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    SubjectRe: [PATCH -mm] vmscan: make mapped executable pages the first class citizen
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    On Sun, 2009-05-10 at 21:39 +0900, KOSAKI Motohiro wrote:
    > >> > They always use mmap(PROT_READ | PROT_WRITE | PROT_EXEC) for anycase.
    > >> > Please google it. you can find various example.
    > >>
    > >> How widely is PROT_EXEC abused? Would you share some of your google results?
    > >
    > > That's a security bug right there and should be fixed regardless of our
    > > heuristics.
    >
    > Yes, should be. but it's not security issue. it doesn't make any security hole.
    > Plus, this claim doesn't help to solve end-user problems.

    Having more stuff executable than absolutely needed is always a security
    issue.

    > I think the basic concept of the patch is right.
    > - executable mapping is important for good latency
    > - executable file is relatively small
    >
    > The last problem is, The patch assume executable mappings is rare, but
    > it isn't guranteed.
    > How do we separate truth executable mapping and mis-used PROT_EXEC usage?

    One could possibly limit the size, but I don't think it pays to bother
    about this until we really run into it, again as Andrew already said,
    there's more ways to screw reclaim if you really want to.





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