tcp buffer limitation: per-cgroup limit

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>
Reviewed-by: Hiroyouki Kamezawa <kamezawa.hiroyu@jp.fujitsu.com>
CC: David S. Miller <davem@davemloft.net>
CC: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index 687dea5..1c9779a 100644 (file)
--- 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/net/tcp_memcontrol.h b/include/net/tcp_memcontrol.h
index 5f5e158..3512082 100644 (file)
--- a/include/net/tcp_memcontrol.h
+++ b/include/net/tcp_memcontrol.h
@@ -14,4 +14,6 @@ struct tcp_memcontrol {
 struct cg_proto *tcp_proto_cgroup(struct mem_cgroup *memcg);
 int tcp_init_cgroup(struct cgroup *cgrp, struct cgroup_subsys *ss);
 void tcp_destroy_cgroup(struct cgroup *cgrp, struct cgroup_subsys *ss);
+unsigned long long tcp_max_memory(const struct mem_cgroup *memcg);
+void tcp_prot_mem(struct mem_cgroup *memcg, long val, int idx);
 #endif /* _TCP_MEMCG_H */

diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index bbd67ab..fe9bf91 100644 (file)
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -24,6 +24,7 @@
 #include <net/cipso_ipv4.h>
 #include <net/inet_frag.h>
 #include <net/ping.h>
+#include <net/tcp_memcontrol.h>
 
 static int zero;
 static int tcp_retr1_max = 255;
@@ -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 *memcg;
+#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();
+       memcg = mem_cgroup_from_task(current);
+
+       tcp_prot_mem(memcg, vec[0], 0);
+       tcp_prot_mem(memcg, vec[1], 1);
+       tcp_prot_mem(memcg, 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];

diff --git a/net/ipv4/tcp_memcontrol.c b/net/ipv4/tcp_memcontrol.c
index bfb0c2b..e353390 100644 (file)
--- a/net/ipv4/tcp_memcontrol.c
+++ b/net/ipv4/tcp_memcontrol.c
@@ -6,6 +6,19 @@
 #include <linux/memcontrol.h>
 #include <linux/module.h>
 
+static u64 tcp_cgroup_read(struct cgroup *cont, struct cftype *cft);
+static int tcp_cgroup_write(struct cgroup *cont, struct cftype *cft,
+                           const char *buffer);
+
+static struct cftype tcp_files[] = {
+       {
+               .name = "kmem.tcp.limit_in_bytes",
+               .write_string = tcp_cgroup_write,
+               .read_u64 = tcp_cgroup_read,
+               .private = RES_LIMIT,
+       },
+};
+
 static inline struct tcp_memcontrol *tcp_from_cgproto(struct cg_proto *cg_proto)
 {
        return container_of(cg_proto, struct tcp_memcontrol, cg_proto);
@@ -34,7 +47,7 @@ int tcp_init_cgroup(struct cgroup *cgrp, struct cgroup_subsys *ss)
 
        cg_proto = tcp_prot.proto_cgroup(memcg);
        if (!cg_proto)
-               return 0;
+               goto create_files;
 
        tcp = tcp_from_cgproto(cg_proto);
 
@@ -57,7 +70,9 @@ int tcp_init_cgroup(struct cgroup *cgrp, struct cgroup_subsys *ss)
        cg_proto->sockets_allocated = &tcp->tcp_sockets_allocated;
        cg_proto->memcg = memcg;
 
-       return 0;
+create_files:
+       return cgroup_add_files(cgrp, ss, tcp_files,
+                               ARRAY_SIZE(tcp_files));
 }
 EXPORT_SYMBOL(tcp_init_cgroup);
 
