Merge branch 'net-speedup-netns-create-delete-time'

Eric Dumazet says:

====================
net: speedup netns create/delete time

When rate of netns creation/deletion is high enough,
we observe softlockups in cleanup_net() caused by huge list
of netns and way too many rcu_barrier() calls.

This patch series does some optimizations in kobject,
and add batching to tunnels so that netns dismantles are
less costly.

IPv6 addrlabels also get a per netns list, and tcp_metrics
also benefit from batch flushing.

This gives me one order of magnitude gain.
(~50 ms -> ~5 ms for one netns create/delete pair)

Tested:

for i in `seq 1 40`
do
 (for j in `seq 1 100` ; do  unshare -n /bin/true >/dev/null ; done) &
done
wait ; grep net_namespace /proc/slabinfo

Before patch series :

$ time ./add_del_unshare.sh
net_namespace        116    258   5504    1    2 : tunables    8    4    0 : slabdata    116    258      0

real	3m24.910s
user	0m0.747s
sys	0m43.162s

After :
$ time ./add_del_unshare.sh
net_namespace        135    291   5504    1    2 : tunables    8    4    0 : slabdata    135    291      0

real	0m22.117s
user	0m0.728s
sys	0m35.328s
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/ip_tunnels.h

@@ -258,7 +258,8 @@ int ip_tunnel_get_iflink(const struct net_device *dev);
 int ip_tunnel_init_net(struct net *net, unsigned int ip_tnl_net_id,
 		       struct rtnl_link_ops *ops, char *devname);
 
-void ip_tunnel_delete_net(struct ip_tunnel_net *itn, struct rtnl_link_ops *ops);
+void ip_tunnel_delete_nets(struct list_head *list_net, unsigned int id,
+			   struct rtnl_link_ops *ops);
 
 void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
 		    const struct iphdr *tnl_params, const u8 protocol);

include/net/netns/ipv6.h

@@ -89,6 +89,11 @@ struct netns_ipv6 {
 	atomic_t		fib6_sernum;
 	struct seg6_pernet_data *seg6_data;
 	struct fib_notifier_ops	*notifier_ops;
+	struct {
+		struct hlist_head head;
+		spinlock_t	lock;
+		u32		seq;
+	} ip6addrlbl_table;
 };
 
 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)

lib/kobject_uevent.c

@@ -294,6 +294,55 @@ static void cleanup_uevent_env(struct subprocess_info *info)
 }
 #endif
 
+static int kobject_uevent_net_broadcast(struct kobject *kobj,
+					struct kobj_uevent_env *env,
+					const char *action_string,
+					const char *devpath)
+{
+	int retval = 0;
+#if defined(CONFIG_NET)
+	struct sk_buff *skb = NULL;
+	struct uevent_sock *ue_sk;
+
+	/* send netlink message */
+	list_for_each_entry(ue_sk, &uevent_sock_list, list) {
+		struct sock *uevent_sock = ue_sk->sk;
+
+		if (!netlink_has_listeners(uevent_sock, 1))
+			continue;
+
+		if (!skb) {
+			/* allocate message with the maximum possible size */
+			size_t len = strlen(action_string) + strlen(devpath) + 2;
+			char *scratch;
+
+			retval = -ENOMEM;
+			skb = alloc_skb(len + env->buflen, GFP_KERNEL);
+			if (!skb)
+				continue;
+
+			/* add header */
+			scratch = skb_put(skb, len);
+			sprintf(scratch, "%s@%s", action_string, devpath);
+
+			skb_put_data(skb, env->buf, env->buflen);
+
+			NETLINK_CB(skb).dst_group = 1;
+		}
+
+		retval = netlink_broadcast_filtered(uevent_sock, skb_get(skb),
+						    0, 1, GFP_KERNEL,
+						    kobj_bcast_filter,
+						    kobj);
+		/* ENOBUFS should be handled in userspace */
+		if (retval == -ENOBUFS || retval == -ESRCH)
+			retval = 0;
+	}
+	consume_skb(skb);
+#endif
+	return retval;
+}
+
 /**
  * kobject_uevent_env - send an uevent with environmental data
  *
@@ -316,9 +365,6 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
 	const struct kset_uevent_ops *uevent_ops;
 	int i = 0;
 	int retval = 0;
-#ifdef CONFIG_NET
-	struct uevent_sock *ue_sk;
-#endif
 
