mm: remove put_page_unless_one()

It has no callers.
Signed-off-by: NVineet Gupta <vgupta@synopsys.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

include/linux/mm.h

@@ -361,18 +361,6 @@ static inline int get_page_unless_zero(struct page *page)
 	return atomic_inc_not_zero(&page->_count);
 }
 
-/*
- * Try to drop a ref unless the page has a refcount of one, return false if
- * that is the case.
- * This is to make sure that the refcount won't become zero after this drop.
- * This can be called when MMU is off so it must not access
- * any of the virtual mappings.
- */
-static inline int put_page_unless_one(struct page *page)
-{
-	return atomic_add_unless(&page->_count, -1, 1);
-}
-
 extern int page_is_ram(unsigned long pfn);
 extern int region_is_ram(resource_size_t phys_addr, unsigned long size);