[ 112/133] revert "mm: mempolicy: Let vma_merge and vma_split handle vma->vm_policy linkages"

Greg Kroah-Hartman
2012-10-11T00:21:55Z

From: KOSAKI Motohiro <kosaki.motohiro@gmail.com>

commit 8d34694c1abf29df1f3c7317936b7e3e2e308d9b upstream.

Commit 05f144a0d5c2 ("mm: mempolicy: Let vma_merge and vma_split handle
vma->vm_policy linkages") removed vma->vm_policy updates code but it is
the purpose of mbind_range(). Now, mbind_range() is virtually a no-op
and while it does not allow memory corruption it is not the right fix.
This patch is a revert.

[mgorman@suse.de: Edited changelog]
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: Josh Boyer <jwboyer@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
mm/mempolicy.c | 41 ++++++++++++++++++++++++-----------------
1 file changed, 24 insertions(+), 17 deletions(-)

--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -607,6 +607,27 @@ check_range(struct mm_struct *mm, unsign
return first;
}

+/* Apply policy to a single VMA */
+static int policy_vma(struct vm_area_struct *vma, struct mempolicy *new)
+{
+ int err = 0;
+ struct mempolicy *old = vma->vm_policy;
+
+ 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)
+ err = vma->vm_ops->set_policy(vma, new);
+ if (!err) {
+ mpol_get(new);
+ vma->vm_policy = new;
+ mpol_put(old);
+ }
+ return err;
+}
+
/* Step 2: apply policy to a range and do splits. */
static int mbind_range(struct mm_struct *mm, unsigned long start,
unsigned long end, struct mempolicy *new_pol)
@@ -655,23 +676,9 @@ static int mbind_range(struct mm_struct
if (err)
goto out;
}
-
- /*
- * Apply policy to a single VMA. The reference counting of
- * policy for vma_policy linkages has already been handled by
- * vma_merge and split_vma as necessary. If this is a shared
- * policy then ->set_policy will increment the reference count
- * for an sp node.
- */
- 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) {
- err = vma->vm_ops->set_policy(vma, new_pol);
- if (err)
- goto out;
- }
+ err = policy_vma(vma, new_pol);
+ if (err)
+ goto out;
}