ACPI: memhotplug: use a single static memory group for a single memory device

Let's group all memory we add for a single memory device - we want a
single node for that (which also seems to be the sane thing to do).

We won't care for now about memory that was already added to the system
(e.g., via e820) -- usually *all* memory of a memory device was already
added and we'll fail acpi_memory_enable_device().

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: David Hildenbrand <[e-mail]>
Acked-by: Rafael J. Wysocki <[e-mail]>
Cc: Anshuman Khandual <[e-mail]>
Cc: Dan Williams <[e-mail]>
Cc: Dave Hansen <[e-mail]>
Cc: Greg Kroah-Hartman <[e-mail]>
Cc: Hui Zhu <[e-mail]>
Cc: Jason Wang <[e-mail]>
Cc: Len Brown <[e-mail]>
Cc: Marek Kedzierski <[e-mail]>
Cc: "Michael S. Tsirkin" <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Mike Rapoport <[e-mail]>
Cc: Oscar Salvador <[e-mail]>
Cc: Pankaj Gupta <[e-mail]>
Cc: Pavel Tatashin <[e-mail]>
Cc: "Rafael J. Wysocki" <[e-mail]>
Cc: Vitaly Kuznetsov <[e-mail]>
Cc: Vlastimil Babka <[e-mail]>
Cc: Wei Yang <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/acpi/acpi_memhotplug.c

···
 struct acpi_memory_device {
 	struct acpi_device *device;
 	struct list_head res_list;
+	int mgid;
 };
 
 static acpi_status
···
 static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
 {
 	acpi_handle handle = mem_device->device->handle;
+	mhp_t mhp_flags = MHP_NID_IS_MGID;
 	int result, num_enabled = 0;
 	struct acpi_memory_info *info;
-	mhp_t mhp_flags = MHP_NONE;
-	int node;
+	u64 total_length = 0;
+	int node, mgid;
 
 	node = acpi_get_node(handle);
+
+	list_for_each_entry(info, &mem_device->res_list, list) {
+		if (!info->length)
+			continue;
+		/* We want a single node for the whole memory group */
+		if (node < 0)
+			node = memory_add_physaddr_to_nid(info->start_addr);
+		total_length += info->length;
+	}
+
+	if (!total_length) {
+		dev_err(&mem_device->device->dev, "device is empty\n");
+		return -EINVAL;
+	}
+
+	mgid = memory_group_register_static(node, PFN_UP(total_length));
+	if (mgid < 0)
+		return mgid;
+	mem_device->mgid = mgid;
+
 	/*
 	 * Tell the VM there is more memory here...
 	 * Note: Assume that this function returns zero on success
···
 		 */
 		if (!info->length)
 			continue;
-		if (node < 0)
-			node = memory_add_physaddr_to_nid(info->start_addr);
 
 		if (mhp_supports_memmap_on_memory(info->length))
 			mhp_flags |= MHP_MEMMAP_ON_MEMORY;
-		result = __add_memory(node, info->start_addr, info->length,
+		result = __add_memory(mgid, info->start_addr, info->length,
 				      mhp_flags);
 
 		/*
···
 	if (!mem_device)
 		return;
 
+	/* In case we succeeded adding *some* memory, unregistering fails. */
+	if (mem_device->mgid >= 0)
+		memory_group_unregister(mem_device->mgid);
+
 	acpi_memory_free_device_resources(mem_device);
 	mem_device->device->driver_data = NULL;
 	kfree(mem_device);
···
 
 	INIT_LIST_HEAD(&mem_device->res_list);
 	mem_device->device = device;
+	mem_device->mgid = -1;
 	sprintf(acpi_device_name(device), "%s", ACPI_MEMORY_DEVICE_NAME);
 	sprintf(acpi_device_class(device), "%s", ACPI_MEMORY_DEVICE_CLASS);
 	device->driver_data = mem_device;