Re: [PATCH] mm/slab: simplify SLAB_* flag handling

[Christoph Lameter (Ampere)]

On Fri, 17 Jan 2025, Kevin Brodsky wrote:

> index a29457bef626..3b07cdaac3ae 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -305,18 +305,6 @@ struct kmem_cache *__kmem_cache_create_args(const char *name,
>  		goto out_unlock;
>  	}
>
> -	/* Refuse requests with allocator specific flags */
> -	if (flags & ~SLAB_FLAGS_PERMITTED) {
> -		err = -EINVAL;
> -		goto out_unlock;
> -	}

I think we should keep checking for invalid flags.
 -
> -	/*
> -	 * Some allocators will constraint the set of valid flags to a subset
> -	 * of all flags. We expect them to define CACHE_CREATE_MASK in this
> -	 * case, and we'll just provide them with a sanitized version of the
> -	 * passed flags.
> -	 */
>  	flags &= CACHE_CREATE_MASK;

This would silently clear some flags instead of creating an error.