Re: [RFC][PATCH 5/4] memcg: don't call res_counter_uncharge when obsolete

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Thu, 15 Jan 2009 10:47:17 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:

> * KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> [2009-01-15 13:52:23]:

> > I think rmdir() should succeed everywhen "there are no tasks and children".
> > And that can be done.
> >
> 
> All I am saying is that let rmdir() fail if there are tasks or
> children, which I suspect cgroup takes care of. The second thing to do would
> be to add a mem_cgroup_get_hierarchical() and _put_hierarchical() API's so
> that we can get references all the way up to the parents. My concern
> is that not calling res_counter_uncharge() can lead to dangling
> references and bad behaviour.
>  
> > With Paul's suggestion, I'll add wait_queue for rmdir of cgroup.
> > 
> 
> That might be a good idea and also a good idea to maintain the
> hierarchy (since we will walk up when we do uncharge) until we know
> that css reference count is down to 0.
> 
It seems Nishimura started his work in that direction. (see other mail.)
Let's wait a bit.

-Kame

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