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    SubjectRe: No more bits in vm_area_struct's vm_flags.
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    Hugh Dickins wrote:
    > On Mon, 28 Sep 2009, KAMEZAWA Hiroyuki wrote:
    >>
    >> What I dislike is making vm_flags to be long long ;)
    >
    > Why?
    I'm sorry if my "dislike" sounds too strong.

    Every time I see long long in the kernel, my concern is
    "do I need spinlock to access this for 32bit arch ? is it safe ?".
    (And it makes binary=>disassemble=>C (by eyes) a bit difficult)
    Then, I don't like long long personally.

    Another reason is some other calls like test_bit() cannot be used against
    long long. (even if it's not used _now_)

    Maybe vm->vm_flags will not require extra locks because
    it can be protected by bigger lock as mmap_sem. Then, please make it
    to be long long if its's recommended.

    keeping vm_flags to be 32bit may makes vma_merge() ugly.
    If so, long long is a choice.

    Thanks,
    -Kame


    > Hugh
    >




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