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Wed, 02 Sep 2026 17:43:32 +0000 X-Mizu-Trace-ID: d841d0e1b85067ee X-Migadu-Flow: FLOW_OUT From: Shakeel Butt To: Andrew Morton Cc: Michal Hocko , Johannes Weiner , Roman Gushchin , Muchun Song , David Hildenbrand , Lorenzo Stoakes , Kairui Song , Qi Zheng , Barry Song , Axel Rasmussen , tjmercier@google.com, Meta kernel team , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 5/8] memcg: remove lru_gen_soft_reclaim() Date: Wed, 2 Sep 2026 10:43:08 -0700 Message-ID: <20260902174311.1772372-6-shakeel.butt@linux.dev> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260902174311.1772372-1-shakeel.butt@linux.dev> References: <20260902174311.1772372-1-shakeel.butt@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 38C01C000B X-Stat-Signature: mh7hqforexz1ecq84go6a95cy33f9ehi X-HE-Tag: 1788371013-678373 X-HE-Meta: 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 VFYTv5DJ 8rFZsnYozvD7gu7QG/V49Z5pT3G7zgkHzMo4uFsOxtloCCcMvGHjD/jAOdwzsH0T7TeOLOCbJ4ZHp60C65zypBk/bwX5x4kuxCvovgo21w7pMDx08jBKa4b0Yiu9PUHbbPp6z6dsnjrLHogMaQucD4aqwCks68jKbHhGASrkYrJw1HeyqBcVX4AtGnSbJgQn39RjTbZ1FGpCS5FubaSiSYwDGq5Ua1rTgFnYK1jeq/i8O2LVWVc0PpbZ5+2cz92T9x7Qa99ruMZHqnu0tuPpzX5Que6lW/X64bPrXW+wT2S0RXyBsi/f6x9TyNf0179Yrha4W Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The soft limit rbtree was the only caller. Dropping it leaves MEMCG_LRU_HEAD unreachable, since nothing else ever rotates a memcg with that op, so remove the op too and update the memcg LRU comment. Signed-off-by: Shakeel Butt Reviewed-by: T.J. Mercier Acked-by: Lorenzo Stoakes (ARM) --- include/linux/mmzone.h | 30 +++++++++++------------------- mm/vmscan.c | 16 ++-------------- 2 files changed, 13 insertions(+), 33 deletions(-) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 67c84a8a7258..84e237f2c17d 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -638,35 +638,32 @@ struct lru_gen_mm_walk { * For each node, memcgs are divided into two generations: the old and the * young. For each generation, memcgs are randomly sharded into multiple bins * to improve scalability. For each bin, the hlist_nulls is virtually divided - * into three segments: the head, the tail and the default. + * into two segments: the tail and the default. * * An onlining memcg is added to the tail of a random bin in the old generation. * The eviction starts at the head of a random bin in the old generation. The * per-node memcg generation counter, whose reminder (mod MEMCG_NR_GENS) indexes * the old generation, is incremented when all its bins become empty. * - * There are four operations: - * 1. MEMCG_LRU_HEAD, which moves a memcg to the head of a random bin in its - * current generation (old or young) and updates its "seg" to "head"; - * 2. MEMCG_LRU_TAIL, which moves a memcg to the tail of a random bin in its + * There are three operations: + * 1. MEMCG_LRU_TAIL, which moves a memcg to the tail of a random bin in its * current generation (old or young) and updates its "seg" to "tail"; - * 3. MEMCG_LRU_OLD, which moves a memcg to the head of a random bin in the old + * 2. MEMCG_LRU_OLD, which moves a memcg to the head of a random bin in the old * generation, updates its "gen" to "old" and resets its "seg" to "default"; - * 4. MEMCG_LRU_YOUNG, which moves a memcg to the tail of a random bin in the + * 3. MEMCG_LRU_YOUNG, which moves a memcg to the tail of