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

From: Benjamin Herrenschmidt <[email-masked]>
Date: Fri, 29 Jun 2012 10:45:20 +1000

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

Ben.