[PATCH v5 06/10] tcp buffer limitation: per-cgroup limit

[Glauber Costa <glommer@parallels.com>]

This patch uses the "tcp.limit_in_bytes" field of the kmem_cgroup to
effectively control the amount of kernel memory pinned by a cgroup.

This value is ignored in the root cgroup, and in all others,
caps the value specified by the admin in the net namespaces'
view of tcp_sysctl_mem.

If namespaces are being used, the admin is allowed to set a
value bigger than cgroup's maximum, the same way it is allowed
to set pretty much unlimited values in a real box.

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: David S. Miller <davem@davemloft.net>
CC: Hiroyouki Kamezawa <kamezawa.hiroyu@jp.fujitsu.com>
CC: Eric W. Biederman <ebiederm@xmission.com>
---
 Documentation/cgroups/memory.txt |    1 +
 include/linux/memcontrol.h       |    9 ++++
 mm/memcontrol.c                  |   76 +++++++++++++++++++++++++++++++++++++-
 net/ipv4/sysctl_net_ipv4.c       |   14 +++++++
 4 files changed, 99 insertions(+), 1 deletions(-)

diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index bf00cd2..c1db134 100644
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -78,6 +78,7 @@ Brief summary of control files.
 
  memory.independent_kmem_limit	 # select whether or not kernel memory limits are
 				   independent of user limits
+ memory.kmem.tcp.limit_in_bytes  # set/show hard limit for tcp buf memory
 
 1. History
 
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 994a06a..d025979 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -402,10 +402,19 @@ void memcg_memory_allocated_sub(struct mem_cgroup *memcg, struct cg_proto *prot,
 				unsigned long amt);
 u64 memcg_memory_allocated_read(struct mem_cgroup *memcg,
 				struct cg_proto *prot);
+unsigned long long tcp_max_memory(const struct mem_cgroup *memcg);
+void tcp_prot_mem(struct mem_cgroup *memcg, long val, int idx);
 #else
 static inline void sock_update_memcg(struct sock *sk)
 {
 }
+static inline unsigned long long tcp_max_memory(const struct mem_cgroup *memcg)
+{
+	return 0;
+}
+static inline void tcp_prot_mem(struct mem_cgroup *memcg, long val, int idx)
+{
+}
 #endif /* CONFIG_CGROUP_MEM_RES_CTLR_KMEM */
 #endif /* CONFIG_INET */
 #endif /* _LINUX_MEMCONTROL_H */
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 63360f8..ee122a6 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -365,6 +365,7 @@ enum mem_type {
 	_MEMSWAP,
 	_OOM_TYPE,
 	_KMEM,
+	_KMEM_TCP,
 };
 
 #define MEMFILE_PRIVATE(x, val)	(((x) << 16) | (val))
@@ -500,6 +501,35 @@ struct percpu_counter *sockets_allocated_tcp(struct mem_cgroup *memcg)
 }
 EXPORT_SYMBOL(sockets_allocated_tcp);
 
+static void tcp_update_limit(struct mem_cgroup *memcg, u64 val)
+{
+	struct net *net = current->nsproxy->net_ns;
+	int i;
+
+	val >>= PAGE_SHIFT;
+
+	for (i = 0; i < 3; i++)
+		memcg->tcp.tcp_prot_mem[i]  = min_t(long, val,
+					     net->ipv4.sysctl_tcp_mem[i]);
+}
+
+static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
+			    const char *buffer);
+
+static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft);
+/*
+ * We need those things internally in pages, so don't reuse
+ * mem_cgroup_{read,write}
+ */
+static struct cftype tcp_files[] = {
+	{
+		.name = "kmem.tcp.limit_in_bytes",
+		.write_string = mem_cgroup_write,
+		.read_u64 = mem_cgroup_read,
+		.private = MEMFILE_PRIVATE(_KMEM_TCP, RES_LIMIT),
+	},
+};
+
 static void tcp_create_cgroup(struct mem_cgroup *cg, struct cgroup_subsys *ss)
 {
 	/*
@@ -527,6 +557,7 @@ static void tcp_create_cgroup(struct mem_cgroup *cg, struct cgroup_subsys *ss)
 int tcp_init_cgroup(struct cgroup *cgrp, struct cgroup_subsys *ss)
 {
 	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+	struct mem_cgroup *parent = parent_mem_cgroup(memcg);
 	struct net *net = current->nsproxy->net_ns;
 	/*
 	 * We need to initialize it at populate, not create time.
@@ -537,7 +568,20 @@ int tcp_init_cgroup(struct cgroup *cgrp, struct cgroup_subsys *ss)
 	memcg->tcp.tcp_prot_mem[1] = net->ipv4.sysctl_tcp_mem[1];
 	memcg->tcp.tcp_prot_mem[2] = net->ipv4.sysctl_tcp_mem[2];
 
