Patch from: Ian Campbell

This changes the atomic_t in struct page named count into a private
member _count which breaks arch/arm/mm/init.c at line 80 which reads
page->count directly in show_mem().
                                                                                
The comments in the above changeset suggest that page_count(page) is
precisely equal to the old page->count semantics, even though the
semantics of _count are different, so I think the following is correct