On 1/15/20 5:39 AM, Li Xinhai wrote:
> Checking hstate at early phase when isolating page, instead of during
> unmap and move phase, to avoid useless isolation.
>
> Signed-off-by: Li Xinhai <lixinhai.lxh@xxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
> ---
> include/linux/hugetlb_inline.h | 7 +++++++
> include/linux/mempolicy.h | 5 ++---
> mm/hugetlb.c | 9 +++++++++
> 3 files changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/hugetlb_inline.h b/include/linux/hugetlb_inline.h
> index 0660a03..fc07139 100644
> --- a/include/linux/hugetlb_inline.h
> +++ b/include/linux/hugetlb_inline.h
> @@ -11,6 +11,8 @@ static inline bool is_vm_hugetlb_page(struct vm_area_struct *vma)
> return !!(vma->vm_flags & VM_HUGETLB);
> }
>
> +extern bool vm_hugepage_migration_supported(struct vm_area_struct *vma);
> +
> #else
>
> static inline bool is_vm_hugetlb_page(struct vm_area_struct *vma)
> @@ -18,6 +20,11 @@ static inline bool is_vm_hugetlb_page(struct vm_area_struct *vma)
> return false;
> }
>
> +static inline bool vm_hugepage_migration_supported(struct vm_area_struct *vma)
> +{
> + return false;
> +}
> +
> #endif
>
> #endif
> diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
> index 5228c62..e9ed49e 100644
> --- a/include/linux/mempolicy.h
> +++ b/include/linux/mempolicy.h
> @@ -185,10 +185,9 @@ static inline bool vma_migratable(struct vm_area_struct *vma)
> if (vma_is_dax(vma))
> return false;
>
> -#ifndef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
> - if (vma->vm_flags & VM_HUGETLB)
> + if (is_vm_hugetlb_page(vma) &&
> + !vm_hugepage_migration_supported(vma))
> return false;
> -#endif
>
> /*
> * Migration allocates pages in the highest zone. If we cannot
There are not many ways to work around the hugepage_migration_supported
dependency issue. I suppose you could have moved vma_migratable() into
mm/mempolicy.c instead of being an inline in the header file. However,
it is probably best to do what you have done and hide the ugly stuff in
the hugetlbfs files.
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index dd8737a..8ce4a98 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1316,6 +1316,15 @@ int PageHeadHuge(struct page *page_head)
> return get_compound_page_dtor(page_head) == free_huge_page;
> }
>
> +bool vm_hugepage_migration_supported(struct vm_area_struct *vma)
> +{
> + VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
This VM_BUG_ON_VMA() seems unnecessary. The only caller is the one
added with this patch which is only called if is_vm_hugetlb_page(vma).
Even though VM_BUG_ON() is only enabled if CONFIG_DEBUG_VM, many distros
(including the one running my desktop) enable CONFIG_DEBUG_VM in their
default kernel.
--
Mike Kravetz
> + if (hugepage_migration_supported(hstate_vma(vma)))
> + return true;
> +
> + return false;
> +}
> +
> pgoff_t __basepage_index(struct page *page)
> {
> struct page *page_head = compound_head(page);
>
