Re: [PATCH v3 04/13] kmem accounting basic infrastructure

[Glauber Costa <glommer@parallels.com>]

On 09/26/2012 08:01 PM, Michal Hocko wrote:
> On Wed 26-09-12 18:33:10, Glauber Costa wrote:
>> On 09/26/2012 06:03 PM, Michal Hocko wrote:
>>> On Tue 18-09-12 18:04:01, Glauber Costa wrote:
> [...]
>>>> @@ -4961,6 +5015,12 @@ mem_cgroup_create(struct cgroup *cont)
>>>>  		int cpu;
>>>>  		enable_swap_cgroup();
>>>>  		parent = NULL;
>>>> +
>>>> +#ifdef CONFIG_MEMCG_KMEM
>>>> +		WARN_ON(cgroup_add_cftypes(&mem_cgroup_subsys,
>>>> +					   kmem_cgroup_files));
>>>> +#endif
>>>> +
>>>>  		if (mem_cgroup_soft_limit_tree_init())
>>>>  			goto free_out;
>>>>  		root_mem_cgroup = memcg;
>>>> @@ -4979,6 +5039,7 @@ mem_cgroup_create(struct cgroup *cont)
>>>>  	if (parent && parent->use_hierarchy) {
>>>>  		res_counter_init(&memcg->res, &parent->res);
>>>>  		res_counter_init(&memcg->memsw, &parent->memsw);
>>>> +		res_counter_init(&memcg->kmem, &parent->kmem);
>>>
>>> Haven't we already discussed that a new memcg should inherit kmem_accounted
>>> from its parent for use_hierarchy?
>>> Say we have
>>> root
>>> |
>>> A (kmem_accounted = 1, use_hierachy = 1)
>>>  \
>>>   B (kmem_accounted = 0)
>>>    \
>>>     C (kmem_accounted = 1)
>>>
>>> B find's itself in an awkward situation becuase it doesn't want to
>>> account u+k but it ends up doing so becuase C.
>>>
>>
>> Ok, I haven't updated it here. But that should be taken care of in the
>> lifecycle patch.
> 
> I am not sure which patch you are thinking about but I would prefer to
> have it here because it is safe wrt. races and it is more obvious as
> well.
> 

The patch where I make kmem_accounted into a bitfield. So any code here
will eventually disappear.

But BTW, I am not saying I won't update the patch - I like that all
patches work and make sense in their own, I am just saying that I forgot
to update this patch, because I added the code in its final version to
the end and then squashed it.