Re: [PATCH v3 4/6] memcg: move charges to root cgroup if use_hierarchy=0.

[KAMEZAWA Hiroyuki]

(2012/05/15 5:14), Tejun Heo wrote:

> On Fri, May 11, 2012 at 06:49:22PM +0900, KAMEZAWA Hiroyuki wrote:
>> @@ -3351,9 +3339,8 @@ int mem_cgroup_move_hugetlb_parent(int idx, struct cgroup *cgroup,
>>  	struct page_cgroup *pc;
>>  	int csize,  ret = 0;
>>  	struct res_counter *fail_res;
>> -	struct cgroup *pcgrp = cgroup->parent;
>> -	struct mem_cgroup *parent = mem_cgroup_from_cont(pcgrp);
>>  	struct mem_cgroup *memcg  = mem_cgroup_from_cont(cgroup);
>> +	struct mem_cgroup *parent = parent_mem_cgroup(memcg);
>>  	struct res_counter *counter;
>>  
>>  	if (!get_page_unless_zero(page))
>> @@ -3366,13 +3353,11 @@ int mem_cgroup_move_hugetlb_parent(int idx, struct cgroup *cgroup,
>>  
>>  	csize = PAGE_SIZE << compound_order(page);
>>  	/* If parent->use_hierarchy == 0, we need to charge parent */
>> -	if (!parent->use_hierarchy) {
>> -		ret = res_counter_charge(&parent->hugepage[idx],
>> -					 csize, &fail_res);
>> -		if (ret) {
>> -			ret = -EBUSY;
>> -			goto err_out;
>> -		}
>> +	if (!parent) {
>> +		parent = root_mem_cgroup;
>> +		/* root has no limit */
>> +		res_counter_charge_nofail(&parent->hugepage[idx],
>> +				 csize, &fail_res);
>>  	}
>>  	counter = &memcg->hugepage[idx];
>>  	res_counter_uncharge_until(counter, counter->parent, csize);
> 
> This function can simply return 0 now, so no point in having int
> return.  Make it return void?
> 
> Also, follow-up patches to cleanup -ENOMEM failure handling in the
> callers would be nice.
> 
Sure, I'll check it.


Thanks,
-Kame


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