 	pr_debug("kobject: '%s' (%p): %s\n",
 		 kobject_name(kobj), kobj, __func__);
@@ -427,46 +473,8 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
 		mutex_unlock(&uevent_sock_mutex);
 		goto exit;
 	}
-
-#if defined(CONFIG_NET)
-	/* send netlink message */
-	list_for_each_entry(ue_sk, &uevent_sock_list, list) {
-		struct sock *uevent_sock = ue_sk->sk;
-		struct sk_buff *skb;
-		size_t len;
-
-		if (!netlink_has_listeners(uevent_sock, 1))
-			continue;
-
-		/* allocate message with the maximum possible size */
-		len = strlen(action_string) + strlen(devpath) + 2;
-		skb = alloc_skb(len + env->buflen, GFP_KERNEL);
-		if (skb) {
-			char *scratch;
-
-			/* add header */
-			scratch = skb_put(skb, len);
-			sprintf(scratch, "%s@%s", action_string, devpath);
-
-			/* copy keys to our continuous event payload buffer */
-			for (i = 0; i < env->envp_idx; i++) {
-				len = strlen(env->envp[i]) + 1;
-				scratch = skb_put(skb, len);
-				strcpy(scratch, env->envp[i]);
-			}
-
-			NETLINK_CB(skb).dst_group = 1;
-			retval = netlink_broadcast_filtered(uevent_sock, skb,
-							    0, 1, GFP_KERNEL,
-							    kobj_bcast_filter,
-							    kobj);
-			/* ENOBUFS should be handled in userspace */
-			if (retval == -ENOBUFS || retval == -ESRCH)
-				retval = 0;
-		} else
-			retval = -ENOMEM;
-	}
-#endif
+	retval = kobject_uevent_net_broadcast(kobj, env, action_string,
+					      devpath);
 	mutex_unlock(&uevent_sock_mutex);
 
 #ifdef CONFIG_UEVENT_HELPER

net/ipv4/ip_gre.c

@@ -1013,15 +1013,14 @@ static int __net_init ipgre_init_net(struct net *net)
 	return ip_tunnel_init_net(net, ipgre_net_id, &ipgre_link_ops, NULL);
 }
 
-static void __net_exit ipgre_exit_net(struct net *net)
+static void __net_exit ipgre_exit_batch_net(struct list_head *list_net)
 {
-	struct ip_tunnel_net *itn = net_generic(net, ipgre_net_id);
-	ip_tunnel_delete_net(itn, &ipgre_link_ops);
+	ip_tunnel_delete_nets(list_net, ipgre_net_id, &ipgre_link_ops);
 }
 
 static struct pernet_operations ipgre_net_ops = {
 	.init = ipgre_init_net,
-	.exit = ipgre_exit_net,
+	.exit_batch = ipgre_exit_batch_net,
 	.id   = &ipgre_net_id,
 	.size = sizeof(struct ip_tunnel_net),
 };
@@ -1540,15 +1539,14 @@ static int __net_init ipgre_tap_init_net(struct net *net)
 	return ip_tunnel_init_net(net, gre_tap_net_id, &ipgre_tap_ops, "gretap0");
 }
 
-static void __net_exit ipgre_tap_exit_net(struct net *net)
+static void __net_exit ipgre_tap_exit_batch_net(struct list_head *list_net)
 {
-	struct ip_tunnel_net *itn = net_generic(net, gre_tap_net_id);
-	ip_tunnel_delete_net(itn, &ipgre_tap_ops);
+	ip_tunnel_delete_nets(list_net, gre_tap_net_id, &ipgre_tap_ops);
 }
 
 static struct pernet_operations ipgre_tap_net_ops = {
 	.init = ipgre_tap_init_net,
-	.exit = ipgre_tap_exit_net,
+	.exit_batch = ipgre_tap_exit_batch_net,
 	.id   = &gre_tap_net_id,
 	.size = sizeof(struct ip_tunnel_net),
 };
@@ -1559,16 +1557,14 @@ static int __net_init erspan_init_net(struct net *net)
 				  &erspan_link_ops, "erspan0");
 }
 
