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.
[rientjes@google.com: fix type of `old_bytes']
Signed-off-by: Sven Wegener <sven.wegener@stealer.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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 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 @@
.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 @@
.mode = 0644,
.proc_handler = &dirty_bytes_handler,
.strategy = &sysctl_intvec,
- .extra1 = &one,
+ .extra1 = &one_ul,
},
{
.procname = "dirty_writeback_centisecs",
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index dc32dae..c17005e 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -209,7 +209,7 @@
struct file *filp, void __user *buffer, size_t *lenp,
loff_t *ppos)
{
- int old_bytes = vm_dirty_bytes;
+ unsigned long old_bytes = vm_dirty_bytes;
int ret;
ret = proc_doulongvec_minmax(table, write, filp, buffer, lenp, ppos);