diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index c502c065d007..28d1f35b11a4 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -3973,6 +3973,14 @@ static int validate_message(struct dlm_lkb *lkb, struct dlm_message *ms)
 	int from = ms->m_header.h_nodeid;
 	int error = 0;
 
+	/* currently mixing of user/kernel locks are not supported */
+	if (ms->m_flags & DLM_IFL_USER && ~lkb->lkb_flags & DLM_IFL_USER) {
+		log_error(lkb->lkb_resource->res_ls,
+			  "got user dlm message for a kernel lock");
+		error = -EINVAL;
+		goto out;
+	}
+
 	switch (ms->m_type) {
 	case DLM_MSG_CONVERT:
 	case DLM_MSG_UNLOCK:
@@ -4001,6 +4009,7 @@ static int validate_message(struct dlm_lkb *lkb, struct dlm_message *ms)
 		error = -EINVAL;
 	}
 
+out:
 	if (error)
 		log_error(lkb->lkb_resource->res_ls,
 			  "ignore invalid message %d from %d %x %x %x %d",