Fixpoint freelist_no_overlap (l: list (block * Z * Z)) : Prop :=
match l with
| nil => True
| (b, lo, hi) :: l' =>
freelist_no_overlap l' /\
(forall b' lo' hi', In (b', lo', hi') l' ->
b' <> b \/ hi' <= lo \/ hi <= lo')
end.

Lemma can_free_list:
forall l m,
(forall b lo hi, In (b, lo, hi) l -> Mem.range_perm m b lo hi Cur Freeable) ->
freelist_no_overlap l ->
exists m', Mem.free_list m l = Some m'.