mm/demotion/dax/kmem: set node's abstract distance to MEMTIER_DEFAULT_DAX_ADISTANCE

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_DEFAULT_DAX_ADISTANCE.  Low-level drivers
like papr_scm or ACPI NFIT can initialize memory device type to a more
accurate value based on device tree details or HMAT.  If the kernel
doesn't find the memory type initialized, a default slower memory type is
assigned by the kmem driver.

[aneesh.kumar@linux.ibm.com: assign correct memory type for multiple dax devices with the same node affinity]
  Link: https://lkml.kernel.org/r/20220826100224.542312-1-aneesh.kumar@linux.ibm.com
Link: https://lkml.kernel.org/r/20220818131042.113280-5-aneesh.kumar@linux.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Wei Xu <weixugc@google.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Bharata B Rao <bharata@amd.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hesham Almatary <hesham.almatary@huawei.com>
Cc: Jagdish Gediya <jvgediya.oss@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tim Chen <tim.c.chen@intel.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 41 insertions, 1 deletions

diff --git a/include/linux/memory-tiers.h b/include/linux/memory-tiers.h
index 7ae6308b2191..49d281866dca 100644
--- a/include/linux/memory-tiers.h
+++ b/include/linux/memory-tiers.h
@@ -2,6 +2,9 @@
 #ifndef _LINUX_MEMORY_TIERS_H
 #define _LINUX_MEMORY_TIERS_H
 
+#include <linux/types.h>
+#include <linux/nodemask.h>
+#include <linux/kref.h>
 /*
  * Each tier cover a abstrace distance chunk size of 128
  */
@@ -16,12 +19,49 @@
 #define MEMTIER_ADISTANCE_DRAM	((4 * MEMTIER_CHUNK_SIZE) + (MEMTIER_CHUNK_SIZE >> 1))
 #define MEMTIER_HOTPLUG_PRIO	100
 
+struct memory_tier;
+struct memory_dev_type {
+	/* list of memory types that 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 kref kref;
+	struct memory_tier *memtier;
+};
+
 #ifdef CONFIG_NUMA
-#include <linux/types.h>
 extern bool numa_demotion_enabled;
+struct memory_dev_type *alloc_memory_type(int adistance);
+void destroy_memory_type(struct memory_dev_type *memtype);
+void init_node_memory_type(int node, struct memory_dev_type *default_type);
+void clear_node_memory_type(int node, struct memory_dev_type *memtype);
 
 #else
 
 #define numa_demotion_enabled	false
+/*
+ * CONFIG_NUMA implementation returns non NULL error.
+ */
+static inline struct memory_dev_type *alloc_memory_type(int adistance)
+{
+	return NULL;
+}
+
+static inline void destroy_memory_type(struct memory_dev_type *memtype)
+{
+
+}
+
+static inline void init_node_memory_type(int node, struct memory_dev_type *default_type)
+{
+
+}
+
+static inline void clear_node_memory_type(int node, struct memory_dev_type *memtype)
+{
+
+}
 #endif	/* CONFIG_NUMA */
 #endif  /* _LINUX_MEMORY_TIERS_H */