mm/memory_hotplug.c: fix building of node hotplug zonelist
During memory hotplug we refresh zonelists when we online a page in a new
zone. It means that the node's zonelist is not initialized until pages
are onlined. So for example, "nid" passed by MEM_GOING_ONLINE notifier
will point to NODE_DATA(nid) which has no zone fallback list. Moreover,
if we hot-add cpu-only nodes, alloc_pages() will do no fallback.
This patch makes a zonelist when a new pgdata is available.
Note: in production, at fujitsu, memory should be onlined before cpu
and our server didn't have any memory-less nodes and had no problems.
But recent changes in MEM_GOING_ONLINE+page_cgroup
will access not initialized zonelist of node.
Anyway, there are memory-less node and we need some care.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 9f64637..02159c7 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -494,6 +494,12 @@
/* init node's zones as empty zones, we don't have any present pages.*/
free_area_init_node(nid, zones_size, start_pfn, zholes_size);
+ /*
+ * The node we allocated has no zone fallback lists. For avoiding
+ * to access not-initialized zonelist, build here.
+ */
+ build_all_zonelists(NULL);
+
return pgdat;
}