This is also simple, but introduces more changes, since 
then mem counter is altered in more places.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>

---
 include/net/inet_frag.h                 |    4 ++--
 include/net/ip.h                        |    2 +-
 include/net/ipv6.h                      |    2 +-
 net/ipv4/inet_fragment.c                |   21 +++++++++++----------
 net/ipv4/ip_fragment.c                  |   29 +++++++++++++++--------------
 net/ipv4/proc.c                         |    2 +-
 net/ipv6/netfilter/nf_conntrack_reasm.c |   14 +++++++-------
 net/ipv6/proc.c                         |    2 +-
 net/ipv6/reassembly.c                   |   28 +++++++++++++++-------------
 9 files changed, 54 insertions(+), 50 deletions(-)

diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h
index d36f3a6..6edce7b 100644
--- a/include/net/inet_frag.h
+++ b/include/net/inet_frag.h
@@ -3,6 +3,7 @@
 
 struct netns_frags {
 	int			nqueues;
+	atomic_t		mem;
 };
 
 struct inet_frag_queue {
@@ -38,7 +39,6 @@ struct inet_frags {
 	rwlock_t		lock;
 	u32			rnd;
 	int			qsize;
-	atomic_t		mem;
 	struct timer_list	secret_timer;
 	struct inet_frags_ctl	*ctl;
 
@@ -60,7 +60,7 @@ void inet_frags_init_net(struct netns_frags *nf);
 void inet_frag_kill(struct inet_frag_queue *q, struct inet_frags *f);
 void inet_frag_destroy(struct inet_frag_queue *q,
 				struct inet_frags *f, int *work);
-int inet_frag_evictor(struct inet_frags *f);
+int inet_frag_evictor(struct netns_frags *nf, struct inet_frags *f);
 struct inet_frag_queue *inet_frag_find(struct netns_frags *nf,
 		struct inet_frags *f, void *key, unsigned int hash);
 
diff --git a/include/net/ip.h b/include/net/ip.h
index 9ea1bc5..d41ff83 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -329,7 +329,7 @@ enum ip_defrag_users
 };
 
 int ip_defrag(struct sk_buff *skb, u32 user);
-int ip_frag_mem(void);
+int ip_frag_mem(struct net *net);
 int ip_frag_nqueues(struct net *net);
 
 /*
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index da1c089..fa80ea4 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -246,7 +246,7 @@ struct ipv6_txoptions *ipv6_fixup_options(struct ipv6_txoptions *opt_space,
 extern int ipv6_opt_accepted(struct sock *sk, struct sk_buff *skb);
 
 int ip6_frag_nqueues(struct net *net);
-int ip6_frag_mem(void);
+int ip6_frag_mem(struct net *net);
 
 #define IPV6_FRAG_TIMEOUT	(60*HZ)		/* 60 seconds */
 
diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c
index 4fec0b9..ad79ae0 100644
--- a/net/ipv4/inet_fragment.c
+++ b/net/ipv4/inet_fragment.c
@@ -63,8 +63,6 @@ void inet_frags_init(struct inet_frags *f)
 	f->rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^
 				   (jiffies ^ (jiffies >> 6)));
 
-	atomic_set(&f->mem, 0);
-
 	setup_timer(&f->secret_timer, inet_frag_secret_rebuild,
 			(unsigned long)f);
 	f->secret_timer.expires = jiffies + f->ctl->secret_interval;
@@ -75,6 +73,7 @@ EXPORT_SYMBOL(inet_frags_init);
 void inet_frags_init_net(struct netns_frags *nf)
 {
 	nf->nqueues = 0;
+	atomic_set(&nf->mem, 0);
 }
 EXPORT_SYMBOL(inet_frags_init_net);
 
@@ -107,13 +106,13 @@ void inet_frag_kill(struct inet_frag_queue *fq, struct inet_frags *f)
 
 EXPORT_SYMBOL(inet_frag_kill);
 
