net: Add a second bind table hashed by port and address

We currently have one tcp bind table (bhash) which hashes by port
number only. In the socket bind path, we check for bind conflicts by
traversing the specified port's inet_bind2_bucket while holding the
bucket's spinlock (see inet_csk_get_port() and inet_csk_bind_conflict()).

In instances where there are tons of sockets hashed to the same port
at different addresses, checking for a bind conflict is time-intensive
and can cause softirq cpu lockups, as well as stops new tcp connections
since __inet_inherit_port() also contests for the spinlock.

This patch proposes adding a second bind table, bhash2, that hashes by
port and ip address. Searching the bhash2 table leads to significantly
faster conflict resolution and less time holding the spinlock.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

include/net/inet_connection_sock.h

@@ -25,6 +25,7 @@
 #undef INET_CSK_CLEAR_TIMERS
 
 struct inet_bind_bucket;
+struct inet_bind2_bucket;
 struct tcp_congestion_ops;
 
 /*
@@ -57,6 +58,7 @@ struct inet_connection_sock_af_ops {
  *
  * @icsk_accept_queue:	   FIFO of established children
  * @icsk_bind_hash:	   Bind node
+ * @icsk_bind2_hash:	   Bind node in the bhash2 table
  * @icsk_timeout:	   Timeout
  * @icsk_retransmit_timer: Resend (no ack)
  * @icsk_rto:		   Retransmit timeout
@@ -83,6 +85,7 @@ struct inet_connection_sock {
 	struct inet_sock	  icsk_inet;
 	struct request_sock_queue icsk_accept_queue;
 	struct inet_bind_bucket	  *icsk_bind_hash;
+	struct inet_bind2_bucket  *icsk_bind2_hash;
 	unsigned long		  icsk_timeout;
  	struct timer_list	  icsk_retransmit_timer;
  	struct timer_list	  icsk_delack_timer;

include/net/inet_hashtables.h

@@ -90,11 +90,32 @@ struct inet_bind_bucket {
 	struct hlist_head	owners;
 };
 
+struct inet_bind2_bucket {
+	possible_net_t		ib_net;
+	int			l3mdev;
+	unsigned short		port;
+	union {
+#if IS_ENABLED(CONFIG_IPV6)
+		struct in6_addr		v6_rcv_saddr;
+#endif
+		__be32			rcv_saddr;
+	};
+	/* Node in the inet2_bind_hashbucket chain */
+	struct hlist_node	node;
+	/* List of sockets hashed to this bucket */
+	struct hlist_head	owners;
+};
+
 static inline struct net *ib_net(struct inet_bind_bucket *ib)
 {
 	return read_pnet(&ib->ib_net);
 }
 
+static inline struct net *ib2_net(struct inet_bind2_bucket *ib)
+{
+	return read_pnet(&ib->ib_net);
+}
+
 #define inet_bind_bucket_for_each(tb, head) \
 	hlist_for_each_entry(tb, head, node)
 
@@ -103,6 +124,15 @@ struct inet_bind_hashbucket {
 	struct hlist_head	chain;
 };
 
+/* This is synchronized using the inet_bind_hashbucket's spinlock.
+ * Instead of having separate spinlocks, the inet_bind2_hashbucket can share
+ * the inet_bind_hashbucket's given that in every case where the bhash2 table
+ * is useful, a lookup in the bhash table also occurs.
+ */
+struct inet_bind2_hashbucket {
+	struct hlist_head	chain;
+};
+
 /* Sockets can be hashed in established or listening table.
  * We must use different 'nulls' end-of-chain value for all hash buckets :
  * A socket might transition from ESTABLISH to LISTEN state without
@@ -134,6 +164,12 @@ struct inet_hashinfo {
 	 */
 	struct kmem_cache		*bind_bucket_cachep;
 	struct inet_bind_hashbucket	*bhash;
+	/* The 2nd binding table hashed by port and address.
+	 * This is used primarily for expediting the resolution of bind
+	 * conflicts.
+	 */
+	struct kmem_cache		*bind2_bucket_cachep;
+	struct inet_bind2_hashbucket	*bhash2;
 	unsigned int			bhash_size;
 
