Definition max_inv mf := forall b ofs, Mem.valid_block mf b ->
                                    permission_at mf b ofs Max = Some Freeable.

Lemma max_inv_store: forall m m' chunk b ofs v pmap (Hlt: permMapLt pmap (getMaxPerm m)) (Hmax: max_inv m) (Hstore: Mem.store chunk (restrPermMap Hlt) b ofs v = Some m'), max_inv m'.