Re: [PATCH] Problems with RAID 4/5/6 and kmem_cache

[Pekka Enberg <penberg@kernel.org>]

On Sun, Sep 22, 2013 at 12:56 AM, Christoph Lameter <cl@linux.com> wrote:
> On Thu, 19 Sep 2013, Jonathan Brassow wrote:
>
>> 4) kmem_cache_create(name="foo-a")
>> - This FAILS because kmem_cache_sanity_check colides with the existing
>>   name ("foo-a") associated with the non-removed cache.
>
> That should not happen. breakage you see will result. Oh. I see the move
> to common code resulted in the SLAB checks being used for SLUB.
>
> The following patch should fix this.
>
> Subject: slab_common: Do not check for duplicate slab names
>
> SLUB can alias multiple slab kmem_create_requests to one slab cache
> to save memory and increase the cache hotness. As a result the name
> of the slab can be stale. Only check the name for duplicates if we are
> in debug mode where we do not merge multiple caches.
>
> Signed-off-by: Christoph Lameter <cl@linux.com>
>
> Index: linux/mm/slab_common.c
> ===================================================================
> --- linux.orig/mm/slab_common.c 2013-09-20 11:49:13.052208294 -0500
> +++ linux/mm/slab_common.c      2013-09-21 16:55:23.097131481 -0500
> @@ -56,6 +56,7 @@
>                         continue;
>                 }
>
> +#if !defined(CONFIG_SLUB) || !defined(CONFIG_SLUB_DEBUG_ON)
>                 /*
>                  * For simplicity, we won't check this in the list of memcg
>                  * caches. We have control over memcg naming, and if there
> @@ -69,6 +70,7 @@
>                         s = NULL;
>                         return -EINVAL;
>                 }
> +#endif
>         }
>
>         WARN_ON(strchr(name, ' '));     /* It confuses parsers */

Applied to slab/urgent, thanks!

Do we need to come up with something less #ifdeffy for v3.13?

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