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

Kirill A. Shutemov
2011-09-17T17:52:09Z

On Wed, Sep 14, 2011 at 10:46:10PM -0300, Glauber Costa wrote:
> 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));
> +}

Do we really need to have these functions in the header?

--
Kirill A. Shutemov