MH_SIZE
#define HW_SIZE(n) (sizeof (modent_step_data_t) + MH_SIZE(n))
if ((mod_hash = kmem_zalloc(MH_SIZE(nchains), sleep)) == NULL)
kmem_free(mod_hash, MH_SIZE(nchains));
kmem_free(hash, MH_SIZE(hash->mh_nchains));