[RFC PATCH v4 4/7] mm/demotion/dax/kmem: Set node's memory tier to MEMORY_TIER_PMEM

["Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>]

From: Jagdish Gediya <jvgediya@linux.ibm.com>

By default, all nodes are assigned to DEFAULT_MEMORY_TIER which
is memory tier 1 which is designated for nodes with DRAM, so it
is not the right tier for dax devices.

Set dax kmem device node's tier to MEMORY_TIER_PMEM, In future,
support should be added to distinguish the dax-devices which should
not be MEMORY_TIER_PMEM and right memory tier should be set for them.

Signed-off-by: Jagdish Gediya <jvgediya@linux.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
---
 drivers/dax/kmem.c | 4 ++++
 mm/migrate.c       | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index a37622060fff..991782aa2448 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/migrate.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_set_memory_tier(numa_node, MEMORY_TIER_PMEM);
+#endif
 	return 0;
 
 err_request_mem:
diff --git a/mm/migrate.c b/mm/migrate.c
index d819a64db5b1..59d8558dd2ee 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2418,6 +2418,8 @@ int node_set_memory_tier(int node, int tier)
 
 	return ret;
 }
+EXPORT_SYMBOL_GPL(node_set_memory_tier);
+
 
 /**
  * next_demotion_node() - Get the next node in the demotion path
-- 
2.36.1