[PATCH 023/150] mm/hotplug: correctly add new zone to all other nodes' zone lists

Luis Henriques luis.henriques at canonical.com
Tue Mar 26 15:18:42 UTC 2013 -stable review patch.  If anyone has any objections, please let me know.


From: Jiang Liu <jiang.liu at huawei.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() {
	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.

		->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 at huawei.com>
Signed-off-by: Jiang Liu <liuj97 at gmail.com>
Cc: Mel Gorman <mgorman at suse.de>
Cc: Michal Hocko <mhocko at suse.cz>
Cc: Minchan Kim <minchan at kernel.org>
Cc: Rusty Russell <rusty at rustcorp.com.au>
Cc: Yinghai Lu <yinghai at kernel.org>
Cc: Tony Luck <tony.luck at intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu at jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro at jp.fujitsu.com>
Cc: David Rientjes <rientjes at google.com>
Cc: Keping Chen <chenkeping at huawei.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
[ luis: backported to 3.5 ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
 mm/memory_hotplug.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 0086ac9..17651cd 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -516,19 +516,20 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages)
 	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);
+	}
-	if (onlined_pages) {
+	if (onlined_pages)
-		node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
-	}
 	vm_total_pages = nr_free_pagecache_pages();

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