[PATCH 1/5] mm: memcg: make memcg huge page split support any order split.

[Zi Yan <zi.yan@xxxxxxxx>]

From: Zi Yan <ziy@xxxxxxxxxx>

It sets memcg information for the pages after the split. A new parameter
new_nr is added to tell the number of subpages in the new page, always 1
for now. It prepares for upcoming changes to support split huge page to
any lower order.

Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
---
 include/linux/memcontrol.h | 5 +++--
 mm/huge_memory.c           | 2 +-
 mm/memcontrol.c            | 8 ++++----
 mm/page_alloc.c            | 2 +-
 4 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index aa69ea98e2d8..ee1021129142 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1151,7 +1151,7 @@ static inline void memcg_memory_event_mm(struct mm_struct *mm,
 	rcu_read_unlock();
 }
 
-void split_page_memcg(struct page *head, unsigned int nr);
+void split_page_memcg(struct page *head, unsigned int nr, unsigned int new_nr);
 
 unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
 						gfp_t gfp_mask,
@@ -1588,7 +1588,8 @@ void count_memcg_event_mm(struct mm_struct *mm, enum vm_event_item idx)
 {
 }
 
-static inline void split_page_memcg(struct page *head, unsigned int nr)
+static inline void split_page_memcg(struct page *head, unsigned int nr,
+						unsigned int new_nr)
 {
 }
 
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 81a5689806af..30e3e300c42e 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2515,7 +2515,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 	int i;
 
 	/* complete memcg works before add pages to LRU */
-	split_page_memcg(head, nr);
+	split_page_memcg(head, nr, 1);
 
 	if (PageAnon(head) && PageSwapCache(head)) {
 		swp_entry_t entry = { .val = page_private(head) };
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 681e7528a714..8e505201baf0 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3414,7 +3414,7 @@ void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size)
 /*
  * Because page_memcg(head) is not set on tails, set it now.
  */
-void split_page_memcg(struct page *head, unsigned int nr)
+void split_page_memcg(struct page *head, unsigned int nr, unsigned int new_nr)
 {
 	struct folio *folio = page_folio(head);
 	struct mem_cgroup *memcg = folio_memcg(folio);
@@ -3423,13 +3423,13 @@ void split_page_memcg(struct page *head, unsigned int nr)
 	if (mem_cgroup_disabled() || !memcg)
 		return;
 
-	for (i = 1; i < nr; i++)
+	for (i = new_nr; i < nr; i += new_nr)
 		folio_page(folio, i)->memcg_data = folio->memcg_data;
 
 	if (folio_memcg_kmem(folio))
-		obj_cgroup_get_many(__folio_objcg(folio), nr - 1);
+		obj_cgroup_get_many(__folio_objcg(folio), nr / new_nr - 1);
 	else
-		css_get_many(&memcg->css, nr - 1);
+		css_get_many(&memcg->css, nr / new_nr - 1);
 }
 
 #ifdef CONFIG_SWAP
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 2e72fdbdd8db..59c2b6696698 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3531,7 +3531,7 @@ 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_memcg(page, 1 << order);
+	split_page_memcg(page, 1 << order, 1);
 }
 EXPORT_SYMBOL_GPL(split_page);
 
-- 
2.39.2