[PATCH 3/7] 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>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Acked-by: Roman Gushchin <guro@fb.com>
---
 include/linux/memcontrol.h | 5 +++--
 mm/huge_memory.c           | 2 +-
 mm/memcontrol.c            | 6 +++---
 3 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index a8d5daf95988..39707feae505 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1062,7 +1062,7 @@ static inline void memcg_memory_event_mm(struct mm_struct *mm,
 }
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
-void mem_cgroup_split_huge_fixup(struct page *head);
+void mem_cgroup_split_huge_fixup(struct page *head, unsigned int new_order);
 #endif
 
 #else /* CONFIG_MEMCG */
@@ -1396,7 +1396,8 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
 	return 0;
 }
 
-static inline void mem_cgroup_split_huge_fixup(struct page *head)
+static inline void mem_cgroup_split_huge_fixup(struct page *head,
+					       unsigned int new_order)
 {
 }
 
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 88d8b7fce5d7..d7ab5cac5851 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2428,7 +2428,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 	lruvec = mem_cgroup_page_lruvec(head, pgdat);
 
 	/* complete memcg works before add pages to LRU */
-	mem_cgroup_split_huge_fixup(head);
+	mem_cgroup_split_huge_fixup(head, 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 de5869dd354d..4521ed3a51b7 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3223,15 +3223,15 @@ void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size)
  * Because tail pages are not marked as "used", set it. We're under
  * pgdat->lru_lock and migration entries setup in all page mappings.
  */
-void mem_cgroup_split_huge_fixup(struct page *head)
+void mem_cgroup_split_huge_fixup(struct page *head, unsigned int new_order)
 {
 	struct mem_cgroup *memcg = page_memcg(head);
-	int i;
+	int i, new_nr = 1 << new_order;
 
 	if (mem_cgroup_disabled())
 		return;
 
-	for (i = 1; i < thp_nr_pages(head); i++) {
+	for (i = new_nr; i < thp_nr_pages(head); i += new_nr) {
 		css_get(&memcg->css);
 		head[i].memcg_data = (unsigned long)memcg;
 	}
-- 
2.28.0