From: Max Kellermann <max.kellermann@ionos.com>
To: akpm@linux-foundation.org, kasong@tencent.com,
qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org,
axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com,
baoquan.he@linux.dev, baolin.wang@linux.alibaba.com,
david@kernel.org, ljs@kernel.org, liam@infradead.org,
vbabka@kernel.org, rppt@kernel.org, surenb@google.com,
mhocko@suse.com, hannes@cmpxchg.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, rcu@vger.kernel.org
Cc: Max Kellermann <max.kellermann@ionos.com>
Subject: [PATCH 2/5] mm/vmscan: move code to lru_gen_{add,del}_memcg()
Date: Mon, 12 Oct 2026 22:54:44 +0200 [thread overview]
Message-ID: <20261012205447.2717801-3-max.kellermann@ionos.com> (raw)
In-Reply-To: <20261012205447.2717801-1-max.kellermann@ionos.com>
Preparation for the following patch that adds tail caching.
For simplicity, hlist_nulls_del_init_rcu() is now always used, which
is also valid during rotation, because the entry is immediately
reinserted under `memcg_lru.lock`.
Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
---
mm/vmscan.c | 36 ++++++++++++++++++++++++++++--------
1 file changed, 28 insertions(+), 8 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index f11491ee9ed5..3d4bc12cf18e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4379,6 +4379,29 @@ enum {
MEMCG_LRU_YOUNG,
};
+static void lru_gen_add_memcg(struct lru_gen_memcg *memcg_lru,
+ struct lru_gen_folio *lrugen,
+ int gen, int bin, bool at_head)
+{
+ struct hlist_nulls_head *head = &memcg_lru->fifo[gen][bin];
+
+ lockdep_assert_held(&memcg_lru->lock);
+
+ if (at_head)
+ hlist_nulls_add_head_rcu(&lrugen->list, head);
+ else
+ hlist_nulls_add_tail_rcu(&lrugen->list, head);
+}
+
+static void lru_gen_del_memcg(struct lru_gen_memcg *memcg_lru,
+ struct lru_gen_folio *lrugen,
+ int gen)
+{
+ lockdep_assert_held(&memcg_lru->lock);
+
+ hlist_nulls_del_init_rcu(&lrugen->list);
+}
+
static void lru_gen_rotate_memcg(struct lruvec *lruvec, int op)
{
int seg;
@@ -4409,12 +4432,9 @@ static void lru_gen_rotate_memcg(struct lruvec *lruvec, int op)
WRITE_ONCE(lruvec->lrugen.seg, seg);
WRITE_ONCE(lruvec->lrugen.gen, new);
- hlist_nulls_del_rcu(&lruvec->lrugen.list);
-
- if (op == MEMCG_LRU_HEAD || op == MEMCG_LRU_OLD)
- hlist_nulls_add_head_rcu(&lruvec->lrugen.list, &pgdat->memcg_lru.fifo[new][bin]);
- else
- hlist_nulls_add_tail_rcu(&lruvec->lrugen.list, &pgdat->memcg_lru.fifo[new][bin]);
+ lru_gen_del_memcg(&pgdat->memcg_lru, &lruvec->lrugen, old);
+ lru_gen_add_memcg(&pgdat->memcg_lru, &lruvec->lrugen, new, bin,
+ op == MEMCG_LRU_HEAD || op == MEMCG_LRU_OLD);
pgdat->memcg_lru.nr_memcgs[old]--;
pgdat->memcg_lru.nr_memcgs[new]++;
@@ -4445,7 +4465,7 @@ void lru_gen_online_memcg(struct mem_cgroup *memcg)
lruvec->lrugen.gen = gen;
- hlist_nulls_add_tail_rcu(&lruvec->lrugen.list, &pgdat->memcg_lru.fifo[gen][bin]);
+ lru_gen_add_memcg(&pgdat->memcg_lru, &lruvec->lrugen, gen, bin, false);
pgdat->memcg_lru.nr_memcgs[gen]++;
spin_unlock_irq(&pgdat->memcg_lru.lock);
@@ -4479,7 +4499,7 @@ void lru_gen_release_memcg(struct mem_cgroup *memcg)
gen = lruvec->lrugen.gen;
- hlist_nulls_del_init_rcu(&lruvec->lrugen.list);
+ lru_gen_del_memcg(&pgdat->memcg_lru, &lruvec->lrugen, gen);
pgdat->memcg_lru.nr_memcgs[gen]--;
if (!pgdat->memcg_lru.nr_memcgs[gen] && gen == get_memcg_gen(pgdat->memcg_lru.seq))
--
2.47.3
next prev parent reply other threads:[~2026-10-12 20:55 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-12 20:54 [PATCH 0/5] mm: multi-gen LRU: reduce memcg rotation overhead Max Kellermann
2026-10-12 20:54 ` [PATCH 1/5] include/linux/rculist_nulls: add hlist_nulls_add_behind_rcu() Max Kellermann
2026-10-12 20:54 ` Max Kellermann [this message]
2026-10-12 20:54 ` [PATCH 3/5] mm/mglru: cache the last memcg node, make tail insertion constant time Max Kellermann
2026-10-12 20:54 ` [PATCH 4/5] mm/mglru: avoid redundant rotations of young memcgs Max Kellermann
2026-10-12 20:54 ` [PATCH 5/5] mm/mglru: reschedule between memcg reclaim attempts Max Kellermann
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