From d0f615513fd403aa51646a1d1c3420c944e58ad2 Mon Sep 17 00:00:00 2001
From: Lee Schermerhorn <lee.schermerhorn@hp.com>
Date: Mon, 28 Apr 2008 02:13:10 -0700
Subject: [PATCH] --- yaml --- r: 94032 b: refs/heads/master c:
 f4e53d910b7dde2685b177f1e7c3e3e0b4a42f7b h: refs/heads/master v: v3

---
 [refs]               |  2 +-
 trunk/mm/mempolicy.c | 13 +++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 452b244241fb..2a69aefb95fb 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 846a16bf0fc80dc95a414ffce465e3cbf9680247
+refs/heads/master: f4e53d910b7dde2685b177f1e7c3e3e0b4a42f7b
diff --git a/trunk/mm/mempolicy.c b/trunk/mm/mempolicy.c
index e9fc1c1ae66c..c6c61ea6bb8c 100644
--- a/trunk/mm/mempolicy.c
+++ b/trunk/mm/mempolicy.c
@@ -591,16 +591,29 @@ static long do_set_mempolicy(unsigned short mode, unsigned short flags,
 			     nodemask_t *nodes)
 {
 	struct mempolicy *new;
+	struct mm_struct *mm = current->mm;
 
 	new = mpol_new(mode, flags, nodes);
 	if (IS_ERR(new))
 		return PTR_ERR(new);
+
+	/*
+	 * prevent changing our mempolicy while show_numa_maps()
+	 * is using it.
+	 * Note:  do_set_mempolicy() can be called at init time
+	 * with no 'mm'.
+	 */
+	if (mm)
+		down_write(&mm->mmap_sem);
 	mpol_put(current->mempolicy);
 	current->mempolicy = new;
 	mpol_set_task_struct_flag();
 	if (new && new->policy == MPOL_INTERLEAVE &&
 	    nodes_weight(new->v.nodes))
 		current->il_next = first_node(new->v.nodes);
+	if (mm)
+		up_write(&mm->mmap_sem);
+
 	return 0;
 }