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

From: Glauber Costa
Date: Mon Oct 03 2011 - 07:04:28 EST

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

Signed-off-by: Glauber Costa<glommer@xxxxxxxxxxxxx>
CC: David S. Miller<davem@xxxxxxxxxxxxx>
CC: Hiroyouki Kamezawa<kamezawa.hiroyu@xxxxxxxxxxxxxx>
CC: Eric W. Biederman<ebiederm@xxxxxxxxxxxx>
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)

+struct sock;
+void sock_update_memcg(struct sock *sk);
+void sock_release_memcg(struct sock *sk);
+static inline void sock_update_memcg(struct sock *sk)
+static inline void sock_release_memcg(struct sock *sk)
+#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 {
__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 */
+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?


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.

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