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Howlett" , Lorenzo Stoakes , Matthew Brost , Mel Gorman , Michal Hocko , Michal Hocko , Mike Rapoport , Muchun Song , Peter Zijlstra , Qi Zheng , Rakie Kim , Roman Gushchin , Shakeel Butt , Steven Rostedt , Suren Baghdasaryan , "T.J. Mercier" , Valentin Schneider , Vincent Guittot , Vlastimil Babka , Wei Xu , Ying Huang , Yosry Ahmed , Yuanchu Xie , Zi Yan , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel-team@meta.com Subject: [RFC PATCH v3 08/14] mm/memcontrol: Make memory.low and memory.min tier-aware Date: Fri, 7 Aug 2026 13:20:51 -0700 Message-ID: <20260807202059.2620949-9-joshua.hahnjy@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260807202059.2620949-1-joshua.hahnjy@gmail.com> References: <20260807202059.2620949-1-joshua.hahnjy@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On machines serving multiple workloads whose memory is isolated via the memory cgroup controller, it is currently impossible to enforce a fair distribution of tiered memory among the workloads, as the only enforceable limits have to do with total memory footprint, but not where that memory resides. This makes ensuring a consistent and baseline performance difficult, as each workload's performance is heavily impacted by workload-external factors such as which other workloads are co-located in the same host, and the order at which different workloads are started. Extend the existing memory.{low, min} protection to be tier-aware in order to enforce proportional best-effort and guaranteed memory protection of higher-tier memory. No-op unless the system has tiered memcg limits enabled. Signed-off-by: Joshua Hahn --- include/linux/memcontrol.h | 25 +++++++++++++++++++++---- mm/memcontrol.c | 11 ++++++++++- mm/vmscan.c | 15 +++++++++------ 3 files changed, 40 insertions(+), 11 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index f7a92b66330ec..ceba0fd6de184 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -18,6 +18,7 @@ #include #include #include +#include #include #include #include @@ -618,21 +619,37 @@ static inline bool mem_cgroup_unprotected(struct mem_cgroup *target, } static inline bool mem_cgroup_below_low(struct mem_cgroup *target, - struct mem_cgroup *memcg) + struct mem_cgroup *memcg, int nid) { if (mem_cgroup_unprotected(target, memcg)) return false; + if (mem_cgroup_tiered_limits()) { + int slot = nid_tier_slot(nid); + + if (slot >= 0) + return READ_ONCE(memcg->tier[slot].elow) >= + page_counter_read(&memcg->tier[slot]); + } + return READ_ONCE(memcg->memory.elow) >= page_counter_read(&memcg->memory); } static inline bool mem_cgroup_below_min(struct mem_cgroup *target, - struct mem_cgroup *memcg) + struct mem_cgroup *memcg, int nid) { if (mem_cgroup_unprotected(target, memcg)) return false; + if (mem_cgroup_tiered_limits()) { + int slot = nid_tier_slot(nid); + + if (slot >= 0) + return READ_ONCE(memcg->tier[slot].emin) >= + page_counter_read(&memcg->tier[slot]); + } + return READ_ONCE(memcg->memory.emin) >= page_counter_read(&memcg->memory); } @@ -1142,13 +1159,13 @@ static inline bool mem_cgroup_unprotected(struct mem_cgroup *target, return true; } static inline bool mem_cgroup_below_low(struct mem_cgroup *target, - struct mem_cgroup *memcg) + struct mem_cgroup *memcg, int nid) { return false; } static inline bool mem_cgroup_below_min(struct mem_cgroup *target, - struct mem_cgroup *memcg) + struct mem_cgroup *memcg, int nid) { return false; } diff --git a/mm/memcontrol.c b/mm/memcontrol.c index f3714dfd85aa0..025496794cb91 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5310,7 +5310,16 @@ void mem_cgroup_calculate_protection(struct mem_cgroup *root, if (!root) root = root_mem_cgroup; - page_counter_calculate_protection(&root->memory, &memcg->memory, recursive_protection); + page_counter_calculate_protection(&root->memory, &memcg->memory, + recursive_protection); + + if (mem_cgroup_tiered_limits()) { + int nr_tier_slots = mt_nr_tier_slots(); + + for (int slot = 0; slot < nr_tier_slots; slot++) + page_counter_calculate_protection(&root->tier[slot], + &memcg->tier[slot], recursive_protection); + } } static int charge_memcg(struct folio *folio, struct mem_cgroup *memcg, diff --git a/mm/vmscan.c b/mm/vmscan.c index ffe7ea3c5aff6..29f3f12042650 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -4190,7 +4190,7 @@ static bool lruvec_is_reclaimable(struct lruvec *lruvec, struct scan_control *sc struct mem_cgroup *memcg = lruvec_memcg(lruvec); DEFINE_MIN_SEQ(lruvec); - if (mem_cgroup_below_min(NULL, memcg)) + if (mem_cgroup_below_min(NULL, memcg, lruvec_pgdat(lruvec)->node_id)) return false; if (!lruvec_is_sizable(lruvec, sc)) @@ -5057,6 +5057,7 @@ static bool try_to_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) bool need_rotate = false, should_age = false; long nr_batch, nr_to_scan; int swappiness = get_swappiness(lruvec, sc); + int nid = lruvec_pgdat(lruvec)->node_id; struct mem_cgroup *memcg = lruvec_memcg(lruvec); nr_to_scan = get_nr_to_scan(lruvec, sc, memcg, swappiness); @@ -5064,7 +5065,7 @@ static bool try_to_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) int delta; DEFINE_MAX_SEQ(lruvec); - if (mem_cgroup_below_min(sc->target_mem_cgroup, memcg)) { + if (mem_cgroup_below_min(sc->target_mem_cgroup, memcg, nid)) { need_rotate = true; break; } @@ -5104,12 +5105,13 @@ static int shrink_one(struct lruvec *lruvec, struct scan_control *sc) unsigned long reclaimed = sc->nr_reclaimed; struct mem_cgroup *memcg = lruvec_memcg(lruvec); struct pglist_data *pgdat = lruvec_pgdat(lruvec); + int nid = pgdat->node_id; /* lru_gen_age_node() called mem_cgroup_calculate_protection() */ - if (mem_cgroup_below_min(NULL, memcg)) + if (mem_cgroup_below_min(NULL, memcg, nid)) return MEMCG_LRU_YOUNG; - if (mem_cgroup_below_low(NULL, memcg)) { + if (mem_cgroup_below_low(NULL, memcg, nid)) { /* see the comment on MEMCG_NR_GENS */ if (READ_ONCE(lruvec->lrugen.seg) != MEMCG_LRU_TAIL) return MEMCG_LRU_TAIL; @@ -6168,6 +6170,7 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc) }; struct mem_cgroup_reclaim_cookie *partial = &reclaim; struct mem_cgroup *memcg; + int nid = pgdat->node_id; /* * In most cases, direct reclaimers can do partial walks @@ -6197,13 +6200,13 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc) mem_cgroup_calculate_protection(target_memcg, memcg); - if (mem_cgroup_below_min(target_memcg, memcg)) { + if (mem_cgroup_below_min(target_memcg, memcg, nid)) { /* * Hard protection. * If there is no reclaimable memory, OOM. */ continue; - } else if (mem_cgroup_below_low(target_memcg, memcg)) { + } else if (mem_cgroup_below_low(target_memcg, memcg, nid)) { /* * Soft protection. * Respect the protection only as long as -- 2.53.0-Meta