linux-kernel - Re: [PATCH v5 17/19] mm: memcg/slab: use a single set of kmem

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <d7cdecbc-db24-8ced-1a86-6f4534613763@suse.cz>
Date:   Fri, 5 Jun 2020 18:24:33 +0200
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Roman Gushchin <guro@...com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Lameter <cl@...ux.com>
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Shakeel Butt <shakeelb@...gle.com>, linux-mm@...ck.org,
        kernel-team@...com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 17/19] mm: memcg/slab: use a single set of kmem_caches
 for all allocations

On 5/28/20 12:34 AM, Roman Gushchin wrote:
> diff --git a/mm/slab.h b/mm/slab.h
> index c49a863adb63..57b425d623e5 100644
> --- a/mm/slab.h
> +++ b/mm/slab.h
...
> @@ -526,8 +430,7 @@ static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x)
>  	 * When kmemcg is not being used, both assignments should return the
>  	 * same value. but we don't want to pay the assignment price in that
>  	 * case. If it is not compiled in, the compiler should be smart enough
> -	 * to not do even the assignment. In that case, slab_equal_or_root
> -	 * will also be a constant.
> +	 * to not do even the assignment.
>  	 */
>  	if (!memcg_kmem_enabled() &&

Just realized that this test can go away - we don't have to call virt_to_cache()
due to kmemcg if there is just a single cache.

>  	    !IS_ENABLED(CONFIG_SLAB_FREELIST_HARDENED) &&
> @@ -535,7 +438,7 @@ static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x)
>  		return s;
>  
>  	cachep = virt_to_cache(x);
> -	WARN_ONCE(cachep && !slab_equal_or_root(cachep, s),
> +	WARN_ONCE(cachep && cachep != s,
>  		  "%s: Wrong slab cache. %s but object is from %s\n",
>  		  __func__, s->name, cachep->name);
>  	return cachep;