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    SubjectRe: [PATCH 1/6] Revert "mm: mempolicy: Let vma_merge and vma_split handle vma->vm_policy linkages"
    On Wed, 30 May 2012, kosaki.motohiro@gmail.com wrote:

    > From: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
    >
    > commit 05f144a0d5 removed vma->vm_policy updates code and it is a purpose of
    > mbind_range(). Now, mbind_range() is virtually no-op. no-op function don't
    > makes any bugs, I agree. but maybe it is not right fix.

    I dont really understand the changelog. But to restore the policy_vma() is
    the right thing to do since there are potential multiple use cases where
    we want to apply a policy to a vma.

    Proposed new changelog:

    Commit 05f144a0d5 folded policy_vma() into mbind_range(). There are
    other use cases of policy_vma(*) though and so revert a piece of
    that commit in order to have a policy_vma() function again.

    > @@ -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.
    > - */

    You are dropping the nice comments by Mel that explain the refcounting.


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