On Mon, Sep 23, 2013 at 11:11:07AM +0100, Marc Zyngier wrote:
[...]
> >
> > +static bool transparent_hugepage_adjust(pfn_t *pfnp, phys_addr_t *ipap)
> > +{
> > + pfn_t pfn = *pfnp;
> > + gfn_t gfn = *ipap >> PAGE_SHIFT;
> > +
> > + if (PageTransCompound(pfn_to_page(pfn))) {
> > + unsigned long mask;
> > + /*
> > + * mmu_notifier_retry was successful and we hold the
> > + * mmu_lock here, so the pmd can't become splitting
> > + * from under us, and in turn
> > + * __split_huge_page_refcount() can't run from under
> > + * us and we can safely transfer the refcount from
> > + * PG_tail to PG_head as we switch the pfn from tail to
> > + * head.
> > + */
>
> -ECANTPARSE. Well, I sort of can, but this deserves a clearer explanation.
>
> > + mask = (PMD_SIZE / PAGE_SIZE) - 1;
>
> mask = PTRS_PER_PMD -1;
>
> > + VM_BUG_ON((gfn & mask) != (pfn & mask));
> > + if (pfn & mask) {
> > + gfn &= ~mask;
>
> This doesn't seem to be used later on.
>
> > + *ipap &= ~(PMD_SIZE - 1);
>
> *ipap &= ~PMD_MASK;
>
damn, I trust you too much, you surely meant
*ipap &= PMD_MASK;
right?
> > + kvm_release_pfn_clean(pfn);
> > + pfn &= ~mask;
> > + kvm_get_pfn(pfn);
> > + *pfnp = pfn;
> > + }
>
>
>
> > + return true;
> > + }
> > +
> > + return false;
> > +}
> > +
-Christoffer
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
