MCHECK
MCHECK(m->m_epg_npgs > 0, "no valid pages"); \
MCHECK(m->m_epg_npgs <= nitems(m->m_epg_pa), \
MCHECK(m->m_epg_nrdy <= m->m_epg_npgs, \
MCHECK(m->m_epg_1st_off < PAGE_SIZE, \
MCHECK(m->m_epg_last_len > 0, "zero last page length"); \
MCHECK(m->m_epg_last_len <= PAGE_SIZE, \
MCHECK(m->m_epg_1st_off + \
MCHECK(m->m_epg_hdrlen <= sizeof(m->m_epg_hdr), \
MCHECK(m->m_epg_trllen <= sizeof(m->m_epg_trail), \