-	return 0;
+	/* Let root cgroup unlimited. All others, respect parent's if needed */
+	if (parent && !parent->use_hierarchy) {
+		unsigned long limit;
+		int ret;
+		limit = nr_free_buffer_pages() / 8;
+		limit = max(limit, 128UL);
+		ret = res_counter_set_limit(&memcg->tcp.tcp_memory_allocated,
+					    limit * 2);
+		if (ret)
+			return ret;
+	}
+
+	return cgroup_add_files(cgrp, ss, tcp_files,
+				ARRAY_SIZE(tcp_files));
 }
 EXPORT_SYMBOL(tcp_init_cgroup);
 
@@ -548,6 +592,18 @@ void tcp_destroy_cgroup(struct cgroup *cgrp, struct cgroup_subsys *ss)
 	percpu_counter_destroy(&memcg->tcp.tcp_sockets_allocated);
 }
 EXPORT_SYMBOL(tcp_destroy_cgroup);
+
+unsigned long long tcp_max_memory(const struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *cmemcg = (struct mem_cgroup *)memcg;
+	return res_counter_read_u64(&cmemcg->tcp.tcp_memory_allocated,
+				    RES_LIMIT);
+}
+
+void tcp_prot_mem(struct mem_cgroup *memcg, long val, int idx)
+{
+	memcg->tcp.tcp_prot_mem[idx] = val;
+}
 #endif /* CONFIG_INET */
 #endif /* CONFIG_CGROUP_MEM_RES_CTLR_KMEM */
 
@@ -4067,6 +4123,15 @@ static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
 		val = res_counter_read_u64(&mem->kmem, name);
 		break;
 
+#if defined(CONFIG_CGROUP_MEM_RES_CTLR_KMEM) && defined(CONFIG_INET)
+	case _KMEM_TCP:
+		/* Be explicit: tcp root does not have a res_counter */
+		if (mem_cgroup_is_root(mem))
+			val = RESOURCE_MAX;
+		else
+			val = res_counter_read_u64(&mem->tcp.tcp_memory_allocated, name);
+		break;
+#endif
 	default:
 		BUG();
 		break;
@@ -4099,6 +4164,15 @@ static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
 			break;
 		if (type == _MEM)
 			ret = mem_cgroup_resize_limit(memcg, val);
+
+#if defined(CONFIG_CGROUP_MEM_RES_CTLR_KMEM) && defined(CONFIG_INET)
+		else if (type == _KMEM_TCP) {
+			ret = res_counter_set_limit(&memcg->tcp.tcp_memory_allocated,
+						    val);
+			if (!ret)
+				tcp_update_limit(memcg, val);
+		}
+#endif
 		else
 			ret = mem_cgroup_resize_memsw_limit(memcg, val);
 		break;
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index bbd67ab..915e192 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -14,6 +14,7 @@
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/nsproxy.h>
+#include <linux/memcontrol.h>
 #include <linux/swap.h>
 #include <net/snmp.h>
 #include <net/icmp.h>
@@ -182,6 +183,9 @@ static int ipv4_tcp_mem(ctl_table *ctl, int write,
 	int ret;
 	unsigned long vec[3];
 	struct net *net = current->nsproxy->net_ns;
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
+	struct mem_cgroup *cg;
+#endif
 
 	ctl_table tmp = {
 		.data = &vec,
@@ -198,6 +202,16 @@ static int ipv4_tcp_mem(ctl_table *ctl, int write,
 	if (ret)
 		return ret;
 
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
+	rcu_read_lock();
+	cg = mem_cgroup_from_task(current);
+
+	tcp_prot_mem(cg, vec[0], 0);
+	tcp_prot_mem(cg, vec[1], 1);
+	tcp_prot_mem(cg, vec[2], 2);
+	rcu_read_unlock();
+#endif
+
 	net->ipv4.sysctl_tcp_mem[0] = vec[0];
 	net->ipv4.sysctl_tcp_mem[1] = vec[1];
 	net->ipv4.sysctl_tcp_mem[2] = vec[2];
-- 
1.7.6.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>