 	/* The 2nd listener table hashed by local port and address */
@@ -193,6 +229,36 @@ inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net,
 void inet_bind_bucket_destroy(struct kmem_cache *cachep,
 			      struct inet_bind_bucket *tb);
 
+static inline bool check_bind_bucket_match(struct inet_bind_bucket *tb,
+					   struct net *net,
+					   const unsigned short port,
+					   int l3mdev)
+{
+	return net_eq(ib_net(tb), net) && tb->port == port &&
+		tb->l3mdev == l3mdev;
+}
+
+struct inet_bind2_bucket *
+inet_bind2_bucket_create(struct kmem_cache *cachep, struct net *net,
+			 struct inet_bind2_hashbucket *head,
+			 const unsigned short port, int l3mdev,
+			 const struct sock *sk);
+
+void inet_bind2_bucket_destroy(struct kmem_cache *cachep,
+			       struct inet_bind2_bucket *tb);
+
+struct inet_bind2_bucket *
+inet_bind2_bucket_find(struct inet_hashinfo *hinfo, struct net *net,
+		       const unsigned short port, int l3mdev,
+		       struct sock *sk,
+		       struct inet_bind2_hashbucket **head);
+
+bool check_bind2_bucket_match_nulladdr(struct inet_bind2_bucket *tb,
+				       struct net *net,
+				       const unsigned short port,
+				       int l3mdev,
+				       const struct sock *sk);
+
 static inline u32 inet_bhashfn(const struct net *net, const __u16 lport,
 			       const u32 bhash_size)
 {
@@ -200,7 +266,7 @@ static inline u32 inet_bhashfn(const struct net *net, const __u16 lport,
 }
 
 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
-		    const unsigned short snum);
+		    struct inet_bind2_bucket *tb2, const unsigned short snum);
 
 /* Caller must disable local BH processing. */
 int __inet_inherit_port(const struct sock *sk, struct sock *child);

include/net/sock.h

@@ -348,6 +348,7 @@ struct sk_filter;
   *	@sk_txtime_report_errors: set report errors mode for SO_TXTIME
   *	@sk_txtime_unused: unused txtime flags
   *	@ns_tracker: tracker for netns reference
+  *	@sk_bind2_node: bind node in the bhash2 table
   */
 struct sock {
 	/*
@@ -537,6 +538,7 @@ struct sock {
 #endif
 	struct rcu_head		sk_rcu;
 	netns_tracker		ns_tracker;
+	struct hlist_node	sk_bind2_node;
 };
 
 enum sk_pacing {
@@ -817,6 +819,16 @@ static inline void sk_add_bind_node(struct sock *sk,
 	hlist_add_head(&sk->sk_bind_node, list);
 }
 
+static inline void __sk_del_bind2_node(struct sock *sk)
+{
+	__hlist_del(&sk->sk_bind2_node);
+}
+
+static inline void sk_add_bind2_node(struct sock *sk, struct hlist_head *list)
+{
+	hlist_add_head(&sk->sk_bind2_node, list);
+}
+
 #define sk_for_each(__sk, list) \
 	hlist_for_each_entry(__sk, list, sk_node)
 #define sk_for_each_rcu(__sk, list) \
@@ -834,6 +846,8 @@ static inline void sk_add_bind_node(struct sock *sk,
 	hlist_for_each_entry_safe(__sk, tmp, list, sk_node)
 #define sk_for_each_bound(__sk, list) \
 	hlist_for_each_entry(__sk, list, sk_bind_node)
+#define sk_for_each_bound_bhash2(__sk, list) \
+	hlist_for_each_entry(__sk, list, sk_bind2_node)
 
