[PATCH 4/7] mm: page_owner: add support for splitting to any order in split page_owner.

[Zi Yan <zi.yan@sent.com>]

From: Zi Yan <ziy@nvidia.com>

It adds a new_order parameter to set new page order in page owner and
uses old_order instead of nr to make the parameters look consistent.
It prepares for upcoming changes to support split huge page to any
lower order.

Signed-off-by: Zi Yan <ziy@nvidia.com>
---
 include/linux/page_owner.h | 10 ++++++----
 mm/huge_memory.c           |  3 ++-
 mm/page_alloc.c            |  2 +-
 mm/page_owner.c            | 13 +++++++------
 4 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/include/linux/page_owner.h b/include/linux/page_owner.h
index 3468794f83d2..9caaed51403c 100644
--- a/include/linux/page_owner.h
+++ b/include/linux/page_owner.h
@@ -11,7 +11,8 @@ extern struct page_ext_operations page_owner_ops;
 extern void __reset_page_owner(struct page *page, unsigned int order);
 extern void __set_page_owner(struct page *page,
 			unsigned int order, gfp_t gfp_mask);
-extern void __split_page_owner(struct page *page, unsigned int nr);
+extern void __split_page_owner(struct page *page, unsigned int old_order,
+			unsigned int new_order);
 extern void __copy_page_owner(struct page *oldpage, struct page *newpage);
 extern void __set_page_owner_migrate_reason(struct page *page, int reason);
 extern void __dump_page_owner(struct page *page);
@@ -31,10 +32,11 @@ static inline void set_page_owner(struct page *page,
 		__set_page_owner(page, order, gfp_mask);
 }
 
-static inline void split_page_owner(struct page *page, unsigned int nr)
+static inline void split_page_owner(struct page *page, unsigned int old_order,
+			unsigned int new_order)
 {
 	if (static_branch_unlikely(&page_owner_inited))
-		__split_page_owner(page, nr);
+		__split_page_owner(page, old_order, new_order);
 }
 static inline void copy_page_owner(struct page *oldpage, struct page *newpage)
 {
@@ -60,7 +62,7 @@ static inline void set_page_owner(struct page *page,
 {
 }
 static inline void split_page_owner(struct page *page,
-			unsigned int order)
+			unsigned int old_order, unsigned int new_order)
 {
 }
 static inline void copy_page_owner(struct page *oldpage, struct page *newpage)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index d7ab5cac5851..aae7405a0989 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2422,6 +2422,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 	struct lruvec *lruvec;
 	struct address_space *swap_cache = NULL;
 	unsigned long offset = 0;
+	unsigned int order = thp_order(head);
 	unsigned int nr = thp_nr_pages(head);
 	int i;
 
@@ -2458,7 +2459,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 
 	ClearPageCompound(head);
 
-	split_page_owner(head, nr);
+	split_page_owner(head, order, 0);
 
 	/* See comment in __split_huge_page_tail() */
 	if (PageAnon(head)) {
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 63d8d8b72c10..414f26950190 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3297,7 +3297,7 @@ void split_page(struct page *page, unsigned int order)
 
 	for (i = 1; i < (1 << order); i++)
 		set_page_refcounted(page + i);
-	split_page_owner(page, 1 << order);
+	split_page_owner(page, order, 0);
 }
 EXPORT_SYMBOL_GPL(split_page);
 
diff --git a/mm/page_owner.c b/mm/page_owner.c
index b735a8eafcdb..00a679a1230b 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -204,19 +204,20 @@ void __set_page_owner_migrate_reason(struct page *page, int reason)
 	page_owner->last_migrate_reason = reason;
 }
 
-void __split_page_owner(struct page *page, unsigned int nr)
+void __split_page_owner(struct page *page, unsigned int old_order,
+			unsigned int new_order)
 {
-	int i;
-	struct page_ext *page_ext = lookup_page_ext(page);
+	int i, old_nr = 1 << old_order, new_nr = 1 << new_order;
+	struct page_ext *page_ext;
 	struct page_owner *page_owner;
 
 	if (unlikely(!page_ext))
 		return;
 
-	for (i = 0; i < nr; i++) {
+	for (i = 0; i < old_nr; i += new_nr) {
+		page_ext = lookup_page_ext(page + i);
 		page_owner = get_page_owner(page_ext);
-		page_owner->order = 0;
-		page_ext = page_ext_next(page_ext);
+		page_owner->order = new_order;
 	}
 }
 
-- 
2.28.0