[PATCH 37/75] mm: Add split_folio_to_list()

[Matthew Wilcox (Oracle)]

This is a convenience function; split_huge_page_to_list() can take
any page in a folio (and does so on purpose because that page will
be the one which keeps the refcount).  But it's convenient for the
callers to pass the folio instead of the first page in the folio.

Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
 include/linux/huge_mm.h |  6 ++++++
 mm/vmscan.c             | 10 +++++-----
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index e4c18ba8d3bf..71c073d411ac 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -483,6 +483,12 @@ static inline bool thp_migration_supported(void)
 }
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
+static inline int split_folio_to_list(struct folio *folio,
+		struct list_head *list)
+{
+	return split_huge_page_to_list(&folio->page, list);
+}
+
 /**
  * thp_size - Size of a transparent huge page.
  * @page: Head page of a transparent huge page.
diff --git a/mm/vmscan.c b/mm/vmscan.c
index e8c5855bc38d..0d23ade9f6e2 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1708,16 +1708,16 @@ static unsigned int shrink_page_list(struct list_head *page_list,
 					 * tail pages can be freed without IO.
 					 */
 					if (!compound_mapcount(page) &&
-					    split_huge_page_to_list(page,
-								    page_list))
+					    split_folio_to_list(folio,
+								page_list))
 						goto activate_locked;
 				}
 				if (!add_to_swap(page)) {
 					if (!PageTransHuge(page))
 						goto activate_locked_split;
 					/* Fallback to swap normal pages */
-					if (split_huge_page_to_list(page,
-								    page_list))
+					if (split_folio_to_list(folio,
+								page_list))
 						goto activate_locked;
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 					count_vm_event(THP_SWPOUT_FALLBACK);
@@ -1733,7 +1733,7 @@ static unsigned int shrink_page_list(struct list_head *page_list,
 			}
 		} else if (unlikely(PageTransHuge(page))) {
 			/* Split file THP */
-			if (split_huge_page_to_list(page, page_list))
+			if (split_folio_to_list(folio, page_list))
 				goto keep_locked;
 		}
 
-- 
2.34.1