[PATCH v2 2/7] socket: initial cgroup code.

Glauber Costa
2011-09-15T01:48:11Z

We aim to control the amount of kernel memory pinned at any
time by tcp sockets. To lay the foundations for this work,
this patch adds a pointer to the kmem_cgroup to the socket
structure.

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>
---
include/linux/memcontrol.h | 38 ++++++++++++++++++++++++++++++++++++++
include/net/sock.h | 2 ++
net/core/sock.c | 3 +++
3 files changed, 43 insertions(+), 0 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 3b535db..be457ce 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -395,5 +395,43 @@ mem_cgroup_print_bad_page(struct page *page)
}
#endif

+#ifdef CONFIG_INET
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
+#include <net/sock.h>
+static inline void sock_update_memcg(struct sock *sk)
+{
+ /* right now a socket spends its whole life in the same cgroup */
+ BUG_ON(sk->sk_cgrp);
+
+ rcu_read_lock();
+ sk->sk_cgrp = mem_cgroup_from_task(current);
+
+ /*
+ * We don't need to protect against anything task-related, because
+ * we are basically stuck with the sock pointer that won't change,
+ * even if the task that originated the socket changes cgroups.
+ *
+ * What we do have to guarantee, is that the chain leading us to
+ * the top level won't change under our noses. Incrementing the
+ * reference count via cgroup_exclude_rmdir guarantees that.
+ */
+ cgroup_exclude_rmdir(mem_cgroup_css(sk->sk_cgrp));
+ rcu_read_unlock();
+}
+
+static inline void sock_release_memcg(struct sock *sk)
+{
+ cgroup_release_and_wakeup_rmdir(mem_cgroup_css(sk->sk_cgrp));
+}
+#else
+#include <net/sock.h>
+static inline void sock_update_memcg(struct sock *sk)
+{
+}
+static inline void sock_release_memcg(struct sock *sk)
+{
+}
+#endif /* CONFIG_CGROUP_MEM_RES_CTLR_KMEM */
+#endif /* CONFIG_INET */
#endif /* _LINUX_MEMCONTROL_H */

diff --git a/include/net/sock.h b/include/net/sock.h
index 8e4062f..afe1467 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -228,6 +228,7 @@ struct sock_common {
* @sk_security: used by security modules
* @sk_mark: generic packet mark
* @sk_classid: this socket's cgroup classid
+ * @sk_cgrp: this socket's kernel memory (kmem) cgroup
* @sk_write_pending: a write to stream socket waits to start
* @sk_state_change: callback to indicate change in the state of the sock
* @sk_data_ready: callback to indicate there is data to be processed
@@ -339,6 +340,7 @@ struct sock {
#endif
__u32 sk_mark;
u32 sk_classid;
+ struct mem_cgroup *sk_cgrp;
void (*sk_state_change)(struct sock *sk);
void (*sk_data_ready)(struct sock *sk, int bytes);
void (*sk_write_space)(struct sock *sk);
diff --git a/net/core/sock.c b/net/core/sock.c
index 3449df8..54ec8ac 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -125,6 +125,7 @@
#include <net/xfrm.h>
#include <linux/ipsec.h>
#include <net/cls_cgroup.h>
+#include <linux/memcontrol.h>

#include <linux/filter.h>

@@ -1139,6 +1140,7 @@ struct sock *sk_alloc(struct net *net, int family, gfp_t priority,
atomic_set(&sk->sk_wmem_alloc, 1);

sock_update_classid(sk);
+ sock_update_memcg(sk);
}

return sk;
@@ -1170,6 +1172,7 @@ static void __sk_free(struct sock *sk)
put_cred(sk->sk_peer_cred);
put_pid(sk->sk_peer_pid);
put_net(sock_net(sk));
+ sock_release_memcg(sk);
sk_prot_free(sk->sk_prot_creator, sk);
}

--
1.7.6