mm: balloon: use general non-lru movable page feature

Now, VM has a feature to migrate non-lru movable pages so balloon
doesn't need custom migration hooks in migrate.c and compaction.c.

Instead, this patch implements the page->mapping->a_ops->
{isolate|migrate|putback} functions.

With that, we could remove hooks for ballooning in general migration
functions and make balloon compaction simple.

[akpm@linux-foundation.org: compaction.h requires that the includer first include node.h]
Link: http://lkml.kernel.org/r/1464736881-24886-4-git-send-email-minchan@kernel.org
Signed-off-by: Gioh Kim <gi-oh.kim@profitbricks.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 17 insertions, 37 deletions

diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_compaction.h
index 9b0a15d06a4f..504bd724e6ab 100644
--- a/include/linux/balloon_compaction.h
+++ b/include/linux/balloon_compaction.h
@@ -45,9 +45,11 @@
 #define _LINUX_BALLOON_COMPACTION_H
 #include <linux/pagemap.h>
 #include <linux/page-flags.h>
-#include <linux/migrate.h>
+#include <linux/node.h>
+#include <linux/compaction.h>
 #include <linux/gfp.h>
 #include <linux/err.h>
+#include <linux/fs.h>
 
 /*
  * Balloon device information descriptor.
@@ -62,6 +64,7 @@ struct balloon_dev_info {
 	struct list_head pages;		/* Pages enqueued & handled to Host */
 	int (*migratepage)(struct balloon_dev_info *, struct page *newpage,
 			struct page *page, enum migrate_mode mode);
+	struct inode *inode;
 };
 
 extern struct page *balloon_page_enqueue(struct balloon_dev_info *b_dev_info);
@@ -73,45 +76,19 @@ static inline void balloon_devinfo_init(struct balloon_dev_info *balloon)
 	spin_lock_init(&balloon->pages_lock);
 	INIT_LIST_HEAD(&balloon->pages);
 	balloon->migratepage = NULL;
+	balloon->inode = NULL;
 }
 
 #ifdef CONFIG_BALLOON_COMPACTION
-extern bool balloon_page_isolate(struct page *page);
+extern const struct address_space_operations balloon_aops;
+extern bool balloon_page_isolate(struct page *page,
+				isolate_mode_t mode);
 extern void balloon_page_putback(struct page *page);
-extern int balloon_page_migrate(struct page *newpage,
+extern int balloon_page_migrate(struct address_space *mapping,
+				struct page *newpage,
 				struct page *page, enum migrate_mode mode);
 
 /*
- * __is_movable_balloon_page - helper to perform @page PageBalloon tests
- */
-static inline bool __is_movable_balloon_page(struct page *page)
-{
-	return PageBalloon(page);
-}
-
-/*
- * balloon_page_movable - test PageBalloon to identify balloon pages
- *			  and PagePrivate to check that the page is not
- *			  isolated and can be moved by compaction/migration.
- *
- * As we might return false positives in the case of a balloon page being just
- * released under us, this need to be re-tested later, under the page lock.
- */
-static inline bool balloon_page_movable(struct page *page)
-{
-	return PageBalloon(page) && PagePrivate(page);
-}
-
-/*
- * isolated_balloon_page - identify an isolated balloon page on private
- *			   compaction/migration page lists.
- */
-static inline bool isolated_balloon_page(struct page *page)
-{
-	return PageBalloon(page);
-}
-
-/*
  * balloon_page_insert - insert a page into the balloon's page list and make
  *			 the page->private assignment accordingly.
  * @balloon : pointer to balloon device
@@ -124,7 +101,7 @@ static inline void balloon_page_insert(struct balloon_dev_info *balloon,
 				       struct page *page)
 {
 	__SetPageBalloon(page);
-	SetPagePrivate(page);
+	__SetPageMovable(page, balloon->inode->i_mapping);
 	set_page_private(page, (unsigned long)balloon);
 	list_add(&page->lru, &balloon->pages);
 }
@@ -140,11 +117,14 @@ static inline void balloon_page_insert(struct balloon_dev_info *balloon,
 static inline void balloon_page_delete(struct page *page)
 {
 	__ClearPageBalloon(page);
+	__ClearPageMovable(page);
 	set_page_private(page, 0);
-	if (PagePrivate(page)) {
-		ClearPagePrivate(page);
+	/*
+	 * No touch page.lru field once @page has been isolated
+	 * because VM is using the field.
+	 */
+	if (!PageIsolated(page))
 		list_del(&page->lru);
-	}
 }
 
 /*