Re: [RFC][PATCH 0/7] memcg: make memcg's life cycle the same as cgroup

Li Zefan
2013-04-07T08:44:07Z

Hi,

I'm rebasing this patchset against latest linux-next, and it conflicts with
"[PATCH v2] memcg: debugging facility to access dangling memcgs." slightly.

That is a debugging patch and will never be pushed into mainline, so should I
still base this patchset on that debugging patch?

Also that patch needs update (and can be simplified) after this patchset:
- move memcg_dangling_add() to mem_cgroup_css_offline()
- remove memcg->memcg_name, and use cgroup_path() in mem_cgroup_dangling_read()?

On 2013/4/3 17:11, Li Zefan wrote:
> (I'll be off from my office soon, and I won't be responsive in the following
> 3 days.)
>
> I'm working on converting memcg to use cgroup->id, and then we can kill css_id.
>
> Now memcg has its own refcnt, so when a cgroup is destroyed, the memcg can
> still be alive. This patchset converts memcg to always use css_get/put, so
> memcg will have the same life cycle as its corresponding cgroup, and then
> it's always safe for memcg to use cgroup->id.
>
> The historical reason that memcg didn't use css_get in some cases, is that
> cgroup couldn't be removed if there're still css refs. The situation has
> changed so that rmdir a cgroup will succeed regardless css refs, but won't
> be freed until css refs goes down to 0.
>
> This is an early post, and it's NOT TESTED. I just want to see if the changes
> are fine in general.
>
> btw, after this patchset I think we don't need to free memcg via RCU, because
> cgroup is already freed in RCU callback.
>
> Note this patchset is based on a few memcg fixes I sent (but hasn't been
> accepted)
>
> --
> kernel/cgroup.c | 10 ++++++++
> mm/memcontrol.c | 129 ++++++++++++++++++++++++++++++++++++++-------------------------------------------------------
> 2 files changed, 62 insertions(+), 77 deletions(-)
>