Re: [PATCH] memcg: fix memcg_cache_name() to use cgroup_name()

Glauber Costa
2013-03-22T09:41:40Z

On 03/22/2013 01:31 PM, Michal Hocko wrote:
> On Fri 22-03-13 12:22:23, Glauber Costa wrote:
>> On 03/22/2013 12:17 PM, Li Zefan wrote:
>>>> GFP_TEMPORARY groups short lived allocations but the mem cache is not
>>>>> an ideal candidate of this type of allocations..
>>>>>
>>> I'm not sure I'm following you...
>>>
>>> char *memcg_cache_name()
>>> {
>>> char *name = alloc();
>>> return name;
>>> }
>>>
>>> kmem_cache_dup()
>>> {
>>> name = memcg_cache_name();
>>> kmem_cache_create_memcg(name);
>>> free(name);
>>> }
>>>
>>> Isn't this a short lived allocation?
>>>
>>
>> Hi,
>>
>> Thanks for identifying and fixing this.
>>
>> Li is right. The cache name will live long, but this is because the
>> slab/slub caches will strdup it internally. So the actual memcg
>> allocation is short lived.
>
> OK, I have totally missed that. Sorry about the confusion. Then all the
> churn around the allocation is pointless, no?
> What about:

If we're really not concerned about stack, then yes. Even if always
running from workqueues, a PAGE_SIZEd stack variable seems risky to me.

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