witness: lock order reversal:
 1st 0xffff8000014e4268 sbufsnd (&so->so_snd.sb_lock)
 2nd 0xfffffd806e27a490 inode (&ip->i_lock)
lock order [1] sbufsnd (&so->so_snd.sb_lock) -> [2] inode (&ip->i_lock)
lock order data 0xffffffff833ce17c -> 0xffffffff833452e1 is missing
lock order [2] inode (&ip->i_lock) -> [3] sbufrcv (&so->so_rcv.sb_lock)
#0  rw_do_enter_write+0xba sys/kern/kern_rwlock.c:234
#1  sblock+0xb6 sys/kern/uipc_socket2.c:536
#2  soreceive+0x27d sys/kern/uipc_socket.c:870
#3  fifo_read+0x117 sys/miscfs/fifofs/fifo_vnops.c:264
#4  VOP_READ+0x101 sys/kern/vfs_vops.c:227
#5  vn_rdwr+0x15b sys/kern/vfs_vnops.c:-1
#6  vndsetcred+0xa1 sys/dev/vnd.c:684
#7  vndioctl+0xdfe sys/dev/vnd.c:485
#8  VOP_IOCTL+0xac sys/kern/vfs_vops.c:264
#9  vn_ioctl+0xf8 sys/kern/vfs_vnops.c:531
#10 sys_ioctl+0x674 sys/kern/sys_generic.c:-1
#11 syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline]
#11 syscall+0xbd4 sys/arch/amd64/amd64/trap.c:748
#12 Xsyscall+0x128
lock order [3] sbufrcv (&so->so_rcv.sb_lock) -> [1] sbufsnd (&so->so_snd.sb_lock)
#0  rw_do_enter_write+0xba sys/kern/kern_rwlock.c:234
#1  sblock+0xb6 sys/kern/uipc_socket2.c:536
#2  sosplice+0x3e1 sys/kern/uipc_socket.c:1347
#3  sys_setsockopt+0x2ba sys/kern/uipc_syscalls.c:1221
#4  syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline]
#4  syscall+0xbd4 sys/arch/amd64/amd64/trap.c:748
#5  Xsyscall+0x128
Stopped at      db_enter+0x25:  addq    $0x8,%rsp