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[96.255.20.138]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-4eda57ad8e6sm3293421cf.27.2025.11.07.14.50.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 07 Nov 2025 14:50:08 -0800 (PST) From: Gregory Price To: linux-mm@kvack.org Cc: linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org, nvdimm@lists.linux.dev, linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org, dave@stgolabs.net, jonathan.cameron@huawei.com, dave.jiang@intel.com, alison.schofield@intel.com, vishal.l.verma@intel.com, ira.weiny@intel.com, dan.j.williams@intel.com, longman@redhat.com, akpm@linux-foundation.org, david@redhat.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, osalvador@suse.de, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, apopple@nvidia.com, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, tj@kernel.org, hannes@cmpxchg.org, mkoutny@suse.com, kees@kernel.org, muchun.song@linux.dev, roman.gushchin@linux.dev, shakeel.butt@linux.dev, rientjes@google.com, jackmanb@google.com, cl@gentwo.org, harry.yoo@oracle.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, zhengqi.arch@bytedance.com, yosry.ahmed@linux.dev, nphamcs@gmail.com, chengming.zhou@linux.dev, fabio.m.de.francesco@linux.intel.com, rrichter@amd.com, ming.li@zohomail.com, usamaarif642@gmail.com, brauner@kernel.org, oleg@redhat.com, namcao@linutronix.de, escape@linux.alibaba.com, dongjoo.seo1@samsung.com Subject: [RFC PATCH 2/9] memory-tiers: create default_sysram_nodes Date: Fri, 7 Nov 2025 17:49:47 -0500 Message-ID: <20251107224956.477056-3-gourry@gourry.net> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20251107224956.477056-1-gourry@gourry.net> References: <20251107224956.477056-1-gourry@gourry.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Record the set of memory nodes present at __init time, so that hotplug memory nodes can choose whether to expose themselves to the page allocator at hotplug time. Do not included non-sysram nodes in demotion targets. Signed-off-by: Gregory Price --- include/linux/memory-tiers.h | 3 +++ mm/memory-tiers.c | 22 ++++++++++++++++++++-- 2 files changed, 23 insertions(+), 2 deletions(-) diff --git a/include/linux/memory-tiers.h b/include/linux/memory-tiers.h index 7a805796fcfd..3d3f3687d134 100644 --- a/include/linux/memory-tiers.h +++ b/include/linux/memory-tiers.h @@ -39,6 +39,9 @@ struct access_coordinate; extern bool numa_demotion_enabled; extern struct memory_dev_type *default_dram_type; extern nodemask_t default_dram_nodes; +extern nodemask_t default_sysram_nodelist; +#define default_sysram_nodes (nodes_empty(default_sysram_nodelist) ? NULL = : \ + &default_sysram_nodelist) struct memory_dev_type *alloc_memory_type(int adistance); void put_memory_type(struct memory_dev_type *memtype); void init_node_memory_type(int node, struct memory_dev_type *default_type); diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c index 0ea5c13f10a2..b2ee4f73ad54 100644 --- a/mm/memory-tiers.c +++ b/mm/memory-tiers.c @@ -44,7 +44,12 @@ static LIST_HEAD(memory_tiers); static LIST_HEAD(default_memory_types); static struct node_memory_type_map node_memory_types[MAX_NUMNODES]; struct memory_dev_type *default_dram_type; -nodemask_t default_dram_nodes __initdata =3D NODE_MASK_NONE; + +/* default_dram_nodes is the list of nodes with both CPUs and RAM */ +nodemask_t default_dram_nodes =3D NODE_MASK_NONE; + +/* default_sysram_nodelist is the list of nodes with RAM at __init time */ +nodemask_t default_sysram_nodelist =3D NODE_MASK_NONE; =20 static const struct bus_type memory_tier_subsys =3D { .name =3D "memory_tiering", @@ -427,6 +432,14 @@ static void establish_demotion_targets(void) disable_all_demotion_targets(); =20 for_each_node_state(node, N_MEMORY) { + /* + * If this is not a sysram node, direct-demotion is not allowed + * and must be managed by special logic that understands the + * memory features of that particular node. + */ + if (!node_isset(node, default_sysram_nodelist)) + continue; + best_distance =3D -1; nd =3D &node_demotion[node]; =20 @@ -457,7 +470,8 @@ static void establish_demotion_targets(void) break; =20 distance =3D node_distance(node, target); - if (distance =3D=3D best_distance || best_distance =3D=3D -1) { + if ((distance =3D=3D best_distance || best_distance =3D=3D -1) && + node_isset(target, default_sysram_nodelist)) { best_distance =3D distance; node_set(target, nd->preferred); } else { @@ -812,6 +826,7 @@ int mt_perf_to_adistance(struct access_coordinate *perf= , int *adist) } EXPORT_SYMBOL_GPL(mt_perf_to_adistance); =20 + /** * register_mt_adistance_algorithm() - Register memory tiering abstract di= stance algorithm * @nb: The notifier block which describe the algorithm @@ -922,6 +937,9 @@ static int __init memory_tier_init(void) nodes_and(default_dram_nodes, node_states[N_MEMORY], node_states[N_CPU]); =20 + /* Record all nodes with non-hotplugged memory as default SYSRAM nodes */ + default_sysram_nodelist =3D node_states[N_MEMORY]; + hotplug_node_notifier(memtier_hotplug_callback, MEMTIER_HOTPLUG_PRI); return 0; } --=20 2.51.1