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    SubjectRe: [PATCH] FRV: Fix mmap2 error handling
    On Thu, Nov 27, 2008 at 03:12:38PM +0000, David Howells wrote:
    > Fix the error handling in sys_mmap2(). Currently, if the pgoff check fails,
    > fput() might have to be called (which it isn't), so do the pgoff check first,
    > before fget() is called.


    My reaction was "Why do we have sys_mmap2 in every architecture?" So I
    started looking. Oh dear, oh dear oh dear.

    /* As with sparc32, make sure the shift for mmap2 is constant
    (12), no matter what PAGE_SIZE we have.... */
    Just uses PAGE_SIZE (currently supported values: 4k, 8k, 16k and 64k).

    So what is poor userspace to do? Check which architecture it's on and
    figure out what PAGE_SIZE to use for mmap2 based on that?

    How about we introduce a sys_mmap6() in common code which takes 'off'
    in multiples of 4k. Then FRV and other sane architectures can replace
    their sys_mmap2 entries in their syscall tables with sys_mmap6. ia64 has
    to keep its insane sys_mmap2 entry, but it can add a sys_mmap6 entry too.

    Matthew Wilcox Intel Open Source Technology Centre
    "Bill, look, we understand that you're interested in selling us this
    operating system, but compare it to ours. We can't possibly take such
    a retrograde step."

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      Last update: 2008-11-27 18:03    [W:0.019 / U:9.104 seconds]
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