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

Sedat Dilek
2013-07-03T13:10:59Z

On Wed, Jul 3, 2013 at 3:09 PM, Sedat Dilek <sedat.dilek@gmail.com> wrote:
> On Wed, Jul 3, 2013 at 2:51 PM, Li Zefan <lizefan@huawei.com> wrote:
>> 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 <sedat.dilek@gmail.com>
>>
>> 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"
>>
>
> Hi Li Zefan,
>
> Can you or a guru from netdev explain me why there exists
> mem_cgroup_sockets_init() and mem_cgroup_sockets_destroy() in
>
> 1. net/core/sock.c <--- AFAICS this includes below sock.h, too.
> 2. net/core/sock.h <--- mm/memcontrol.c is including this one.
>

*** include/net/sock.h ***

- Sedat -

> Make me less confused.
>
> And can you explain why your approach is "better" to do the change in
> memcontrol.c than in sock.h (see sock.c).
>
> Thanks in advance.
>
> - Sedat -
>
>> =======================
>>
>> [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 <fengguang.wu@intel.com>
>> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
>> Signed-off-by: Li Zefan <lizefan@huawei.com>
>> ---
>> 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
>>>
>>