Subject: [RFC PATCH 7/12] memory-hotplug : check page type in get_page_bootmem

From: Yasuaki Ishimatsu <[email-masked]>
Date: Wed, 27 Jun 2012 14:53:17 +0900

There is a possibility that get_page_bootmem() is called to the same page many
times. So when get_page_bootmem is called to the same page, the function only
increments page->_count.

CC: Len Brown <[email-masked]>
CC: Benjamin Herrenschmidt <[email-masked]>
CC: Paul Mackerras <[email-masked]>
CC: Christoph Lameter <[email-masked]>
Cc: Minchan Kim <[email-masked]>
CC: Andrew Morton <[email-masked]>
CC: KOSAKI Motohiro <[email-masked]>
CC: Wen Congyang <[email-masked]>
Signed-off-by: Yasuaki Ishimatsu <[email-masked]>

Index: linux-3.5-rc4/mm/memory_hotplug.c
===================================================================
--- linux-3.5-rc4.orig/mm/memory_hotplug.c	2012-06-26 13:56:34.371988312 +0900
+++ linux-3.5-rc4/mm/memory_hotplug.c	2012-06-26 14:03:37.564697621 +0900
@@ -95,10 +95,17 @@ static void release_memory_resource(stru
 static void get_page_bootmem(unsigned long info,  struct page *page,
 			     unsigned long type)
 {
-	page->lru.next = (struct list_head *) type;
-	SetPagePrivate(page);
-	set_page_private(page, info);
-	atomic_inc(&page->_count);
+	unsigned long page_type;
+
+	page_type = (unsigned long) page->lru.next;
+	if (type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE ||
+	    type > MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE){
+		page->lru.next = (struct list_head *) type;
+		SetPagePrivate(page);
+		set_page_private(page, info);
+		atomic_inc(&page->_count);
+	} else
+		atomic_inc(&page->_count);
 }

 /* reference to __meminit __free_pages_bootmem is valid