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

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

From: Zi Yan <ziy@nvidia.com>

It sets memcg information for the pages after the split. A new parameter
new_order is added to tell the new page order, always 0 for now. It
prepares for upcoming changes to support split huge page to any lower
order.

Signed-off-by: Zi Yan <ziy@nvidia.com>
---
 include/linux/memcontrol.h |  2 +-
 mm/huge_memory.c           |  2 +-
 mm/memcontrol.c            | 10 +++++-----
 mm/page_alloc.c            |  2 +-
 4 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 89b14729d59f..e71189454bf0 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1116,7 +1116,7 @@ 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_order);
 
 unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
 						gfp_t gfp_mask,
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 2fe38212e07c..640040c386f0 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2371,7 +2371,7 @@ 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, 0);
 
 	if (PageAnon(head) && PageSwapCache(head)) {
 		swp_entry_t entry = { .val = page_private(head) };
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 43b2a22ce812..e7da413ac174 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3262,22 +3262,22 @@ 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_order)
 {
 	struct folio *folio = page_folio(head);
 	struct mem_cgroup *memcg = folio_memcg(folio);
-	int i;
+	int i, new_nr = 1 << new_order;
 
 	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_MEMCG_SWAP
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f648decfe39d..d982919b9e51 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3515,7 +3515,7 @@ 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, 0);
 }
 EXPORT_SYMBOL_GPL(split_page);
 
-- 
2.35.1