mm/migrate: factor out movable_ops page handling into migrate_movable_ops_page() (b9ed0048) · Commits · git / linux-net

mm/migrate.c

+47 −37

Original line number	Diff line number	Diff line
		@@ -159,6 +159,47 @@ static void putback_movable_ops_page(struct page *page)
		folio_put(folio);
		}

		/**
		* migrate_movable_ops_page - migrate an isolated movable_ops page
		* @dst: The destination page.
		* @src: The source page.
		* @mode: The migration mode.
		*
		* Migrate an isolated movable_ops page.
		*
		* If the src page was already released by its owner, the src page is
		* un-isolated (putback) and migration succeeds; the migration core will be the
		* owner of both pages.
		*
		* If the src page was not released by its owner and the migration was
		* successful, the owner of the src page and the dst page are swapped and
		* the src page is un-isolated.
		*
		* If migration fails, the ownership stays unmodified and the src page
		* remains isolated: migration may be retried later or the page can be putback.
		*
		* TODO: migration core will treat both pages as folios and lock them before
		* this call to unlock them after this call. Further, the folio refcounts on
		* src and dst are also released by migration core. These pages will not be
		* folios in the future, so that must be reworked.
		*
		* Returns MIGRATEPAGE_SUCCESS on success, otherwise a negative error
		* code.
		*/
		static int migrate_movable_ops_page(struct page dst, struct page src,
		enum migrate_mode mode)
		{
		int rc = MIGRATEPAGE_SUCCESS;

		VM_WARN_ON_ONCE_PAGE(!PageIsolated(src), src);
		/* If the page was released by it's owner, there is nothing to do. */
		if (PageMovable(src))
		rc = page_movable_ops(src)->migrate_page(dst, src, mode);
		if (rc == MIGRATEPAGE_SUCCESS)
		ClearPageIsolated(src);
		return rc;
		}

		/*
		* Put previously isolated pages back onto the appropriate lists
		* from where they were once taken off for compaction/migration.
		@@ -1023,51 +1064,20 @@ static int move_to_new_folio(struct folio dst, struct folio src,
		mode);
		else
		rc = fallback_migrate_folio(mapping, dst, src, mode);
		} else {
		const struct movable_operations *mops;

		/*
		* In case of non-lru page, it could be released after
		* isolation step. In that case, we shouldn't try migration.
		*/
		VM_BUG_ON_FOLIO(!folio_test_isolated(src), src);
		if (!folio_test_movable(src)) {
		rc = MIGRATEPAGE_SUCCESS;
		folio_clear_isolated(src);
		if (rc != MIGRATEPAGE_SUCCESS)
		goto out;
		}

		mops = folio_movable_ops(src);
		rc = mops->migrate_page(&dst->page, &src->page, mode);
		WARN_ON_ONCE(rc == MIGRATEPAGE_SUCCESS &&
		!folio_test_isolated(src));
		}

		/*
		* When successful, old pagecache src->mapping must be cleared before
		* src is freed; but stats require that PageAnon be left as PageAnon.
		* For pagecache folios, src->mapping must be cleared before src
		* is freed. Anonymous folios must stay anonymous until freed.
		*/
		if (rc == MIGRATEPAGE_SUCCESS) {
		if (__folio_test_movable(src)) {
		VM_BUG_ON_FOLIO(!folio_test_isolated(src), src);

		/*
		* We clear PG_movable under page_lock so any compactor
		* cannot try to migrate this page.
		*/
		folio_clear_isolated(src);
		}

		/*
		* Anonymous and movable src->mapping will be cleared by
		* free_pages_prepare so don't reset it here for keeping
		* the type to work PageAnon, for example.
		*/
		if (!folio_mapping_flags(src))
		if (!folio_test_anon(src))
		src->mapping = NULL;

		if (likely(!folio_is_zone_device(dst)))
		flush_dcache_folio(dst);
		} else {
		rc = migrate_movable_ops_page(&dst->page, &src->page, mode);
		}
		out:
		return rc;