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    SubjectRe: BUG: about flush TLB during unmapping a page in memory subsystem
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    On Fri, 2006-10-20 at 13:10 +0800, yunfeng zhang wrote:
    > Maybe, the solution is below
    >
    > ...
    > // >>> ptep_clear((__vma)->vm_mm, __address, __ptep);
    > // >>> flush_tlb_page(__vma, __address);
    > // >>> __ptep;
    > ...
    >
    > And even so, we also get a pte with present = 0 AND its dirty = 1, an odd pte.
    >
    > Remember B dirtied the pte before A executes flush_tlb_page.

    It's very much architecture specific. I suppose x86 must have some HW
    requirements of checking if the PTE is still present atomically when
    setting the dirty bit but I can't tell for sure :)

    On PowerPC, we don't use HW dirty bits, we use SW for that, thus the
    ptep_get_and_clear will be enough to prevent any further dirty bit to be
    set.

    Ben.


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