mempolicy: fix is_valid_nodemask()

is_valid_nodemask() was introduced by commit 19770b32609b ("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 commit b377fd3982ad ("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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 22 insertions, 14 deletions

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index e2df1c1fb41f..6f7979c566d9 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -161,19 +161,7 @@ static const struct mempolicy_operations {
 /* Check that the nodemask contains at least one populated zone */
 static int is_valid_nodemask(const nodemask_t *nodemask)
 {
-        int nd, k;
-
-        for_each_node_mask(nd, *nodemask) {
-                struct zone *z;
-
-                for (k = 0; k <= policy_zone; k++) {
-                        z = &NODE_DATA(nd)->node_zones[k];
-                        if (z->present_pages > 0)
-                                return 1;
-                }
-        }
-
-        return 0;
+        return nodes_intersects(*nodemask, node_states[N_MEMORY]);
 }
 
 static inline int mpol_store_user_nodemask(const struct mempolicy *pol)
@@ -1644,6 +1632,26 @@ struct mempolicy *get_vma_policy(struct task_struct *task,
         return pol;
 }
 
+static int apply_policy_zone(struct mempolicy *policy, enum zone_type zone)
+{
+        enum zone_type dynamic_policy_zone = policy_zone;
+
+        BUG_ON(dynamic_policy_zone == ZONE_MOVABLE);
+
+        /*
+         * if policy->v.nodes has movable memory only,
+         * we apply policy when gfp_zone(gfp) = ZONE_MOVABLE only.
+         *
+         * policy->v.nodes is intersect with node_states[N_MEMORY].
+         * so if the following test faile, it implies
+         * policy->v.nodes has movable memory only.
+         */
+        if (!nodes_intersects(policy->v.nodes, node_states[N_HIGH_MEMORY]))
+                dynamic_policy_zone = ZONE_MOVABLE;
+
+        return zone >= dynamic_policy_zone;
+}
+
 /*
  * Return a nodemask representing a mempolicy for filtering nodes for
  * page allocation
@@ -1652,7 +1660,7 @@ static nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *policy)
 {
         /* Lower zones don't get a nodemask applied for MPOL_BIND */
         if (unlikely(policy->mode == MPOL_BIND) &&
-                        gfp_zone(gfp) >= policy_zone &&
+                        apply_policy_zone(policy, gfp_zone(gfp)) &&
                         cpuset_nodemask_valid_mems_allowed(&policy->v.nodes))
                 return &policy->v.nodes;