memcg: remove the per-node soft limit tree fields

tree_node, usage_in_excess and on_tree only existed for the soft limit
rbtree. They also doubled as the buffer between the read-mostly head of
struct mem_cgroup_per_node and its update-often tail, so replace them
with the explicit padding that CONFIG_MEMCG_V1=n already used.

Link: https://lore.kernel.org/20260902174311.1772372-7-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: T.J. Mercier <tjmercier@google.com>

1 files changed, 0 insertions, 13 deletions

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 11c1fa88d6fd..1eababed16f5 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -95,20 +95,7 @@ struct mem_cgroup_per_node {
 	struct lruvec_stats			*lruvec_stats;
 	struct shrinker_info __rcu	*shrinker_info;
 
-#ifdef CONFIG_MEMCG_V1
-	/*
-	 * Memcg-v1 only stuff in middle as buffer between read mostly fields
-	 * and update often fields to avoid false sharing. If v1 stuff is
-	 * not present, an explicit padding is needed.
-	 */
-
-	struct rb_node		tree_node;	/* RB tree node */
-	unsigned long		usage_in_excess;/* Set to the value by which */
-						/* the soft limit is exceeded*/
-	bool			on_tree;
-#else
 	CACHELINE_PADDING(_pad1_);
-#endif
 
 	/* Fields which get updated often at the end. */
 	struct lruvec		lruvec;