On Fri 22-03-13 16:23:48, Naoya Horiguchi wrote:
> Currently migrate_huge_page() takes a pointer to a hugepage to be
> migrated as an argument, instead of taking a pointer to the list of
> hugepages to be migrated. This behavior was introduced in commit
> 189ebff28 ("hugetlb: simplify migrate_huge_page()"), and was OK
> because until now hugepage migration is enabled only for soft-offlining
> which takes only one hugepage in a single call.
>
> But the situation will change in the later patches in this series
> which enable other users of page migration to support hugepage migration.
> They can kick migration for both of normal pages and hugepages
> in a single call, so we need to go back to original implementation
> of using linked lists to collect the hugepages to be migrated.
If the purpose of this patch is to reduce code duplication then you
should remove migrate_huge_page as it doesn't have any caller anymore.
[...]
> @@ -1482,12 +1483,20 @@ static int soft_offline_huge_page(struct page *page,
> int flags)
> unlock_page(hpage);
>
> /* Keep page count to indicate a given hugepage is isolated. */
> - ret = migrate_huge_page(hpage, new_page, MPOL_MF_MOVE_ALL,
> - MIGRATE_SYNC);
> - put_page(hpage);
> + list_move(&hpage->lru, &pagelist);
> + ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL,
> + MIGRATE_SYNC, MR_MEMORY_FAILURE);
> if (ret) {
> pr_info("soft offline: %#lx: migration failed %d, type %lx\n",
> pfn, ret, page->flags);
> + /*
> + * We know that soft_offline_huge_page() tries to migrate
> + * only one hugepage pointed to by hpage, so we need not
> + * run through the pagelist here.
> + */
> + putback_active_hugepage(hpage);
Maybe I am missing something but why we didn't need to call this before
when using migrate_huge_page?
> + if (ret > 0)
> + ret = -EIO;
> } else {
> set_page_hwpoison_huge_page(hpage);
> dequeue_hwpoisoned_huge_page(hpage);
> diff --git v3.9-rc3.orig/mm/migrate.c v3.9-rc3/mm/migrate.c
> index f69f354..66030b6 100644
> --- v3.9-rc3.orig/mm/migrate.c
> +++ v3.9-rc3/mm/migrate.c
> @@ -981,6 +981,8 @@ static int unmap_and_move_huge_page(new_page_t
> get_new_page,
>
> unlock_page(hpage);
> out:
> + if (rc != -EAGAIN)
> + putback_active_hugepage(hpage);
And why do you put it here? If it is called from migrate_pages then the
caller already does the clean-up (putback_lru_pages).
> put_page(new_hpage);
> if (result) {
> if (rc)
> --
> 1.7.11.7
>
--
Michal Hocko
SUSE Labs
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