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

Michal Hocko
2013-07-03T15:21:03Z

On Wed 03-07-13 20:51:00, Li Zefan wrote:
[...]
> [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>

I am seeing the same thing I just didn't get to reporting it.
The other approach is not bad as well but I find this tiny better
because mem_cgroup_css_free should care only about a single cleanup
function for whole kmem. If that one needs to do tcp kmem specific
cleanup then it should be done inside kmem_cgroup_css_offline.

Andrew could you add this as
memcg-use-css_get-put-when-charging-uncharging-kmem-fix.patch, please?

Acked-by: Michal Hocko <mhocko@suse.cz>

Thanks

> ---
> 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
> >
>
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--
Michal Hocko
SUSE Labs