witness: lock order reversal:
 1st 0xffff800000e53bf8 sbufsnd (&so->so_snd.sb_lock)
 2nd 0xfffffd8068041c48 inode (&ip->i_lock)
lock order [1] sbufsnd (&so->so_snd.sb_lock) -> [2] inode (&ip->i_lock)
lock order data 0xffffffff8292c146 -> 0xffffffff828d64a9 is missing
lock order [2] inode (&ip->i_lock) -> [3] sbufrcv (&so->so_rcv.sb_lock)
#0  rw_enter+0xd1
#1  sblock+0x8a sys/kern/uipc_socket2.c:548
#2  soreceive+0x201 sys/kern/uipc_socket.c:876
#3  fifo_read+0xd2 sys/miscfs/fifofs/fifo_vnops.c:256
#4  VOP_READ+0xc3 sys/kern/vfs_vops.c:227
#5  vn_rdwr+0x10a
#6  vndsetcred+0x86 sys/dev/vnd.c:684
#7  vndioctl+0xac1 sys/dev/vnd.c:485
#8  VOP_IOCTL+0x9a sys/kern/vfs_vops.c:264
#9  vn_ioctl+0xc0 sys/kern/vfs_vnops.c:525
#10 sys_ioctl+0x4a9
#11 syscall+0x8cf mi_syscall sys/sys/syscall_mi.h:180 [inline]
#11 syscall+0x8cf sys/arch/amd64/amd64/trap.c:577
#12 Xsyscall+0x128
lock order [3] sbufrcv (&so->so_rcv.sb_lock) -> [1] sbufsnd (&so->so_snd.sb_lock)
#0  rw_enter+0xd1
#1  sblock+0x8a sys/kern/uipc_socket2.c:548
#2  sosplice+0x2a7 sys/kern/uipc_socket.c:1385
#3  sys_setsockopt+0x1d7 sys/kern/uipc_syscalls.c:1231
#4  syscall+0x8cf mi_syscall sys/sys/syscall_mi.h:180 [inline]
#4  syscall+0x8cf sys/arch/amd64/amd64/trap.c:577
#5  Xsyscall+0x128
Stopped at      db_enter+0x1c:  addq    $0x8,%rsp