witness: lock order reversal:
 1st 0xffff800010fdfc68 sbufsnd (&so->so_snd.sb_lock)
 2nd 0xfffffd806bdf4c60 inode (&ip->i_lock)
lock order [1] sbufsnd (&so->so_snd.sb_lock) -> [2] inode (&ip->i_lock)
lock order data 0xffffffff8350c936 -> 0xffffffff834792c6 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:890
#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:685
#7  vndioctl+0xdfc sys/dev/vnd.c:486
#8  VOP_IOCTL+0xac sys/kern/vfs_vops.c:264
#9  vn_ioctl+0xf8 sys/kern/vfs_vnops.c:537
#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:783
#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+0x312 sys/kern/uipc_socket.c:1347
#3  sys_setsockopt+0x2ba sys/kern/uipc_syscalls.c:1226
#4  syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline]
#4  syscall+0xbd4 sys/arch/amd64/amd64/trap.c:783
#5  Xsyscall+0x128
Stopped at      db_enter+0x25:  addq    $0x8,%rsp
ddb{0}> 
ddb{0}> set $lines = 0
ddb{0}> set $maxwidth = 0
ddb{0}> show panic
the kernel did not panic
ddb{0}> trace
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
witness_checkorder(fffffd806bdf4c60,9,0) at witness_checkorder+0x10d1 sys/kern/subr_witness.c:-1
rw_do_enter_write(fffffd806bdf4c48,1) at rw_do_enter_write+0xba sys/kern/kern_rwlock.c:234
rrw_enter(fffffd806bdf4c48,1) at rrw_enter+0xc6 sys/kern/kern_rwlock.c:621
VOP_LOCK(fffffd8077b188b0,2001) at VOP_LOCK+0xbd sys/kern/vfs_vops.c:527
vn_lock(fffffd8077b188b0,2001) at vn_lock+0xa4 sys/kern/vfs_vnops.c:576
vfs_lookup(ffff800037b94ff0) at vfs_lookup+0x10f sys/kern/vfs_lookup.c:431
namei(ffff800037b94ff0) at namei+0x7c5 sys/kern/vfs_lookup.c:250
unp_connect(ffff800010fdfa80,fffffd807809cc00,ffff8000ffff3c98) at unp_connect+0x29d sys/kern/uipc_usrreq.c:872
uipc_dgram_send(ffff800010fdfa80,fffffd806c27cb00,fffffd807809cc00,fffffd806c449100) at uipc_dgram_send+0x163 sys/kern/uipc_usrreq.c:609
sosend(ffff800010fdfa80,fffffd807809cc00,ffff800037b95278,0,fffffd806c449100,0) at sosend+0x804 sys/kern/uipc_socket.c:-1
sendit(ffff8000ffff3c98,4,ffff800037b953f8,0,ffff800037b954b0) at sendit+0x5a5 sys/kern/uipc_syscalls.c:785
sys_sendmsg(ffff8000ffff3c98,ffff800037b95560,ffff800037b954b0) at sys_sendmsg+0x246 sys/kern/uipc_syscalls.c:603
syscall(ffff800037b95560) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff800037b95560) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x25d1b5d27f0, count: -15
ddb{0}> show registers
rdi                                0
rsi                          0x80000    acpi_pdirpa+0x6be71
rbp               0xffff800037b94c60
rbx                                0
rdx               0xffff8000015f5d40
rcx               0xffff8000ffff3c98
rax                          0x7ffff    acpi_pdirpa+0x6be70
r8                0xffff800037b94b40
r9                0x8080808080808080
r10               0x41a4392ab7cca131
r11               0x6a7d53863ace7cbc
r12               0xfffffd80040ad8c0
r13               0xfffffd8004894b58
r14                              0x3
r15               0xffffffff83514d06    substchar+0x11a61
rip               0xffffffff8194f6b5    db_enter+0x25
cs                               0x8
rflags                         0x246
rsp               0xffff800037b94c50
ss                              0x10
db_enter+0x25:  addq    $0x8,%rsp
ddb{0}>