[Devel] Re: [RFC] Containers infrastructure problems

[Pavel Emelianov]

Paul Menage wrote:
> On 3/5/07, Pavel Emelianov <xemul at sw.ru> wrote:
>> Hi.
>>
>> I'm trying to implement RSS accounting via containers and
>> I have some difficulties and proposals.
>>
>> 1. Fork
>>
>> container_fork() is placed before new task obtains its
>> new mm_struct, files_struct, signal_struct etc. Isn't it
>> better to move container fork at the place where newly
>> created task it fully initialized to give controller
>> possibility to work with new mm, signals etc?
> 
> Yes, that seems reasonable.
> 
>>
>> 2. Early container usage
>>
>> Consider the following code:
>>
>>   struct my_container *cnt;
>>
>>   cnt = my_cnt_from_cont(task_container(current, &my_subsys));
>>
>> the problem is that when it is used before I register my
>> rss subsystem in initcall task_container returns me
>> dummytop container which is not my_container actually :(
> 
> By definition all tasks are in dummytop (the top container in the
> dummy hierarchy) since you can't create sub-containers in the dummy
> hierarchy.
> 
> You're right that before you're registered, the current container
> won't have a pointer for your subsystem. But calling
> container_register_subsys() from container_rss_init_early(), and
> having that called early on from init/main.c should be OK.

It is OK, but ->create callback should be aware of
the fact it is called on system boot time and thus
it mustn't call kmalloc() :)

> 
> Paul
>