-static void __net_exit erspan_exit_net(struct net *net)
+static void __net_exit erspan_exit_batch_net(struct list_head *net_list)
 {
-	struct ip_tunnel_net *itn = net_generic(net, erspan_net_id);
-
-	ip_tunnel_delete_net(itn, &erspan_link_ops);
+	ip_tunnel_delete_nets(net_list, erspan_net_id, &erspan_link_ops);
 }
 
 static struct pernet_operations erspan_net_ops = {
 	.init = erspan_init_net,
-	.exit = erspan_exit_net,
+	.exit_batch = erspan_exit_batch_net,
 	.id   = &erspan_net_id,
 	.size = sizeof(struct ip_tunnel_net),
 };

net/ipv4/ip_tunnel.c

@@ -1061,16 +1061,22 @@ static void ip_tunnel_destroy(struct ip_tunnel_net *itn, struct list_head *head,
 	}
 }
 
-void ip_tunnel_delete_net(struct ip_tunnel_net *itn, struct rtnl_link_ops *ops)
+void ip_tunnel_delete_nets(struct list_head *net_list, unsigned int id,
+			   struct rtnl_link_ops *ops)
 {
+	struct ip_tunnel_net *itn;
+	struct net *net;
 	LIST_HEAD(list);
 
 	rtnl_lock();
-	ip_tunnel_destroy(itn, &list, ops);
+	list_for_each_entry(net, net_list, exit_list) {
+		itn = net_generic(net, id);
+		ip_tunnel_destroy(itn, &list, ops);
+	}
 	unregister_netdevice_many(&list);
 	rtnl_unlock();
 }
-EXPORT_SYMBOL_GPL(ip_tunnel_delete_net);
+EXPORT_SYMBOL_GPL(ip_tunnel_delete_nets);
 
 int ip_tunnel_newlink(struct net_device *dev, struct nlattr *tb[],
 		      struct ip_tunnel_parm *p, __u32 fwmark)

net/ipv4/ip_vti.c

@@ -452,15 +452,14 @@ static int __net_init vti_init_net(struct net *net)
 	return 0;
 }
 
-static void __net_exit vti_exit_net(struct net *net)
+static void __net_exit vti_exit_batch_net(struct list_head *list_net)
 {
-	struct ip_tunnel_net *itn = net_generic(net, vti_net_id);
-	ip_tunnel_delete_net(itn, &vti_link_ops);
+	ip_tunnel_delete_nets(list_net, vti_net_id, &vti_link_ops);
 }
 
 static struct pernet_operations vti_net_ops = {
 	.init = vti_init_net,
-	.exit = vti_exit_net,
+	.exit_batch = vti_exit_batch_net,
 	.id   = &vti_net_id,
 	.size = sizeof(struct ip_tunnel_net),
 };

net/ipv4/ipip.c

@@ -634,15 +634,14 @@ static int __net_init ipip_init_net(struct net *net)
 	return ip_tunnel_init_net(net, ipip_net_id, &ipip_link_ops, "tunl0");
 }
 
-static void __net_exit ipip_exit_net(struct net *net)
+static void __net_exit ipip_exit_batch_net(struct list_head *list_net)
 {
-	struct ip_tunnel_net *itn = net_generic(net, ipip_net_id);
-	ip_tunnel_delete_net(itn, &ipip_link_ops);
+	ip_tunnel_delete_nets(list_net, ipip_net_id, &ipip_link_ops);
 }
 
 static struct pernet_operations ipip_net_ops = {
 	.init = ipip_init_net,
-	.exit = ipip_exit_net,
+	.exit_batch = ipip_exit_batch_net,
 	.id   = &ipip_net_id,
 	.size = sizeof(struct ip_tunnel_net),
 };

net/ipv4/tcp_metrics.c

@@ -892,10 +892,14 @@ static void tcp_metrics_flush_all(struct net *net)
 
 	for (row = 0; row < max_rows; row++, hb++) {
 		struct tcp_metrics_block __rcu **pp;
+		bool match;
+
 		spin_lock_bh(&tcp_metrics_lock);
 		pp = &hb->chain;
 		for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
-			if (net_eq(tm_net(tm), net)) {
+			match = net ? net_eq(tm_net(tm), net) :
+				!atomic_read(&tm_net(tm)->count);
+			if (match) {
 				*pp = tm->tcpm_next;
 				kfree_rcu(tm, rcu_head);
 			} else {
@@ -1018,14 +1022,14 @@ static int __net_init tcp_net_metrics_init(struct net *net)
 	return 0;
 }
 
