[PATCH v2 4/5] mm: migrate: add isolate_folio_to_list()

[Kefeng Wang <wangkefeng.wang@huawei.com>]

Add isolate_folio_to_list() helper to try to isolate HugeTLB,
no-LRU movable and LRU folios to a list, which will be reused by
do_migrate_range() from memory hotplug soon, also drop the
mf_isolate_folio() since we could directly use new helper in
the soft_offline_in_use_page().

Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 include/linux/migrate.h |  3 +++
 mm/memory-failure.c     | 46 ++++++++++-------------------------------
 mm/migrate.c            | 27 ++++++++++++++++++++++++
 3 files changed, 41 insertions(+), 35 deletions(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 644be30b69c8..002e49b2ebd9 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -70,6 +70,7 @@ int migrate_pages(struct list_head *l, new_folio_t new, free_folio_t free,
 		  unsigned int *ret_succeeded);
 struct folio *alloc_migration_target(struct folio *src, unsigned long private);
 bool isolate_movable_page(struct page *page, isolate_mode_t mode);
+bool isolate_folio_to_list(struct folio *folio, struct list_head *list);
 
 int migrate_huge_page_move_mapping(struct address_space *mapping,
 		struct folio *dst, struct folio *src);
@@ -91,6 +92,8 @@ static inline struct folio *alloc_migration_target(struct folio *src,
 	{ return NULL; }
 static inline bool isolate_movable_page(struct page *page, isolate_mode_t mode)
 	{ return false; }
+static inline bool isolate_folio_to_list(struct folio *folio, struct list_head *list)
+	{ return false; }
 
 static inline int migrate_huge_page_move_mapping(struct address_space *mapping,
 				  struct folio *dst, struct folio *src)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 93848330de1f..d8298017bd99 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -2659,40 +2659,6 @@ EXPORT_SYMBOL(unpoison_memory);
 #undef pr_fmt
 #define pr_fmt(fmt) "Soft offline: " fmt
 
-static bool mf_isolate_folio(struct folio *folio, struct list_head *pagelist)
-{
-	bool isolated = false;
-
-	if (folio_test_hugetlb(folio)) {
-		isolated = isolate_hugetlb(folio, pagelist);
-	} else {
-		bool lru = !__folio_test_movable(folio);
-
-		if (lru)
-			isolated = folio_isolate_lru(folio);
-		else
-			isolated = isolate_movable_page(&folio->page,
-							ISOLATE_UNEVICTABLE);
-
-		if (isolated) {
-			list_add(&folio->lru, pagelist);
-			if (lru)
-				node_stat_add_folio(folio, NR_ISOLATED_ANON +
-						    folio_is_file_lru(folio));
-		}
-	}
-
-	/*
-	 * If we succeed to isolate the folio, we grabbed another refcount on
-	 * the folio, so we can safely drop the one we got from get_any_page().
-	 * If we failed to isolate the folio, it means that we cannot go further
-	 * and we will return an error, so drop the reference we got from
-	 * get_any_page() as well.
-	 */
-	folio_put(folio);
-	return isolated;
-}
-
 /*
  * soft_offline_in_use_page handles hugetlb-pages and non-hugetlb pages.
  * If the page is a non-dirty unmapped page-cache page, it simply invalidates.
@@ -2744,7 +2710,7 @@ static int soft_offline_in_use_page(struct page *page)
 		return 0;
 	}
 
-	if (mf_isolate_folio(folio, &pagelist)) {
+	if (isolate_folio_to_list(folio, &pagelist)) {
 		ret = migrate_pages(&pagelist, alloc_migration_target, NULL,
 			(unsigned long)&mtc, MIGRATE_SYNC, MR_MEMORY_FAILURE, NULL);
 		if (!ret) {
@@ -2766,6 +2732,16 @@ static int soft_offline_in_use_page(struct page *page)
 			pfn, msg_page[huge], page_count(page), &page->flags);
 		ret = -EBUSY;
 	}
+
+	/*
+	 * If we succeed to isolate the folio, we grabbed another refcount on
+	 * the folio, so we can safely drop the one we got from get_any_page().
+	 * If we failed to isolate the folio, it means that we cannot go further
+	 * and we will return an error, so drop the reference we got from
+	 * get_any_page() as well.
+	 */
+	folio_put(folio);
+
 	return ret;
 }
 
diff --git a/mm/migrate.c b/mm/migrate.c
index 6e32098ac2dc..7b7b5b16e610 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -178,6 +178,33 @@ void putback_movable_pages(struct list_head *l)
 	}
 }
 
+/* Must be called with an elevated refcount on the non-hugetlb folio */
+bool isolate_folio_to_list(struct folio *folio, struct list_head *list)
+{
+	bool isolated = false;
+
+	if (folio_test_hugetlb(folio)) {
+		isolated = isolate_hugetlb(folio, list);
+	} else {
+		bool lru = !__folio_test_movable(folio);
+
+		if (lru)
+			isolated = folio_isolate_lru(folio);
+		else
+			isolated = isolate_movable_page(&folio->page,
+							ISOLATE_UNEVICTABLE);
+
+		if (isolated) {
+			list_add(&folio->lru, list);
+			if (lru)
+				node_stat_add_folio(folio, NR_ISOLATED_ANON +
+						    folio_is_file_lru(folio));
+		}
+	}
+
+	return isolated;
+}
+
 static bool try_to_map_unused_to_zeropage(struct page_vma_mapped_walk *pvmw,
 					  struct folio *folio,
 					  unsigned long idx)
-- 
2.27.0