mempolicy: remove mempolicy sharing

[pandora-kernel.git] / mm / mempolicy.c

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 11b8d47..ede5489 100644 (file)
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -607,24 +607,39 @@ check_range(struct mm_struct *mm, unsigned long start, unsigned long end,
        return first;
 }
 
-/* Apply policy to a single VMA */
-static int policy_vma(struct vm_area_struct *vma, struct mempolicy *new)
+/*
+ * Apply policy to a single VMA
+ * This must be called with the mmap_sem held for writing.
+ */
+static int vma_replace_policy(struct vm_area_struct *vma,
+                                               struct mempolicy *pol)
 {
-       int err = 0;
-       struct mempolicy *old = vma->vm_policy;
+       int err;
+       struct mempolicy *old;
+       struct mempolicy *new;
 
        pr_debug("vma %lx-%lx/%lx vm_ops %p vm_file %p set_policy %p\n",
                 vma->vm_start, vma->vm_end, vma->vm_pgoff,
                 vma->vm_ops, vma->vm_file,
                 vma->vm_ops ? vma->vm_ops->set_policy : NULL);
 
-       if (vma->vm_ops && vma->vm_ops->set_policy)
+       new = mpol_dup(pol);
+       if (IS_ERR(new))
+               return PTR_ERR(new);
+
+       if (vma->vm_ops && vma->vm_ops->set_policy) {
                err = vma->vm_ops->set_policy(vma, new);
-       if (!err) {
-               mpol_get(new);
-               vma->vm_policy = new;
-               mpol_put(old);
+               if (err)
+                       goto err_out;
        }
+
+       old = vma->vm_policy;
+       vma->vm_policy = new; /* protected by mmap_sem */
+       mpol_put(old);
+
+       return 0;
+ err_out:
+       mpol_put(new);
        return err;
 }
 
@@ -675,7 +690,7 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
                        if (err)
                                goto out;
                }
-               err = policy_vma(vma, new_pol);
+               err = vma_replace_policy(vma, new_pol);
                if (err)
                        goto out;
        }
@@ -2117,15 +2132,24 @@ static void sp_delete(struct shared_policy *sp, struct sp_node *n)
 static struct sp_node *sp_alloc(unsigned long start, unsigned long end,
                                struct mempolicy *pol)
 {
-       struct sp_node *n = kmem_cache_alloc(sn_cache, GFP_KERNEL);
+       struct sp_node *n;
+       struct mempolicy *newpol;
 
+       n = kmem_cache_alloc(sn_cache, GFP_KERNEL);
        if (!n)
                return NULL;
+
+       newpol = mpol_dup(pol);
+       if (IS_ERR(newpol)) {
+               kmem_cache_free(sn_cache, n);
+               return NULL;
+       }
+       newpol->flags |= MPOL_F_SHARED;
+
        n->start = start;
        n->end = end;
-       mpol_get(pol);
-       pol->flags |= MPOL_F_SHARED;    /* for unref */
-       n->policy = pol;
+       n->policy = newpol;
+
        return n;
 }