3.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: KOSAKI Motohiro <kosaki.motoh...@jp.fujitsu.com>

commit 63f74ca21f1fad36d075e063f06dcc6d39fe86b2 upstream.

When shared_policy_replace() fails to allocate new->policy is not freed
correctly by mpol_set_shared_policy().  The problem is that shared
mempolicy code directly call kmem_cache_free() in multiple places where
it is easy to make a mistake.

This patch creates an sp_free wrapper function and uses it. The bug was
introduced pre-git age (IOW, before 2.6.12-rc2).

[mgor...@suse.de: Editted changelog]
Signed-off-by: KOSAKI Motohiro <kosaki.motoh...@jp.fujitsu.com>
Signed-off-by: Mel Gorman <mgor...@suse.de>
Reviewed-by: Christoph Lameter <c...@linux.com>
Cc: Josh Boyer <jwbo...@gmail.com>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 mm/mempolicy.c |   15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2095,12 +2095,17 @@ mpol_shared_policy_lookup(struct shared_
        return pol;
 }
 
+static void sp_free(struct sp_node *n)
+{
+       mpol_put(n->policy);
+       kmem_cache_free(sn_cache, n);
+}
+
 static void sp_delete(struct shared_policy *sp, struct sp_node *n)
 {
        pr_debug("deleting %lx-l%lx\n", n->start, n->end);
        rb_erase(&n->nd, &sp->root);
-       mpol_put(n->policy);
-       kmem_cache_free(sn_cache, n);
+       sp_free(n);
 }
 
 static struct sp_node *sp_alloc(unsigned long start, unsigned long end,
@@ -2239,7 +2244,7 @@ int mpol_set_shared_policy(struct shared
        }
        err = shared_policy_replace(info, vma->vm_pgoff, vma->vm_pgoff+sz, new);
        if (err && new)
-               kmem_cache_free(sn_cache, new);
+               sp_free(new);
        return err;
 }
 
@@ -2256,9 +2261,7 @@ void mpol_free_shared_policy(struct shar
        while (next) {
                n = rb_entry(next, struct sp_node, nd);
                next = rb_next(&n->nd);
-               rb_erase(&n->nd, &p->root);
-               mpol_put(n->policy);
-               kmem_cache_free(sn_cache, n);
+               sp_delete(p, n);
        }
        mutex_unlock(&p->mutex);
 }


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