-static void __net_exit tcp_net_metrics_exit(struct net *net)
+static void __net_exit tcp_net_metrics_exit_batch(struct list_head *net_exit_list)
 {
-	tcp_metrics_flush_all(net);
+	tcp_metrics_flush_all(NULL);
 }
 
 static __net_initdata struct pernet_operations tcp_net_metrics_ops = {
-	.init	=	tcp_net_metrics_init,
-	.exit	=	tcp_net_metrics_exit,
+	.init		=	tcp_net_metrics_init,
+	.exit_batch	=	tcp_net_metrics_exit_batch,
 };
 
 void __init tcp_metrics_init(void)

net/ipv6/addrlabel.c

@@ -30,7 +30,6 @@
  * Policy Table
  */
 struct ip6addrlbl_entry {
-	possible_net_t lbl_net;
 	struct in6_addr prefix;
 	int prefixlen;
 	int ifindex;
@@ -41,19 +40,6 @@ struct ip6addrlbl_entry {
 	struct rcu_head rcu;
 };
 
-static struct ip6addrlbl_table
-{
-	struct hlist_head head;
-	spinlock_t lock;
-	u32 seq;
-} ip6addrlbl_table;
-
-static inline
-struct net *ip6addrlbl_net(const struct ip6addrlbl_entry *lbl)
-{
-	return read_pnet(&lbl->lbl_net);
-}
-
 /*
  * Default policy table (RFC6724 + extensions)
  *
@@ -148,13 +134,10 @@ static inline void ip6addrlbl_put(struct ip6addrlbl_entry *p)
 }
 
 /* Find label */
-static bool __ip6addrlbl_match(struct net *net,
-			       const struct ip6addrlbl_entry *p,
+static bool __ip6addrlbl_match(const struct ip6addrlbl_entry *p,
 			       const struct in6_addr *addr,
 			       int addrtype, int ifindex)
 {
-	if (!net_eq(ip6addrlbl_net(p), net))
-		return false;
 	if (p->ifindex && p->ifindex != ifindex)
 		return false;
 	if (p->addrtype && p->addrtype != addrtype)
@@ -169,8 +152,9 @@ static struct ip6addrlbl_entry *__ipv6_addr_label(struct net *net,
 						  int type, int ifindex)
 {
 	struct ip6addrlbl_entry *p;
-	hlist_for_each_entry_rcu(p, &ip6addrlbl_table.head, list) {
-		if (__ip6addrlbl_match(net, p, addr, type, ifindex))
+
+	hlist_for_each_entry_rcu(p, &net->ipv6.ip6addrlbl_table.head, list) {
+		if (__ip6addrlbl_match(p, addr, type, ifindex))
 			return p;
 	}
 	return NULL;
@@ -196,8 +180,7 @@ u32 ipv6_addr_label(struct net *net,
 }
 
 /* allocate one entry */
-static struct ip6addrlbl_entry *ip6addrlbl_alloc(struct net *net,
-						 const struct in6_addr *prefix,
+static struct ip6addrlbl_entry *ip6addrlbl_alloc(const struct in6_addr *prefix,
 						 int prefixlen, int ifindex,
 						 u32 label)
 {
@@ -236,24 +219,23 @@ static struct ip6addrlbl_entry *ip6addrlbl_alloc(struct net *net,
 	newp->addrtype = addrtype;
 	newp->label = label;
 	INIT_HLIST_NODE(&newp->list);
-	write_pnet(&newp->lbl_net, net);
 	refcount_set(&newp->refcnt, 1);
 	return newp;
 }
 
 /* add a label */
-static int __ip6addrlbl_add(struct ip6addrlbl_entry *newp, int replace)
+static int __ip6addrlbl_add(struct net *net, struct ip6addrlbl_entry *newp,
+			    int replace)
 {
-	struct hlist_node *n;
 	struct ip6addrlbl_entry *last = NULL, *p = NULL;
+	struct hlist_node *n;
 	int ret = 0;
 
 	ADDRLABEL(KERN_DEBUG "%s(newp=%p, replace=%d)\n", __func__, newp,
 		  replace);
 