 /**
  * sk_for_each_entry_offset_rcu - iterate over a list at a given struct offset

net/dccp/proto.c

@@ -1120,6 +1120,12 @@ static int __init dccp_init(void)
 				  SLAB_HWCACHE_ALIGN | SLAB_ACCOUNT, NULL);
 	if (!dccp_hashinfo.bind_bucket_cachep)
 		goto out_free_hashinfo2;
+	dccp_hashinfo.bind2_bucket_cachep =
+		kmem_cache_create("dccp_bind2_bucket",
+				  sizeof(struct inet_bind2_bucket), 0,
+				  SLAB_HWCACHE_ALIGN | SLAB_ACCOUNT, NULL);
+	if (!dccp_hashinfo.bind2_bucket_cachep)
+		goto out_free_bind_bucket_cachep;
 
 	/*
 	 * Size and allocate the main established and bind bucket
@@ -1150,7 +1156,7 @@ static int __init dccp_init(void)
 
 	if (!dccp_hashinfo.ehash) {
 		DCCP_CRIT("Failed to allocate DCCP established hash table");
-		goto out_free_bind_bucket_cachep;
+		goto out_free_bind2_bucket_cachep;
 	}
 
 	for (i = 0; i <= dccp_hashinfo.ehash_mask; i++)
@@ -1176,14 +1182,23 @@ static int __init dccp_init(void)
 		goto out_free_dccp_locks;
 	}
 
+	dccp_hashinfo.bhash2 = (struct inet_bind2_hashbucket *)
+		__get_free_pages(GFP_ATOMIC | __GFP_NOWARN, bhash_order);
+
+	if (!dccp_hashinfo.bhash2) {
+		DCCP_CRIT("Failed to allocate DCCP bind2 hash table");
+		goto out_free_dccp_bhash;
+	}
+
 	for (i = 0; i < dccp_hashinfo.bhash_size; i++) {
 		spin_lock_init(&dccp_hashinfo.bhash[i].lock);
 		INIT_HLIST_HEAD(&dccp_hashinfo.bhash[i].chain);
+		INIT_HLIST_HEAD(&dccp_hashinfo.bhash2[i].chain);
 	}
 
 	rc = dccp_mib_init();
 	if (rc)
-		goto out_free_dccp_bhash;
+		goto out_free_dccp_bhash2;
 
 	rc = dccp_ackvec_init();
 	if (rc)
@@ -1207,30 +1222,38 @@ static int __init dccp_init(void)
 	dccp_ackvec_exit();
 out_free_dccp_mib:
 	dccp_mib_exit();
+out_free_dccp_bhash2:
+	free_pages((unsigned long)dccp_hashinfo.bhash2, bhash_order);
 out_free_dccp_bhash:
 	free_pages((unsigned long)dccp_hashinfo.bhash, bhash_order);
 out_free_dccp_locks:
 	inet_ehash_locks_free(&dccp_hashinfo);
 out_free_dccp_ehash:
 	free_pages((unsigned long)dccp_hashinfo.ehash, ehash_order);
+out_free_bind2_bucket_cachep:
+	kmem_cache_destroy(dccp_hashinfo.bind2_bucket_cachep);
 out_free_bind_bucket_cachep:
 	kmem_cache_destroy(dccp_hashinfo.bind_bucket_cachep);
 out_free_hashinfo2:
 	inet_hashinfo2_free_mod(&dccp_hashinfo);
 out_fail:
 	dccp_hashinfo.bhash = NULL;
+	dccp_hashinfo.bhash2 = NULL;
 	dccp_hashinfo.ehash = NULL;
 	dccp_hashinfo.bind_bucket_cachep = NULL;
+	dccp_hashinfo.bind2_bucket_cachep = NULL;
 	return rc;
 }
 
