1 files changed, 25 insertions, 0 deletions

diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_compaction.h
index f7f1d7169b11..089743ade734 100644
--- a/include/linux/balloon_compaction.h
+++ b/include/linux/balloon_compaction.h
@@ -159,6 +159,26 @@ static inline bool balloon_page_movable(struct page *page)
 }
 
 /*
+ * isolated_balloon_page - identify an isolated balloon page on private
+ *                         compaction/migration page lists.
+ *
+ * After a compaction thread isolates a balloon page for migration, it raises
+ * the page refcount to prevent concurrent compaction threads from re-isolating
+ * the same page. For that reason putback_movable_pages(), or other routines
+ * that need to identify isolated balloon pages on private pagelists, cannot
+ * rely on balloon_page_movable() to accomplish the task.
+ */
+static inline bool isolated_balloon_page(struct page *page)
+{
+        /* Already isolated balloon pages, by default, have a raised refcount */
+        if (page_flags_cleared(page) && !page_mapped(page) &&
+            page_count(page) >= 2)
+                return __is_movable_balloon_page(page);
+
+        return false;
+}
+
+/*
  * balloon_page_insert - insert a page into the balloon's page list and make
  *                       the page->mapping assignment accordingly.
  * @page    : page to be assigned as a 'balloon page'
@@ -243,6 +263,11 @@ static inline bool balloon_page_movable(struct page *page)
         return false;
 }
 
+static inline bool isolated_balloon_page(struct page *page)
+{
+        return false;
+}
+
 static inline bool balloon_page_isolate(struct page *page)
 {
         return false;