diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index fe80bb48ab1f..a24a57593202 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -158,6 +158,7 @@ extern struct net init_net;
 struct net *copy_net_ns(unsigned long flags, struct user_namespace *user_ns,
 			struct net *old_net);
 
+void net_ns_barrier(void);
 #else /* CONFIG_NET_NS */
 #include <linux/sched.h>
 #include <linux/nsproxy.h>
@@ -168,6 +169,8 @@ static inline struct net *copy_net_ns(unsigned long flags,
 		return ERR_PTR(-EINVAL);
 	return old_net;
 }
+
+static inline void net_ns_barrier(void) {}
 #endif /* CONFIG_NET_NS */
 
 
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 1934efd4a9d4..1f15abb1d733 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -482,6 +482,23 @@ static void cleanup_net(struct work_struct *work)
 		net_drop_ns(net);
 	}
 }
+
+/**
+ * net_ns_barrier - wait until concurrent net_cleanup_work is done
+ *
+ * cleanup_net runs from work queue and will first remove namespaces
+ * from the global list, then run net exit functions.
+ *
+ * Call this in module exit path to make sure that all netns
+ * ->exit ops have been invoked before the function is removed.
+ */
+void net_ns_barrier(void)
+{
+	mutex_lock(&net_mutex);
+	mutex_unlock(&net_mutex);
+}
+EXPORT_SYMBOL(net_ns_barrier);
+
 static DECLARE_WORK(net_cleanup_work, cleanup_net);
 
 void __put_net(struct net *net)
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index c3bd9b086dcc..9979f46c81dc 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1720,6 +1720,8 @@ EXPORT_SYMBOL_GPL(nf_ct_iterate_cleanup_net);
  * Like nf_ct_iterate_cleanup, but first marks conntracks on the
  * unconfirmed list as dying (so they will not be inserted into
  * main table).
+ *
+ * Can only be called in module exit path.
  */
 void
 nf_ct_iterate_destroy(int (*iter)(struct nf_conn *i, void *data), void *data)
@@ -1734,6 +1736,13 @@ nf_ct_iterate_destroy(int (*iter)(struct nf_conn *i, void *data), void *data)
 	}
 	rtnl_unlock();
 
+	/* Need to wait for netns cleanup worker to finish, if its
+	 * running -- it might have deleted a net namespace from
+	 * the global list, so our __nf_ct_unconfirmed_destroy() might
+	 * not have affected all namespaces.
+	 */
+	net_ns_barrier();
+
 	/* a conntrack could have been unlinked from unconfirmed list
 	 * before we grabbed pcpu lock in __nf_ct_unconfirmed_destroy().
 	 * This makes sure its inserted into conntrack table.