diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 97b91d62589d5f..770a63103c7a42 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -74,6 +74,9 @@ static __read_mostly struct kmem_cache *nf_conntrack_cachep;
 static DEFINE_SPINLOCK(nf_conntrack_locks_all_lock);
 static __read_mostly bool nf_conntrack_locks_all;
 
+/* serialize hash resizes and nf_ct_iterate_cleanup */
+static DEFINE_MUTEX(nf_conntrack_mutex);
+
 #define GC_SCAN_INTERVAL	(120u * HZ)
 #define GC_SCAN_MAX_DURATION	msecs_to_jiffies(10)
 
@@ -2263,28 +2266,31 @@ get_next_corpse(int (*iter)(struct nf_conn *i, void *data),
 	spinlock_t *lockp;
 
 	for (; *bucket < nf_conntrack_htable_size; (*bucket)++) {
+		struct hlist_nulls_head *hslot = &nf_conntrack_hash[*bucket];
+
+		if (hlist_nulls_empty(hslot))
+			continue;
+
 		lockp = &nf_conntrack_locks[*bucket % CONNTRACK_LOCKS];
 		local_bh_disable();
 		nf_conntrack_lock(lockp);
-		if (*bucket < nf_conntrack_htable_size) {
-			hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[*bucket], hnnode) {
-				if (NF_CT_DIRECTION(h) != IP_CT_DIR_REPLY)
-					continue;
-				/* All nf_conn objects are added to hash table twice, one
-				 * for original direction tuple, once for the reply tuple.
-				 *
-				 * Exception: In the IPS_NAT_CLASH case, only the reply
-				 * tuple is added (the original tuple already existed for
-				 * a different object).
-				 *
-				 * We only need to call the iterator once for each
-				 * conntrack, so we just use the 'reply' direction
-				 * tuple while iterating.
-				 */
-				ct = nf_ct_tuplehash_to_ctrack(h);
-				if (iter(ct, data))
-					goto found;
-			}
+		hlist_nulls_for_each_entry(h, n, hslot, hnnode) {
+			if (NF_CT_DIRECTION(h) != IP_CT_DIR_REPLY)
+				continue;
+			/* All nf_conn objects are added to hash table twice, one
+			 * for original direction tuple, once for the reply tuple.
+			 *
+			 * Exception: In the IPS_NAT_CLASH case, only the reply
+			 * tuple is added (the original tuple already existed for
+			 * a different object).
+			 *
+			 * We only need to call the iterator once for each
+			 * conntrack, so we just use the 'reply' direction
+			 * tuple while iterating.
+			 */
+			ct = nf_ct_tuplehash_to_ctrack(h);
+			if (iter(ct, data))
+				goto found;
 		}
 		spin_unlock(lockp);
 		local_bh_enable();
@@ -2302,26 +2308,20 @@ get_next_corpse(int (*iter)(struct nf_conn *i, void *data),
 static void nf_ct_iterate_cleanup(int (*iter)(struct nf_conn *i, void *data),
 				  void *data, u32 portid, int report)
 {
-	unsigned int bucket = 0, sequence;
+	unsigned int bucket = 0;
 	struct nf_conn *ct;
 
 	might_sleep();
 
-	for (;;) {
-		sequence = read_seqcount_begin(&nf_conntrack_generation);
-
-		while ((ct = get_next_corpse(iter, data, &bucket)) != NULL) {
-			/* Time to push up daises... */
+	mutex_lock(&nf_conntrack_mutex);
+	while ((ct = get_next_corpse(iter, data, &bucket)) != NULL) {
+		/* Time to push up daises... */
 
-			nf_ct_delete(ct, portid, report);
-			nf_ct_put(ct);
-			cond_resched();
-		}
-
-		if (!read_seqcount_retry(&nf_conntrack_generation, sequence))
-			break;
-		bucket = 0;
+		nf_ct_delete(ct, portid, report);
+		nf_ct_put(ct);
+		cond_resched();
 	}
+	mutex_unlock(&nf_conntrack_mutex);
 }
 
 struct iter_data {
@@ -2557,8 +2557,10 @@ int nf_conntrack_hash_resize(unsigned int hashsize)
 	if (!hash)
 		return -ENOMEM;
 
+	mutex_lock(&nf_conntrack_mutex);
 	old_size = nf_conntrack_htable_size;
 	if (old_size == hashsize) {
+		mutex_unlock(&nf_conntrack_mutex);
 		kvfree(hash);
 		return 0;
 	}
@@ -2598,6 +2600,8 @@ int nf_conntrack_hash_resize(unsigned int hashsize)
 	nf_conntrack_all_unlock();
 	local_bh_enable();
 
+	mutex_unlock(&nf_conntrack_mutex);
+
 	synchronize_net();
 	kvfree(old_hash);
 	return 0;