Re: [PATCH v2 3/9] socket: initial cgroup code.

On 09/07/2011 02:26 AM, Paul Menage wrote:

On Tue, Sep 6, 2011 at 9:23 PM, Glauber Costa[off-list ref]  wrote:

quoted

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<redacted>
CC: David S. Miller<davem@davemloft.net>
CC: Hiroyouki Kamezawa<redacted>
CC: Eric W. Biederman<redacted>
---
  include/linux/kmem_cgroup.h |   29 +++++++++++++++++++++++++++++
  include/net/sock.h          |    2 ++
  net/core/sock.c             |    5 ++---
  3 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/include/linux/kmem_cgroup.h b/include/linux/kmem_cgroup.h
index 0e4a74b..77076d8 100644
--- a/include/linux/kmem_cgroup.h
+++ b/include/linux/kmem_cgroup.h

@@ -49,5 +49,34 @@ static inline struct kmem_cgroup *kcg_from_task(struct task_struct *tsk)
        return NULL;
  }
  #endif /* CONFIG_CGROUP_KMEM */
+
+#ifdef CONFIG_INET
+#include<net/sock.h>
+static inline void sock_update_kmem_cgrp(struct sock *sk)
+{
+#ifdef CONFIG_CGROUP_KMEM
+       sk->sk_cgrp = kcg_from_task(current);

BUG_ON(sk->sk_cgrp) ? Or else release the old cgroup if necessary.

Since at least in this current incarnation, I am not doing migrations,
I definitely don't expect to have a pointer already present here.
BUG_ON() it is.

quoted

@@ -339,6 +340,7 @@ struct sock {
  #endif
        __u32                   sk_mark;
        u32                     sk_classid;
+       struct kmem_cgroup      *sk_cgrp;

Should this be protected by a #ifdef?

I don't particularly like it. I think that ifdef'ing fields
in structures, while allowing for size optimization, takes away
size and alignment predictability. But... can do.