linux-kernel - [PATCH v3 26/30 fix] mm: mglru: do not call update_lru

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Message-ID: <20260115104444.85986-1-qi.zheng@linux.dev>
Date: Thu, 15 Jan 2026 18:44:44 +0800
From: Qi Zheng <qi.zheng@...ux.dev>
To: hannes@...xchg.org,
	hughd@...gle.com,
	mhocko@...e.com,
	roman.gushchin@...ux.dev,
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	lance.yang@...ux.dev
Cc: linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	cgroups@...r.kernel.org,
	Qi Zheng <zhengqi.arch@...edance.com>
Subject: [PATCH v3 26/30 fix] mm: mglru: do not call update_lru_size() during reparenting

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

Only non-hierarchical lruvec_stats->state_local needs to be reparented,
so handle it in reparent_state_local(), and remove the unreasonable
update_lru_size() call in __lru_gen_reparent_memcg().

Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
---
 mm/vmscan.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 56714f3bc6f88..5e7a32e3cffbc 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4544,7 +4544,6 @@ static void __lru_gen_reparent_memcg(struct lruvec *child_lruvec, struct lruvec
 				     int zone, int type)
 {
 	struct lru_gen_folio *child_lrugen, *parent_lrugen;
-	enum lru_list lru = type * LRU_INACTIVE_FILE;
 	int i;
 
 	child_lrugen = &child_lruvec->lrugen;
@@ -4553,7 +4552,6 @@ static void __lru_gen_reparent_memcg(struct lruvec *child_lruvec, struct lruvec
 	for (i = 0; i < get_nr_gens(child_lruvec, type); i++) {
 		int gen = lru_gen_from_seq(child_lrugen->max_seq - i);
 		long nr_pages = child_lrugen->nr_pages[gen][type][zone];
-		int dst_lru_active = lru_gen_is_active(parent_lruvec, gen) ? LRU_ACTIVE : 0;
 
 		/* Assuming that child pages are colder than parent pages */
 		list_splice_init(&child_lrugen->folios[gen][type][zone],
@@ -4562,8 +4560,6 @@ static void __lru_gen_reparent_memcg(struct lruvec *child_lruvec, struct lruvec
 		WRITE_ONCE(child_lrugen->nr_pages[gen][type][zone], 0);
 		WRITE_ONCE(parent_lrugen->nr_pages[gen][type][zone],
 			   parent_lrugen->nr_pages[gen][type][zone] + nr_pages);
-
-		update_lru_size(parent_lruvec, lru + dst_lru_active, zone, nr_pages);
 	}
 }
 
@@ -4575,15 +4571,21 @@ void lru_gen_reparent_memcg(struct mem_cgroup *memcg, struct mem_cgroup *parent)
 		struct lruvec *child_lruvec, *parent_lruvec;
 		int type, zid;
 		struct zone *zone;
+		enum lru_list lru;
 
 		child_lruvec = get_lruvec(memcg, nid);
 		parent_lruvec = get_lruvec(parent, nid);
 
-		for_each_managed_zone_pgdat(zone, NODE_DATA(nid), zid, MAX_NR_ZONES - 1) {
+		for_each_managed_zone_pgdat(zone, NODE_DATA(nid), zid, MAX_NR_ZONES - 1)
 			for (type = 0; type < ANON_AND_FILE; type++)
 				__lru_gen_reparent_memcg(child_lruvec, parent_lruvec, zid, type);
-			mem_cgroup_update_lru_size(parent_lruvec, LRU_UNEVICTABLE, zid,
-				mem_cgroup_get_zone_lru_size(child_lruvec, LRU_UNEVICTABLE, zid));
+
+		for_each_lru(lru) {
+			for_each_managed_zone_pgdat(zone, NODE_DATA(nid), zid, MAX_NR_ZONES - 1) {
+				unsigned long size = mem_cgroup_get_zone_lru_size(child_lruvec, lru, zid);
+
+				mem_cgroup_update_lru_size(parent_lruvec, lru, zid, size);
+			}
 		}
 	}
 }
-- 
2.20.1