linux-kernel - [PATCH] memory hotplug: memmap_init

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Date:	Fri, 9 May 2008 08:04:25 +0200
From:	Heiko Carstens <heiko.carstens@...ibm.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Yasunori Goto <y-goto@...fujitsu.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Dave Hansen <haveblue@...ibm.com>,
	Gerald Schaefer <gerald.schaefer@...ibm.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH] memory hotplug: memmap_init_zone called twice.

Subject: [PATCH] memory hotplug: memmap_init_zone called twice.

From: Heiko Carstens <heiko.carstens@...ibm.com>

__add_zone calls memmap_init_zone twice if memory gets attached to
an empty zone. Once via init_currently_empty_zone and once explictly
right after that call.
Looks like this is currently not a bug, however the call is
superfluous and might lead to subtle bugs if memmap_init_zone gets
changed. So make sure it is called only once.

Cc: Yasunori Goto <y-goto@...fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc: Dave Hansen <haveblue@...ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@...ibm.com>
---
 mm/memory_hotplug.c |   10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

Index: linux-2.6/mm/memory_hotplug.c
===================================================================
--- linux-2.6.orig/mm/memory_hotplug.c
+++ linux-2.6/mm/memory_hotplug.c
@@ -167,13 +167,9 @@ static int __add_zone(struct zone *zone,
 	int zone_type;
 
 	zone_type = zone - pgdat->node_zones;
-	if (!zone->wait_table) {
-		int ret = 0;
-		ret = init_currently_empty_zone(zone, phys_start_pfn,
-						nr_pages, MEMMAP_HOTPLUG);
-		if (ret < 0)
-			return ret;
-	}
+	if (!zone->wait_table)
+		return init_currently_empty_zone(zone, phys_start_pfn,
+						 nr_pages, MEMMAP_HOTPLUG);
 	memmap_init_zone(nr_pages, nid, zone_type,
 			 phys_start_pfn, MEMMAP_HOTPLUG);
 	return 0;
--
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