| Message ID | 20180918115839.22154-1-aneesh.kumar@linux.ibm.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | mm/kvm/vfio/ppc64: Migrate compound pages out of CMA region | expand |
Hi Andrew, "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> writes: > 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. > > Aneesh Kumar K.V (2): > mm: Add get_user_pages_cma_migrate > powerpc/mm/iommu: Allow migration of cma allocated pages during > mm_iommu_get > > arch/powerpc/mm/mmu_context_iommu.c | 120 ++++++++----------------- > include/linux/hugetlb.h | 2 + > include/linux/migrate.h | 3 + > mm/hugetlb.c | 4 +- > mm/migrate.c | 132 ++++++++++++++++++++++++++++ > 5 files changed, 174 insertions(+), 87 deletions(-) Any feedback on this. -aneesh
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. Aneesh Kumar K.V (2): mm: Add get_user_pages_cma_migrate powerpc/mm/iommu: Allow migration of cma allocated pages during mm_iommu_get arch/powerpc/mm/mmu_context_iommu.c | 120 ++++++++----------------- include/linux/hugetlb.h | 2 + include/linux/migrate.h | 3 + mm/hugetlb.c | 4 +- mm/migrate.c | 132 ++++++++++++++++++++++++++++ 5 files changed, 174 insertions(+), 87 deletions(-)