kill mm argument of vm_munmap()

it's always current->mm

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/mm/nommu.c b/mm/nommu.c
index dd00383..bb8f4f0 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1734,8 +1734,9 @@
 }
 EXPORT_SYMBOL(do_munmap);
 
-int vm_munmap(struct mm_struct *mm, unsigned long addr, size_t len)
+int vm_munmap(unsigned long addr, size_t len)
 {
+	struct mm_struct *mm = current->mm;
 	int ret;
 
 	down_write(&mm->mmap_sem);
@@ -1747,7 +1748,7 @@
 
 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
 {
-	return vm_munmap(current->mm, addr, len);
+	return vm_munmap(addr, len);
 }
 
 /*