1 files changed, 5 insertions, 0 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index f5b5f029288c..5be8107e7758 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -286,6 +286,11 @@ static inline int page_mapping_inuse(struct page *page)
 
 static inline int is_page_cache_freeable(struct page *page)
 {
+        /*
+         * A freeable page cache page is referenced only by the caller
+         * that isolated the page, the page cache radix tree and
+         * optional buffer heads at page->private.
+         */
         return page_count(page) - page_has_private(page) == 2;
 }