[RFC PATCH 0/3] Add support for compound page migration in mm_iommu_get

[Aneesh Kumar K.V]

On 09/03/2018 10:07 PM, Aneesh Kumar K.V wrote:
> This patch series add support for migrating compound pages if we find them in the
> CMA area before taking long term page reference for VFIO.

We now call lru_add_drain_all instead of lru_add_drain() which means we 
now have higher chances of isolate_lru_page succeeding. The patch also 
migrate all the pages in one call, instead of one page at a time.


> 
> Testing:
> * TODO: test with hugetlb backed guest ram.
> * Testing done with a code change as below
> 
> -		if (is_migrate_cma_page(pages[i]) && migrate_allow) {
> +		if (migrate_allow) {
> 
> ...
> +	migrate_allow = false;
> 
> 
> Aneesh Kumar K.V (3):
>    mm: Export alloc_migrate_huge_page
>    powerpc/mm/iommu: Allow large IOMMU page size only for hugetlb backing
>    powerpc/mm/iommu: Allow migration of cma allocated pages during
>      mm_iommu_get
> 
>   arch/powerpc/mm/mmu_context_iommu.c | 209 +++++++++++++++++-----------
>   include/linux/hugetlb.h             |   2 +
>   mm/hugetlb.c                        |   4 +-
>   3 files changed, 128 insertions(+), 87 deletions(-)
>