[PATCH mm-unstable v2 0/4] Convert a couple migrate functions to use folios

[PATCH mm-unstable v2 0/4] Convert a couple migrate functions to use folios

[Vishal Moola (Oracle)]

This patch set introduces folio_movable_ops() and converts 3 functions
in mm/migrate.c to use folios. It also introduces
folio_get_nontail_page() for folio conversions which may want to
distinguish between head and tail pages.

---
v2:
  - Add folio_get_nontail_page() to fix behavior in isolate_movable_page()
  - Rebase on latest mm-unstable

Vishal Moola (Oracle) (4):
  mm: Add folio_get_nontail_page()
  mm/migrate: Add folio_movable_ops()
  mm/migrate: Convert isolate_movable_page() to use folios
  mm/migrate: Convert putback_movable_pages() to use folios

 include/linux/migrate.h |  9 +++++
 include/linux/mm.h      |  7 ++++
 mm/migrate.c            | 87 +++++++++++++++++++++--------------------
 3 files changed, 60 insertions(+), 43 deletions(-)

-- 
2.38.1

[PATCH mm-unstable v2 1/4] mm: Add folio_get_nontail_page()

[Vishal Moola (Oracle)]

folio_get_nontail_page() returns the folio associated with a head
page. This is necessary for folio conversions where the behavior of that
function differs between head pages and tail pages.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
 include/linux/mm.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index dd295c020e85..5da260346406 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -879,6 +879,13 @@ static inline bool get_page_unless_zero(struct page *page)
 	return page_ref_add_unless(page, 1, 0);
 }
 
+static inline struct folio *folio_get_nontail_page(struct page *page)
+{
+	if (unlikely(!get_page_unless_zero(page)))
+		return NULL;
+	return (struct folio *)page;
+}
+
 extern int page_is_ram(unsigned long pfn);
 
 enum {
-- 
2.38.1

[PATCH mm-unstable v2 2/4] mm/migrate: Add folio_movable_ops()

[Vishal Moola (Oracle)]

folio_movable_ops() does the same as page_movable_ops() except uses
folios instead of pages. This function will help make folio conversions
in migrate.c more readable.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
 include/linux/migrate.h | 9 +++++++++
 mm/migrate.c            | 2 +-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 7376074f2e1e..c88b96b48be7 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -123,6 +123,15 @@ static inline bool folio_test_movable(struct folio *folio)
 	return PageMovable(&folio->page);
 }
 
+static inline
+const struct movable_operations *folio_movable_ops(struct folio *folio)
+{
+	VM_BUG_ON(!__folio_test_movable(folio));
+
+	return (const struct movable_operations *)
+		((unsigned long)folio->mapping - PAGE_MAPPING_MOVABLE);
+}
+
 static inline
 const struct movable_operations *page_movable_ops(struct page *page)
 {
diff --git a/mm/migrate.c b/mm/migrate.c
index b971edbf32fc..fcb2e9fa1953 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -990,7 +990,7 @@ static int move_to_new_folio(struct folio *dst, struct folio *src,
 			goto out;
 		}
 
-		mops = page_movable_ops(&src->page);
+		mops = folio_movable_ops(src);
 		rc = mops->migrate_page(&dst->page, &src->page, mode);
 		WARN_ON_ONCE(rc == MIGRATEPAGE_SUCCESS &&
 				!folio_test_isolated(src));
-- 
2.38.1

[PATCH mm-unstable v2 3/4] mm/migrate: Convert isolate_movable_page() to use folios

[Vishal Moola (Oracle)]

Removes 6 calls to compound_head() and prepares the function to take in a
folio instead of page argument.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
 mm/migrate.c | 39 ++++++++++++++++++++-------------------
 1 file changed, 20 insertions(+), 19 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index fcb2e9fa1953..c20d9f531db4 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -60,6 +60,7 @@
 
 int isolate_movable_page(struct page *page, isolate_mode_t mode)
 {
+	struct folio *folio = folio_get_nontail_page(page);
 	const struct movable_operations *mops;
 
 	/*
@@ -71,11 +72,11 @@ int isolate_movable_page(struct page *page, isolate_mode_t mode)
 	 * the put_page() at the end of this block will take care of
 	 * release this page, thus avoiding a nasty leakage.
 	 */
-	if (unlikely(!get_page_unless_zero(page)))
+	if (!folio)
 		goto out;
 
-	if (unlikely(PageSlab(page)))
-		goto out_putpage;
+	if (unlikely(folio_test_slab(folio)))
+		goto out_putfolio;
 	/* Pairs with smp_wmb() in slab freeing, e.g. SLUB's __free_slab() */
 	smp_rmb();
 	/*
@@ -83,12 +84,12 @@ int isolate_movable_page(struct page *page, isolate_mode_t mode)
 	 * we use non-atomic bitops on newly allocated page flags so
 	 * unconditionally grabbing the lock ruins page's owner side.
 	 */
-	if (unlikely(!__PageMovable(page)))
-		goto out_putpage;
+	if (unlikely(!__folio_test_movable(folio)))
+		goto out_putfolio;
 	/* Pairs with smp_wmb() in slab allocation, e.g. SLUB's alloc_slab_page() */
 	smp_rmb();
-	if (unlikely(PageSlab(page)))
-		goto out_putpage;
+	if (unlikely(folio_test_slab(folio)))
+		goto out_putfolio;
 
