Re: [PATCH v3 13/14] mm: migrate: move_pages() supports thp migration

From: Naoya Horiguchi
Date: Thu Feb 09 2017 - 04:21:30 EST


On Sun, Feb 05, 2017 at 11:12:51AM -0500, Zi Yan wrote:
> From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
>
> This patch enables thp migration for move_pages(2).
>
> Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
> ---
> mm/migrate.c | 37 ++++++++++++++++++++++++++++---------
> 1 file changed, 28 insertions(+), 9 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 84181a3668c6..9bcaccb481ac 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1413,7 +1413,17 @@ static struct page *new_page_node(struct page *p, unsigned long private,
> if (PageHuge(p))
> return alloc_huge_page_node(page_hstate(compound_head(p)),
> pm->node);
> - else
> + else if (thp_migration_supported() && PageTransHuge(p)) {
> + struct page *thp;
> +
> + thp = alloc_pages_node(pm->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(pm->node,
> GFP_HIGHUSER_MOVABLE | __GFP_THISNODE, 0);
> }
> @@ -1440,6 +1450,8 @@ static int do_move_page_to_node_array(struct mm_struct *mm,
> for (pp = pm; pp->node != MAX_NUMNODES; pp++) {
> struct vm_area_struct *vma;
> struct page *page;
> + struct page *head;
> + unsigned int follflags;
>
> err = -EFAULT;
> vma = find_vma(mm, pp->addr);
> @@ -1447,8 +1459,10 @@ static int do_move_page_to_node_array(struct mm_struct *mm,
> goto set_status;
>
> /* FOLL_DUMP to ignore special (like zero) pages */
> - page = follow_page(vma, pp->addr,
> - FOLL_GET | FOLL_SPLIT | FOLL_DUMP);
> + follflags = FOLL_GET | FOLL_SPLIT | FOLL_DUMP;

FOLL_SPLIT should be added depending on thp_migration_supported().

Thanks,
Naoya Horiguchi

> + if (!thp_migration_supported())
> + follflags |= FOLL_SPLIT;
> + page = follow_page(vma, pp->addr, follflags);
>
> err = PTR_ERR(page);
> if (IS_ERR(page))
> @@ -1458,7 +1472,6 @@ static int do_move_page_to_node_array(struct mm_struct *mm,
> if (!page)
> goto set_status;
>
> - pp->page = page;
> err = page_to_nid(page);
>
> if (err == pp->node)
> @@ -1473,16 +1486,22 @@ static int do_move_page_to_node_array(struct mm_struct *mm,
> goto put_and_set;
>
> if (PageHuge(page)) {
> - if (PageHead(page))
> + if (PageHead(page)) {
> isolate_huge_page(page, &pagelist);
> + err = 0;
> + pp->page = page;
> + }
> goto put_and_set;
> }
>
> - err = isolate_lru_page(page);
> + pp->page = compound_head(page);
> + head = compound_head(page);
> + err = isolate_lru_page(head);
> if (!err) {
> - list_add_tail(&page->lru, &pagelist);
> - inc_node_page_state(page, NR_ISOLATED_ANON +
> - page_is_file_cache(page));
> + list_add_tail(&head->lru, &pagelist);
> + mod_node_page_state(page_pgdat(head),
> + NR_ISOLATED_ANON + page_is_file_cache(head),
> + hpage_nr_pages(head));
> }
> put_and_set:
> /*
> --
> 2.11.0
>