Re: [PATCH 2/6] KVM MMU: fix kvm_mmu_zap_page() and its calling path

Marcelo Tosatti
2010-04-13T14:59:27Z

On Tue, Apr 13, 2010 at 09:34:14AM +0800, Xiao Guangrong wrote:
>
>
> Marcelo Tosatti wrote:
>
> >> @@ -1483,8 +1483,8 @@ static int mmu_zap_unsync_children(struct kvm *kvm,
> >> for_each_sp(pages, sp, parents, i) {
> >> kvm_mmu_zap_page(kvm, sp);
> >> mmu_pages_clear_parents(&parents);
> >> + zapped++;
> >> }
> >> - zapped += pages.nr;
> >> kvm_mmu_pages_init(parent, &parents, &pages);
> >> }
> >
> > Don't see why this is needed? The for_each_sp loop uses pvec.nr.
>
> I think mmu_zap_unsync_children() should return the number of zapped pages then we
> can adjust the number of free pages in kvm_mmu_change_mmu_pages(), but pages.nr no
> only includes the unsync/zapped pages but also includes their parents.

Oh i see. I think its safer to check for list_empty then to rely on
proper accounting there, like __kvm_mmu_free_some_pages does.