umem_cache_walk_t
umem_cache_walk_t *ucw;
ucw = mdb_alloc(sizeof (umem_cache_walk_t), UM_SLEEP);
umem_cache_walk_t *ucw = wsp->walk_data;
umem_cache_walk_t *ucw = wsp->walk_data;
mdb_free(ucw, sizeof (umem_cache_walk_t));