-	hlist_for_each_entry_safe(p, n,	&ip6addrlbl_table.head, list) {
+	hlist_for_each_entry_safe(p, n,	&net->ipv6.ip6addrlbl_table.head, list) {
 		if (p->prefixlen == newp->prefixlen &&
-		    net_eq(ip6addrlbl_net(p), ip6addrlbl_net(newp)) &&
 		    p->ifindex == newp->ifindex &&
 		    ipv6_addr_equal(&p->prefix, &newp->prefix)) {
 			if (!replace) {
@@ -273,10 +255,10 @@ static int __ip6addrlbl_add(struct ip6addrlbl_entry *newp, int replace)
 	if (last)
 		hlist_add_behind_rcu(&newp->list, &last->list);
 	else
-		hlist_add_head_rcu(&newp->list, &ip6addrlbl_table.head);
+		hlist_add_head_rcu(&newp->list, &net->ipv6.ip6addrlbl_table.head);
 out:
 	if (!ret)
-		ip6addrlbl_table.seq++;
+		net->ipv6.ip6addrlbl_table.seq++;
 	return ret;
 }
 
@@ -292,12 +274,12 @@ static int ip6addrlbl_add(struct net *net,
 		  __func__, prefix, prefixlen, ifindex, (unsigned int)label,
 		  replace);
 
-	newp = ip6addrlbl_alloc(net, prefix, prefixlen, ifindex, label);
+	newp = ip6addrlbl_alloc(prefix, prefixlen, ifindex, label);
 	if (IS_ERR(newp))
 		return PTR_ERR(newp);
-	spin_lock(&ip6addrlbl_table.lock);
-	ret = __ip6addrlbl_add(newp, replace);
-	spin_unlock(&ip6addrlbl_table.lock);
+	spin_lock(&net->ipv6.ip6addrlbl_table.lock);
+	ret = __ip6addrlbl_add(net, newp, replace);
+	spin_unlock(&net->ipv6.ip6addrlbl_table.lock);
 	if (ret)
 		ip6addrlbl_free(newp);
 	return ret;
@@ -315,9 +297,8 @@ static int __ip6addrlbl_del(struct net *net,
 	ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d)\n",
 		  __func__, prefix, prefixlen, ifindex);
 
-	hlist_for_each_entry_safe(p, n, &ip6addrlbl_table.head, list) {
+	hlist_for_each_entry_safe(p, n, &net->ipv6.ip6addrlbl_table.head, list) {
 		if (p->prefixlen == prefixlen &&
-		    net_eq(ip6addrlbl_net(p), net) &&
 		    p->ifindex == ifindex &&
 		    ipv6_addr_equal(&p->prefix, prefix)) {
 			hlist_del_rcu(&p->list);
@@ -340,9 +321,9 @@ static int ip6addrlbl_del(struct net *net,
 		  __func__, prefix, prefixlen, ifindex);
 
 	ipv6_addr_prefix(&prefix_buf, prefix, prefixlen);
-	spin_lock(&ip6addrlbl_table.lock);
+	spin_lock(&net->ipv6.ip6addrlbl_table.lock);
 	ret = __ip6addrlbl_del(net, &prefix_buf, prefixlen, ifindex);
-	spin_unlock(&ip6addrlbl_table.lock);
+	spin_unlock(&net->ipv6.ip6addrlbl_table.lock);
 	return ret;
 }
 
@@ -354,6 +335,9 @@ static int __net_init ip6addrlbl_net_init(struct net *net)
 
 	ADDRLABEL(KERN_DEBUG "%s\n", __func__);
 
+	spin_lock_init(&net->ipv6.ip6addrlbl_table.lock);
+	INIT_HLIST_HEAD(&net->ipv6.ip6addrlbl_table.head);
+
 	for (i = 0; i < ARRAY_SIZE(ip6addrlbl_init_table); i++) {
 		int ret = ip6addrlbl_add(net,
 					 ip6addrlbl_init_table[i].prefix,
@@ -373,14 +357,12 @@ static void __net_exit ip6addrlbl_net_exit(struct net *net)
 	struct hlist_node *n;
 
