linux-kernel - Re: [PATCH 15/16] mm/slab_common: move definition of _

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Message-ID: <35ee9435-97b4-4161-b21c-15467b56d004@suse.cz>
Date:   Fri, 29 Jul 2022 13:47:23 +0200
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Hyeonggon Yoo <42.hyeyoo@...il.com>,
        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>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Joe Perches <joe@...ches.com>,
        Vasily Averin <vasily.averin@...ux.dev>,
        Matthew WilCox <willy@...radead.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH 15/16] mm/slab_common: move definition of __ksize() to
 mm/slab.h

On 7/12/22 15:39, Hyeonggon Yoo wrote:
> __ksize() is only called by KASAN. Remove export symbol and move
> definition to mm/slab.h as we don't want to grow its callers.
> 
> Signed-off-by: Hyeonggon Yoo <42.hyeyoo@...il.com>
> Reviewed-by: Vlastimil Babka <vbabka@...e.cz>

Nit: The subject and changelog should probably say declaration, not definition.

> ---
>  include/linux/slab.h |  1 -
>  mm/slab.h            |  2 ++
>  mm/slab_common.c     | 11 +----------
>  mm/slob.c            |  1 -
>  4 files changed, 3 insertions(+), 12 deletions(-)
> 
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 4ee5b2fed164..701fe538650f 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -187,7 +187,6 @@ int kmem_cache_shrink(struct kmem_cache *s);
>  void * __must_check krealloc(const void *objp, size_t new_size, gfp_t flags) __alloc_size(2);
>  void kfree(const void *objp);
>  void kfree_sensitive(const void *objp);
> -size_t __ksize(const void *objp);
>  size_t ksize(const void *objp);
>  #ifdef CONFIG_PRINTK
>  bool kmem_valid_obj(void *object);
> diff --git a/mm/slab.h b/mm/slab.h
> index 9193e9c1f040..ad634e02b3cb 100644
> --- a/mm/slab.h
> +++ b/mm/slab.h
> @@ -678,6 +678,8 @@ void free_large_kmalloc(struct folio *folio, void *object);
>  
>  #endif /* CONFIG_SLOB */
>  
> +size_t __ksize(const void *objp);
> +
>  static inline size_t slab_ksize(const struct kmem_cache *s)
>  {
>  #ifndef CONFIG_SLUB
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index c01c6b8f0d34..1f8db7959366 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -1003,15 +1003,7 @@ void kfree(const void *object)
>  }
>  EXPORT_SYMBOL(kfree);
>  
> -/**
> - * __ksize -- Uninstrumented ksize.
> - * @objp: pointer to the object
> - *
> - * Unlike ksize(), __ksize() is uninstrumented, and does not provide the same
> - * safety checks as ksize() with KASAN instrumentation enabled.
> - *
> - * Return: size of the actual memory used by @objp in bytes
> - */
> +/* Uninstrumented ksize. Only called by KASAN. */
>  size_t __ksize(const void *object)
>  {
>  	struct folio *folio;
> @@ -1026,7 +1018,6 @@ size_t __ksize(const void *object)
>  
>  	return slab_ksize(folio_slab(folio)->slab_cache);
>  }
> -EXPORT_SYMBOL(__ksize);
>  #endif /* !CONFIG_SLOB */
>  
>  gfp_t kmalloc_fix_flags(gfp_t flags)
> diff --git a/mm/slob.c b/mm/slob.c
> index 97a4d2407f96..91d6e2b19929 100644
> --- a/mm/slob.c
> +++ b/mm/slob.c
> @@ -584,7 +584,6 @@ size_t __ksize(const void *block)
>  	m = (unsigned int *)(block - align);
>  	return SLOB_UNITS(*m) * SLOB_UNIT;
>  }
> -EXPORT_SYMBOL(__ksize);
>  
>  int __kmem_cache_create(struct kmem_cache *c, slab_flags_t flags)
>  {