From: Qi Zheng <zhengqi.arch@bytedance.com>

Refactor the memcg_reparent_objcgs() to facilitate subsequent reparenting
non-hierarchical stats.

Co-developed-by: Yosry Ahmed <yosry@kernel.org>
Signed-off-by: Yosry Ahmed <yosry@kernel.org>
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
---
 mm/memcontrol.c | 50 ++++++++++++++++++++++++++++++-------------------
 1 file changed, 31 insertions(+), 19 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 5929e397c3c31..23b70bd80ddc9 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -718,21 +718,12 @@ static int memcg_state_val_in_pages(int idx, int val)
 		return max(val * unit / PAGE_SIZE, 1UL);
 }
 
-/**
- * mod_memcg_state - update cgroup memory statistics
- * @memcg: the memory cgroup
- * @idx: the stat item - can be enum memcg_stat_item or enum node_stat_item
- * @val: delta to add to the counter, can be negative
- */
-void mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx,
-		       int val)
+static void __mod_memcg_state(struct mem_cgroup *memcg,
+			      enum memcg_stat_item idx, int val)
 {
 	int i = memcg_stats_index(idx);
 	int cpu;
 
-	if (mem_cgroup_disabled())
-		return;
-
 	if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx))
 		return;
 
@@ -746,6 +737,21 @@ void mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx,
 	put_cpu();
 }
 
+/**
+ * mod_memcg_state - update cgroup memory statistics
+ * @memcg: the memory cgroup
+ * @idx: the stat item - can be enum memcg_stat_item or enum node_stat_item
+ * @val: delta to add to the counter, can be negative
+ */
+void mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx,
+		       int val)
+{
+	if (mem_cgroup_disabled())
+		return;
+
+	__mod_memcg_state(memcg, idx, val);
+}
+
 #ifdef CONFIG_MEMCG_V1
 /* idx can be of type enum memcg_stat_item or node_stat_item. */
 unsigned long memcg_page_state_local(struct mem_cgroup *memcg, int idx)
@@ -765,21 +771,16 @@ unsigned long memcg_page_state_local(struct mem_cgroup *memcg, int idx)
 }
 #endif
 
-static void mod_memcg_lruvec_state(struct lruvec *lruvec,
-				     enum node_stat_item idx,
-				     int val)
+static void __mod_memcg_lruvec_state(struct mem_cgroup_per_node *pn,
+				     enum node_stat_item idx, int val)
 {
-	struct mem_cgroup_per_node *pn;
-	struct mem_cgroup *memcg;
+	struct mem_cgroup *memcg = pn->memcg;
 	int i = memcg_stats_index(idx);
 	int cpu;
 
 	if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx))
 		return;
 
-	pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
-	memcg = pn->memcg;
-
 	cpu = get_cpu();
 
 	/* Update memcg */
@@ -795,6 +796,17 @@ static void mod_memcg_lruvec_state(struct lruvec *lruvec,
 	put_cpu();
 }
 
+static void mod_memcg_lruvec_state(struct lruvec *lruvec,
+				     enum node_stat_item idx,
+				     int val)
+{
+	struct mem_cgroup_per_node *pn;
+
+	pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
+
+	__mod_memcg_lruvec_state(pn, idx, val);
+}
+
 /**
  * mod_lruvec_state - update lruvec memory statistics
  * @lruvec: the lruvec
-- 
2.20.1