mm: constify nmask argument to set_mempolicy()

The nmask argument to set_mempolicy() is const according to the user-space
header numaif.h, and since the kernel does indeed not modify it, it might
as well be declared const in the kernel.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index bfef0be..b0881a0 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -711,7 +711,7 @@
 
 asmlinkage long sys_ioprio_set(int which, int who, int ioprio);
 asmlinkage long sys_ioprio_get(int which, int who);
-asmlinkage long sys_set_mempolicy(int mode, unsigned long __user *nmask,
+asmlinkage long sys_set_mempolicy(int mode, const unsigned long __user *nmask,
 				unsigned long maxnode);
 asmlinkage long sys_migrate_pages(pid_t pid, unsigned long maxnode,
 				const unsigned long __user *from,
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 727187f..b09586d 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1383,7 +1383,7 @@
 }
 
 /* Set the process memory policy */
-SYSCALL_DEFINE3(set_mempolicy, int, mode, unsigned long __user *, nmask,
+SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned long __user *, nmask,
 		unsigned long, maxnode)
 {
 	int err;