linux-kernel - [PATCH] mm: Fix dirty_bytes/dirty_background

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Date:	Sun, 1 Feb 2009 02:22:54 +0100 (CET)
From:	Sven Wegener <sven.wegener@...aler.net>
To:	David Rientjes <rientjes@...gle.com>
cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Dave Chinner <david@...morbit.com>,
	Christoph Lameter <cl@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] mm: Fix dirty_bytes/dirty_background_bytes sysctls on 64bit
 arches

We need to pass an unsigned long as the minimum, because it gets casted
to an unsigned long in the sysctl handler. If we pass an int, we'll
access four more bytes on 64bit arches, resulting in a random minimum
value.

Signed-off-by: Sven Wegener <sven.wegener@...aler.net>
---
 kernel/sysctl.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 790f9d7..c5ef44f 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -101,6 +101,7 @@ static int two = 2;
 
 static int zero;
 static int one = 1;
+static unsigned long one_ul = 1;
 static int one_hundred = 100;
 
 /* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */
@@ -974,7 +975,7 @@ static struct ctl_table vm_table[] = {
 		.mode		= 0644,
 		.proc_handler	= &dirty_background_bytes_handler,
 		.strategy	= &sysctl_intvec,
-		.extra1		= &one,
+		.extra1		= &one_ul,
 	},
 	{
 		.ctl_name	= VM_DIRTY_RATIO,
@@ -995,7 +996,7 @@ static struct ctl_table vm_table[] = {
 		.mode		= 0644,
 		.proc_handler	= &dirty_bytes_handler,
 		.strategy	= &sysctl_intvec,
-		.extra1		= &one,
+		.extra1		= &one_ul,
 	},
 	{
 		.procname	= "dirty_writeback_centisecs",
--
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