[RFC PATCH v4 8/13] memory-hotplug : check page type in get_page_bootmem

From: Yasuaki Ishimatsu
Date: Wed Jul 18 2012 - 06:13:13 EST


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: David Rientjes <rientjes@xxxxxxxxxx>
CC: Jiang Liu <liuj97@xxxxxxxxx>
CC: Len Brown <len.brown@xxxxxxxxx>
CC: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
CC: Paul Mackerras <paulus@xxxxxxxxx>
CC: Christoph Lameter <cl@xxxxxxxxx>
Cc: Minchan Kim <minchan.kim@xxxxxxxxx>
CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
CC: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
CC: Wen Congyang <wency@xxxxxxxxxxxxxx>
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>

---
mm/memory_hotplug.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)

Index: linux-3.5-rc6/mm/memory_hotplug.c
===================================================================
--- linux-3.5-rc6.orig/mm/memory_hotplug.c 2012-07-18 18:01:02.070712487 +0900
+++ linux-3.5-rc6/mm/memory_hotplug.c 2012-07-18 18:01:12.586581077 +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

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