Netgraph/mpd5 stability issues

[Przemyslaw Frasunek]

> (kgdb) print *ng_name_hash[116].lh_first

It looks like this one is corrupted:

(kgdb) print
*ng_name_hash[116].lh_first.nd_nodes.le_next.nd_nodes.le_next.nd_nodes.le_next.nd_nodes.le_next
$19 = {nd_name = "ng258", '\0' <repeats 26 times>, nd_type = 0xc61871a0,
  nd_flags = 0, nd_refs = 1, nd_numhooks = 0, nd_private = 0xccabdbc0,
  nd_ID = 454433, nd_hooks = {lh_first = 0x0}, nd_nodes = {
    le_next = 0xcc28c380, le_prev = 0xcbadadbc}, nd_idnodes = {
    le_next = 0xcc410400, le_prev = 0xc5f4f764}, nd_work = {tqe_next = 0x0,
    tqe_prev = 0x0}, nd_input_queue = {q_flags = 0, q_mtx = {lock_object = {
        lo_name = 0xc5f4e986 "ng_node", lo_type = 0xc5f4e986 "ng_node",
        lo_flags = 16973824, lo_witness_data = {lod_list = {stqe_next = 0x0},
          lod_witness = 0x0}}, mtx_lock = 4, mtx_recurse = 0}, queue = 0x0,
    last = 0xc69e16f0, q_node = 0xc69e1680}}

nd_nodes->le_prev is 0xcbadadbc

(kgdb) print
*ng_name_hash[116].lh_first.nd_nodes.le_next.nd_nodes.le_next.nd_nodes.le_next.nd_nodes.le_next.nd_nodes.le_next
$20 = {
  nd_name = "\b\000\000\000
\000\000\000\005\000\000\000\000\000\000\000\220_q\001\036QĆCcmd5\000\000\000",
nd_type = 0x0, nd_flags = 0, nd_refs = 0,
  nd_numhooks = 0, nd_private = 0x0, nd_ID = 0, nd_hooks = {
    lh_first = 0x68676972}, nd_nodes = {le_next = 0x74, le_prev = 0x0},
  nd_idnodes = {le_next = 0x0, le_prev = 0x0}, nd_work = {tqe_next = 0x0,
    tqe_prev = 0x0}, nd_input_queue = {q_flags = 0, q_mtx = {lock_object = {
        lo_name = 0x0, lo_type = 0x0, lo_flags = 1, lo_witness_data = {
          lod_list = {stqe_next = 0x6}, lod_witness = 0x6}}, mtx_lock = 0,
      mtx_recurse = 0}, queue = 0x0, last = 0xcc28c3f0, q_node = 0xcc28c380}}

(kgdb) print
*ng_name_hash[116].lh_first.nd_nodes.le_next.nd_nodes.le_next.nd_nodes.le_next.nd_nodes.le_next.nd_nodes.le_next.nd_nodes.le_next
Cannot access memory at address 0x74