[PATCH] mm: memcontrol: factor out memcg kmem uncharge sequence

[Guopeng Zhang <guopeng.zhang@linux.dev>]

From: Guopeng Zhang <zhangguopeng@kylinos.cn>

The kmem-uncharge sequence (mod_memcg_state(MEMCG_KMEM) +
memcg1_account_kmem + conditional memcg_uncharge) is duplicated verbatim
in obj_cgroup_release() and drain_obj_stock_slot(). Factor it into a
small memcg_uncharge_kmem() helper. The reference get/put stays at the
call sites, as they differ.

No functional change.

Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
---
 mm/memcontrol.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 22f55aeb94f3..86acfe55a201 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -137,6 +137,14 @@ bool mem_cgroup_kmem_disabled(void)
 
 static void memcg_uncharge(struct mem_cgroup *memcg, unsigned int nr_pages);
 
+static void memcg_uncharge_kmem(struct mem_cgroup *memcg, unsigned int nr_pages)
+{
+	mod_memcg_state(memcg, MEMCG_KMEM, -nr_pages);
+	memcg1_account_kmem(memcg, -nr_pages);
+	if (!mem_cgroup_is_root(memcg))
+		memcg_uncharge(memcg, nr_pages);
+}
+
 static void obj_cgroup_release(struct percpu_ref *ref)
 {
 	struct obj_cgroup *objcg = container_of(ref, struct obj_cgroup, refcnt);
@@ -172,10 +180,7 @@ static void obj_cgroup_release(struct percpu_ref *ref)
 		struct mem_cgroup *memcg;
 
 		memcg = get_mem_cgroup_from_objcg(objcg);
-		mod_memcg_state(memcg, MEMCG_KMEM, -nr_pages);
-		memcg1_account_kmem(memcg, -nr_pages);
-		if (!mem_cgroup_is_root(memcg))
-			memcg_uncharge(memcg, nr_pages);
+		memcg_uncharge_kmem(memcg, nr_pages);
 		mem_cgroup_put(memcg);
 	}
 
@@ -3329,10 +3334,7 @@ static void drain_obj_stock_slot(struct obj_stock_pcp *stock, int i)
 
 			memcg = get_mem_cgroup_from_objcg(old);
 
-			mod_memcg_state(memcg, MEMCG_KMEM, -nr_pages);
-			memcg1_account_kmem(memcg, -nr_pages);
-			if (!mem_cgroup_is_root(memcg))
-				memcg_uncharge(memcg, nr_pages);
+			memcg_uncharge_kmem(memcg, nr_pages);
 
 			css_put(&memcg->css);
 		}
-- 
2.43.0