-static inline void frag_kfree_skb(struct inet_frags *f, struct sk_buff *skb,
-						int *work)
+static inline void frag_kfree_skb(struct netns_frags *nf, struct inet_frags *f,
+		struct sk_buff *skb, int *work)
 {
 	if (work)
 		*work -= skb->truesize;
 
-	atomic_sub(skb->truesize, &f->mem);
+	atomic_sub(skb->truesize, &nf->mem);
 	if (f->skb_free)
 		f->skb_free(skb);
 	kfree_skb(skb);
@@ -123,22 +122,24 @@ void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f,
 					int *work)
 {
 	struct sk_buff *fp;
+	struct netns_frags *nf;
 
 	BUG_TRAP(q->last_in & COMPLETE);
 	BUG_TRAP(del_timer(&q->timer) == 0);
 
 	/* Release all fragment data. */
 	fp = q->fragments;
+	nf = q->net;
 	while (fp) {
 		struct sk_buff *xp = fp->next;
 
-		frag_kfree_skb(f, fp, work);
+		frag_kfree_skb(nf, f, fp, work);
 		fp = xp;
 	}
 
 	if (work)
 		*work -= f->qsize;
-	atomic_sub(f->qsize, &f->mem);
+	atomic_sub(f->qsize, &nf->mem);
 
 	if (f->destructor)
 		f->destructor(q);
@@ -147,12 +148,12 @@ void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f,
 }
 EXPORT_SYMBOL(inet_frag_destroy);
 
-int inet_frag_evictor(struct inet_frags *f)
+int inet_frag_evictor(struct netns_frags *nf, struct inet_frags *f)
 {
 	struct inet_frag_queue *q;
 	int work, evicted = 0;
 
-	work = atomic_read(&f->mem) - f->ctl->low_thresh;
+	work = atomic_read(&nf->mem) - f->ctl->low_thresh;
 	while (work > 0) {
 		read_lock(&f->lock);
 		if (list_empty(&f->lru_list)) {
@@ -226,7 +227,7 @@ static struct inet_frag_queue *inet_frag_alloc(struct netns_frags *nf,
 		return NULL;
 
 	f->constructor(q, arg);
-	atomic_add(f->qsize, &f->mem);
+	atomic_add(f->qsize, &nf->mem);
 	setup_timer(&q->timer, f->frag_expire, (unsigned long)q);
 	spin_lock_init(&q->lock);
 	atomic_set(&q->refcnt, 1);
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index cd8c830..4f01334 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -100,9 +100,9 @@ int ip_frag_nqueues(struct net *net)
 	return net->ipv4.frags.nqueues;
 }
 
-int ip_frag_mem(void)
+int ip_frag_mem(struct net *net)
 {
-	return atomic_read(&ip4_frags.mem);
+	return atomic_read(&net->ipv4.frags.mem);
 }
 
 static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
@@ -142,11 +142,12 @@ static int ip4_frag_match(struct inet_frag_queue *q, void *a)
 }
 
 /* Memory Tracking Functions. */
-static __inline__ void frag_kfree_skb(struct sk_buff *skb, int *work)
+static __inline__ void frag_kfree_skb(struct netns_frags *nf,
+		struct sk_buff *skb, int *work)
 {
 	if (work)
 		*work -= skb->truesize;
-	atomic_sub(skb->truesize, &ip4_frags.mem);
+	atomic_sub(skb->truesize, &nf->mem);
 	kfree_skb(skb);
 }
 
@@ -192,11 +193,11 @@ static void ipq_kill(struct ipq *ipq)
 /* Memory limiting on fragments.  Evictor trashes the oldest
  * fragment queue until we are back under the threshold.
  */
-static void ip_evictor(void)
+static void ip_evictor(struct net *net)
 {
 	int evicted;
 
