5 files changed, 51 insertions, 0 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 949d7c325133..534d30cff9d7 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -36,6 +36,7 @@
 #include <linux/numa.h>
 #include <linux/page_owner.h>
 #include <linux/sched/sysctl.h>
+#include <linux/memory-tiers.h>
 
 #include <asm/tlb.h>
 #include <asm/pgalloc.h>
diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c
index 45dd6fa4e2d1..c82eb0111383 100644
--- a/mm/memory-tiers.c
+++ b/mm/memory-tiers.c
@@ -37,6 +37,7 @@ static LIST_HEAD(memory_tiers);
 static struct node_memory_type_map node_memory_types[MAX_NUMNODES];
 static struct memory_dev_type *default_dram_type;
 #ifdef CONFIG_MIGRATION
+static int top_tier_adistance;
 /*
  * node_demotion[] examples:
  *
@@ -162,6 +163,31 @@ static struct memory_tier *__node_get_memory_tier(int node)
 }
 
 #ifdef CONFIG_MIGRATION
+bool node_is_toptier(int node)
+{
+	bool toptier;
+	pg_data_t *pgdat;
+	struct memory_tier *memtier;
+
+	pgdat = NODE_DATA(node);
+	if (!pgdat)
+		return false;
+
+	rcu_read_lock();
+	memtier = rcu_dereference(pgdat->memtier);
+	if (!memtier) {
+		toptier = true;
+		goto out;
+	}
+	if (memtier->adistance_start <= top_tier_adistance)
+		toptier = true;
+	else
+		toptier = false;
+out:
+	rcu_read_unlock();
+	return toptier;
+}
+
 void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets)
 {
 	struct memory_tier *memtier;
@@ -320,6 +346,27 @@ static void establish_demotion_targets(void)
 		} while (1);
 	}
 	/*
+	 * Promotion is allowed from a memory tier to higher
+	 * memory tier only if the memory tier doesn't include
+	 * compute. We want to skip promotion from a memory tier,
+	 * if any node that is part of the memory tier have CPUs.
+	 * Once we detect such a memory tier, we consider that tier
+	 * as top tiper from which promotion is not allowed.
+	 */
+	list_for_each_entry_reverse(memtier, &memory_tiers, list) {
+		tier_nodes = get_memtier_nodemask(memtier);
+		nodes_and(tier_nodes, node_states[N_CPU], tier_nodes);
+		if (!nodes_empty(tier_nodes)) {
+			/*
+			 * abstract distance below the max value of this memtier
+			 * is considered toptier.
+			 */
+			top_tier_adistance = memtier->adistance_start +
+						MEMTIER_CHUNK_SIZE - 1;
+			break;
+		}
+	}
+	/*
 	 * Now build the lower_tier mask for each node collecting node mask from
 	 * all memory tier below it. This allows us to fallback demotion page
 	 * allocation to a set of nodes that is closer the above selected
diff --git a/mm/memory.c b/mm/memory.c
index 63832dab15d3..cb955c0b7738 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -66,6 +66,7 @@
 #include <linux/gfp.h>
 #include <linux/migrate.h>
 #include <linux/string.h>
+#include <linux/memory-tiers.h>
 #include <linux/debugfs.h>
 #include <linux/userfaultfd_k.h>
 #include <linux/dax.h>
diff --git a/mm/migrate.c b/mm/migrate.c
index 2a2329bf7c1a..d74573c36573 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -50,6 +50,7 @@
 #include <linux/memory.h>
 #include <linux/random.h>
 #include <linux/sched/sysctl.h>
+#include <linux/memory-tiers.h>
 
 #include <asm/tlbflush.h>
 
diff --git a/mm/mprotect.c b/mm/mprotect.c
index ed013f836b4a..55ed4a889990 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -31,6 +31,7 @@
 #include <linux/pgtable.h>
 #include <linux/sched/sysctl.h>
 #include <linux/userfaultfd_k.h>
+#include <linux/memory-tiers.h>
 #include <asm/cacheflush.h>
 #include <asm/mmu_context.h>
 #include <asm/tlbflush.h>