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SubjectRe: [PATCH 03/36] mmu_notifier: pass page pointer to mmu_notifier_invalidate_page()
On Wed, May 27, 2015 at 10:47:44AM +0530, Aneesh Kumar K.V wrote:
> j.glisse@gmail.com writes:
>
> > From: Jérôme Glisse <jglisse@redhat.com>
> >
> > Listener of mm event might not have easy way to get the struct page
> > behind and address invalidated with mmu_notifier_invalidate_page()
> > function as this happens after the cpu page table have been clear/
> > updated. This happens for instance if the listener is storing a dma
> > mapping inside its secondary page table. To avoid complex reverse
> > dma mapping lookup just pass along a pointer to the page being
> > invalidated.
>
> .....
>
> > diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
> > index ada3ed1..283ad26 100644
> > --- a/include/linux/mmu_notifier.h
> > +++ b/include/linux/mmu_notifier.h
> > @@ -172,6 +172,7 @@ struct mmu_notifier_ops {
> > void (*invalidate_page)(struct mmu_notifier *mn,
> > struct mm_struct *mm,
> > unsigned long address,
> > + struct page *page,
> > enum mmu_event event);
> >
>
> How do we handle this w.r.t invalidate_range ?

With range invalidation the CPU page table is still reliable when
invalidate_range_start() callback happen. So we can lookup the CPU
page table to get the page backing the address.

Cheers,
Jérôme


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