Re: [PATCH] mm/slab.c: use 'ac' from the caller

[Matthew Wilcox]

On Wed, Apr 21, 2021 at 10:25:17AM +0800, Yejune Deng wrote:
> @@ -3045,12 +3044,7 @@ static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
>  	}
>  
>  	STATS_INC_ALLOCMISS(cachep);
> -	objp = cache_alloc_refill(cachep, flags);
> -	/*
> -	 * the 'ac' may be updated by cache_alloc_refill(),
> -	 * and kmemleak_erase() requires its correct value.
> -	 */
> -	ac = cpu_cache_get(cachep);
> +	objp = cache_alloc_refill(cachep, ac, flags);

I think passing 'ac' in is fine (probably?  I don't know this code
deeply), but deleting this call to 'ac' is clearly wrong.  The comment
even tells you that!  I just verified the code, and the comment is
correct.