On Sun 07-04-13 14:00:24, Li Zefan wrote: > On 2013/4/4 20:00, Michal Hocko wrote: > > On Wed 03-04-13 17:11:15, 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. > > > > yes, I like the approach and it looks correct as well (some minor things > > mentioned in the patches). Thanks a lot Li! This will make our lifes much > > easier. The separate ref counting was PITA especially after > > introduction of kmem accounting which made its usage even more trickier. > > > >> btw, after this patchset I think we don't need to free memcg via RCU, because > >> cgroup is already freed in RCU callback. > > > > But this depends on changes waiting in for-3.10 branch, right? > > What changes? memcg changes or cgroup core changes? I don't think this depends > on anything in cgroup 3.10 branch. cgroup (be445626 e.g.) but now I've noticed that those are already merged in Linus tree. FYI: I've cherry-picked themo my -mm git tree. -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>