[PATCH v1 1/2] mm: multi-gen LRU: use mem_cgroup_lruvec() in get

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* [PATCH v1 1/2] mm: multi-gen LRU: use mem_cgroup_lruvec() in get_lruvec()
@ 2026-10-21 23:56 Siddharth Chintamaneni
  2026-10-21 23:56 ` [PATCH v1 2/2] mm: multi-gen LRU: remove get_lruvec() Siddharth Chintamaneni
  0 siblings, 1 reply; 2+ messages in thread
From: Siddharth Chintamaneni @ 2026-10-21 23:56 UTC (permalink / raw)
  To: akpm, hannes
  Cc: david, mhocko, qi.zheng, shakeel.butt, ljs, kasong, baohua,
	axelrasmussen, yuanchu, weixugc, baoquan.he, baolin.wang, yuzhao,
	linux-mm, linux-kernel, apais, rlmenge, Siddharth Chintamaneni,
	Hardik Garg

Andrew Morton noted that get_lruvec() has the same pattern as
lru_gen_shrink_node(): when memcg is disabled on the command line
(cgroup_disable=memory), it returns &pgdat->__lruvec directly instead of
going through mem_cgroup_lruvec(), which initializes lruvec->pgdat.

In practice all callers of get_lruvec() run after kswapd_init() has
already initialized pgdat->__lruvec.pgdat on every N_MEMORY node, so
this is not a runtime bug. Have get_lruvec() delegate to
mem_cgroup_lruvec() directly.

Signed-off-by: Siddharth Chintamaneni <sidchintamaneni@gmail.com>
Signed-off-by: Hardik Garg <hargar@linux.microsoft.com>
---
 mm/vmscan.c | 15 ++-------------
 1 file changed, 2 insertions(+), 13 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 0c57e4f1eb15..99e9f07fa2e1 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2745,20 +2745,9 @@ static struct lruvec *get_lruvec(struct mem_cgroup *memcg, int nid)
 {
 	struct pglist_data *pgdat = NODE_DATA(nid);
 
-#ifdef CONFIG_MEMCG
-	if (memcg) {
-		struct lruvec *lruvec = &memcg->nodeinfo[nid]->lruvec;
-
-		/* see the comment in mem_cgroup_lruvec() */
-		if (!lruvec->pgdat)
-			lruvec->pgdat = pgdat;
-
-		return lruvec;
-	}
-#endif
-	VM_WARN_ON_ONCE(!mem_cgroup_disabled());
+	VM_WARN_ON_ONCE(!memcg && !mem_cgroup_disabled());
 
-	return &pgdat->__lruvec;
+	return mem_cgroup_lruvec(memcg, pgdat);
 }
 
 static int get_swappiness(struct lruvec *lruvec, struct scan_control *sc)
-- 
2.45.4


^ permalink raw reply	[flat|nested] 2+ messages in thread

* [PATCH v1 2/2] mm: multi-gen LRU: remove get_lruvec()
  2026-10-21 23:56 [PATCH v1 1/2] mm: multi-gen LRU: use mem_cgroup_lruvec() in get_lruvec() Siddharth Chintamaneni
@ 2026-10-21 23:56 ` Siddharth Chintamaneni
  0 siblings, 0 replies; 2+ messages in thread
From: Siddharth Chintamaneni @ 2026-10-21 23:56 UTC (permalink / raw)
  To: akpm, hannes
  Cc: david, mhocko, qi.zheng, shakeel.butt, ljs, kasong, baohua,
	axelrasmussen, yuanchu, weixugc, baoquan.he, baolin.wang, yuzhao,
	linux-mm, linux-kernel, apais, rlmenge, Siddharth Chintamaneni,
	Hardik Garg

get_lruvec() was originally introduced in commit ec1c86b25f4b ("mm:
multi-gen LRU: groundwork") to guard against NULL NODE_DATA(nid) on
uninitialized NUMA nodes (`return pgdat ? &pgdat->__lruvec : NULL;`).
After commit 09f49dca570a ("mm: handle uninitialized numa nodes
gracefully") and commit 931b6a8b36a2 ("mm: multi-gen LRU: remove NULL
checks on NODE_DATA()"), that NULL check was removed, leaving
get_lruvec() as a thin wrapper around mem_cgroup_lruvec().

