diff --git a/mm/folio.c b/mm/folio.c
index 59c477120b9a..c02dcea9c03c 100644
--- a/mm/folio.c
+++ b/mm/folio.c
@@ -1130,7 +1130,16 @@ static void lruvec_reparent_lru(struct lruvec *child_lruvec,
 	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);
 
+		if (!size)
+			continue;
+
+		/*
+		 * The folios are accounted to the parent from now on, so the
+		 * size has to be moved, not just copied. Leaving it behind
+		 * makes the dying child describe folios it no longer owns.
+		 */
 		mem_cgroup_update_lru_size(parent_lruvec, lru, zid, size);
+		mem_cgroup_update_lru_size(child_lruvec, lru, zid, -(long)size);
 	}
 }
 
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b569eeca590d..73a81b4a3e16 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4635,7 +4635,12 @@ void lru_gen_reparent_memcg(struct mem_cgroup *memcg, struct mem_cgroup *parent,
 		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);
 
+			if (!size)
+				continue;
+
+			/* Move the accounting, do not duplicate it. */
 			mem_cgroup_update_lru_size(parent_lruvec, lru, zid, size);
+			mem_cgroup_update_lru_size(child_lruvec, lru, zid, -(long)size);
 		}
 	}
 }