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[RFC V7 PATCH 13/19] memory-hotplug: check page type in get_page_bootmem



From: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>

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 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 5f9f8c7..d85af6d 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -95,10 +95,17 @@ static void release_memory_resource(struct resource *res)
 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
-- 
1.7.1

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