[PATCH 03/15] mm/huge_memory: use folio_page() in THP split paths

[Nilay Vaish]

As part of the memdescs effort, struct folio will be allocated
separately from struct page and will no longer overlay the head page.

Replace direct &folio->page uses and pointer arithmetic with
folio_page() in __split_folio_to_order(), __split_frozen_folio(),
folio_split_unmapped(), __split_huge_page_to_list_to_order(),
folio_split(), and split_folio_to_list().

No functional change intended.

Assisted-by: LLM
Signed-off-by: Nilay Vaish <nilayvaish@xxxxxxxxxx>
---
 mm/huge_memory.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 31af817eeded..58fbc4d4ddb8 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3711,7 +3711,7 @@ static void __split_folio_to_order(struct folio *folio, int old_order,
 	 * the flags from the original folio.
 	 */
 	for (i = new_nr_pages; i < nr_pages; i += new_nr_pages) {
-		struct page *new_head = &folio->page + i;
+		struct page *new_head = folio_page(folio, i);
 		/*
 		 * Careful: new_folio is not a "real" folio before we cleared PageTail.
 		 * Don't pass it around before clear_compound_head().
@@ -3808,7 +3808,7 @@ static void __split_folio_to_order(struct folio *folio, int old_order,
 	if (new_order)
 		folio_set_order(folio, new_order);
 	else
-		ClearPageCompound(&folio->page);
+		ClearPageCompound(folio_page(folio, 0));
 }
 
 /**
@@ -3898,7 +3898,7 @@ static int __split_frozen_folio(struct folio *folio, int new_order,
 		}
 
 		folio_split_memcg_refs(folio, old_order, split_order);
-		split_page_owner(&folio->page, old_order, split_order);
+		split_page_owner(folio_page(folio, 0), old_order, split_order);
 		pgalloc_tag_split(folio, old_order, split_order);
 		__split_folio_to_order(folio, old_order, split_order);
 
@@ -4394,7 +4394,7 @@ int folio_split_unmapped(struct folio *folio, unsigned int new_order)
 	VM_WARN_ON_ONCE_FOLIO(!folio_test_large(folio), folio);
 	VM_WARN_ON_ONCE_FOLIO(!folio_test_anon(folio), folio);
 
-	return __folio_freeze_split_anon(folio, new_order, &folio->page,
+	return __folio_freeze_split_anon(folio, new_order, folio_page(folio, 0),
 					 false, NULL, SPLIT_TYPE_UNIFORM);
 }
 
@@ -4450,7 +4450,7 @@ int __split_huge_page_to_list_to_order(struct page *page, struct list_head *list
 {
 	struct folio *folio = page_folio(page);
 
-	return __folio_split(folio, new_order, &folio->page, page, list,
+	return __folio_split(folio, new_order, folio_page(folio, 0), page, list,
 			     SPLIT_TYPE_UNIFORM);
 }
 
@@ -4481,8 +4481,8 @@ int __split_huge_page_to_list_to_order(struct page *page, struct list_head *list
 int folio_split(struct folio *folio, unsigned int new_order,
 		struct page *split_at, struct list_head *list)
 {
-	return __folio_split(folio, new_order, split_at, &folio->page, list,
-			     SPLIT_TYPE_NON_UNIFORM);
+	return __folio_split(folio, new_order, split_at, folio_page(folio, 0),
+			     list, SPLIT_TYPE_NON_UNIFORM);
 }
 
 /**
@@ -4514,7 +4514,7 @@ unsigned int min_order_for_split(struct folio *folio)
 
 int split_folio_to_list(struct folio *folio, struct list_head *list)
 {
-	return split_huge_page_to_list_to_order(&folio->page, list, 0);
+	return split_huge_page_to_list_to_order(folio_page(folio, 0), list, 0);
 }
 
 /*
-- 
2.56.0.rc1.315.gc6ed9934b7-goog