mm: remove the total_mapcount argument from page_trans_huge_mapcount()

All callers pass NULL, so we can stop calculating the value we would
store in it.

Link: https://lkml.kernel.org/r/20211220205943.456187-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/mm.h

@@ -799,19 +799,15 @@ static inline int page_mapcount(struct page *page)
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 int total_mapcount(struct page *page);
-int page_trans_huge_mapcount(struct page *page, int *total_mapcount);
+int page_trans_huge_mapcount(struct page *page);
 #else
 static inline int total_mapcount(struct page *page)
 {
 	return page_mapcount(page);
 }
-static inline int page_trans_huge_mapcount(struct page *page,
-					   int *total_mapcount)
+static inline int page_trans_huge_mapcount(struct page *page)
 {
-	int mapcount = page_mapcount(page);
-	if (total_mapcount)
-		*total_mapcount = mapcount;
-	return mapcount;
+	return page_mapcount(page);
 }
 #endif
 

include/linux/swap.h

@@ -681,7 +681,7 @@ static inline int swp_swapcount(swp_entry_t entry)
 }
 
 #define reuse_swap_page(page) \
-	(page_trans_huge_mapcount(page, NULL) == 1)
+	(page_trans_huge_mapcount(page) == 1)
 
 static inline int try_to_free_swap(struct page *page)
 {

mm/huge_memory.c

@@ -2542,38 +2542,28 @@ int total_mapcount(struct page *page)
  * need full accuracy to avoid breaking page pinning, because
  * page_trans_huge_mapcount() is slower than page_mapcount().
  */
-int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
+int page_trans_huge_mapcount(struct page *page)
 {
-	int i, ret, _total_mapcount, mapcount;
+	int i, ret;
 
 	/* hugetlbfs shouldn't call it */
 	VM_BUG_ON_PAGE(PageHuge(page), page);
 
-	if (likely(!PageTransCompound(page))) {
-		mapcount = atomic_read(&page->_mapcount) + 1;
-		if (total_mapcount)
-			*total_mapcount = mapcount;
-		return mapcount;
-	}
+	if (likely(!PageTransCompound(page)))
+		return atomic_read(&page->_mapcount) + 1;
 
 	page = compound_head(page);
 
-	_total_mapcount = ret = 0;
+	ret = 0;
 	for (i = 0; i < thp_nr_pages(page); i++) {
-		mapcount = atomic_read(&page[i]._mapcount) + 1;
+		int mapcount = atomic_read(&page[i]._mapcount) + 1;
 		ret = max(ret, mapcount);
-		_total_mapcount += mapcount;
 	}
-	if (PageDoubleMap(page)) {
+
+	if (PageDoubleMap(page))
 		ret -= 1;
-		_total_mapcount -= thp_nr_pages(page);
-	}
-	mapcount = compound_mapcount(page);
-	ret += mapcount;
-	_total_mapcount += mapcount;
-	if (total_mapcount)
-		*total_mapcount = _total_mapcount;
-	return ret;
+
+	return ret + compound_mapcount(page);
 }
 
 /* Racy check whether the huge page can be split */

mm/swapfile.c

@@ -1619,7 +1619,7 @@ static int page_trans_huge_map_swapcount(struct page *page,
 			swapcount = page_swapcount(page);
 		if (total_swapcount)
 			*total_swapcount = swapcount;
-		return swapcount + page_trans_huge_mapcount(page, NULL);
+		return swapcount + page_trans_huge_mapcount(page);
 	}
 
 	page = compound_head(page);