[PATCH v2 2/5] mm/memory_hotplug: add 'online_type' argument to add_memory_driver_managed

[Gregory Price <gourry@gourry.net>]

Enable external callers to select how to online the memory rather than
implicitly depending on the system defauilt.

Refactor: Extract __add_memory_resource to take an explicit online type,
and update add_memory_resource to pass the system default.

Export mhp_get_default_online_type() and update existing callers of
add_memory_driver_managed to use it explicitly to make it clear what the
behavior of the function is.

dax_kmem and virtio_mem drivers were updated.

Signed-off-by: Gregory Price <gourry@gourry.net>
---
 drivers/dax/kmem.c             |  3 ++-
 drivers/virtio/virtio_mem.c    |  3 ++-
 include/linux/memory_hotplug.h |  2 +-
 mm/memory_hotplug.c            | 31 +++++++++++++++++++++++--------
 4 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index c036e4d0b610..bb13d9ced2e9 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -175,7 +175,8 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
 		 * this as RAM automatically.
 		 */
 		rc = add_memory_driver_managed(data->mgid, range.start,
-				range_len(&range), kmem_name, mhp_flags);
+				range_len(&range), kmem_name, mhp_flags,
+				mhp_get_default_online_type());
 
 		if (rc) {
 			dev_warn(dev, "mapping%d: %#llx-%#llx memory add failed\n",
diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index 1688ecd69a04..63c0b2b235ab 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -654,7 +654,8 @@ static int virtio_mem_add_memory(struct virtio_mem *vm, uint64_t addr,
 	/* Memory might get onlined immediately. */
 	atomic64_add(size, &vm->offline_size);
 	rc = add_memory_driver_managed(vm->mgid, addr, size, vm->resource_name,
-				       MHP_MERGE_RESOURCE | MHP_NID_IS_MGID);
+				       MHP_MERGE_RESOURCE | MHP_NID_IS_MGID,
+				       mhp_get_default_online_type());
 	if (rc) {
 		atomic64_sub(size, &vm->offline_size);
 		dev_warn(&vm->vdev->dev, "adding memory failed: %d\n", rc);
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index f2f16cdd73ee..b68bc410db67 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -295,7 +295,7 @@ extern int add_memory_resource(int nid, struct resource *resource,
 			       mhp_t mhp_flags);
 extern int add_memory_driver_managed(int nid, u64 start, u64 size,
 				     const char *resource_name,
-				     mhp_t mhp_flags);
+				     mhp_t mhp_flags, int online_type);
 extern void move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
 				   unsigned long nr_pages,
 				   struct vmem_altmap *altmap, int migratetype,
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 5718556121f0..2b4e31161fc1 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -239,6 +239,7 @@ int mhp_get_default_online_type(void)
 
 	return mhp_default_online_type;
 }
+EXPORT_SYMBOL_GPL(mhp_get_default_online_type);
 
 void mhp_set_default_online_type(int online_type)
 {
@@ -1490,7 +1491,8 @@ static int create_altmaps_and_memory_blocks(int nid, struct memory_group *group,
  *
  * we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG
  */
-int add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
+static int __add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags,
+				 int online_type)
 {
 	struct mhp_params params = { .pgprot = pgprot_mhp(PAGE_KERNEL) };
 	enum memblock_flags memblock_flags = MEMBLOCK_NONE;
@@ -1580,12 +1582,9 @@ int add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
 		merge_system_ram_resource(res);
 
 	/* online pages if requested */
-	if (mhp_get_default_online_type() != MMOP_OFFLINE) {
-		int online_type = mhp_get_default_online_type();
-
+	if (online_type != MMOP_OFFLINE)
 		walk_memory_blocks(start, size, &online_type,
 				   online_memory_block);
-	}
 
 	return ret;
 error:
@@ -1601,7 +1600,13 @@ int add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
 	return ret;
 }
 
-/* requires device_hotplug_lock, see add_memory_resource() */
+int add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
+{
+	return __add_memory_resource(nid, res, mhp_flags,
+				     mhp_get_default_online_type());
+}
+
+/* requires device_hotplug_lock, see __add_memory_resource() */
 int __add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags)
 {
 	struct resource *res;
@@ -1649,9 +1654,16 @@ EXPORT_SYMBOL_GPL(add_memory);
  *
  * The resource_name (visible via /proc/iomem) has to have the format
  * "System RAM ($DRIVER)".
+ *
+ * @online_type specifies the online behavior: MMOP_ONLINE, MMOP_ONLINE_KERNEL,
+ * MMOP_ONLINE_MOVABLE to online with that type, MMOP_OFFLINE to leave offline.
+ * Users that want the system default should call mhp_get_default_online_type().
+ *
+ * Returns 0 on success, negative error code on failure.
  */
 int add_memory_driver_managed(int nid, u64 start, u64 size,
-			      const char *resource_name, mhp_t mhp_flags)
+			      const char *resource_name, mhp_t mhp_flags,
+			      int online_type)
 {
 	struct resource *res;
 	int rc;
@@ -1661,6 +1673,9 @@ int add_memory_driver_managed(int nid, u64 start, u64 size,
 	    resource_name[strlen(resource_name) - 1] != ')')
 		return -EINVAL;
 
+	if (online_type < 0 || online_type > MMOP_ONLINE_MOVABLE)
+		return -EINVAL;
+
 	lock_device_hotplug();
 
 	res = register_memory_resource(start, size, resource_name);
@@ -1669,7 +1684,7 @@ int add_memory_driver_managed(int nid, u64 start, u64 size,
 		goto out_unlock;
 	}
 
-	rc = add_memory_resource(nid, res, mhp_flags);
+	rc = __add_memory_resource(nid, res, mhp_flags, online_type);
 	if (rc < 0)
 		release_memory_resource(res);
 
-- 
2.52.0