[PATCH] Fix bogus get_page() calls in hugepage code

[PATCH] Fix bogus get_page() calls in hugepage code

From: David Gibson <david@gibson.dropbear.id.au>

Some versions of follow_huge_addr() and follow_huge_pmd() are doing a
get_page() on the target page.  They shouldn't: follow_page() returns an
unpinned page and it is the caller's responsibility to pin the page (if
desired) before dropping page_table_lock.