MT_FREE
if (__predict_false(m->m_type == MT_FREE)) {
m->m_type = MT_FREE;
if (__predict_false(m->m_type == MT_FREE)) {
m->m_type = MT_FREE;
if (__predict_false(n->m_type == MT_FREE)) {
KASSERT(type != MT_FREE);
KASSERT((t) != MT_FREE); \
seen[MT_FREE] = YES;
m->m_type = MT_FREE;
assert(m->m_type != MT_FREE);