[PATCH 5/10] memory-hotplug : memory-hotplug: check page type in get_page_bootmem

Yasuaki Ishimatsu isimatu.yasuaki at jp.fujitsu.com
Fri Oct 5 12:32:22 EST 2012


The function get_page_bootmem() may be called more than one time to the same
page. There is no need to set page's type, private if the function is not
the first time called to the page.

Note: the patch is just optimization and does not fix any problem.

CC: David Rientjes <rientjes at google.com>
CC: Jiang Liu <liuj97 at gmail.com>
CC: Len Brown <len.brown at intel.com>
CC: Christoph Lameter <cl at linux.com>
Cc: Minchan Kim <minchan.kim at gmail.com>
CC: Andrew Morton <akpm at linux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motohiro at jp.fujitsu.com>
CC: Wen Congyang <wency at cn.fujitsu.com>
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki at jp.fujitsu.com>
---
 mm/memory_hotplug.c |   15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

Index: linux-3.6/mm/memory_hotplug.c
===================================================================
--- linux-3.6.orig/mm/memory_hotplug.c	2012-10-04 18:29:58.284676075 +0900
+++ linux-3.6/mm/memory_hotplug.c	2012-10-04 18:30:03.454680542 +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 (page_type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE ||
+	    page_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



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