Subject: Re: [PATCH powerpc 2/2] kfree the cache name of pgtable cache if SLUB is used

From: Zhong Li <[email-masked]>
Date: Fri, 29 Jun 2012 09:41:33 +0800

On 06/29/2012 08:45 AM, Benjamin Herrenschmidt wrote:
> On Mon, 2012-06-25 at 17:54 +0800, Li Zhong wrote:
> 
>> diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
>> index 620b7ac..c9d2a7f 100644
>> --- a/arch/powerpc/mm/init_64.c
>> +++ b/arch/powerpc/mm/init_64.c
>> @@ -130,6 +130,9 @@ void pgtable_cache_add(unsigned shift, void
>> (*ctor)(void *))
>>  	align = max_t(unsigned long, align, minalign);
>>  	name = kasprintf(GFP_KERNEL, "pgtable-2^%d", shift);
>>  	new = kmem_cache_create(name, table_size, align, 0, ctor);
>> +#ifdef CONFIG_SLUB
>> +	kfree(name); /* SLUB duplicates the cache name */
>> +#endif
>>  	PGT_CACHE(shift) = new;
>>  
>>  	pr_debug("Allocated pgtable cache for order %d\n", shift);
> 
> This is very gross ... and fragile. Also the subtle difference in
> semantics between SLUB and SLAB is a VERY BAD IDEA.

I agree.

> I reckon you should make the other allocators all copy the name
> instead.

Thank you for the suggestion. I will do it in the next version.

Thanks, Zhong

> Ben.