memory hotplug: alloc page from other node in memory online

To initialize hotadded node, some pages are allocated.  At that time, the
node hasn't memory, this makes the allocation always fail.  In such case,
let's allocate pages from other nodes.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Yakui Zhao <yakui.zhao@intel.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/sparse.c b/mm/sparse.c
index da432d9..6ce4aab 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -62,9 +62,12 @@
 	unsigned long array_size = SECTIONS_PER_ROOT *
 				   sizeof(struct mem_section);
 
-	if (slab_is_available())
-		section = kmalloc_node(array_size, GFP_KERNEL, nid);
-	else
+	if (slab_is_available()) {
+		if (node_state(nid, N_HIGH_MEMORY))
+			section = kmalloc_node(array_size, GFP_KERNEL, nid);
+		else
+			section = kmalloc(array_size, GFP_KERNEL);
+	} else
 		section = alloc_bootmem_node(NODE_DATA(nid), array_size);
 
 	if (section)