-	evicted = inet_frag_evictor(&ip4_frags);
+	evicted = inet_frag_evictor(&net->ipv4.frags, &ip4_frags);
 	if (evicted)
 		IP_ADD_STATS_BH(IPSTATS_MIB_REASMFAILS, evicted);
 }
@@ -294,7 +295,7 @@ static int ip_frag_reinit(struct ipq *qp)
 	fp = qp->q.fragments;
 	do {
 		struct sk_buff *xp = fp->next;
-		frag_kfree_skb(fp, NULL);
+		frag_kfree_skb(qp->q.net, fp, NULL);
 		fp = xp;
 	} while (fp);
 
@@ -431,7 +432,7 @@ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
 				qp->q.fragments = next;
 
 			qp->q.meat -= free_it->len;
-			frag_kfree_skb(free_it, NULL);
+			frag_kfree_skb(qp->q.net, free_it, NULL);
 		}
 	}
 
@@ -451,7 +452,7 @@ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
 	}
 	qp->q.stamp = skb->tstamp;
 	qp->q.meat += skb->len;
-	atomic_add(skb->truesize, &ip4_frags.mem);
+	atomic_add(skb->truesize, &qp->q.net->mem);
 	if (offset == 0)
 		qp->q.last_in |= FIRST_IN;
 
@@ -534,12 +535,12 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
 		head->len -= clone->len;
 		clone->csum = 0;
 		clone->ip_summed = head->ip_summed;
-		atomic_add(clone->truesize, &ip4_frags.mem);
+		atomic_add(clone->truesize, &qp->q.net->mem);
 	}
 
 	skb_shinfo(head)->frag_list = head->next;
 	skb_push(head, head->data - skb_network_header(head));
-	atomic_sub(head->truesize, &ip4_frags.mem);
+	atomic_sub(head->truesize, &qp->q.net->mem);
 
 	for (fp=head->next; fp; fp = fp->next) {
 		head->data_len += fp->len;
@@ -549,7 +550,7 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
 		else if (head->ip_summed == CHECKSUM_COMPLETE)
 			head->csum = csum_add(head->csum, fp->csum);
 		head->truesize += fp->truesize;
-		atomic_sub(fp->truesize, &ip4_frags.mem);
+		atomic_sub(fp->truesize, &qp->q.net->mem);
 	}
 
 	head->next = NULL;
@@ -588,8 +589,8 @@ int ip_defrag(struct sk_buff *skb, u32 user)
 
 	net = skb->dev->nd_net;
 	/* Start by cleaning up the memory. */
-	if (atomic_read(&ip4_frags.mem) > ip4_frags_ctl.high_thresh)
-		ip_evictor();
+	if (atomic_read(&net->ipv4.frags.mem) > ip4_frags_ctl.high_thresh)
+		ip_evictor(net);
 
 	/* Lookup (or create) queue header */
 	if ((qp = ip_find(net, ip_hdr(skb), user)) != NULL) {
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index bae3280..d63474c 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -62,7 +62,7 @@ static int sockstat_seq_show(struct seq_file *seq, void *v)
 	seq_printf(seq, "UDPLITE: inuse %d\n", sock_prot_inuse_get(&udplite_prot));
 	seq_printf(seq, "RAW: inuse %d\n", sock_prot_inuse_get(&raw_prot));
 	seq_printf(seq,  "FRAG: inuse %d memory %d\n",
-			ip_frag_nqueues(&init_net), ip_frag_mem());
+			ip_frag_nqueues(&init_net), ip_frag_mem(&init_net));
 	return 0;
 }
 
diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
index 0b9d009..cb826be 100644
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -155,7 +155,7 @@ static inline void frag_kfree_skb(struct sk_buff *skb, unsigned int *work)
 {
 	if (work)
 		*work -= skb->truesize;
-	atomic_sub(skb->truesize, &nf_frags.mem);
+	atomic_sub(skb->truesize, &nf_init_frags.mem);
 	nf_skb_free(skb);
 	kfree_skb(skb);
 }
@@ -177,7 +177,7 @@ static __inline__ void fq_kill(struct nf_ct_frag6_queue *fq)
 