@@ -66,6 +81,7 @@ void tcp_destroy_cgroup(struct cgroup *cgrp, struct cgroup_subsys *ss)
        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
        struct cg_proto *cg_proto;
        struct tcp_memcontrol *tcp;
+       u64 val;
 
        cg_proto = tcp_prot.proto_cgroup(memcg);
        if (!cg_proto)
@@ -73,5 +89,122 @@ void tcp_destroy_cgroup(struct cgroup *cgrp, struct cgroup_subsys *ss)
 
        tcp = tcp_from_cgproto(cg_proto);
        percpu_counter_destroy(&tcp->tcp_sockets_allocated);
+
+       val = res_counter_read_u64(&tcp->tcp_memory_allocated, RES_USAGE);
+
+       if (val != RESOURCE_MAX)
+               jump_label_dec(&memcg_socket_limit_enabled);
 }
 EXPORT_SYMBOL(tcp_destroy_cgroup);
+
+static int tcp_update_limit(struct mem_cgroup *memcg, u64 val)
+{
+       struct net *net = current->nsproxy->net_ns;
+       struct tcp_memcontrol *tcp;
+       struct cg_proto *cg_proto;
+       u64 old_lim;
+       int i;
+       int ret;
+
+       cg_proto = tcp_prot.proto_cgroup(memcg);
+       if (!cg_proto)
+               return -EINVAL;
+
+       if (val > RESOURCE_MAX)
+               val = RESOURCE_MAX;
+
+       tcp = tcp_from_cgproto(cg_proto);
+
+       old_lim = res_counter_read_u64(&tcp->tcp_memory_allocated, RES_LIMIT);
+       ret = res_counter_set_limit(&tcp->tcp_memory_allocated, val);
+       if (ret)
+               return ret;
+
+       for (i = 0; i < 3; i++)
+               tcp->tcp_prot_mem[i] = min_t(long, val >> PAGE_SHIFT,
+                                            net->ipv4.sysctl_tcp_mem[i]);
+
+       if (val == RESOURCE_MAX && old_lim != RESOURCE_MAX)
+               jump_label_dec(&memcg_socket_limit_enabled);
+       else if (old_lim == RESOURCE_MAX && val != RESOURCE_MAX)
+               jump_label_inc(&memcg_socket_limit_enabled);
+
+       return 0;
+}
+
+static int tcp_cgroup_write(struct cgroup *cont, struct cftype *cft,
+                           const char *buffer)
+{
+       struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+       unsigned long long val;
+       int ret = 0;
+
+       switch (cft->private) {
+       case RES_LIMIT:
+               /* see memcontrol.c */
+               ret = res_counter_memparse_write_strategy(buffer, &val);
+               if (ret)
+                       break;
+               ret = tcp_update_limit(memcg, val);
+               break;
+       default:
+               ret = -EINVAL;
+               break;
+       }
+       return ret;
+}
+
+static u64 tcp_read_stat(struct mem_cgroup *memcg, int type, u64 default_val)
+{
+       struct tcp_memcontrol *tcp;
+       struct cg_proto *cg_proto;
+
+       cg_proto = tcp_prot.proto_cgroup(memcg);
+       if (!cg_proto)
+               return default_val;
+
+       tcp = tcp_from_cgproto(cg_proto);
+       return res_counter_read_u64(&tcp->tcp_memory_allocated, type);
+}
+
+static u64 tcp_cgroup_read(struct cgroup *cont, struct cftype *cft)
+{
+       struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+       u64 val;
+
+       switch (cft->private) {
+       case RES_LIMIT:
+               val = tcp_read_stat(memcg, RES_LIMIT, RESOURCE_MAX);
+               break;
+       default:
+               BUG();
+       }
+       return val;
+}
+
+unsigned long long tcp_max_memory(const struct mem_cgroup *memcg)
+{
+       struct tcp_memcontrol *tcp;
+       struct cg_proto *cg_proto;
+
+       cg_proto = tcp_prot.proto_cgroup((struct mem_cgroup *)memcg);
+       if (!cg_proto)
+               return 0;
+
+       tcp = tcp_from_cgproto(cg_proto);
+       return res_counter_read_u64(&tcp->tcp_memory_allocated, RES_LIMIT);
+}
+
+void tcp_prot_mem(struct mem_cgroup *memcg, long val, int idx)
+{
+       struct tcp_memcontrol *tcp;
+       struct cg_proto *cg_proto;
+
+       cg_proto = tcp_prot.proto_cgroup(memcg);
+       if (!cg_proto)
+               return;
+
+       tcp = tcp_from_cgproto(cg_proto);
+
+       tcp->tcp_prot_mem[idx] = val;
+}