 static void __exit dccp_fini(void)
 {
+	int bhash_order = get_order(dccp_hashinfo.bhash_size *
+				    sizeof(struct inet_bind_hashbucket));
+
 	ccid_cleanup_builtins();
 	dccp_mib_exit();
-	free_pages((unsigned long)dccp_hashinfo.bhash,
-		   get_order(dccp_hashinfo.bhash_size *
-			     sizeof(struct inet_bind_hashbucket)));
+	free_pages((unsigned long)dccp_hashinfo.bhash, bhash_order);
+	free_pages((unsigned long)dccp_hashinfo.bhash2, bhash_order);
 	free_pages((unsigned long)dccp_hashinfo.ehash,
 		   get_order((dccp_hashinfo.ehash_mask + 1) *
 			     sizeof(struct inet_ehash_bucket)));

net/ipv4/inet_hashtables.c

@@ -81,6 +81,41 @@ struct inet_bind_bucket *inet_bind_bucket_create(struct kmem_cache *cachep,
 	return tb;
 }
 
+struct inet_bind2_bucket *inet_bind2_bucket_create(struct kmem_cache *cachep,
+						   struct net *net,
+						   struct inet_bind2_hashbucket *head,
+						   const unsigned short port,
+						   int l3mdev,
+						   const struct sock *sk)
+{
+	struct inet_bind2_bucket *tb = kmem_cache_alloc(cachep, GFP_ATOMIC);
+
+	if (tb) {
+		write_pnet(&tb->ib_net, net);
+		tb->l3mdev    = l3mdev;
+		tb->port      = port;
+#if IS_ENABLED(CONFIG_IPV6)
+		if (sk->sk_family == AF_INET6)
+			tb->v6_rcv_saddr = sk->sk_v6_rcv_saddr;
+		else
+#endif
+			tb->rcv_saddr = sk->sk_rcv_saddr;
+		INIT_HLIST_HEAD(&tb->owners);
+		hlist_add_head(&tb->node, &head->chain);
+	}
+	return tb;
+}
+
+static bool bind2_bucket_addr_match(struct inet_bind2_bucket *tb2, struct sock *sk)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+	if (sk->sk_family == AF_INET6)
+		return ipv6_addr_equal(&tb2->v6_rcv_saddr,
+				       &sk->sk_v6_rcv_saddr);
+#endif
+	return tb2->rcv_saddr == sk->sk_rcv_saddr;
+}
+
 /*
  * Caller must hold hashbucket lock for this tb with local BH disabled
  */
@@ -92,12 +127,25 @@ void inet_bind_bucket_destroy(struct kmem_cache *cachep, struct inet_bind_bucket
 	}
 }
 
+/* Caller must hold the lock for the corresponding hashbucket in the bhash table
+ * with local BH disabled
+ */
+void inet_bind2_bucket_destroy(struct kmem_cache *cachep, struct inet_bind2_bucket *tb)
+{
+	if (hlist_empty(&tb->owners)) {
+		__hlist_del(&tb->node);
+		kmem_cache_free(cachep, tb);
+	}
+}
+
 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
-		    const unsigned short snum)
+		    struct inet_bind2_bucket *tb2, const unsigned short snum)
 {
 	inet_sk(sk)->inet_num = snum;
 	sk_add_bind_node(sk, &tb->owners);
 	inet_csk(sk)->icsk_bind_hash = tb;
+	sk_add_bind2_node(sk, &tb2->owners);
+	inet_csk(sk)->icsk_bind2_hash = tb2;
 }
 
 /*
@@ -109,6 +157,7 @@ static void __inet_put_port(struct sock *sk)
 	const int bhash = inet_bhashfn(sock_net(sk), inet_sk(sk)->inet_num,
 			hashinfo->bhash_size);
 	struct inet_bind_hashbucket *head = &hashinfo->bhash[bhash];
+	struct inet_bind2_bucket *tb2;
 	struct inet_bind_bucket *tb;
 
 	spin_lock(&head->lock);
@@ -117,6 +166,13 @@ static void __inet_put_port(struct sock *sk)
 	inet_csk(sk)->icsk_bind_hash = NULL;
 	inet_sk(sk)->inet_num = 0;
 	inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
+
+	if (inet_csk(sk)->icsk_bind2_hash) {
+		tb2 = inet_csk(sk)->icsk_bind2_hash;
+		__sk_del_bind2_node(sk);
+		inet_csk(sk)->icsk_bind2_hash = NULL;
+		inet_bind2_bucket_destroy(hashinfo->bind2_bucket_cachep, tb2);
+	}
 	spin_unlock(&head->lock);
 }
 
