1 files changed, 15 insertions, 5 deletions

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 31c237a00c48..8122018d3000 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -13,12 +13,16 @@ struct mem_section;
 #ifdef CONFIG_MEMORY_HOTPLUG
 
 /*
- * Types for free bootmem.
- * The normal smallest mapcount is -1. Here is smaller value than it.
+ * Types for free bootmem stored in page->lru.next. These have to be in
+ * some random range in unsigned long space for debugging purposes.
  */
-#define SECTION_INFO            (-1 - 1)
-#define MIX_SECTION_INFO        (-1 - 2)
-#define NODE_INFO               (-1 - 3)
+enum {
+        MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE = 12,
+        SECTION_INFO = MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE,
+        MIX_SECTION_INFO,
+        NODE_INFO,
+        MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE = NODE_INFO,
+};
 
 /*
  * pgdat resizing functions
@@ -161,6 +165,12 @@ extern void register_page_bootmem_info_node(struct pglist_data *pgdat);
 extern void put_page_bootmem(struct page *page);
 #endif
 
+/*
+ * Lock for memory hotplug guarantees 1) all callbacks for memory hotplug
+ * notifier will be called under this. 2) offline/online/add/remove memory
+ * will not run simultaneously.
+ */
+
 void lock_memory_hotplug(void);
 void unlock_memory_hotplug(void);