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    SubjectRe: [PATCH] Use correct page protection for put_dirty_page
    On Sun, May 11, 2003 at 10:08:41AM +0200, Andi Kleen wrote:
    > put_page_dirty must use the page protection of the stack VMA, not hardcoded
    > PAGE_COPY. They can be different e.g. when the stack is set non executable
    > via VM_STACK_FLAGS.
    > I added an fallback path for now because I'm not sure if the stack VMA
    > is always predowngrowed here, if the printk better it may be also needed
    > to add an stack extension here.

    We know which vma is involved at the callsite and what we just set its
    vma->vm_page_prot to; I suggest this patch instead.


    -- wli


    diff -prauN linux-2.5.69-1/fs/exec.c exec-2.5.69-1/fs/exec.c
    --- linux-2.5.69-1/fs/exec.c Wed Apr 16 15:34:51 2003
    +++ exec-2.5.69-1/exec.c Sun May 11 01:27:47 2003
    @@ -314,7 +314,7 @@
    }
    lru_cache_add_active(page);
    flush_dcache_page(page);
    - set_pte(pte, pte_mkdirty(pte_mkwrite(mk_pte(page, PAGE_COPY))));
    + set_pte(pte, pte_mkdirty(pte_mkwrite(mk_pte(page, protection_map[VM_STACK_FLAGS & 0x7]))));
    pte_chain = page_add_rmap(page, pte, pte_chain);
    pte_unmap(pte);
    tsk->mm->rss++;
    -
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