mempolicy: fix is_valid_nodemask()

mempolicy: fix is_valid_nodemask()

is_valid_nodemask() was introduced by 19770b32 ("mm: filter based on a
nodemask as well as a gfp_mask").  but it does not match its comments,
because it does not check the zone which > policy_zone.

Also in b377fd ("Apply memory policies to top two highest zones when
highest zone is ZONE_MOVABLE"), this commits told us, if highest zone is
ZONE_MOVABLE, we should also apply memory policies to it.  so ZONE_MOVABLE
should be valid zone for policies.  is_valid_nodemask() need to be changed
to match it.

Fix: check all zones, even its zoneid > policy_zone.  Use
nodes_intersects() instead open code to check it.

Reported-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Jiang Liu <jiang.liu@huawei.com>
Cc: Jianguo Wu <wujianguo@huawei.com>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>