linux-kernel - [PATCH v5 3/8] mm/memcg: use order instead of nr in split_page

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Date: Mon, 26 Feb 2024 15:55:29 -0500
From: Zi Yan <zi.yan@...t.com>
To: "Pankaj Raghav (Samsung)" <kernel@...kajraghav.com>,
	linux-mm@...ck.org
Cc: Zi Yan <ziy@...dia.com>,
	"Matthew Wilcox (Oracle)" <willy@...radead.org>,
	David Hildenbrand <david@...hat.com>,
	Yang Shi <shy828301@...il.com>,
	Yu Zhao <yuzhao@...gle.com>,
	"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
	Ryan Roberts <ryan.roberts@....com>,
	Michal Koutný <mkoutny@...e.com>,
	Roman Gushchin <roman.gushchin@...ux.dev>,
	"Zach O'Keefe" <zokeefe@...gle.com>,
	Hugh Dickins <hughd@...gle.com>,
	Luis Chamberlain <mcgrof@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	cgroups@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	linux-kselftest@...r.kernel.org
Subject: [PATCH v5 3/8] mm/memcg: use order instead of nr in split_page_memcg()

From: Zi Yan <ziy@...dia.com>

We do not have non power of two pages, using nr is error prone if nr
is not power-of-two. Use page order instead.

Signed-off-by: Zi Yan <ziy@...dia.com>
Acked-by: David Hildenbrand <david@...hat.com>
---
 include/linux/memcontrol.h | 4 ++--
 mm/huge_memory.c           | 5 +++--
 mm/memcontrol.c            | 3 ++-
 mm/page_alloc.c            | 4 ++--
 4 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 4e4caeaea404..173bbb53c1ec 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, unsigned int nr);
+void split_page_memcg(struct page *head, int 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, unsigned int nr)
+static inline void split_page_memcg(struct page *head, int order)
 {
 }
 
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 9840f312c08f..96ac7c62c375 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2889,11 +2889,12 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 	struct lruvec *lruvec;
 	struct address_space *swap_cache = NULL;
 	unsigned long offset = 0;
-	unsigned int nr = thp_nr_pages(head);
 	int i, nr_dropped = 0;
+	int order = folio_order(folio);
+	unsigned int nr = 1 << order;
 
 	/* complete memcg works before add pages to LRU */
-	split_page_memcg(head, nr);
+	split_page_memcg(head, order);
 
 	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 95c3fccb321b..1a09f0e77c44 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3608,11 +3608,12 @@ 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, int order)
 {
 	struct folio *folio = page_folio(head);
 	struct mem_cgroup *memcg = folio_memcg(folio);
 	int i;
+	unsigned int nr = 1 << order;
 
 	if (mem_cgroup_disabled() || !memcg)
 		return;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 96839b210abe..a7a96bc97e0b 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, 1 << order);
-	split_page_memcg(page, 1 << order);
+	split_page_memcg(page, order);
 }
 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, 1 << order);
-		split_page_memcg(page, 1 << order);
+		split_page_memcg(page, order);
 		while (page < --last)
 			set_page_refcounted(last);
 
-- 
2.43.0