mem-hotplug: use nodes that contain memory as mask in new_node_page()

9bb627b ("mem-hotplug: don't clear the only node in new_node_page()")
prevents allocating from an empty nodemask, but as David points out, it is
still wrong.  As node_online_map may include memoryless nodes, only
allocating from these nodes is meaningless.

This patch uses node_states[N_MEMORY] mask to prevent the above case.

Fixes: 9bb627b ("mem-hotplug: don't clear the only node in new_node_page()")
Fixes: 394e31d ("mem-hotplug: alloc new page from a nearest neighbor node when mem-offline")
Link: http://lkml.kernel.org/r/1474447117.28370.6.camel@TP420
Signed-off-by: Li Zhong <[email protected]>
Suggested-by: David Rientjes <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: John Allen <[email protected]>
Cc: Xishi Qiu <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Cc: Tetsuo Handa <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: Li Zhong

mm/memory_hotplug.c

@@ -1555,8 +1555,8 @@ static struct page *new_node_page(struct page *page, unsigned long private,
 {
 	gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;
 	int nid = page_to_nid(page);
-	nodemask_t nmask = node_online_map;
-	struct page *new_page;
+	nodemask_t nmask = node_states[N_MEMORY];
+	struct page *new_page = NULL;
 
 	/*
 	 * TODO: allocate a destination hugepage from a nearest neighbor node,
@@ -1567,14 +1567,14 @@ static struct page *new_node_page(struct page *page, unsigned long private,
 		return alloc_huge_page_node(page_hstate(compound_head(page)),
 					next_node_in(nid, nmask));
 
-	if (nid != next_node_in(nid, nmask))
-		node_clear(nid, nmask);
+	node_clear(nid, nmask);
 
 	if (PageHighMem(page)
 	    || (zone_idx(page_zone(page)) == ZONE_MOVABLE))
 		gfp_mask |= __GFP_HIGHMEM;
 
-	new_page = __alloc_pages_nodemask(gfp_mask, 0,
+	if (!nodes_empty(nmask))
+		new_page = __alloc_pages_nodemask(gfp_mask, 0,
 					node_zonelist(nid, gfp_mask), &nmask);
 	if (!new_page)
 		new_page = __alloc_pages(gfp_mask, 0,