mm: simplify split_page_memcg()

The last argument to split_page_memcg() is now always 0, so remove it,
effectively reverting commit b8791381d7ed.

Link: https://lkml.kernel.org/r/20250314133617.138071-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Zi Yan <ziy@nvidia.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index d090089c549741d38f3c37c0d493cb115cb5842a..ea28cacfb0d266be2c8753ac1daabe7b5d4f4cae 100644 (file)
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1038,7 +1038,7 @@ static inline void memcg_memory_event_mm(struct mm_struct *mm,
        rcu_read_unlock();
 }
 
-void split_page_memcg(struct page *head, int old_order, int new_order);
+void split_page_memcg(struct page *first, unsigned order);
 void folio_split_memcg_refs(struct folio *folio, unsigned old_order,
                unsigned new_order);
 
@@ -1461,7 +1461,7 @@ void count_memcg_event_mm(struct mm_struct *mm, enum vm_event_item idx)
 {
 }
 
-static inline void split_page_memcg(struct page *head, int old_order, int new_order)
+static inline void split_page_memcg(struct page *first, unsigned order)
 {
 }
 

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f267b309b5b7194fcb96e6b9cff9eb7dbbe97804..fa7a3a1b710a42c7efae532a44efa53d28d72542 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3066,22 +3066,21 @@ void __memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab,
 }
 
 /*
- * Because folio_memcg(head) is not set on tails, set it now.
+ * The objcg is only set on the first page, so transfer it to all the
+ * other pages.
  */
-void split_page_memcg(struct page *head, int old_order, int new_order)
+void split_page_memcg(struct page *first, unsigned order)
 {
-       struct folio *folio = page_folio(head);
-       int i;
-       unsigned int old_nr = 1 << old_order;
-       unsigned int new_nr = 1 << new_order;
+       struct folio *folio = page_folio(first);
+       unsigned int i, nr = 1 << order;
 
        if (mem_cgroup_disabled() || !folio_memcg_charged(folio))
                return;
 
-       for (i = new_nr; i < old_nr; i += new_nr)
+       for (i = 1; i < nr; i++)
                folio_page(folio, i)->memcg_data = folio->memcg_data;
 
-       obj_cgroup_get_many(__folio_objcg(folio), old_nr / new_nr - 1);
+       obj_cgroup_get_many(__folio_objcg(folio), nr - 1);
 }
 
 void folio_split_memcg_refs(struct folio *folio, unsigned old_order,

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 4337467eaf5a730f86221e3d1a02e43cbdae18ae..a6d060eea638065eea19c50fcc929d55b6950a2f 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2778,7 +2778,7 @@ void split_page(struct page *page, unsigned int order)
                set_page_refcounted(page + i);
        split_page_owner(page, order, 0);
        pgalloc_tag_split(page_folio(page), order, 0);
-       split_page_memcg(page, order, 0);
+       split_page_memcg(page, order);
 }
 EXPORT_SYMBOL_GPL(split_page);
 
@@ -4992,7 +4992,7 @@ static void *make_alloc_exact(unsigned long addr, unsigned int order,
 
                split_page_owner(page, order, 0);
                pgalloc_tag_split(page_folio(page), order, 0);
-               split_page_memcg(page, order, 0);
+               split_page_memcg(page, order);
                while (page < --last)
                        set_page_refcounted(last);