mm: mempolicy: turn vma_set_policy() into vma_dup_policy()

Simple cleanup.  Every user of vma_set_policy() does the same work, this
looks a bit annoying imho.  And the new trivial helper which does
mpol_dup() + vma_set_policy() to simplify the callers.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 6 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index 84703db06cf3..81ccb4f010c2 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -351,7 +351,6 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
         struct rb_node **rb_link, *rb_parent;
         int retval;
         unsigned long charge;
-        struct mempolicy *pol;
 
         uprobe_start_dup_mmap();
         down_write(&oldmm->mmap_sem);
@@ -400,11 +399,9 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
                         goto fail_nomem;
                 *tmp = *mpnt;
                 INIT_LIST_HEAD(&tmp->anon_vma_chain);
-                pol = mpol_dup(vma_policy(mpnt));
-                retval = PTR_ERR(pol);
-                if (IS_ERR(pol))
+                retval = vma_dup_policy(mpnt, tmp);
+                if (retval)
                         goto fail_nomem_policy;
-                vma_set_policy(tmp, pol);
                 tmp->vm_mm = mm;
                 if (anon_vma_fork(tmp, mpnt))
                         goto fail_nomem_anon_vma_fork;
@@ -472,7 +469,7 @@ out:
         uprobe_end_dup_mmap();
         return retval;
 fail_nomem_anon_vma_fork:
-        mpol_put(pol);
+        mpol_put(vma_policy(tmp));
 fail_nomem_policy:
         kmem_cache_free(vm_area_cachep, tmp);
 fail_nomem: