[PATCH 1/6] Revert "mm: mempolicy: Let vma_merge and vma_split handle vma->vm_policy linkages"

kosaki.motohiro
2012-06-11T09:18:17Z

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

commit 05f144a0d5 "mm: mempolicy: Let vma_merge and vma_split handle
vma->vm_policy linkages" removed a vma->vm_policy updates. But it is
a primary purpose of mbind_range(). Now, mbind(2) is no-op in several
case unintentionally. It is not ideal fix. This patch reverts it.

Cc: Dave Jones <davej@redhat.com>,
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>,
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
---
mm/mempolicy.c | 41 ++++++++++++++++++++++++-----------------
1 files changed, 24 insertions(+), 17 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index f15c1b2..0a60def 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -607,6 +607,27 @@ 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)
+{
+ 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 *mm, unsigned long start,
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;
}

out:
--
1.7.1