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    Subject[PATCH v8 6/9] tcp buffer limitation: per-cgroup limit
    Date
    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/net/tcp_memcontrol.h | 2 +
    net/ipv4/sysctl_net_ipv4.c | 14 ++++
    net/ipv4/tcp_memcontrol.c | 137 +++++++++++++++++++++++++++++++++++++-
    4 files changed, 152 insertions(+), 2 deletions(-)

    diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
    index 687dea5..1c9779a 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/net/tcp_memcontrol.h b/include/net/tcp_memcontrol.h
    index 5f5e158..3512082 100644
    --- 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
    --- 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
    --- 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;
    +}
    --
    1.7.6.4


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