 	/*
 	 * As movable pages are not isolated from LRU lists, concurrent
@@ -101,29 +102,29 @@ int isolate_movable_page(struct page *page, isolate_mode_t mode)
 	 * lets be sure we have the page lock
 	 * before proceeding with the movable page isolation steps.
 	 */
-	if (unlikely(!trylock_page(page)))
-		goto out_putpage;
+	if (unlikely(!folio_trylock(folio)))
+		goto out_putfolio;
 
-	if (!PageMovable(page) || PageIsolated(page))
+	if (!folio_test_movable(folio) || folio_test_isolated(folio))
 		goto out_no_isolated;
 
-	mops = page_movable_ops(page);
-	VM_BUG_ON_PAGE(!mops, page);
+	mops = folio_movable_ops(folio);
+	VM_BUG_ON_FOLIO(!mops, folio);
 
-	if (!mops->isolate_page(page, mode))
+	if (!mops->isolate_page(&folio->page, mode))
 		goto out_no_isolated;
 
 	/* Driver shouldn't use PG_isolated bit of page->flags */
-	WARN_ON_ONCE(PageIsolated(page));
-	SetPageIsolated(page);
-	unlock_page(page);
+	WARN_ON_ONCE(folio_test_isolated(folio));
+	folio_set_isolated(folio);
+	folio_unlock(folio);
 
 	return 0;
 
 out_no_isolated:
-	unlock_page(page);
-out_putpage:
-	put_page(page);
+	folio_unlock(folio);
+out_putfolio:
+	folio_put(folio);
 out:
 	return -EBUSY;
 }
-- 
2.38.1

[PATCH mm-unstable v2 4/4] mm/migrate: Convert putback_movable_pages() to use folios

[Vishal Moola (Oracle)]

Removes 6 calls to compound_head(), and replaces putback_movable_page()
with putback_movable_folio() as well.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
 mm/migrate.c | 46 +++++++++++++++++++++++-----------------------
 1 file changed, 23 insertions(+), 23 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index c20d9f531db4..db480dc08bac 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -129,12 +129,12 @@ int isolate_movable_page(struct page *page, isolate_mode_t mode)
 	return -EBUSY;
 }
 
-static void putback_movable_page(struct page *page)
+static void putback_movable_folio(struct folio *folio)
 {
-	const struct movable_operations *mops = page_movable_ops(page);
+	const struct movable_operations *mops = folio_movable_ops(folio);
 
-	mops->putback_page(page);
-	ClearPageIsolated(page);
+	mops->putback_page(&folio->page);
+	folio_clear_isolated(folio);
 }
 
 /*
@@ -147,33 +147,33 @@ static void putback_movable_page(struct page *page)
  */
 void putback_movable_pages(struct list_head *l)
 {
-	struct page *page;
-	struct page *page2;
+	struct folio *folio;
+	struct folio *folio2;
 
-	list_for_each_entry_safe(page, page2, l, lru) {
-		if (unlikely(PageHuge(page))) {
-			folio_putback_active_hugetlb(page_folio(page));
+	list_for_each_entry_safe(folio, folio2, l, lru) {
+		if (unlikely(folio_test_hugetlb(folio))) {
+			folio_putback_active_hugetlb(folio);
 			continue;
 		}
-		list_del(&page->lru);
+		list_del(&folio->lru);
 		/*
-		 * We isolated non-lru movable page so here we can use
-		 * __PageMovable because LRU page's mapping cannot have
+		 * We isolated non-lru movable folio so here we can use
+		 * __PageMovable because LRU folio's mapping cannot have
 		 * PAGE_MAPPING_MOVABLE.
 		 */
-		if (unlikely(__PageMovable(page))) {
-			VM_BUG_ON_PAGE(!PageIsolated(page), page);
-			lock_page(page);
-			if (PageMovable(page))
-				putback_movable_page(page);
+		if (unlikely(__folio_test_movable(folio))) {
+			VM_BUG_ON_FOLIO(!folio_test_isolated(folio), folio);
+			folio_lock(folio);
+			if (folio_test_movable(folio))
+				putback_movable_folio(folio);
 			else
-				ClearPageIsolated(page);
-			unlock_page(page);
-			put_page(page);
+				folio_clear_isolated(folio);
+			folio_unlock(folio);
+			folio_put(folio);
 		} else {
-			mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON +
-					page_is_file_lru(page), -thp_nr_pages(page));
-			putback_lru_page(page);
+			node_stat_mod_folio(folio, NR_ISOLATED_ANON +
+					folio_is_file_lru(folio), -folio_nr_pages(folio));
+			folio_putback_lru(folio);
 		}
 	}
 }
-- 
2.38.1