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Date: Thu, 16 Aug 2012 09:40:10 +0300
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Subject: Re: [PATCH v3] mm: Restructure kmem_cache_create() to move debug
 cache integrity checks into a new function
From: Pekka Enberg <penberg@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: shuah.khan@hp.com, "Christoph Lameter (Open Source)" <cl@linux.com>,
        glommer@parallels.com, js1304@gmail.com,
        David Rientjes <rientjes@google.com>, linux-mm@kvack.org,
        LKML <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>, shuahkhan@gmail.com
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On Thu, Aug 16, 2012 at 2:53 AM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Sun, 12 Aug 2012 10:40:18 -0600
> Shuah Khan <shuah.khan@hp.com> wrote:
>
>> kmem_cache_create() does cache integrity checks when CONFIG_DEBUG_VM
>> is defined. These checks interspersed with the regular code path has
>> lead to compile time warnings when compiled without CONFIG_DEBUG_VM
>> defined. Restructuring the code to move the integrity checks in to a new
>> function would eliminate the current compile warning problem and also
>> will allow for future changes to the debug only code to evolve without
>> introducing new warnings in the regular path. This restructuring work
>> is based on the discussion in the following thread:
>
> Your patch appears to be against some ancient old kernel, such as 3.5.
> I did this:
>
> --- a/mm/slab_common.c~mm-slab_commonc-restructure-kmem_cache_create-to-move-debug-cache-integrity-checks-into-a-new-function-fix
> +++ a/mm/slab_common.c
> @@ -101,15 +101,8 @@ struct kmem_cache *kmem_cache_create(con
>
>         get_online_cpus();
>         mutex_lock(&slab_mutex);
> -
> -       if (kmem_cache_sanity_check(name, size))
> -               goto oops;
> -
> -       s = __kmem_cache_create(name, size, align, flags, ctor);
> -
> -#ifdef CONFIG_DEBUG_VM
> -oops:
> -#endif
> +       if (kmem_cache_sanity_check(name, size) == 0)
> +               s = __kmem_cache_create(name, size, align, flags, ctor);
>         mutex_unlock(&slab_mutex);
>         put_online_cpus();

Yup. Shuah, care to spin another version against slab/next?