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

Glauber Costa
2011-09-18T03:33:19Z

On 09/17/2011 02:52 PM, Kirill A. Shutemov wrote:
> 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?
>
No, I can move it to memcontrol.c