Re: [PATCH v2 4/7] mm/migrate: remove putback_lru_pages, fix comment on putback_movable_pages

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

On Mon, Dec 09, 2013 at 06:10:45PM +0900, Joonsoo Kim wrote:
>Some part of putback_lru_pages() and putback_movable_pages() is
>duplicated, so it could confuse us what we should use.
>We can remove putback_lru_pages() since it is not really needed now.
>This makes us undestand and maintain the code more easily.
>
>And comment on putback_movable_pages() is stale now, so fix it.
>
>Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>
>diff --git a/include/linux/migrate.h b/include/linux/migrate.h
>index f5096b5..e4671f9 100644
>--- a/include/linux/migrate.h
>+++ b/include/linux/migrate.h
>@@ -35,7 +35,6 @@ enum migrate_reason {
>
> #ifdef CONFIG_MIGRATION
>
>-extern void putback_lru_pages(struct list_head *l);
> extern void putback_movable_pages(struct list_head *l);
> extern int migrate_page(struct address_space *,
> 			struct page *, struct page *, enum migrate_mode);
>@@ -58,7 +57,6 @@ extern int migrate_page_move_mapping(struct address_space *mapping,
> 		struct buffer_head *head, enum migrate_mode mode);
> #else
>
>-static inline void putback_lru_pages(struct list_head *l) {}
> 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)
>diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>index b7c1716..1debdea 100644
>--- a/mm/memory-failure.c
>+++ b/mm/memory-failure.c
>@@ -1569,7 +1569,13 @@ static int __soft_offline_page(struct page *page, int flags)
> 		ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL,
> 					MIGRATE_SYNC, MR_MEMORY_FAILURE);
> 		if (ret) {
>-			putback_lru_pages(&pagelist);
>+			if (!list_empty(&pagelist)) {
>+				list_del(&page->lru);
>+				dec_zone_page_state(page, NR_ISOLATED_ANON +
>+						page_is_file_cache(page));
>+				putback_lru_page(page);
>+			}
>+
> 			pr_info("soft offline: %#lx: migration failed %d, type %lx\n",
> 				pfn, ret, page->flags);
> 			if (ret > 0)
>diff --git a/mm/migrate.c b/mm/migrate.c
>index b1cfd01..cdafdc0 100644
>--- a/mm/migrate.c
>+++ b/mm/migrate.c
>@@ -71,28 +71,12 @@ int migrate_prep_local(void)
> }
>
> /*
>- * Add isolated pages on the list back to the LRU under page lock
>- * to avoid leaking evictable pages back onto unevictable list.
>- */
>-void putback_lru_pages(struct list_head *l)
>-{
>-	struct page *page;
>-	struct page *page2;
>-
>-	list_for_each_entry_safe(page, page2, l, lru) {
>-		list_del(&page->lru);
>-		dec_zone_page_state(page, NR_ISOLATED_ANON +
>-				page_is_file_cache(page));
>-			putback_lru_page(page);
>-	}
>-}
>-
>-/*
>  * Put previously isolated pages back onto the appropriate lists
>  * from where they were once taken off for compaction/migration.
>  *
>- * This function shall be used instead of putback_lru_pages(),
>- * whenever the isolated pageset has been built by isolate_migratepages_range()
>+ * This function shall be used whenever the isolated pageset has been
>+ * built from lru, balloon, hugetlbfs page. See isolate_migratepages_range()
>+ * and isolate_huge_page().
>  */
> void putback_movable_pages(struct list_head *l)
> {
>@@ -1704,6 +1688,12 @@ int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
> 	nr_remaining = migrate_pages(&migratepages, alloc_misplaced_dst_page,
> 				     node, MIGRATE_ASYNC, MR_NUMA_MISPLACED);
> 	if (nr_remaining) {
>+		if (!list_empty(&migratepages)) {
>+			list_del(&page->lru);
>+			dec_zone_page_state(page, NR_ISOLATED_ANON +
>+					page_is_file_cache(page));
>+			putback_lru_page(page);
>+		}
> 		putback_lru_pages(&migratepages);

You should remove this line. Otherwise,

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

> 		isolated = 0;
> 	} else
>-- 
>1.7.9.5
>
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