mm: uninline page_mapped()

It's huge.  Uninlining it saves 206 bytes per callsite.  Shaves 4924
bytes from the x86_64 allmodconfig vmlinux.

[akpm@linux-foundation.org: coding-style fixes]
Cc: Steve Capper <steve.capper@arm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 5b37513..9c2852c 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1032,26 +1032,7 @@
 	return page->index;
 }
 
-/*
- * Return true if this page is mapped into pagetables.
- * For compound page it returns true if any subpage of compound page is mapped.
- */
-static inline bool page_mapped(struct page *page)
-{
-	int i;
-	if (likely(!PageCompound(page)))
-		return atomic_read(&page->_mapcount) >= 0;
-	page = compound_head(page);
-	if (atomic_read(compound_mapcount_ptr(page)) >= 0)
-		return true;
-	if (PageHuge(page))
-		return false;
-	for (i = 0; i < hpage_nr_pages(page); i++) {
-		if (atomic_read(&page[i]._mapcount) >= 0)
-			return true;
-	}
-	return false;
-}
+bool page_mapped(struct page *page);
 
 /*
  * Return true only if the page has been allocated with