[PATCH] fix mmap(MAP_LOCKED)

From Hubertus Franke.

The MAP_LOCKED flag to mmap() currently does nothing.  Hubertus' patch
fixes it so that the relevant mapping is locked into memory, if the
called has CAP_IPC_LOCK.

mm/mmap.c

@@ -463,6 +463,11 @@ unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
 	 */
 	vm_flags = calc_vm_flags(prot,flags) | mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
 
+	if (flags & MAP_LOCKED) {
+		if (!capable(CAP_IPC_LOCK))
+			return -EPERM;
+		vm_flags |= VM_LOCKED;
+	}
 	/* mlock MCL_FUTURE? */
 	if (vm_flags & VM_LOCKED) {
 		unsigned long locked = mm->locked_vm << PAGE_SHIFT;