Subject: Re: [PATCH next-20130703] net: sock: Add ifdef CONFIG_MEMCG_KMEM for mem_cgroup_sockets_{init,destroy}

From: Li Zefan <[email-masked]>
Date: Wed, 3 Jul 2013 20:51:00 +0800

On 2013/7/3 20:19, Sedat Dilek wrote:
> When "CONFIG_MEMCG_KMEM=n" I see this in my build-log:
> 
>  LD      init/built-in.o
> mm/built-in.o: In function `mem_cgroup_css_free':
> memcontrol.c:(.text+0x5caa6): undefined reference to `mem_cgroup_sockets_destroy'
> make[2]: *** [vmlinux] Error 1
> 
> Inspired by the ifdef for mem_cgroup_sockets_{init,destroy} here...
> 
> [ net/core/sock.c ]
> 
>  #ifdef CONFIG_MEMCG_KMEM
>  int mem_cgroup_sockets_init()
>  ...
>  void mem_cgroup_sockets_destroy()
>  ...
>  #endif
> 
> ...I did the the same for both in "include/net/sock.h".
> 
> This fixes the issue for me in next-20130703.
> 
> Signed-off-by: Sedat Dilek <[email-masked]>

Maybe it's better to add memcg_destroy_kmem(), to pair with
memcg_init_kmem().

This patch can be folded into "memcg: use css_get/put when charging/uncharging kmem"

=======================

[PATCH] memcg: fix build error if CONFIG_MEMCG_KMEM=n

Fix this build error:

mm/built-in.o: In function `mem_cgroup_css_free':
memcontrol.c:(.text+0x5caa6): undefined reference to
'mem_cgroup_sockets_destroy'

Reported-by: Fengguang Wu <[email-masked]>
Reported-by: Stephen Rothwell <[email-masked]>
Signed-off-by: Li Zefan <[email-masked]>
---
 mm/memcontrol.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 234f311..59ea6f9 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5876,6 +5876,11 @@ static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
 	return mem_cgroup_sockets_init(memcg, ss);
 }
 
+static void memcg_destroy_kmem(struct mem_cgroup *memcg)
+{
+	mem_cgroup_sockets_destroy(memcg);
+}
+
 static void kmem_cgroup_css_offline(struct mem_cgroup *memcg)
 {
 	if (!memcg_kmem_is_active(memcg))
@@ -5915,6 +5920,10 @@ static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
 	return 0;
 }
 
+static void memcg_destroy_kmem(struct mem_cgroup *memcg)
+{
+}
+
 static void kmem_cgroup_css_offline(struct mem_cgroup *memcg)
 {
 }
@@ -6312,8 +6321,7 @@ static void mem_cgroup_css_free(struct cgroup *cont)
 {
 	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
 
-	mem_cgroup_sockets_destroy(memcg);
-
+	memcg_destroy_kmem(memcg);
 	__mem_cgroup_free(memcg);
 }
 
-- 
1.8.0.2

> ---
> [ v2: git dislikes lines beginning with hash ('#'). ]
> 
>  include/net/sock.h | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/include/net/sock.h b/include/net/sock.h
> index ea6206c..ad4bf7f 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -71,6 +71,7 @@
>  struct cgroup;
>  struct cgroup_subsys;
>  #ifdef CONFIG_NET
> +#ifdef CONFIG_MEMCG_KMEM

#if defined(CONFIG_NET) && defined(CONFIG_MEMCG_KMEM)

>  int mem_cgroup_sockets_init(struct mem_cgroup *memcg, struct cgroup_subsys *ss);
>  void mem_cgroup_sockets_destroy(struct mem_cgroup *memcg);
>  #else
> @@ -83,7 +84,8 @@ static inline
>  void mem_cgroup_sockets_destroy(struct mem_cgroup *memcg)
>  {
>  }
> -#endif
> +#endif /* CONFIG_NET */
> +#endif /* CONFIG_MEMCG_KMEM */
>  /*
>   * This structure really needs to be cleaned up.
>   * Most of it is for TCP, and not used by any of
>