 	/* Remove all labels belonging to the exiting net */
-	spin_lock(&ip6addrlbl_table.lock);
-	hlist_for_each_entry_safe(p, n, &ip6addrlbl_table.head, list) {
-		if (net_eq(ip6addrlbl_net(p), net)) {
-			hlist_del_rcu(&p->list);
-			ip6addrlbl_put(p);
-		}
+	spin_lock(&net->ipv6.ip6addrlbl_table.lock);
+	hlist_for_each_entry_safe(p, n, &net->ipv6.ip6addrlbl_table.head, list) {
+		hlist_del_rcu(&p->list);
+		ip6addrlbl_put(p);
 	}
-	spin_unlock(&ip6addrlbl_table.lock);
+	spin_unlock(&net->ipv6.ip6addrlbl_table.lock);
 }
 
 static struct pernet_operations ipv6_addr_label_ops = {
@@ -390,8 +372,6 @@ static struct pernet_operations ipv6_addr_label_ops = {
 
 int __init ipv6_addr_label_init(void)
 {
-	spin_lock_init(&ip6addrlbl_table.lock);
-
 	return register_pernet_subsys(&ipv6_addr_label_ops);
 }
 
@@ -510,11 +490,10 @@ static int ip6addrlbl_dump(struct sk_buff *skb, struct netlink_callback *cb)
 	int err;
 
 	rcu_read_lock();
-	hlist_for_each_entry_rcu(p, &ip6addrlbl_table.head, list) {
-		if (idx >= s_idx &&
-		    net_eq(ip6addrlbl_net(p), net)) {
+	hlist_for_each_entry_rcu(p, &net->ipv6.ip6addrlbl_table.head, list) {
+		if (idx >= s_idx) {
 			err = ip6addrlbl_fill(skb, p,
-					      ip6addrlbl_table.seq,
+					      net->ipv6.ip6addrlbl_table.seq,
 					      NETLINK_CB(cb->skb).portid,
 					      cb->nlh->nlmsg_seq,
 					      RTM_NEWADDRLABEL,
@@ -571,7 +550,7 @@ static int ip6addrlbl_get(struct sk_buff *in_skb, struct nlmsghdr *nlh,
 	p = __ipv6_addr_label(net, addr, ipv6_addr_type(addr), ifal->ifal_index);
 	if (p && !ip6addrlbl_hold(p))
 		p = NULL;
-	lseq = ip6addrlbl_table.seq;
+	lseq = net->ipv6.ip6addrlbl_table.seq;
 	rcu_read_unlock();
 
 	if (!p) {

net/ipv6/ip6_gre.c

@@ -1155,19 +1155,21 @@ static int __net_init ip6gre_init_net(struct net *net)
 	return err;
 }
 
-static void __net_exit ip6gre_exit_net(struct net *net)
+static void __net_exit ip6gre_exit_batch_net(struct list_head *net_list)
 {
+	struct net *net;
 	LIST_HEAD(list);
 
 	rtnl_lock();
-	ip6gre_destroy_tunnels(net, &list);
+	list_for_each_entry(net, net_list, exit_list)
+		ip6gre_destroy_tunnels(net, &list);
 	unregister_netdevice_many(&list);
 	rtnl_unlock();
 }
 
 static struct pernet_operations ip6gre_net_ops = {
 	.init = ip6gre_init_net,
-	.exit = ip6gre_exit_net,
+	.exit_batch = ip6gre_exit_batch_net,
 	.id   = &ip6gre_net_id,
 	.size = sizeof(struct ip6gre_net),
 };

net/ipv6/ip6_tunnel.c

@@ -2167,17 +2167,16 @@ static struct xfrm6_tunnel ip6ip6_handler __read_mostly = {
 	.priority	=	1,
 };
 
-static void __net_exit ip6_tnl_destroy_tunnels(struct net *net)
+static void __net_exit ip6_tnl_destroy_tunnels(struct net *net, struct list_head *list)
 {
 	struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);
 	struct net_device *dev, *aux;
 	int h;
 	struct ip6_tnl *t;
-	LIST_HEAD(list);
 
 	for_each_netdev_safe(net, dev, aux)
 		if (dev->rtnl_link_ops == &ip6_link_ops)
-			unregister_netdevice_queue(dev, &list);
+			unregister_netdevice_queue(dev, list);
 
 	for (h = 0; h < IP6_TUNNEL_HASH_SIZE; h++) {
 		t = rtnl_dereference(ip6n->tnls_r_l[h]);
@@ -2186,12 +2185,10 @@ static void __net_exit ip6_tnl_destroy_tunnels(struct net *net)
 			 * been added to the list by the previous loop.
 			 */
 			if (!net_eq(dev_net(t->dev), net))
-				unregister_netdevice_queue(t->dev, &list);
+				unregister_netdevice_queue(t->dev, list);
 			t = rtnl_dereference(t->next);
 		}
 	}
-
-	unregister_netdevice_many(&list);
 }
 
 static int __net_init ip6_tnl_init_net(struct net *net)
@@ -2235,16 +2232,21 @@ static int __net_init ip6_tnl_init_net(struct net *net)
 	return err;
 }
 
