Re: [PATCH V7 0/4] mm/kvm/vfio/ppc64: Migrate compound pages out of CMA region

[Andrew Morton]

On Mon, 14 Jan 2019 15:24:32 +0530 "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxx> wrote:

> ppc64 use CMA area for the allocation of guest page table (hash page table). We won't
> be able to start guest if we fail to allocate hash page table. We have observed
> hash table allocation failure because we failed to migrate pages out of CMA region
> because they were pinned. This happen when we are using VFIO. VFIO on ppc64 pins
> the entire guest RAM. If the guest RAM pages get allocated out of CMA region, we
> won't be able to migrate those pages. The pages are also pinned for the lifetime of the
> guest.
> 
> Currently we support migration of non-compound pages. With THP and with the addition of
>  hugetlb migration we can end up allocating compound pages from CMA region. This
> patch series add support for migrating compound pages. 

Very little review activity is in evidence.  Please identify some
appropriate reviewers and ask them to take a look?