| Subject | Re: [PATCHv5 06/19] mm/khugepaged: Handle encrypted pages | From | Dave Hansen <> | Date | Wed, 18 Jul 2018 16:11:57 -0700 |
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On 07/17/2018 04:20 AM, Kirill A. Shutemov wrote: > khugepaged allocates page in advance, before we found a VMA for > collapse. We don't yet know which KeyID to use for the allocation.
That's not really true. We have the VMA and the address in the caller (khugepaged_scan_pmd()), but we drop the lock and have to revalidate the VMA.
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 5ae34097aed1..d116f4ebb622 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -1056,6 +1056,16 @@ static void collapse_huge_page(struct mm_struct *mm, > */ > anon_vma_unlock_write(vma->anon_vma); > > + /* > + * At this point new_page is allocated as non-encrypted. > + * If VMA's KeyID is non-zero, we need to prepare it to be encrypted > + * before coping data. > + */ > + if (vma_keyid(vma)) { > + prep_encrypted_page(new_page, HPAGE_PMD_ORDER, > + vma_keyid(vma), false); > + }
I guess this isn't horribly problematic now, but if we ever keep pools of preassigned-keyids, this won't work any more.
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