From ceddc3a52d783fabbf1ba623601419b9d6337194 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Mon, 21 Sep 2009 17:03:00 -0700 Subject: [PATCH] mm: document is_page_cache_freeable() Enlighten the reader of this code about what reference count makes a page cache page freeable. Signed-off-by: Johannes Weiner Cc: Christoph Lameter Reviewed-by: Christoph Lameter Reviewed-by: KOSAKI Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 5 +++++ 1 file changed, 5 insertions(+) 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; } -- 2.34.1