 static void nf_ct_frag6_evictor(void)
 {
-	inet_frag_evictor(&nf_frags);
+	inet_frag_evictor(&nf_init_frags, &nf_frags);
 }
 
 static void nf_ct_frag6_expire(unsigned long data)
@@ -382,7 +382,7 @@ static int nf_ct_frag6_queue(struct nf_ct_frag6_queue *fq, struct sk_buff *skb,
 	skb->dev = NULL;
 	fq->q.stamp = skb->tstamp;
 	fq->q.meat += skb->len;
-	atomic_add(skb->truesize, &nf_frags.mem);
+	atomic_add(skb->truesize, &nf_init_frags.mem);
 
 	/* The first fragment.
 	 * nhoffset is obtained from the first fragment, of course.
@@ -459,7 +459,7 @@ nf_ct_frag6_reasm(struct nf_ct_frag6_queue *fq, struct net_device *dev)
 		clone->ip_summed = head->ip_summed;
 
 		NFCT_FRAG6_CB(clone)->orig = NULL;
-		atomic_add(clone->truesize, &nf_frags.mem);
+		atomic_add(clone->truesize, &nf_init_frags.mem);
 	}
 
 	/* We have to remove fragment header from datagram and to relocate
@@ -473,7 +473,7 @@ nf_ct_frag6_reasm(struct nf_ct_frag6_queue *fq, struct net_device *dev)
 	skb_shinfo(head)->frag_list = head->next;
 	skb_reset_transport_header(head);
 	skb_push(head, head->data - skb_network_header(head));
-	atomic_sub(head->truesize, &nf_frags.mem);
+	atomic_sub(head->truesize, &nf_init_frags.mem);
 
 	for (fp=head->next; fp; fp = fp->next) {
 		head->data_len += fp->len;
@@ -483,7 +483,7 @@ nf_ct_frag6_reasm(struct nf_ct_frag6_queue *fq, struct net_device *dev)
 		else if (head->ip_summed == CHECKSUM_COMPLETE)
 			head->csum = csum_add(head->csum, fp->csum);
 		head->truesize += fp->truesize;
-		atomic_sub(fp->truesize, &nf_frags.mem);
+		atomic_sub(fp->truesize, &nf_init_frags.mem);
 	}
 
 	head->next = NULL;
@@ -633,7 +633,7 @@ struct sk_buff *nf_ct_frag6_gather(struct sk_buff *skb)
 		goto ret_orig;
 	}
 
-	if (atomic_read(&nf_frags.mem) > nf_frags_ctl.high_thresh)
+	if (atomic_read(&nf_init_frags.mem) > nf_frags_ctl.high_thresh)
 		nf_ct_frag6_evictor();
 
 	fq = fq_find(fhdr->identification, &hdr->saddr, &hdr->daddr);
diff --git a/net/ipv6/proc.c b/net/ipv6/proc.c
index 0b55785..c51cf34 100644
--- a/net/ipv6/proc.c
+++ b/net/ipv6/proc.c
@@ -44,7 +44,7 @@ static int sockstat6_seq_show(struct seq_file *seq, void *v)
 	seq_printf(seq, "RAW6: inuse %d\n",
 		       sock_prot_inuse_get(&rawv6_prot));
 	seq_printf(seq, "FRAG6: inuse %d memory %d\n",
-		       ip6_frag_nqueues(&init_net), ip6_frag_mem());
+		       ip6_frag_nqueues(&init_net), ip6_frag_mem(&init_net));
 	return 0;
 }
 
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index 77a8740..241b2cc 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -89,9 +89,9 @@ int ip6_frag_nqueues(struct net *net)
 	return net->ipv6.frags.nqueues;
 }
 
-int ip6_frag_mem(void)
+int ip6_frag_mem(struct net *net)
 {
-	return atomic_read(&ip6_frags.mem);
+	return atomic_read(&net->ipv6.frags.mem);
 }
 
 static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
@@ -149,11 +149,12 @@ int ip6_frag_match(struct inet_frag_queue *q, void *a)
 EXPORT_SYMBOL(ip6_frag_match);
 
