[ 30/56] mm/hotplug: correctly add new zone to all other nodes zone lists

Greg Kroah-Hartman
2013-04-02T22:50:56Z

From: Jiang Liu <jiang.liu@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() {
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@huawei.com>
Signed-off-by: Jiang Liu <liuj97@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Keping Chen <chenkeping@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
mm/memory_hotplug.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)

--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -453,19 +453,20 @@ 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();