On Thu, 2006-12-21 at 10:16 +0100, Martin Schwidefsky wrote:
> On Thu, 2006-12-21 at 00:03 +0100, Peter Zijlstra wrote:
> > current version
>
> Nitpicking ..
>
> > @@ -444,17 +444,18 @@ static int page_mkclean_one(struct page
> > if (!pte)
> > goto out;
> >
> > - if (!pte_dirty(*pte) && !pte_write(*pte))
> > - goto unlock;
> > + while (pte_dirty(*pte) || pte_write(*pte)) {
> > + pte_t entry;
> >
> > - entry = ptep_get_and_clear(mm, address, pte);
> > - entry = pte_mkclean(entry);
> > - entry = pte_wrprotect(entry);
> > - ptep_establish(vma, address, pte, entry);
> > - lazy_mmu_prot_update(entry);
> > - ret = 1;
> > + flush_cache_page(vma, address, pte_pfn(*pte));
> > + entry = ptep_clear_flush(vma, address, pte);
> > + entry = pte_wrprotect(entry);
> > + entry = pte_mkclean(entry);
> > + ptep_establish(vma, address, pte, entry);
>
> Now you are flushing the tlb twice. ptep_clear_flush clears the pte and
> flushes the tlb, ptep_establish sets the new pte and flushes the tlb.
> Not good. Use set_pte_at instead of the ptep_establish.
Yeah, sorry, I already noticed and corrected that :-|
Also, I'm dubious about the while thing and stuck a WARN_ON(ret) thing
at the beginning of the loop. flush_tlb_page() does IPI the other cpus
to flush their tlb too, so there should not be a SMP race, Arjan?
> > + lazy_mmu_prot_update(entry);
> > + ret = 1;
> > + }
> >
> > -unlock:
> > pte_unmap_unlock(pte, ptl);
> > out:
> > return ret;
>
-
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