linux-kernel - [PATCH 3/5] lumpy: ensure that we compare PageActive and active safely

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Message-ID: <e64dea44318a03a559d7a230d9b14e42@kernel>
Date:	Tue, 27 Feb 2007 11:35:23 -0800
From:	Andy Whitcroft <apw@...dowen.org>
To:	Andrew Morton <akpm@...l.org>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Andy Whitcroft <apw@...dowen.org>, Mel Gorman <mel@....ul.ie>
Subject: [PATCH 3/5] lumpy: ensure that we compare PageActive and active safely


Now that we are passing in a boolean active flag we need to
ensure that the result of PageActive(page) is comparible
to that boolean.

Signed-off-by: Andy Whitcroft <apw@...dowen.org>
---
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b878d54..2bfad79 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -632,7 +632,12 @@ static int __isolate_lru_page(struct page *page, int active)
 {
 	int ret = -EINVAL;
 
-	if (PageLRU(page) && (PageActive(page) == active)) {
+	/*
+	 * When checking the active state, we need to be sure we are
+	 * dealing with comparible boolean values.  Take the logical not
+	 * of each.
+	 */
+	if (PageLRU(page) && (!PageActive(page) == !active)) {
 		ret = -EBUSY;
 		if (likely(get_page_unless_zero(page))) {
 			/*
-
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