A few quick mmap questions

[Ken Brown]

Hi Corinna,

I plan to keep working on mmap issues while you're on vacation.  A few 
questions have come up while I've been looking at the code.

1. The function is_mmapped_region() doesn't seem to be used anywhere. 
Is it OK to remove it?

2. I can't find any uses of filler pages, in spite of the comment 
preceding the definition of __PROT_FILLER.  Is it OK to remove all 
references to __PROT_FILLER and the associated methods?

3. I'm still puzzled about mmap_is_attached_or_noreserve().  See my 
email from yesterday on the cygwin ML.  I think it's broken but I may be 
wrong.  If I'm right, I don't see an easy way to fix it.  As I said 
before, the only thing I can think of is to sort the mmap_list of 
anonymous mappings.  But I'm afraid that would be too expensive (in 
terms of time).

4. On the other hand, maybe we should always keep it sorted as we insert 
elements.  That would simplify the task of recycling a region that 
overlaps more than one mmap_record.  I can't guess how expensive that 
would be.  I guess the question is how long that list might get in 
real-world applications.

Thanks.

Ken