Re: [PATCH v4 2/8] socket: initial cgroup code.

["Kirill A. Shutemov" <kirill@shutemov.name>]

On Mon, Oct 03, 2011 at 02:48:15PM +0400, Glauber Costa wrote:
> On 10/03/2011 02:47 PM, Kirill A. Shutemov wrote:
> > On Mon, Oct 03, 2011 at 02:18:37PM +0400, 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 |   15 +++++++++++++++
> >>   include/net/sock.h         |    2 ++
> >>   mm/memcontrol.c            |   33 +++++++++++++++++++++++++++++++++
> >>   net/core/sock.c            |    3 +++
> >>   4 files changed, 53 insertions(+), 0 deletions(-)
> >>
> >> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> >> index 3b535db..2cb9226 100644
> >> --- a/include/linux/memcontrol.h
> >> +++ b/include/linux/memcontrol.h
> >> @@ -395,5 +395,20 @@ mem_cgroup_print_bad_page(struct page *page)
> >>   }
> >>   #endif
> >>
> >> +#ifdef CONFIG_INET
> >> +struct sock;
> >> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> >> +void sock_update_memcg(struct sock *sk);
> >> +void sock_release_memcg(struct sock *sk);
> >> +
> >> +#else
> >> +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/mm/memcontrol.c b/mm/memcontrol.c
> >> index 8aaf4ce..08a520e 100644
> >> --- a/mm/memcontrol.c
> >> +++ b/mm/memcontrol.c
> >> @@ -339,6 +339,39 @@ struct mem_cgroup {
> >>   	spinlock_t pcp_counter_lock;
> >>   };
> >>
> >> +/* Writing them here to avoid exposing memcg's inner layout */
> >> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> >> +#ifdef CONFIG_INET
> >> +#include<net/sock.h>
> >> +
> >> +void sock_update_memcg(struct sock *sk)
> >> +{
> >> +	/* right now a socket spends its whole life in the same cgroup */
> >> +	BUG_ON(sk->sk_cgrp);
> >
> > Do we really want to panic in this case?
> >
> > What about WARN() + return?
> 
> Kirill,
> 
> I am keeping this code just to have something workable in between.
> If you take a look at the last patch, this hunk is going away anyway.
> 
> So if you don't oppose it, I'll just keep it to avoid rebasing it.

Sorry, but I don't see where you remove BUG_ON().
You remove only cgroup_exclude_rmdir().

-- 
 Kirill A. Shutemov

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