[PATCH Bug fix 2/5] Bug-fix: mempolicy: fix is_valid_nodemask()

Tang Chen
2013-01-22T11:45:20Z

From: Lai Jiangshan <laijs@cn.fujitsu.com>

is_valid_nodemask() is introduced by 19770b32. but it does not match
its comments, because it does not check the zone which > policy_zone.

Also in b377fd, 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>
---
mm/mempolicy.c | 36 ++++++++++++++++++++++--------------
1 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index af8a121..6f7979c 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->managed_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;

--
1.7.1