@@ -133,14 +189,19 @@ int __inet_inherit_port(const struct sock *sk, struct sock *child)
 	struct inet_hashinfo *table = sk->sk_prot->h.hashinfo;
 	unsigned short port = inet_sk(child)->inet_num;
 	const int bhash = inet_bhashfn(sock_net(sk), port,
-			table->bhash_size);
+				       table->bhash_size);
 	struct inet_bind_hashbucket *head = &table->bhash[bhash];
+	struct inet_bind2_hashbucket *head_bhash2;
+	bool created_inet_bind_bucket = false;
+	struct net *net = sock_net(sk);
+	struct inet_bind2_bucket *tb2;
 	struct inet_bind_bucket *tb;
 	int l3mdev;
 
 	spin_lock(&head->lock);
 	tb = inet_csk(sk)->icsk_bind_hash;
-	if (unlikely(!tb)) {
+	tb2 = inet_csk(sk)->icsk_bind2_hash;
+	if (unlikely(!tb || !tb2)) {
 		spin_unlock(&head->lock);
 		return -ENOENT;
 	}
@@ -153,25 +214,45 @@ int __inet_inherit_port(const struct sock *sk, struct sock *child)
 		 * as that of the child socket. We have to look up or
 		 * create a new bind bucket for the child here. */
 		inet_bind_bucket_for_each(tb, &head->chain) {
-			if (net_eq(ib_net(tb), sock_net(sk)) &&
-			    tb->l3mdev == l3mdev && tb->port == port)
+			if (check_bind_bucket_match(tb, net, port, l3mdev))
 				break;
 		}
 		if (!tb) {
 			tb = inet_bind_bucket_create(table->bind_bucket_cachep,
-						     sock_net(sk), head, port,
-						     l3mdev);
+						     net, head, port, l3mdev);
 			if (!tb) {
 				spin_unlock(&head->lock);
 				return -ENOMEM;
 			}
+			created_inet_bind_bucket = true;
 		}
 		inet_csk_update_fastreuse(tb, child);
+
+		goto bhash2_find;
+	} else if (!bind2_bucket_addr_match(tb2, child)) {
+		l3mdev = inet_sk_bound_l3mdev(sk);
+
+bhash2_find:
+		tb2 = inet_bind2_bucket_find(table, net, port, l3mdev, child,
+					     &head_bhash2);
+		if (!tb2) {
+			tb2 = inet_bind2_bucket_create(table->bind2_bucket_cachep,
+						       net, head_bhash2, port,
+						       l3mdev, child);
+			if (!tb2)
+				goto error;
+		}
 	}
-	inet_bind_hash(child, tb, port);
+	inet_bind_hash(child, tb, tb2, port);
 	spin_unlock(&head->lock);
 
 	return 0;
+
+error:
+	if (created_inet_bind_bucket)
+		inet_bind_bucket_destroy(table->bind_bucket_cachep, tb);
+	spin_unlock(&head->lock);
+	return -ENOMEM;
 }
 EXPORT_SYMBOL_GPL(__inet_inherit_port);
 
@@ -675,6 +756,76 @@ void inet_unhash(struct sock *sk)
 }
 EXPORT_SYMBOL_GPL(inet_unhash);
 
