From 448f0997919e01c705b602d3bb558cba15ad20f8 Mon Sep 17 00:00:00 2001
From: Mel Gorman <mgorman@suse.de>
Date: Fri, 21 Dec 2012 23:10:25 +0000
Subject: [PATCH] --- yaml --- r: 348111 b: refs/heads/master c:
 42288fe366c4f1ce7522bc9f27d0bc2a81c55264 h: refs/heads/master i:   348109:
 236016b7207fb3b95e92e3233a57d0430889726b   348107:
 cfa6b2dbd6cd211ba839d920ab9b11eab14274d5   348103:
 dfdbe7550d427cb00b64a244f0fb2655676a7fce   348095:
 d4ab858c0431a2ac2243da4c0e7b0eeb1f5f858f v: v3

---
 [refs]                          |  2 +-
 trunk/include/linux/mempolicy.h |  2 +-
 trunk/mm/mempolicy.c            | 68 +++++++++++++++++++++++----------
 3 files changed, 50 insertions(+), 22 deletions(-)

diff --git a/[refs] b/[refs]
index e7d517896c27..1b8aa0882e02 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 5439ca6b8ff8cf8d758c19eb28b617a5912904ee
+refs/heads/master: 42288fe366c4f1ce7522bc9f27d0bc2a81c55264
diff --git a/trunk/include/linux/mempolicy.h b/trunk/include/linux/mempolicy.h
index 92bc9988a180..0d7df39a5885 100644
--- a/trunk/include/linux/mempolicy.h
+++ b/trunk/include/linux/mempolicy.h
@@ -123,7 +123,7 @@ struct sp_node {
 
 struct shared_policy {
 	struct rb_root root;
-	struct mutex mutex;
+	spinlock_t lock;
 };
 
 void mpol_shared_policy_init(struct shared_policy *sp, struct mempolicy *mpol);
diff --git a/trunk/mm/mempolicy.c b/trunk/mm/mempolicy.c
index 1cb200af3828..e2df1c1fb41f 100644
--- a/trunk/mm/mempolicy.c
+++ b/trunk/mm/mempolicy.c
@@ -2132,7 +2132,7 @@ bool __mpol_equal(struct mempolicy *a, struct mempolicy *b)
  */
 
 /* lookup first element intersecting start-end */
-/* Caller holds sp->mutex */
+/* Caller holds sp->lock */
 static struct sp_node *
 sp_lookup(struct shared_policy *sp, unsigned long start, unsigned long end)
 {
@@ -2196,13 +2196,13 @@ mpol_shared_policy_lookup(struct shared_policy *sp, unsigned long idx)
 
 	if (!sp->root.rb_node)
 		return NULL;
-	mutex_lock(&sp->mutex);
+	spin_lock(&sp->lock);
 	sn = sp_lookup(sp, idx, idx+1);
 	if (sn) {
 		mpol_get(sn->policy);
 		pol = sn->policy;
 	}
-	mutex_unlock(&sp->mutex);
+	spin_unlock(&sp->lock);
 	return pol;
 }
 
@@ -2328,6 +2328,14 @@ static void sp_delete(struct shared_policy *sp, struct sp_node *n)
 	sp_free(n);
 }
 
+static void sp_node_init(struct sp_node *node, unsigned long start,
+			unsigned long end, struct mempolicy *pol)
+{
+	node->start = start;
+	node->end = end;
+	node->policy = pol;
+}
+
 static struct sp_node *sp_alloc(unsigned long start, unsigned long end,
 				struct mempolicy *pol)
 {
@@ -2344,10 +2352,7 @@ static struct sp_node *sp_alloc(unsigned long start, unsigned long end,
 		return NULL;
 	}
 	newpol->flags |= MPOL_F_SHARED;
-
-	n->start = start;
-	n->end = end;
-	n->policy = newpol;
+	sp_node_init(n, start, end, newpol);
 
 	return n;
 }
@@ -2357,9 +2362,12 @@ static int shared_policy_replace(struct shared_policy *sp, unsigned long start,
 				 unsigned long end, struct sp_node *new)
 {
 	struct sp_node *n;
+	struct sp_node *n_new = NULL;
+	struct mempolicy *mpol_new = NULL;
 	int ret = 0;
 
-	mutex_lock(&sp->mutex);
+restart:
+	spin_lock(&sp->lock);
 	n = sp_lookup(sp, start, end);
 	/* Take care of old policies in the same range. */
 	while (n && n->start < end) {
@@ -2372,14 +2380,16 @@ static int shared_policy_replace(struct shared_policy *sp, unsigned long start,
 		} else {
 			/* Old policy spanning whole new range. */
 			if (n->end > end) {
-				struct sp_node *new2;
-				new2 = sp_alloc(end, n->end, n->policy);
-				if (!new2) {
-					ret = -ENOMEM;
-					goto out;
-				}
+				if (!n_new)
+					goto alloc_new;
+
+				*mpol_new = *n->policy;
+				atomic_set(&mpol_new->refcnt, 1);
+				sp_node_init(n_new, n->end, end, mpol_new);
+				sp_insert(sp, n_new);
 				n->end = start;
-				sp_insert(sp, new2);
+				n_new = NULL;
+				mpol_new = NULL;
 				break;
 			} else
 				n->end = start;
@@ -2390,9 +2400,27 @@ static int shared_policy_replace(struct shared_policy *sp, unsigned long start,
 	}
 	if (new)
 		sp_insert(sp, new);
-out:
-	mutex_unlock(&sp->mutex);
+	spin_unlock(&sp->lock);
+	ret = 0;
+
+err_out:
+	if (mpol_new)
+		mpol_put(mpol_new);
+	if (n_new)
+		kmem_cache_free(sn_cache, n_new);
+
 	return ret;
+
+alloc_new:
+	spin_unlock(&sp->lock);
+	ret = -ENOMEM;
+	n_new = kmem_cache_alloc(sn_cache, GFP_KERNEL);
+	if (!n_new)
+		goto err_out;
+	mpol_new = kmem_cache_alloc(policy_cache, GFP_KERNEL);
+	if (!mpol_new)
+		goto err_out;
+	goto restart;
 }
 
 /**
@@ -2410,7 +2438,7 @@ void mpol_shared_policy_init(struct shared_policy *sp, struct mempolicy *mpol)
 	int ret;
 
 	sp->root = RB_ROOT;		/* empty tree == default mempolicy */
-	mutex_init(&sp->mutex);
+	spin_lock_init(&sp->lock);
 
 	if (mpol) {
 		struct vm_area_struct pvma;
@@ -2476,14 +2504,14 @@ void mpol_free_shared_policy(struct shared_policy *p)
 
 	if (!p->root.rb_node)
 		return;
-	mutex_lock(&p->mutex);
+	spin_lock(&p->lock);
 	next = rb_first(&p->root);
 	while (next) {
 		n = rb_entry(next, struct sp_node, nd);
 		next = rb_next(&n->nd);
 		sp_delete(p, n);
 	}
-	mutex_unlock(&p->mutex);
+	spin_unlock(&p->lock);
 }
 
 #ifdef CONFIG_NUMA_BALANCING