-static void __net_exit ip6_tnl_exit_net(struct net *net)
+static void __net_exit ip6_tnl_exit_batch_net(struct list_head *net_list)
 {
+	struct net *net;
+	LIST_HEAD(list);
+
 	rtnl_lock();
-	ip6_tnl_destroy_tunnels(net);
+	list_for_each_entry(net, net_list, exit_list)
+		ip6_tnl_destroy_tunnels(net, &list);
+	unregister_netdevice_many(&list);
 	rtnl_unlock();
 }
 
 static struct pernet_operations ip6_tnl_net_ops = {
 	.init = ip6_tnl_init_net,
-	.exit = ip6_tnl_exit_net,
+	.exit_batch = ip6_tnl_exit_batch_net,
 	.id   = &ip6_tnl_net_id,
 	.size = sizeof(struct ip6_tnl_net),
 };

net/ipv6/ip6_vti.c

@@ -1052,23 +1052,22 @@ static struct rtnl_link_ops vti6_link_ops __read_mostly = {
 	.get_link_net	= ip6_tnl_get_link_net,
 };
 
-static void __net_exit vti6_destroy_tunnels(struct vti6_net *ip6n)
+static void __net_exit vti6_destroy_tunnels(struct vti6_net *ip6n,
+					    struct list_head *list)
 {
 	int h;
 	struct ip6_tnl *t;
-	LIST_HEAD(list);
 
 	for (h = 0; h < IP6_VTI_HASH_SIZE; h++) {
 		t = rtnl_dereference(ip6n->tnls_r_l[h]);
 		while (t) {
-			unregister_netdevice_queue(t->dev, &list);
+			unregister_netdevice_queue(t->dev, list);
 			t = rtnl_dereference(t->next);
 		}
 	}
 
 	t = rtnl_dereference(ip6n->tnls_wc[0]);
-	unregister_netdevice_queue(t->dev, &list);
-	unregister_netdevice_many(&list);
+	unregister_netdevice_queue(t->dev, list);
 }
 
 static int __net_init vti6_init_net(struct net *net)
@@ -1108,18 +1107,24 @@ static int __net_init vti6_init_net(struct net *net)
 	return err;
 }
 
-static void __net_exit vti6_exit_net(struct net *net)
+static void __net_exit vti6_exit_batch_net(struct list_head *net_list)
 {
-	struct vti6_net *ip6n = net_generic(net, vti6_net_id);
+	struct vti6_net *ip6n;
+	struct net *net;
+	LIST_HEAD(list);
 
 	rtnl_lock();
-	vti6_destroy_tunnels(ip6n);
+	list_for_each_entry(net, net_list, exit_list) {
+		ip6n = net_generic(net, vti6_net_id);
+		vti6_destroy_tunnels(ip6n, &list);
+	}
+	unregister_netdevice_many(&list);
 	rtnl_unlock();
 }
 
 static struct pernet_operations vti6_net_ops = {
 	.init = vti6_init_net,
-	.exit = vti6_exit_net,
+	.exit_batch = vti6_exit_batch_net,
 	.id   = &vti6_net_id,
 	.size = sizeof(struct vti6_net),
 };

net/ipv6/sit.c

@@ -1848,19 +1848,22 @@ static int __net_init sit_init_net(struct net *net)
 	return err;
 }
 
-static void __net_exit sit_exit_net(struct net *net)
+static void __net_exit sit_exit_batch_net(struct list_head *net_list)
 {
 	LIST_HEAD(list);
+	struct net *net;
 
 	rtnl_lock();
-	sit_destroy_tunnels(net, &list);
+	list_for_each_entry(net, net_list, exit_list)
+		sit_destroy_tunnels(net, &list);
+
 	unregister_netdevice_many(&list);
 	rtnl_unlock();
 }
 
 static struct pernet_operations sit_net_ops = {
 	.init = sit_init_net,
-	.exit = sit_exit_net,
+	.exit_batch = sit_exit_batch_net,
 	.id   = &sit_net_id,
 	.size = sizeof(struct sit_net),
 };