_ioctl+0x2cd/frame 0xfffffe007bcf9750
sys_ioctl() at sys_ioctl+0x16f/frame 0xfffffe007bcf9830
amd64_syscall() at amd64_syscall+0x589/frame 0xfffffe007bcf99b0
Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe007bcf99b0
--- syscall (54, FreeBSD ELF64, sys_ioctl), rip = 0x80051367a, rsp = 0x7fffffffe7f8, rbp = 0x7fffffffea90 ---
KDB: enter: panic
[ thread pid 688 tid 100116 ]
Stopped at      kdb_enter+0x3b: movq    $0,kdb_why