Re: VM map freeze corruption

IMO the cause is the totally_frozen variable, which starts life in a
bogus state (true) and the different code paths can set it to the right
state, or by inaction end up deciding that the initial bogus state was
correct in the first place.  Errors of omission are far too easy in that
kind of model, ISTM, so I propose this slightly different patch, which
albeit yet untested seems easier to verify and easier to get right.