linux-kernel - [ 76/82] mm/hotplug: correctly add new zone to all other nodes zone lists

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Message-Id: <20130318042151.627904620@decadent.org.uk>
Date:	Mon, 18 Mar 2013 04:23:00 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	akpm@...ux-foundation.org, Jiang Liu <jiang.liu@...wei.com>,
	Jianguo Wu <wujianguo@...wei.com>,
	Jiang Liu <liuj97@...il.com>, Mel Gorman <mgorman@...e.de>,
	Michal Hocko <mhocko@...e.cz>,
	Minchan Kim <minchan@...nel.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Yinghai Lu <yinghai@...nel.org>,
	Tony Luck <tony.luck@...el.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	David Rientjes <rientjes@...gle.com>,
	Keping Chen <chenkeping@...wei.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [ 76/82] mm/hotplug: correctly add new zone to all other nodes zone lists

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jiang Liu <jiang.liu@...wei.com>

commit 08dff7b7d629807dbb1f398c68dd9cd58dd657a1 upstream.

When online_pages() is called to add new memory to an empty zone, it
rebuilds all zone lists by calling build_all_zonelists().  But there's a
bug which prevents the new zone to be added to other nodes' zone lists.

online_pages() {
	build_all_zonelists()
	.....
	node_set_state(zone_to_nid(zone), N_HIGH_MEMORY)
}

Here the node of the zone is put into N_HIGH_MEMORY state after calling
build_all_zonelists(), but build_all_zonelists() only adds zones from
nodes in N_HIGH_MEMORY state to the fallback zone lists.
build_all_zonelists()

    ->__build_all_zonelists()
	->build_zonelists()
	    ->find_next_best_node()
		->for_each_node_state(n, N_HIGH_MEMORY)

So memory in the new zone will never be used by other nodes, and it may
cause strange behavor when system is under memory pressure.  So put node
into N_HIGH_MEMORY state before calling build_all_zonelists().

Signed-off-by: Jianguo Wu <wujianguo@...wei.com>
Signed-off-by: Jiang Liu <liuj97@...il.com>
Cc: Mel Gorman <mgorman@...e.de>
Cc: Michal Hocko <mhocko@...e.cz>
Cc: Minchan Kim <minchan@...nel.org>
Cc: Rusty Russell <rusty@...tcorp.com.au>
Cc: Yinghai Lu <yinghai@...nel.org>
Cc: Tony Luck <tony.luck@...el.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc: David Rientjes <rientjes@...gle.com>
Cc: Keping Chen <chenkeping@...wei.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 mm/memory_hotplug.c |   15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -515,19 +515,20 @@ int __ref online_pages(unsigned long pfn
 
 	zone->present_pages += onlined_pages;
 	zone->zone_pgdat->node_present_pages += onlined_pages;
-	if (need_zonelists_rebuild)
-		build_all_zonelists(zone);
-	else
-		zone_pcp_update(zone);
+	if (onlined_pages) {
+		node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
+		if (need_zonelists_rebuild)
+			build_all_zonelists(zone);
+		else
+			zone_pcp_update(zone);
+	}
 
 	mutex_unlock(&zonelists_mutex);
 
 	init_per_zone_wmark_min();
 
-	if (onlined_pages) {
+	if (onlined_pages)
 		kswapd_run(zone_to_nid(zone));
-		node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
-	}
 
 	vm_total_pages = nr_free_pagecache_pages();
 


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