[Devel] Re: [PATCH 02/10] consider a memcg parameter in kmem_create_cache

[Glauber Costa]

On 07/25/2012 10:10 PM, Kirill A. Shutemov wrote:
> On Wed, Jul 25, 2012 at 06:38:13PM +0400, Glauber Costa wrote:
> 
> ...
> 
>> @@ -337,6 +341,12 @@ extern void *__kmalloc_track_caller(size_t, gfp_t, unsigned long);
>>  	__kmalloc(size, flags)
>>  #endif /* DEBUG_SLAB */
>>  
>> +#ifdef CONFIG_MEMCG_KMEM
>> +#define MAX_KMEM_CACHE_TYPES 400
>> +#else
>> +#define MAX_KMEM_CACHE_TYPES 0
>> +#endif /* CONFIG_MEMCG_KMEM */
>> +
>>  #ifdef CONFIG_NUMA
>>  /*
>>   * kmalloc_node_track_caller is a special version of kmalloc_node that
> 
> ...
> 
>> @@ -527,6 +532,24 @@ static inline bool memcg_kmem_enabled(struct mem_cgroup *memcg)
>>  		memcg->kmem_accounted;
>>  }
>>  
>> +struct ida cache_types;
>> +
>> +void memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *cachep)
>> +{
>> +	int id = -1;
>> +
>> +	if (!memcg)
>> +		id = ida_simple_get(&cache_types, 0, MAX_KMEM_CACHE_TYPES,
>> +				    GFP_KERNEL);
> 
> MAX_KMEM_CACHE_TYPES is 0 if CONFIG_MEMCG_KMEM undefined.
> If 'end' parameter of ida_simple_get() is 0 it will use default max value
> which is 0x80000000.
> I guess you want MAX_KMEM_CACHE_TYPES to be 1 for !CONFIG_MEMCG_KMEM.
> 
ida_simple_get will not, and should never be called for !CONFIG_MEMCG_KMEM.