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From: Chen Ridong <chenridong@huaweicloud.com>
To: akpm@linux-foundation.org,
	mhocko@kernel.org,
	hannes@cmpxchg.org,
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Cc: linux-mm@kvack.org,
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	chenridong@huawei.com,
	wangweiyang2@huawei.com
Subject: [PATCH v3 next 3/5] memcg: factor out the replace_stock_objcg
 function
Date: Fri, 17 Jan 2025 01:46:43 +0000
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From: Chen Ridong <chenridong@huawei.com>

Factor out the 'replace_stock_objcg' function to make the code more
cohesive.

Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
---
 mm/memcontrol.c | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 98f84a9fa228..b10e0a8f3375 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2691,6 +2691,20 @@ void __memcg_kmem_uncharge_page(struct page *page, i=
nt order)
 	obj_cgroup_put(objcg);
 }
=20
+/* Replace the stock objcg with objcg, return the old objcg */
+static struct obj_cgroup *replace_stock_objcg(struct memcg_stock_pcp *stoc=
k,
+					     struct obj_cgroup *objcg)
+{
+	struct obj_cgroup *old =3D NULL;
+
+	old =3D drain_obj_stock(stock);
+	obj_cgroup_get(objcg);
+	stock->nr_bytes =3D atomic_read(&objcg->nr_charged_bytes)
+			? atomic_xchg(&objcg->nr_charged_bytes, 0) : 0;
+	WRITE_ONCE(stock->cached_objcg, objcg);
+	return old;
+}
+
 static void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *=
pgdat,
 		     enum node_stat_item idx, int nr)
 {
@@ -2708,11 +2722,7 @@ static void mod_objcg_state(struct obj_cgroup *objcg=
, struct pglist_data *pgdat,
 	 * changes.
 	 */
 	if (READ_ONCE(stock->cached_objcg) !=3D objcg) {
-		old =3D drain_obj_stock(stock);
-		obj_cgroup_get(objcg);
-		stock->nr_bytes =3D atomic_read(&objcg->nr_charged_bytes)
-				? atomic_xchg(&objcg->nr_charged_bytes, 0) : 0;
-		WRITE_ONCE(stock->cached_objcg, objcg);
+		old =3D replace_stock_objcg(stock, objcg);
 		stock->cached_pgdat =3D pgdat;
 	} else if (stock->cached_pgdat !=3D pgdat) {
 		/* Flush the existing cached vmstat data */
@@ -2866,11 +2876,7 @@ static void refill_obj_stock(struct obj_cgroup *objc=
g, unsigned int nr_bytes,
=20
 	stock =3D this_cpu_ptr(&memcg_stock);
 	if (READ_ONCE(stock->cached_objcg) !=3D objcg) { /* reset if necessary */
-		old =3D drain_obj_stock(stock);
-		obj_cgroup_get(objcg);
-		WRITE_ONCE(stock->cached_objcg, objcg);
-		stock->nr_bytes =3D atomic_read(&objcg->nr_charged_bytes)
-				? atomic_xchg(&objcg->nr_charged_bytes, 0) : 0;
+		old =3D replace_stock_objcg(stock, objcg);
 		allow_uncharge =3D true;	/* Allow uncharge when objcg changes */
 	}
 	stock->nr_bytes +=3D nr_bytes;
--=20
2.34.1