mm/migrate: convert isolate_movable_page() to use folios

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

Link: https://lkml.kernel.org/r/20230130214352.40538-4-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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;
 }