On Fri 07-12-18 15:12:26, Andrew Morton wrote: > On Wed, 21 Nov 2018 14:52:56 +0530 "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxx> wrote: > > > Subject: [PATCH V4 0/3] * mm/kvm/vfio/ppc64: Migrate compound pages out of CMA region > > Asterisk in title is strange? > > > 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. The first path adds the helper > > get_user_pages_cma_migrate() which pin the page making sure we migrate them out of > > CMA region before incrementing the reference count. > > Very little review activity. Perhaps Andrey and/or Michal can find the > time.. I will unlikely find some time before the end of the year. Sorry about that. -- Michal Hocko SUSE Labs
