Re: [PATCH -next 2/2] mm/kasan: simplify is_kmalloc check

[Feng Tang]

On Mon, Nov 21, 2022 at 09:50:24PM +0800, Tang, Feng wrote:
> Use new is_kmalloc_cache() to simplify the code of checking whether
> a kmem_cache is a kmalloc cache.
> 
> Signed-off-by: Feng Tang <feng.tang@xxxxxxxxx>
> ---
>  include/linux/kasan.h | 9 ---------
>  mm/kasan/common.c     | 9 ++-------
>  mm/slab_common.c      | 1 -
>  3 files changed, 2 insertions(+), 17 deletions(-)
> 
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index dff604912687..fc46f5d6f404 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -102,7 +102,6 @@ struct kasan_cache {
>  	int alloc_meta_offset;
>  	int free_meta_offset;
>  #endif
> -	bool is_kmalloc;
>  };
>  
>  void __kasan_unpoison_range(const void *addr, size_t size);
> @@ -129,13 +128,6 @@ static __always_inline bool kasan_unpoison_pages(struct page *page,
>  	return false;
>  }
>  
> -void __kasan_cache_create_kmalloc(struct kmem_cache *cache);
> -static __always_inline void kasan_cache_create_kmalloc(struct kmem_cache *cache)
> -{
> -	if (kasan_enabled())
> -		__kasan_cache_create_kmalloc(cache);
> -}
> -
>  void __kasan_poison_slab(struct slab *slab);
>  static __always_inline void kasan_poison_slab(struct slab *slab)
>  {
> @@ -252,7 +244,6 @@ static inline void kasan_poison_pages(struct page *page, unsigned int order,
>  				      bool init) {}
>  static inline bool kasan_unpoison_pages(struct page *page, unsigned int order,
>  					bool init) { return false; }
> -static inline void kasan_cache_create_kmalloc(struct kmem_cache *cache) {}
>  static inline void kasan_poison_slab(struct slab *slab) {}
>  static inline void kasan_unpoison_object_data(struct kmem_cache *cache,
>  					void *object) {}
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index 1f30080a7a4c..f7e0e5067e7a 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -122,11 +122,6 @@ void __kasan_poison_pages(struct page *page, unsigned int order, bool init)
>  			     KASAN_PAGE_FREE, init);
>  }
>  
> -void __kasan_cache_create_kmalloc(struct kmem_cache *cache)
> -{
> -	cache->kasan_info.is_kmalloc = true;
> -}
> -
>  void __kasan_poison_slab(struct slab *slab)
>  {
>  	struct page *page = slab_page(slab);
> @@ -326,7 +321,7 @@ void * __must_check __kasan_slab_alloc(struct kmem_cache *cache,
>  	kasan_unpoison(tagged_object, cache->object_size, init);
>  
>  	/* Save alloc info (if possible) for non-kmalloc() allocations. */
> -	if (kasan_stack_collection_enabled() && !cache->kasan_info.is_kmalloc)
> +	if (kasan_stack_collection_enabled() && is_kmalloc_cache(cache))

Sorry, it should be: 

 -	if (kasan_stack_collection_enabled() && !cache->kasan_info.is_kmalloc)
 +	if (kasan_stack_collection_enabled() && !is_kmalloc_cache(cache))

Thanks,
Feng

>  		kasan_save_alloc_info(cache, tagged_object, flags);
>  
>  	return tagged_object;
> @@ -372,7 +367,7 @@ static inline void *____kasan_kmalloc(struct kmem_cache *cache,
>  	 * Save alloc info (if possible) for kmalloc() allocations.
>  	 * This also rewrites the alloc info when called from kasan_krealloc().
>  	 */
> -	if (kasan_stack_collection_enabled() && cache->kasan_info.is_kmalloc)
> +	if (kasan_stack_collection_enabled() && is_kmalloc_cache(cache))
>  		kasan_save_alloc_info(cache, (void *)object, flags);
>  
>  	/* Keep the tag that was set by kasan_slab_alloc(). */
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index 8276022f0da4..a5480d67f391 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -663,7 +663,6 @@ struct kmem_cache *__init create_kmalloc_cache(const char *name,
>  
>  	create_boot_cache(s, name, size, flags | SLAB_KMALLOC, useroffset,
>  								usersize);
> -	kasan_cache_create_kmalloc(s);
>  	list_add(&s->list, &slab_caches);
>  	s->refcount = 1;
>  	return s;
> -- 
> 2.34.1
>