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    SubjectRe: [PATCH 4/4] mm: variable length argument support
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    On Wed, 2007-06-06 at 02:06 -0700, Andrew Morton wrote:
    > On Wed, 06 Jun 2007 10:54:21 +0200 Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
    >
    > > > > It is a bit peculiar in that we have one task with two mm's, one of which is
    > > > > inactive.
    > > > >
    > > > > ...
    > > > >
    > > > > + flush_cache_page(bprm->vma, kpos,
    > > > > + page_to_pfn(kmapped_page));
    > >
    > > Bah, and my frv cross build bums out on an unrelated change,..
    > > I'll see if I can get a noMMU arch building, in the mean time, would you
    > > try this:
    > >
    > > ---
    > >
    > > Since no-MMU doesn't do the fancy inactive mm access there is no need to
    > > flush cache.
    > >
    > > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    > > ---
    > >
    > > Index: linux-2.6-2/fs/exec.c
    > > ===================================================================
    > > --- linux-2.6-2.orig/fs/exec.c 2007-06-05 16:48:52.000000000 +0200
    > > +++ linux-2.6-2/fs/exec.c 2007-06-06 10:49:19.000000000 +0200
    > > @@ -428,8 +428,10 @@ static int copy_strings(int argc, char _
    > > kmapped_page = page;
    > > kaddr = kmap(kmapped_page);
    > > kpos = pos & PAGE_MASK;
    > > +#ifdef CONFIG_MMU
    > > flush_cache_page(bprm->vma, kpos,
    > > page_to_pfn(kmapped_page));
    > > +#endif
    > > }
    > > if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
    > > ret = -EFAULT;
    > >
    >
    > I think the same problem will happen on NOMMU && STACK_GROWS_UP. There are
    > several new references to bprm->vma in there, not all inside CONFIG_MMU.

    Right, which archs have that combo? I'll go gather cross compilers.

    Perhaps I'd better create a flush_arg_page() function and stick that in
    the mmu/nommu section somewhere earlier on in that file. Patch in a few.

    A related question; does anybody know of a no-MMU arch that uses
    fs/compat.c ? If there is such a beast, that would need some work.

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