Re: [PATCH v5 09/11] mm: mempolicy: mbind and migrate_pages support thp migration

[Anshuman Khandual <khandual@linux.vnet.ibm.com>]

On 04/21/2017 02:17 AM, Zi Yan wrote:
> From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> 
> This patch enables thp migration for mbind(2) and migrate_pages(2).
> 
> Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> ---
> ChangeLog v1 -> v2:
> - support pte-mapped and doubly-mapped thp
> ---
>  mm/mempolicy.c | 108 +++++++++++++++++++++++++++++++++++++++++----------------
>  1 file changed, 79 insertions(+), 29 deletions(-)

Snip

> @@ -981,7 +1012,17 @@ static struct page *new_node_page(struct page *page, unsigned long node, int **x
>  	if (PageHuge(page))
>  		return alloc_huge_page_node(page_hstate(compound_head(page)),
>  					node);
> -	else
> +	else if (thp_migration_supported() && PageTransHuge(page)) {
> +		struct page *thp;
> +
> +		thp = alloc_pages_node(node,
> +			(GFP_TRANSHUGE | __GFP_THISNODE) & ~__GFP_RECLAIM,
> +			HPAGE_PMD_ORDER);
> +		if (!thp)
> +			return NULL;
> +		prep_transhuge_page(thp);
> +		return thp;
> +	} else
>  		return __alloc_pages_node(node, GFP_HIGHUSER_MOVABLE |
>  						    __GFP_THISNODE, 0);
>  }
> @@ -1147,6 +1188,15 @@ static struct page *new_page(struct page *page, unsigned long start, int **x)
>  	if (PageHuge(page)) {
>  		BUG_ON(!vma);
>  		return alloc_huge_page_noerr(vma, address, 1);
> +	} else if (thp_migration_supported() && PageTransHuge(page)) {
> +		struct page *thp;
> +
> +		thp = alloc_hugepage_vma(GFP_TRANSHUGE, vma, address,
> +					 HPAGE_PMD_ORDER);
> +		if (!thp)
> +			return NULL;
> +		prep_transhuge_page(thp);
> +		return thp;

GFP flags in both these new page allocation functions should be the same.
Does alloc_hugepage_vma() will eventually call page allocation with the
following flags.

(GFP_TRANSHUGE | __GFP_THISNODE) & ~__GFP_RECLAIM