linux-kernel - [RFC PATCH v2 8/13] memory-hotplug : check page type in get_page

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Message-ID: <4FF28ABE.4010200@jp.fujitsu.com>
Date:	Tue, 3 Jul 2012 15:01:34 +0900
From:	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
To:	<linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
	<linuxppc-dev@...ts.ozlabs.org>, <linux-acpi@...r.kernel.org>
CC:	<rientjes@...gle.com>, <liuj97@...il.com>, <len.brown@...el.com>,
	<benh@...nel.crashing.org>, <paulus@...ba.org>, <cl@...ux.com>,
	<minchan.kim@...il.com>, <akpm@...ux-foundation.org>,
	<kosaki.motohiro@...fujitsu.com>
Subject: [RFC PATCH v2 8/13] memory-hotplug : check page type in get_page_bootmem

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@...gle.com>
CC: Jiang Liu <liuj97@...il.com>
CC: Len Brown <len.brown@...el.com>
CC: Benjamin Herrenschmidt <benh@...nel.crashing.org>
CC: Paul Mackerras <paulus@...ba.org>
CC: Christoph Lameter <cl@...ux.com>
Cc: Minchan Kim <minchan.kim@...il.com>
CC: Andrew Morton <akpm@...ux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>

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

Index: linux-3.5-rc4/mm/memory_hotplug.c
===================================================================
--- linux-3.5-rc4.orig/mm/memory_hotplug.c	2012-07-03 14:22:10.170116406 +0900
+++ linux-3.5-rc4/mm/memory_hotplug.c	2012-07-03 14:22:12.299089413 +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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