On Wed 17-02-21 11:08:16, Oscar Salvador wrote:
> In-use hugetlb pages can be migrated as any other page (LRU
> and Movable), so let alloc_contig_range handle them.
>
> All we need is to succesfully isolate such page.
>
> Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
> ---
> include/linux/hugetlb.h | 5 +++--
> mm/compaction.c | 11 ++++++++++-
> mm/hugetlb.c | 6 ++++--
> mm/vmscan.c | 5 +++--
> 4 files changed, 20 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index 72352d718829..8c17d0dbc87c 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -505,7 +505,7 @@ struct huge_bootmem_page {
> struct hstate *hstate;
> };
>
> -bool isolate_or_dissolve_huge_page(struct page *page);
> +bool isolate_or_dissolve_huge_page(struct page *page, struct list_head *list);
> struct page *alloc_huge_page(struct vm_area_struct *vma,
> unsigned long addr, int avoid_reserve);
> struct page *alloc_huge_page_nodemask(struct hstate *h, int preferred_nid,
> @@ -776,7 +776,8 @@ void set_page_huge_active(struct page *page);
> #else /* CONFIG_HUGETLB_PAGE */
> struct hstate {};
>
> -static inline bool isolate_or_dissolve_huge_page(struct page *page)
> +static inline bool isolate_or_dissolve_huge_page(struct page *page,
> + struct list_head *list)
> {
> return false;
> }
> diff --git a/mm/compaction.c b/mm/compaction.c
> index d52506ed9db7..55a41a9228a9 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -906,9 +906,17 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
> }
>
> if (PageHuge(page) && cc->alloc_contig) {
> - if (!isolate_or_dissolve_huge_page(page))
> + if (!isolate_or_dissolve_huge_page(page, &cc->migratepages))
> goto isolate_fail;
>
> + if (PageHuge(page)) {
> + /*
> + * Hugepage was succesfully isolated.
> + */
> + low_pfn += compound_nr(page) - 1;
> + goto isolate_success_no_list;
> + }
> +
> /*
> * Ok, the hugepage was dissolved. Now these pages are
> * Buddy and cannot be re-allocated because they are
> @@ -1053,6 +1061,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
>
> isolate_success:
> list_add(&page->lru, &cc->migratepages);
> +isolate_success_no_list:
> cc->nr_migratepages += compound_nr(page);
I do not follow. You have successfully isolated huge pages so why don't
you add that page to the migratepages list to be migrated?
--
Michal Hocko
SUSE Labs
