I am really confused about these two functions. The following code snippet:

	if (unlikely(atomic_read(&page->_mapcount) != -1))
		bad_reason = "nonzero mapcount";
	if (unlikely(page->mapping != NULL))
		bad_reason = "non-NULL mapping";
	if (unlikely(page_ref_count(page) != 0))
		bad_reason = "nonzero _count";
        ...
Wouldn't the previous value of "bad_reason" be overwritten by 
the later? Hope to receive from you.