[PATCH v11 4/8] mm/demotion/dax/kmem: Set node's abstract distance to MEMTIER_ADISTANCE_PMEM

[Aneesh Kumar K.V]

By default, all nodes are assigned to the default memory tier which
is the memory tier designated for nodes with DRAM

Set dax kmem device node's tier to slower memory tier by assigning
abstract distance to MEMTIER_ADISTANCE_PMEM. PMEM tier
appears below the default memory tier in demotion order.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
---
 drivers/dax/kmem.c           |  9 +++++++++
 include/linux/memory-tiers.h | 19 ++++++++++++++++++-
 mm/memory-tiers.c            | 28 ++++++++++++++++------------
 3 files changed, 43 insertions(+), 13 deletions(-)

diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index a37622060fff..6b0d5de9a3e9 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -11,6 +11,7 @@
 #include <linux/fs.h>
 #include <linux/mm.h>
 #include <linux/mman.h>
+#include <linux/memory-tiers.h>
 #include "dax-private.h"
 #include "bus.h"
 
@@ -41,6 +42,12 @@ struct dax_kmem_data {
 	struct resource *res[];
 };
 
+static struct memory_dev_type default_pmem_type  = {
+	.adistance = MEMTIER_ADISTANCE_PMEM,
+	.tier_sibiling = LIST_HEAD_INIT(default_pmem_type.tier_sibiling),
+	.nodes  = NODE_MASK_NONE,
+};
+
 static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
 {
 	struct device *dev = &dev_dax->dev;
@@ -62,6 +69,8 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
 		return -EINVAL;
 	}
 
+	init_node_memory_type(numa_node, &default_pmem_type);
+
 	for (i = 0; i < dev_dax->nr_range; i++) {
 		struct range range;
 
diff --git a/include/linux/memory-tiers.h b/include/linux/memory-tiers.h
index 976f43a5e3be..4f4baf0bf430 100644
--- a/include/linux/memory-tiers.h
+++ b/include/linux/memory-tiers.h
@@ -2,6 +2,8 @@
 #ifndef _LINUX_MEMORY_TIERS_H
 #define _LINUX_MEMORY_TIERS_H
 
+#include <linux/types.h>
+#include <linux/nodemask.h>
 /*
  * Each tier cover a abstrace distance chunk size of 128
  */
@@ -15,12 +17,27 @@
 #define MEMTIER_ADISTANCE_PMEM	(1 << MEMTIER_CHUNK_BITS)
 #define MEMTIER_HOTPLUG_PRIO	100
 
+struct memory_tier;
+struct memory_dev_type {
+	/* list of memory types that are are part of same tier as this type */
+	struct list_head tier_sibiling;
+	/* abstract distance for this specific memory type */
+	int adistance;
+	/* Nodes of same abstract distance */
+	nodemask_t nodes;
+	struct memory_tier *memtier;
+};
+
 #ifdef CONFIG_NUMA
-#include <linux/types.h>
 extern bool numa_demotion_enabled;
+struct memory_dev_type *init_node_memory_type(int node, struct memory_dev_type *default_type);
 
 #else
 
 #define numa_demotion_enabled	false
+static inline struct memory_dev_type *init_node_memory_type(int node, struct memory_dev_type *default_type)
+{
+	return ERR_PTR(-EINVAL);
+}
 #endif	/* CONFIG_NUMA */
 #endif  /* _LINUX_MEMORY_TIERS_H */
diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c
index c9854a394d9b..109be75fa554 100644
--- a/mm/memory-tiers.c
+++ b/mm/memory-tiers.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#include <linux/types.h>
-#include <linux/nodemask.h>
 #include <linux/slab.h>
 #include <linux/lockdep.h>
 #include <linux/memory.h>
@@ -19,16 +17,6 @@ struct memory_tier {
 	int adistance_start;
 };
 
-struct memory_dev_type {
-	/* list of memory types that are are part of same tier as this type */
-	struct list_head tier_sibiling;
-	/* abstract distance for this specific memory type */
-	int adistance;
-	/* Nodes of same abstract distance */
-	nodemask_t nodes;
-	struct memory_tier *memtier;
-};
-
 static DEFINE_MUTEX(memory_tier_lock);
 static LIST_HEAD(memory_tiers);
 struct memory_dev_type *node_memory_types[MAX_NUMNODES];
@@ -141,6 +129,22 @@ static void clear_node_memory_tier(int node)
 	mutex_unlock(&memory_tier_lock);
 }
 
+struct memory_dev_type *init_node_memory_type(int node, struct memory_dev_type *default_type)
+{
+	struct memory_dev_type *mem_type;
+
+	mutex_lock(&memory_tier_lock);
+	if (node_memory_types[node]) {
+		mem_type = node_memory_types[node];
+	} else {
+		node_memory_types[node] = default_type;
+		node_set(node, default_type->nodes);
+		mem_type = default_type;
+	}
+	mutex_unlock(&memory_tier_lock);
+	return mem_type;
+}
+
 static int __meminit memtier_hotplug_callback(struct notifier_block *self,
 					      unsigned long action, void *_arg)
 {
-- 
2.37.1