[PATCH v5 5/8] mm: memcg: make memcg huge page split support any order split.

[Zi Yan]

From: Zi Yan <z...@nvidia.com>

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

Signed-off-by: Zi Yan <z...@nvidia.com>
Acked-by: David Hildenbrand <da...@redhat.com>
---
 include/linux/memcontrol.h |  4 ++--
 mm/huge_memory.c           |  2 +-
 mm/memcontrol.c            | 11 ++++++-----
 mm/page_alloc.c            |  4 ++--
 4 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 173bbb53c1ec..9a2dea92be0e 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1163,7 +1163,7 @@ static inline void memcg_memory_event_mm(struct mm_struct 
*mm,
        rcu_read_unlock();
 }
 
-void split_page_memcg(struct page *head, int order);
+void split_page_memcg(struct page *head, int old_order, int new_order);
 
 unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
                                                gfp_t gfp_mask,
@@ -1621,7 +1621,7 @@ void count_memcg_event_mm(struct mm_struct *mm, enum 
vm_event_item idx)
 {
 }
 
-static inline void split_page_memcg(struct page *head, int order)
+static inline void split_page_memcg(struct page *head, int old_order, int 
new_order)
 {
 }
 
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 2b95dbc95fae..5d4b7c17b9bc 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2894,7 +2894,7 @@ static void __split_huge_page(struct page *page, struct 
list_head *list,
        unsigned int nr = 1 << order;
 
        /* complete memcg works before add pages to LRU */
-       split_page_memcg(head, order);
+       split_page_memcg(head, order, 0);
 
        if (folio_test_anon(folio) && folio_test_swapcache(folio)) {
                offset = swp_offset(folio->swap);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 1a09f0e77c44..669bc8de3780 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3608,23 +3608,24 @@ 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, int order)
+void split_page_memcg(struct page *head, int old_order, int new_order)
 {
        struct folio *folio = page_folio(head);
        struct mem_cgroup *memcg = folio_memcg(folio);
        int i;
-       unsigned int nr = 1 << order;
+       unsigned int old_nr = 1 << old_order;
+       unsigned int new_nr = 1 << new_order;
 
        if (mem_cgroup_disabled() || !memcg)
                return;
 
-       for (i = 1; i < nr; i++)
+       for (i = new_nr; i < old_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), old_nr / new_nr - 1);
        else
-               css_get_many(&memcg->css, nr - 1);
+               css_get_many(&memcg->css, old_nr / new_nr - 1);
 }
 
 #ifdef CONFIG_SWAP
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index eae77e76a671..c31a468fe317 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2653,7 +2653,7 @@ 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, order);
-       split_page_memcg(page, order);
+       split_page_memcg(page, order, 0);
 }
 EXPORT_SYMBOL_GPL(split_page);
 
@@ -4840,7 +4840,7 @@ static void *make_alloc_exact(unsigned long addr, 
unsigned int order,
                struct page *last = page + nr;
 
                split_page_owner(page, order);
-               split_page_memcg(page, order);
+               split_page_memcg(page, order, 0);
                while (page < --last)
                        set_page_refcounted(last);
 
-- 
2.43.0