a random bin in the * young generation, updates its "gen" to "young" and resets its "seg" to * "default". * * The events that trigger the above operations are: - * 1. Exceeding the soft limit, which triggers MEMCG_LRU_HEAD; - * 2. The first attempt to reclaim a memcg below low, which triggers + * 1. The first attempt to reclaim a memcg below low, which triggers * MEMCG_LRU_TAIL; - * 3. The first attempt to reclaim a memcg offlined or below reclaimable size + * 2. The first attempt to reclaim a memcg offlined or below reclaimable size * threshold, which triggers MEMCG_LRU_TAIL; - * 4. The second attempt to reclaim a memcg offlined or below reclaimable size + * 3. The second attempt to reclaim a memcg offlined or below reclaimable size * threshold, which triggers MEMCG_LRU_YOUNG; - * 5. Attempting to reclaim a memcg below min, which triggers MEMCG_LRU_YOUNG; - * 6. Finishing the aging on the eviction path, which triggers MEMCG_LRU_YOUNG; - * 7. Offlining a memcg, which triggers MEMCG_LRU_OLD. + * 4. Attempting to reclaim a memcg below min, which triggers MEMCG_LRU_YOUNG; + * 5. Finishing the aging on the eviction path, which triggers MEMCG_LRU_YOUNG; + * 6. Offlining a memcg, which triggers MEMCG_LRU_OLD. * * Notes: * 1. Memcg LRU only applies to global reclaim, and the round-robin incrementing @@ -699,7 +696,6 @@ void lru_gen_exit_memcg(struct mem_cgroup *memcg); void lru_gen_online_memcg(struct mem_cgroup *memcg); void lru_gen_offline_memcg(struct mem_cgroup *memcg); void lru_gen_release_memcg(struct mem_cgroup *memcg); -void lru_gen_soft_reclaim(struct mem_cgroup *memcg, int nid); void max_lru_gen_memcg(struct mem_cgroup *memcg, int nid); bool recheck_lru_gen_max_memcg(struct mem_cgroup *memcg, int nid); void lru_gen_reparent_memcg(struct mem_cgroup *memcg, struct mem_cgroup *parent, int nid); @@ -740,10 +736,6 @@ static inline void lru_gen_release_memcg(struct mem_cgroup *memcg) { } -static inline void lru_gen_soft_reclaim(struct mem_cgroup *memcg, int nid) -{ -} - static inline void max_lru_gen_memcg(struct mem_cgroup *memcg, int nid) { } diff --git a/mm/vmscan.c b/mm/vmscan.c index d66b5cd167d6..deb087c57007 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -4373,7 +4373,6 @@ bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw, unsigned int nr) /* see the comment on MEMCG_NR_GENS */ enum { MEMCG_LRU_NOP, - MEMCG_LRU_HEAD, MEMCG_LRU_TAIL, MEMCG_LRU_OLD, MEMCG_LRU_YOUNG, @@ -4395,9 +4394,7 @@ static void lru_gen_rotate_memcg(struct lruvec *lruvec, int op) new = old = lruvec->lrugen.gen; /* see the comment on MEMCG_NR_GENS */ - if (op == MEMCG_LRU_HEAD) - seg = MEMCG_LRU_HEAD; - else if (op == MEMCG_LRU_TAIL) + if (op == MEMCG_LRU_TAIL) seg = MEMCG_LRU_TAIL; else if (op == MEMCG_LRU_OLD) new = get_memcg_gen(pgdat->memcg_lru.seq); @@ -4411,7 +4408,7 @@ static void lru_gen_rotate_memcg(struct lruvec *lruvec, int op) hlist_nulls_del_rcu(&lruvec->lrugen.list); - if (op == MEMCG_LRU_HEAD || op == MEMCG_LRU_OLD) + if (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]); @@ -4489,15 +4486,6 @@ 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); - - /* see the comment on MEMCG_NR_GENS */ - if (READ_ONCE(lruvec->lrugen.seg) != MEMCG_LRU_HEAD) - lru_gen_rotate_memcg(lruvec, MEMCG_LRU_HEAD); -} - bool recheck_lru_gen_max_memcg(struct mem_cgroup *memcg, int nid) { struct lruvec *lruvec = get_lruvec(memcg, nid); -- 2.53.0-Meta