+static bool check_bind2_bucket_match(struct inet_bind2_bucket *tb,
+				     struct net *net, unsigned short port,
+				     int l3mdev, struct sock *sk)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+	if (sk->sk_family == AF_INET6)
+		return net_eq(ib2_net(tb), net) && tb->port == port &&
+			tb->l3mdev == l3mdev &&
+			ipv6_addr_equal(&tb->v6_rcv_saddr, &sk->sk_v6_rcv_saddr);
+	else
+#endif
+		return net_eq(ib2_net(tb), net) && tb->port == port &&
+			tb->l3mdev == l3mdev && tb->rcv_saddr == sk->sk_rcv_saddr;
+}
+
+bool check_bind2_bucket_match_nulladdr(struct inet_bind2_bucket *tb,
+				       struct net *net, const unsigned short port,
+				       int l3mdev, const struct sock *sk)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+	struct in6_addr nulladdr = {};
+
+	if (sk->sk_family == AF_INET6)
+		return net_eq(ib2_net(tb), net) && tb->port == port &&
+			tb->l3mdev == l3mdev &&
+			ipv6_addr_equal(&tb->v6_rcv_saddr, &nulladdr);
+	else
+#endif
+		return net_eq(ib2_net(tb), net) && tb->port == port &&
+			tb->l3mdev == l3mdev && tb->rcv_saddr == 0;
+}
+
+static struct inet_bind2_hashbucket *
+inet_bhashfn_portaddr(struct inet_hashinfo *hinfo, const struct sock *sk,
+		      const struct net *net, unsigned short port)
+{
+	u32 hash;
+
+#if IS_ENABLED(CONFIG_IPV6)
+	if (sk->sk_family == AF_INET6)
+		hash = ipv6_portaddr_hash(net, &sk->sk_v6_rcv_saddr, port);
+	else
+#endif
+		hash = ipv4_portaddr_hash(net, sk->sk_rcv_saddr, port);
+	return &hinfo->bhash2[hash & (hinfo->bhash_size - 1)];
+}
+
+/* This should only be called when the spinlock for the socket's corresponding
+ * bind_hashbucket is held
+ */
+struct inet_bind2_bucket *
+inet_bind2_bucket_find(struct inet_hashinfo *hinfo, struct net *net,
+		       const unsigned short port, int l3mdev, struct sock *sk,
+		       struct inet_bind2_hashbucket **head)
+{
+	struct inet_bind2_bucket *bhash2 = NULL;
+	struct inet_bind2_hashbucket *h;
+
+	h = inet_bhashfn_portaddr(hinfo, sk, net, port);
+	inet_bind_bucket_for_each(bhash2, &h->chain) {
+		if (check_bind2_bucket_match(bhash2, net, port, l3mdev, sk))
+			break;
+	}
+
+	if (head)
+		*head = h;
+
+	return bhash2;
+}
+
 /* RFC 6056 3.3.4.  Algorithm 4: Double-Hash Port Selection Algorithm
  * Note that we use 32bit integers (vs RFC 'short integers')
  * because 2^16 is not a multiple of num_ephemeral and this
@@ -695,10 +846,13 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 {
 	struct inet_hashinfo *hinfo = death_row->hashinfo;
 	struct inet_timewait_sock *tw = NULL;
+	struct inet_bind2_hashbucket *head2;
 	struct inet_bind_hashbucket *head;
 	int port = inet_sk(sk)->inet_num;
 	struct net *net = sock_net(sk);
+	struct inet_bind2_bucket *tb2;
 	struct inet_bind_bucket *tb;
+	bool tb_created = false;
 	u32 remaining, offset;
 	int ret, i, low, high;
 	int l3mdev;
@@ -755,8 +909,7 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 		 * the established check is already unique enough.
 		 */
 		inet_bind_bucket_for_each(tb, &head->chain) {
-			if (net_eq(ib_net(tb), net) && tb->l3mdev == l3mdev &&
-			    tb->port == port) {
+			if (check_bind_bucket_match(tb, net, port, l3mdev)) {
 				if (tb->fastreuse >= 0 ||
 				    tb->fastreuseport >= 0)
 					goto next_port;
@@ -774,6 +927,7 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 			spin_unlock_bh(&head->lock);
 			return -ENOMEM;
 		}
+		tb_created = true;
 		tb->fastreuse = -1;
 		tb->fastreuseport = -1;
 		goto ok;
@@ -789,6 +943,17 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 	return -EADDRNOTAVAIL;
 
