Re: [PATCH 2/8] soft-offline: use migrate_pages() instead of migrate_huge_page()

[Wanpeng Li <liwanp@linux.vnet.ibm.com>]

On Thu, Jul 18, 2013 at 05:34:26PM -0400, 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 migrates 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
>which uses linked lists to collect the hugepages to be migrated.
>
>With this patch, soft_offline_huge_page() switches to use migrate_pages(),
>and migrate_huge_page() is not used any more. So let's remove it.
>
>ChangeLog v3:
> - Merged with another cleanup patch (4/10 in previous version)
>

Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>

>Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
>---
> include/linux/migrate.h |  5 -----
> mm/memory-failure.c     | 15 ++++++++++++---
> mm/migrate.c            | 28 ++--------------------------
> 3 files changed, 14 insertions(+), 34 deletions(-)
>
>diff --git v3.11-rc1.orig/include/linux/migrate.h v3.11-rc1/include/linux/migrate.h
>index a405d3dc..6fe5214 100644
>--- v3.11-rc1.orig/include/linux/migrate.h
>+++ v3.11-rc1/include/linux/migrate.h
>@@ -41,8 +41,6 @@ extern int migrate_page(struct address_space *,
> 			struct page *, struct page *, enum migrate_mode);
> extern int migrate_pages(struct list_head *l, new_page_t x,
> 		unsigned long private, enum migrate_mode mode, int reason);
>-extern int migrate_huge_page(struct page *, new_page_t x,
>-		unsigned long private, enum migrate_mode mode);
>
> extern int fail_migrate_page(struct address_space *,
> 			struct page *, struct page *);
>@@ -62,9 +60,6 @@ static inline void putback_movable_pages(struct list_head *l) {}
> static inline int migrate_pages(struct list_head *l, new_page_t x,
> 		unsigned long private, enum migrate_mode mode, int reason)
> 	{ return -ENOSYS; }
>-static inline int migrate_huge_page(struct page *page, new_page_t x,
>-		unsigned long private, enum migrate_mode mode)
>-	{ return -ENOSYS; }
>
> static inline int migrate_prep(void) { return -ENOSYS; }
> static inline int migrate_prep_local(void) { return -ENOSYS; }
>diff --git v3.11-rc1.orig/mm/memory-failure.c v3.11-rc1/mm/memory-failure.c
>index 2c13aa7..af6f61c 100644
>--- v3.11-rc1.orig/mm/memory-failure.c
>+++ v3.11-rc1/mm/memory-failure.c
>@@ -1467,6 +1467,7 @@ static int soft_offline_huge_page(struct page *page, int flags)
> 	int ret;
> 	unsigned long pfn = page_to_pfn(page);
> 	struct page *hpage = compound_head(page);
>+	LIST_HEAD(pagelist);
>
> 	/*
> 	 * This double-check of PageHWPoison is to avoid the race with
>@@ -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);
>+		if (ret > 0)
>+			ret = -EIO;
> 	} else {
> 		set_page_hwpoison_huge_page(hpage);
> 		dequeue_hwpoisoned_huge_page(hpage);
>diff --git v3.11-rc1.orig/mm/migrate.c v3.11-rc1/mm/migrate.c
>index b44a067..3ec47d3 100644
>--- v3.11-rc1.orig/mm/migrate.c
>+++ v3.11-rc1/mm/migrate.c
>@@ -979,6 +979,8 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
>
> 	unlock_page(hpage);
> out:
>+	if (rc != -EAGAIN)
>+		putback_active_hugepage(hpage);
> 	put_page(new_hpage);
> 	if (result) {
> 		if (rc)
>@@ -1066,32 +1068,6 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
> 	return rc;
> }
>
>-int migrate_huge_page(struct page *hpage, new_page_t get_new_page,
>-		      unsigned long private, enum migrate_mode mode)
>-{
>-	int pass, rc;
>-
>-	for (pass = 0; pass < 10; pass++) {
>-		rc = unmap_and_move_huge_page(get_new_page, private,
>-						hpage, pass > 2, mode);
>-		switch (rc) {
>-		case -ENOMEM:
>-			goto out;
>-		case -EAGAIN:
>-			/* try again */
>-			cond_resched();
>-			break;
>-		case MIGRATEPAGE_SUCCESS:
>-			goto out;
>-		default:
>-			rc = -EIO;
>-			goto out;
>-		}
>-	}
>-out:
>-	return rc;
>-}
>-
> #ifdef CONFIG_NUMA
> /*
>  * Move a list of individual pages
>-- 
>1.8.3.1
>
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