memcg: call the free function when allocation of pn fails

The 'free_mem_cgroup_per_node_info' function is used to free the
'mem_cgroup_per_node' struct.  Using 'pn' as the input for the
free_mem_cgroup_per_node_info function will be much clearer.  Call
'free_mem_cgroup_per_node_info' when 'alloc_mem_cgroup_per_node_info'
fails, to free 'pn' as a whole, which makes the code more cohesive.

Link: https://lkml.kernel.org/r/20250124073514.2375622-3-chenridong@huaweicloud.com
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: David Finkel <davidf@vimeo.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wang Weiyang <wangweiyang2@huawei.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: Chen Ridong

mm/memcontrol.c

@@ -3433,6 +3433,16 @@ struct mem_cgroup *mem_cgroup_get_from_ino(unsigned long ino)
 }
 #endif
 
+static void free_mem_cgroup_per_node_info(struct mem_cgroup_per_node *pn)
+{
+	if (!pn)
+		return;
+
+	free_percpu(pn->lruvec_stats_percpu);
+	kfree(pn->lruvec_stats);
+	kfree(pn);
+}
+
 static bool alloc_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node)
 {
 	struct mem_cgroup_per_node *pn;
@@ -3457,31 +3467,18 @@ static bool alloc_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node)
 	memcg->nodeinfo[node] = pn;
 	return true;
 fail:
-	kfree(pn->lruvec_stats);
-	kfree(pn);
+	free_mem_cgroup_per_node_info(pn);
 	return false;
 }
 
-static void free_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node)
-{
-	struct mem_cgroup_per_node *pn = memcg->nodeinfo[node];
-
-	if (!pn)
-		return;
-
-	free_percpu(pn->lruvec_stats_percpu);
-	kfree(pn->lruvec_stats);
-	kfree(pn);
-}
-
 static void __mem_cgroup_free(struct mem_cgroup *memcg)
 {
 	int node;
 
 	obj_cgroup_put(memcg->orig_objcg);
 
 	for_each_node(node)
-		free_mem_cgroup_per_node_info(memcg, node);
+		free_mem_cgroup_per_node_info(memcg->nodeinfo[node]);
 	memcg1_free_events(memcg);
 	kfree(memcg->vmstats);
 	free_percpu(memcg->vmstats_percpu);