[PATCH v6 04/13] mm/demotion/dax/kmem: Set node's memory tier to MEMORY_TIER_PMEM

["Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxx>]

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

Set dax kmem device node's tier to MEMORY_TIER_PMEM. MEMORY_TIER_PMEM
is assigned a default rank value of 100 and appears below DEFAULT_MEMORY_TIER
in demotion order.

Signed-off-by: Jagdish Gediya <jvgediya@xxxxxxxxxxxxx>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
---
 drivers/dax/kmem.c           |  4 ++
 include/linux/memory-tiers.h |  1 +
 mm/memory-tiers.c            | 78 ++++++++++++++++++++++++++++++++++++
 3 files changed, 83 insertions(+)

diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index a37622060fff..0cb3de3d138f 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"
 
@@ -147,6 +148,9 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
 
 	dev_set_drvdata(dev, data);
 
+#ifdef CONFIG_TIERED_MEMORY
+	node_create_and_set_memory_tier(numa_node, MEMORY_TIER_PMEM);
+#endif
 	return 0;
 
 err_request_mem:
diff --git a/include/linux/memory-tiers.h b/include/linux/memory-tiers.h
index 44c3c3b16a36..e102ec73ab80 100644
--- a/include/linux/memory-tiers.h
+++ b/include/linux/memory-tiers.h
@@ -18,6 +18,7 @@
 #define MAX_MEMORY_TIERS  3
 
 extern bool numa_demotion_enabled;
+int node_create_and_set_memory_tier(int node, int tier);
 #else
 #define numa_demotion_enabled	false
 
diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c
index c3123a457d90..00d393a5a628 100644
--- a/mm/memory-tiers.c
+++ b/mm/memory-tiers.c
@@ -67,6 +67,84 @@ static struct memory_tier *register_memory_tier(unsigned int tier,
 	return memtier;
 }
 
+static struct memory_tier *__node_get_memory_tier(int node)
+{
+	struct memory_tier *memtier;
+
+	list_for_each_entry(memtier, &memory_tiers, list) {
+		if (node_isset(node, memtier->nodelist))
+			return memtier;
+	}
+	return NULL;
+}
+
+static struct memory_tier *__get_memory_tier_from_id(int id)
+{
+	struct memory_tier *memtier;
+
+	list_for_each_entry(memtier, &memory_tiers, list) {
+		if (memtier->id == id)
+			return memtier;
+	}
+	return NULL;
+}
+
+static int __node_create_and_set_memory_tier(int node, int tier)
+{
+	int ret = 0;
+	struct memory_tier *memtier;
+
+	memtier = __get_memory_tier_from_id(tier);
+	if (!memtier) {
+		int rank;
+
+		rank = get_rank_from_tier(tier);
+		if (rank == -1) {
+			ret = -EINVAL;
+			goto out;
+		}
+		memtier = register_memory_tier(tier, rank);
+		if (!memtier) {
+			ret = -EINVAL;
+			goto out;
+		}
+	}
+	node_set(node, memtier->nodelist);
+out:
+	return ret;
+}
+
+int node_create_and_set_memory_tier(int node, int tier)
+{
+	struct memory_tier *current_tier;
+	int ret = 0;
+
+	mutex_lock(&memory_tier_lock);
+
+	current_tier = __node_get_memory_tier(node);
+	if (!current_tier) {
+		ret = __node_create_and_set_memory_tier(node, tier);
+		goto out;
+	}
+
+	if (current_tier->id == tier)
+		goto out;
+
+	node_clear(node, current_tier->nodelist);
+
+	ret = __node_create_and_set_memory_tier(node, tier);
+	if (ret) {
+		/* reset it back to older tier */
+		node_set(node, current_tier->nodelist);
+		goto out;
+	}
+out:
+	mutex_unlock(&memory_tier_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(node_create_and_set_memory_tier);
+
 static int __init memory_tier_init(void)
 {
 	struct memory_tier *memtier;
-- 
2.36.1