 /* Memory Tracking Functions. */
-static inline void frag_kfree_skb(struct sk_buff *skb, int *work)
+static inline void frag_kfree_skb(struct netns_frags *nf,
+		struct sk_buff *skb, int *work)
 {
 	if (work)
 		*work -= skb->truesize;
-	atomic_sub(skb->truesize, &ip6_frags.mem);
+	atomic_sub(skb->truesize, &nf->mem);
 	kfree_skb(skb);
 }
 
@@ -183,11 +184,11 @@ static __inline__ void fq_kill(struct frag_queue *fq)
 	inet_frag_kill(&fq->q, &ip6_frags);
 }
 
-static void ip6_evictor(struct inet6_dev *idev)
+static void ip6_evictor(struct net *net, struct inet6_dev *idev)
 {
 	int evicted;
 
-	evicted = inet_frag_evictor(&ip6_frags);
+	evicted = inet_frag_evictor(&net->ipv6.frags, &ip6_frags);
 	if (evicted)
 		IP6_ADD_STATS_BH(idev, IPSTATS_MIB_REASMFAILS, evicted);
 }
@@ -389,7 +390,7 @@ static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
 				fq->q.fragments = next;
 
 			fq->q.meat -= free_it->len;
-			frag_kfree_skb(free_it, NULL);
+			frag_kfree_skb(fq->q.net, free_it, NULL);
 		}
 	}
 
@@ -409,7 +410,7 @@ static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
 	}
 	fq->q.stamp = skb->tstamp;
 	fq->q.meat += skb->len;
-	atomic_add(skb->truesize, &ip6_frags.mem);
+	atomic_add(skb->truesize, &fq->q.net->mem);
 
 	/* The first fragment.
 	 * nhoffset is obtained from the first fragment, of course.
@@ -503,7 +504,7 @@ static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
 		head->len -= clone->len;
 		clone->csum = 0;
 		clone->ip_summed = head->ip_summed;
-		atomic_add(clone->truesize, &ip6_frags.mem);
+		atomic_add(clone->truesize, &fq->q.net->mem);
 	}
 
 	/* We have to remove fragment header from datagram and to relocate
@@ -518,7 +519,7 @@ static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
 	skb_shinfo(head)->frag_list = head->next;
 	skb_reset_transport_header(head);
 	skb_push(head, head->data - skb_network_header(head));
-	atomic_sub(head->truesize, &ip6_frags.mem);
+	atomic_sub(head->truesize, &fq->q.net->mem);
 
 	for (fp=head->next; fp; fp = fp->next) {
 		head->data_len += fp->len;
@@ -528,7 +529,7 @@ static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
 		else if (head->ip_summed == CHECKSUM_COMPLETE)
 			head->csum = csum_add(head->csum, fp->csum);
 		head->truesize += fp->truesize;
-		atomic_sub(fp->truesize, &ip6_frags.mem);
+		atomic_sub(fp->truesize, &fq->q.net->mem);
 	}
 
 	head->next = NULL;
@@ -600,8 +601,9 @@ static int ipv6_frag_rcv(struct sk_buff *skb)
 	}
 
 	net = skb->dev->nd_net;
-	if (atomic_read(&ip6_frags.mem) > init_net.ipv6.sysctl.frags.high_thresh)
-		ip6_evictor(ip6_dst_idev(skb->dst));
+	if (atomic_read(&net->ipv6.frags.mem) >
+			init_net.ipv6.sysctl.frags.high_thresh)
+		ip6_evictor(net, ip6_dst_idev(skb->dst));
 
 	if ((fq = fq_find(net, fhdr->identification, &hdr->saddr, &hdr->daddr,
 			  ip6_dst_idev(skb->dst))) != NULL) {
-- 
1.5.3.4