On 10/03/2011 03:02 PM, Kirill A. Shutemov wrote:

On Mon, Oct 03, 2011 at 02:48:15PM +0400, Glauber Costa wrote:

quoted

On 10/03/2011 02:47 PM, Kirill A. Shutemov wrote:

quoted

On Mon, Oct 03, 2011 at 02:18:37PM +0400, Glauber Costa 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/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().

Oh yeah, you are right, sorry.

So, I guess some kind of check is sane here. I am happy to change it to 
WARN_ON.