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 <zhong@linux.vnet.ibm.com>
Suggested-by: David Rientjes <rientjes@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: John Allen <jallen@linux.vnet.ibm.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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,