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    SubjectRe: [RFC] mm/mremap: Remove redundant checks inside vma_expandable()
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    On 07/11/2017 08:50 AM, Michal Hocko wrote:
    > On Tue 11-07-17 08:26:40, Vlastimil Babka wrote:
    >> On 07/11/2017 08:03 AM, Michal Hocko wrote:
    >>>
    >>> Are you telling me that two if conditions cause more than a second
    >>> difference? That sounds suspicious.
    >>
    >> It's removing also a call to get_unmapped_area(), AFAICS. That means a
    >> vma search?
    >
    > Ohh, right. I have somehow missed that. Is this removal intentional?

    I think it is: "Checking for availability of virtual address range at
    the end of the VMA for the incremental size is also reduntant at this
    point."

    > The
    > changelog is silent about it.

    It doesn't explain why it's redundant, indeed. Unfortunately, the commit
    f106af4e90ea ("fix checks for expand-in-place mremap") which added this,
    also doesn't explain why it's needed.

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