From ceddc3a52d783fabbf1ba623601419b9d6337194 Mon Sep 17 00:00:00 2001
From: Johannes Weiner <hannes@cmpxchg.org>
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 <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/vmscan.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index f5b5f029288c6..5be8107e77580 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;
}
--
GitLab