Remove get_lruvec() and call mem_cgroup_lruvec() directly at all call
sites.

Cc: Barry Song <baohua@kernel.org>
Signed-off-by: Siddharth Chintamaneni <sidchintamaneni@gmail.com>
Signed-off-by: Hardik Garg <hargar@linux.microsoft.com>
---
 mm/vmscan.c | 39 +++++++++++++++------------------------
 1 file changed, 15 insertions(+), 24 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 99e9f07fa2e1..5767b94fd8e8 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2741,15 +2741,6 @@ static bool should_clear_pmd_young(void)
 #define get_memcg_gen(seq)	((seq) % MEMCG_NR_GENS)
 #define get_memcg_bin(bin)	((bin) % MEMCG_NR_BINS)
 
-static struct lruvec *get_lruvec(struct mem_cgroup *memcg, int nid)
-{
-	struct pglist_data *pgdat = NODE_DATA(nid);
-
-	VM_WARN_ON_ONCE(!memcg && !mem_cgroup_disabled());
-
-	return mem_cgroup_lruvec(memcg, pgdat);
-}
-
 static int get_swappiness(struct lruvec *lruvec, struct scan_control *sc)
 {
 	struct mem_cgroup *memcg = lruvec_memcg(lruvec);
@@ -2942,7 +2933,7 @@ void lru_gen_add_mm(struct mm_struct *mm)
 	spin_lock(&mm_list->lock);
 
 	for_each_node_state(nid, N_MEMORY) {
-		struct lruvec *lruvec = get_lruvec(memcg, nid);
+		struct lruvec *lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid));
 		struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
 
 		/* the first addition since the last iteration */
@@ -2972,7 +2963,7 @@ void lru_gen_del_mm(struct mm_struct *mm)
 	spin_lock(&mm_list->lock);
 
 	for_each_node(nid) {
-		struct lruvec *lruvec = get_lruvec(memcg, nid);
+		struct lruvec *lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid));
 		struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
 
 		/* where the current iteration continues after */
@@ -4424,7 +4415,7 @@ void lru_gen_online_memcg(struct mem_cgroup *memcg)
 
 	for_each_node(nid) {
 		struct pglist_data *pgdat = NODE_DATA(nid);
-		struct lruvec *lruvec = get_lruvec(memcg, nid);
+		struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
 
 		spin_lock_irq(&pgdat->memcg_lru.lock);
 
@@ -4446,7 +4437,7 @@ void lru_gen_offline_memcg(struct mem_cgroup *memcg)
 	int nid;
 
 	for_each_node(nid) {
-		struct lruvec *lruvec = get_lruvec(memcg, nid);
+		struct lruvec *lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid));
 
 		lru_gen_rotate_memcg(lruvec, MEMCG_LRU_OLD);
 	}
@@ -4459,7 +4450,7 @@ void lru_gen_release_memcg(struct mem_cgroup *memcg)
 
 	for_each_node(nid) {
 		struct pglist_data *pgdat = NODE_DATA(nid);
-		struct lruvec *lruvec = get_lruvec(memcg, nid);
+		struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
 
 		spin_lock_irq(&pgdat->memcg_lru.lock);
 
@@ -4480,7 +4471,7 @@ void lru_gen_release_memcg(struct mem_cgroup *memcg)
 
 void lru_gen_soft_reclaim(struct mem_cgroup *memcg, int nid)
 {
-	struct lruvec *lruvec = get_lruvec(memcg, nid);
+	struct lruvec *lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid));
 
