linux-kernel - Re: [PATCH] mm: provide interface for retrieving kmem

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Date:   Thu, 7 Nov 2019 12:58:06 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Knut Omang <knut.omang@...cle.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] mm: provide interface for retrieving kmem_cache name

On Thu 07-11-19 12:54:04, Knut Omang wrote:
> With the restructuring done in commit 9adeaa226988
> ("mm, slab: move memcg_cache_params structure to mm/slab.h")
> 
> it is no longer possible for code external to mm to access
> the name of a kmem_cache as struct kmem_cache has effectively become
> opaque. Having access to the cache name is helpful to kernel testing
> infrastructure.
> 
> Expose a new function kmem_cache_name to mitigate that.

Who is going to use that symbol? It is preferred that a user is added in
the same patch as the newly added symbol.

> Signed-off-by: Knut Omang <knut.omang@...cle.com>
> ---
>  include/linux/slab.h | 1 +
>  mm/slab_common.c     | 9 +++++++++
>  2 files changed, 10 insertions(+)
> 
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 4d2a2fa55ed5..3298c9db6e46 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -702,6 +702,7 @@ static inline void *kzalloc_node(size_t size, gfp_t flags, int node)
>  }
>  
>  unsigned int kmem_cache_size(struct kmem_cache *s);
> +const char *kmem_cache_name(struct kmem_cache *s);
>  void __init kmem_cache_init_late(void);
>  
>  #if defined(CONFIG_SMP) && defined(CONFIG_SLAB)
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index f9fb27b4c843..269a99dc8214 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -82,6 +82,15 @@ unsigned int kmem_cache_size(struct kmem_cache *s)
>  }
>  EXPORT_SYMBOL(kmem_cache_size);
>  
> +/*
> + * Get the name of a slab object
> + */
> +const char *kmem_cache_name(struct kmem_cache *s)
> +{
> +	return s->name;
> +}
> +EXPORT_SYMBOL(kmem_cache_name);
> +
>  #ifdef CONFIG_DEBUG_VM
>  static int kmem_cache_sanity_check(const char *name, unsigned int size)
>  {
> -- 
> 2.20.1

-- 
Michal Hocko
SUSE Labs