drivers/acpi/acpi_memhotplug.c | 42 +++++++++++++++++++++++++++++++++---------
  1 file changed, 33 insertions(+), 9 deletions(-)

diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index e52ad5d..f7e3007 100644
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c

@@ -78,6 +78,7 @@ struct acpi_memory_info {
  	unsigned short caching;	/* memory cache attribute */
  	unsigned short write_protect;	/* memory read/write attribute */
  	unsigned int enabled:1;
+	unsigned int failed:1;
  };
  
  struct acpi_memory_device {

@@ -257,9 +258,23 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
  			node = memory_add_physaddr_to_nid(info->start_addr);
  
  		result = add_memory(node, info->start_addr, info->length);
-		if (result)
+
+		/*
+		 * If the memory block has been used by the kernel, add_memory()
+		 * returns -EEXIST. If add_memory() returns the other error, it
+		 * means that this memory block is not used by the kernel.
+		 */
+		if (result && result != -EEXIST) {
+			info->failed = 1;
  			continue;
-		info->enabled = 1;
+		}
+
+		if (!result)
+			info->enabled = 1;
+		/*
+		 * Add num_enable even if add_memory() returns -EEXIST, so the
+		 * device is bound to this driver.
+		 */
  		num_enabled++;
  	}
  	if (!num_enabled) {

@@ -280,21 +295,30 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
  
  static int acpi_memory_remove_memory(struct acpi_memory_device *mem_device)
  {
-	int result;
+	int result = 0;
  	struct acpi_memory_info *info, *n;
  
  	list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
-		if (info->enabled) {
-			result = remove_memory(info->start_addr, info->length);
-			if (result)
-				return result;
-		}
+		if (info->failed)
+			/* The kernel does not use this memory block */
+			continue;
+
+		if (!info->enabled)
+			/*
+			 * The kernel uses this memory block, but it may be not
+			 * managed by us.
+			 */
+			return -EBUSY;
+
+		result = remove_memory(info->start_addr, info->length);
+		if (result)
+			return result;
  
  		list_del(&info->list);
  		kfree(info);
  	}
  
-	return 0;
+	return result;
  }
  
  static void acpi_memory_device_notify(acpi_handle handle, u32 event, void *data)