mm: update references to page _refcount

Commit 0139aa7b ("mm: rename _count, field of the struct page, to
_refcount") left out a couple of references to the old field name.  Fix
that.

Link: http://lkml.kernel.org/r/cedf87b02eb8a6b3eac57e8e91da53fb15c3c44c.1556537475.git.baruch@tkos.co.il
Fixes: 0139aa7b ("mm: rename _count, field of the struct page, to _refcount")
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/debug.c

@@ -67,7 +67,7 @@ void __dump_page(struct page *page, const char *reason)
 	 */
 	mapcount = PageSlab(page) ? 0 : page_mapcount(page);
 
-	pr_warn("page:%px count:%d mapcount:%d mapping:%px index:%#lx",
+	pr_warn("page:%px refcount:%d mapcount:%d mapping:%px index:%#lx",
 		  page, page_ref_count(page), mapcount,
 		  page->mapping, page_to_pgoff(page));
 	if (PageCompound(page))

mm/page_alloc.c

@@ -1986,7 +1986,7 @@ static void check_new_page_bad(struct page *page)
 	if (unlikely(page->mapping != NULL))
 		bad_reason = "non-NULL mapping";
 	if (unlikely(page_ref_count(page) != 0))
-		bad_reason = "nonzero _count";
+		bad_reason = "nonzero _refcount";
 	if (unlikely(page->flags & __PG_HWPOISON)) {
 		bad_reason = "HWPoisoned (hardware-corrupted)";
 		bad_flags = __PG_HWPOISON;