 ok:
+	/* Find the corresponding tb2 bucket since we need to
+	 * add the socket to the bhash2 table as well
+	 */
+	tb2 = inet_bind2_bucket_find(hinfo, net, port, l3mdev, sk, &head2);
+	if (!tb2) {
+		tb2 = inet_bind2_bucket_create(hinfo->bind2_bucket_cachep, net,
+					       head2, port, l3mdev, sk);
+		if (!tb2)
+			goto error;
+	}
+
 	/* Here we want to add a little bit of randomness to the next source
 	 * port that will be chosen. We use a max() with a random here so that
 	 * on low contention the randomness is maximal and on high contention
@@ -798,7 +963,7 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 	WRITE_ONCE(table_perturb[index], READ_ONCE(table_perturb[index]) + i + 2);
 
 	/* Head lock still held and bh's disabled */
-	inet_bind_hash(sk, tb, port);
+	inet_bind_hash(sk, tb, tb2, port);
 	if (sk_unhashed(sk)) {
 		inet_sk(sk)->inet_sport = htons(port);
 		inet_ehash_nolisten(sk, (struct sock *)tw, NULL);
@@ -810,6 +975,12 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 		inet_twsk_deschedule_put(tw);
 	local_bh_enable();
 	return 0;
+
+error:
+	if (tb_created)
+		inet_bind_bucket_destroy(hinfo->bind_bucket_cachep, tb);
+	spin_unlock_bh(&head->lock);
+	return -ENOMEM;
 }
 
 /*

net/ipv4/tcp.c

@@ -4604,6 +4604,12 @@ void __init tcp_init(void)
 				  SLAB_HWCACHE_ALIGN | SLAB_PANIC |
 				  SLAB_ACCOUNT,
 				  NULL);
+	tcp_hashinfo.bind2_bucket_cachep =
+		kmem_cache_create("tcp_bind2_bucket",
+				  sizeof(struct inet_bind2_bucket), 0,
+				  SLAB_HWCACHE_ALIGN | SLAB_PANIC |
+				  SLAB_ACCOUNT,
+				  NULL);
 
 	/* Size and allocate the main established and bind bucket
 	 * hash tables.
@@ -4626,8 +4632,9 @@ void __init tcp_init(void)
 	if (inet_ehash_locks_alloc(&tcp_hashinfo))
 		panic("TCP: failed to alloc ehash_locks");
 	tcp_hashinfo.bhash =
-		alloc_large_system_hash("TCP bind",
-					sizeof(struct inet_bind_hashbucket),
+		alloc_large_system_hash("TCP bind bhash tables",
+					sizeof(struct inet_bind_hashbucket) +
+					sizeof(struct inet_bind2_hashbucket),
 					tcp_hashinfo.ehash_mask + 1,
 					17, /* one slot per 128 KB of memory */
 					0,
@@ -4636,9 +4643,12 @@ void __init tcp_init(void)
 					0,
 					64 * 1024);
 	tcp_hashinfo.bhash_size = 1U << tcp_hashinfo.bhash_size;
+	tcp_hashinfo.bhash2 =
+		(struct inet_bind2_hashbucket *)(tcp_hashinfo.bhash + tcp_hashinfo.bhash_size);
 	for (i = 0; i < tcp_hashinfo.bhash_size; i++) {
 		spin_lock_init(&tcp_hashinfo.bhash[i].lock);
 		INIT_HLIST_HEAD(&tcp_hashinfo.bhash[i].chain);
+		INIT_HLIST_HEAD(&tcp_hashinfo.bhash2[i].chain);
 	}