 	/* see the comment on MEMCG_NR_GENS */
 	if (READ_ONCE(lruvec->lrugen.seg) != MEMCG_LRU_HEAD)
@@ -4489,7 +4480,7 @@ void lru_gen_soft_reclaim(struct mem_cgroup *memcg, int nid)
 
 bool recheck_lru_gen_max_memcg(struct mem_cgroup *memcg, int nid)
 {
-	struct lruvec *lruvec = get_lruvec(memcg, nid);
+	struct lruvec *lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid));
 	int type;
 
 	for (type = 0; type < ANON_AND_FILE; type++) {
@@ -4536,7 +4527,7 @@ static void try_to_inc_max_seq_nowalk(struct mem_cgroup *memcg,
  */
 void max_lru_gen_memcg(struct mem_cgroup *memcg, int nid)
 {
-	struct lruvec *lruvec = get_lruvec(memcg, nid);
+	struct lruvec *lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid));
 	int type;
 
 	for (type = 0; type < ANON_AND_FILE; type++) {
@@ -4613,8 +4604,8 @@ void lru_gen_reparent_memcg(struct mem_cgroup *memcg, struct mem_cgroup *parent,
 	struct zone *zone;
 	enum lru_list lru;
 
-	child_lruvec = get_lruvec(memcg, nid);
-	parent_lruvec = get_lruvec(parent, nid);
+	child_lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid));
+	parent_lruvec = mem_cgroup_lruvec(parent, NODE_DATA(nid));
 
 	for_each_managed_zone_pgdat(zone, NODE_DATA(nid), zid, MAX_NR_ZONES - 1)
 		for (type = 0; type < ANON_AND_FILE; type++)
@@ -5370,7 +5361,7 @@ static void lru_gen_change_state(bool enabled)
 		int nid;
 
 		for_each_node(nid) {
-			struct lruvec *lruvec = get_lruvec(memcg, nid);
+			struct lruvec *lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid));
 
 			lruvec_lock_irq(lruvec);
 
@@ -5501,7 +5492,7 @@ static void *lru_gen_seq_start(struct seq_file *m, loff_t *pos)
 
 		for_each_node_state(nid, N_MEMORY) {
 			if (!nr_to_skip--)
-				return get_lruvec(memcg, nid);
+				return mem_cgroup_lruvec(memcg, NODE_DATA(nid));
 		}
 	} while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)));
 
@@ -5533,7 +5524,7 @@ static void *lru_gen_seq_next(struct seq_file *m, void *v, loff_t *pos)
 		nid = first_memory_node;
 	}
 
-	return get_lruvec(memcg, nid);
+	return mem_cgroup_lruvec(memcg, NODE_DATA(nid));
 }
 
 static void lru_gen_seq_show_full(struct seq_file *m, struct lruvec *lruvec,
@@ -5715,7 +5706,7 @@ static int run_cmd(char cmd, u64 memcg_id, int nid, unsigned long seq,
 		goto done;
 
 	sc->target_mem_cgroup = memcg;
-	lruvec = get_lruvec(memcg, nid);
+	lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid));
 
 	if (swappiness < MIN_SWAPPINESS)
 		swappiness = get_swappiness(lruvec, sc);
@@ -5899,7 +5890,7 @@ void lru_gen_exit_memcg(struct mem_cgroup *memcg)
 	VM_WARN_ON_ONCE(mm_list && !list_empty(&mm_list->fifo));
 
 	for_each_node(nid) {
-		struct lruvec *lruvec = get_lruvec(memcg, nid);
+		struct lruvec *lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid));
 		struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
 
 		VM_WARN_ON_ONCE(memchr_inv(lruvec->lrugen.nr_pages, 0,
-- 
2.45.4


^ permalink raw reply	[flat|nested] 2+ messages in thread

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2026-10-21 23:56 [PATCH v1 1/2] mm: multi-gen LRU: use mem_cgroup_lruvec() in get_lruvec() Siddharth Chintamaneni
2026-10-21 23:56 ` [PATCH v1 2/2] mm: multi-gen LRU: remove get_lruvec() Siddharth Chintamaneni

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