linux-kernel - Re: 2.6.21-rc5-mm4 (SLUB)

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Date:	Wed, 04 Apr 2007 15:53:04 -0700
From:	Badari Pulavarty <pbadari@...il.com>
To:	Christoph Lameter <clameter@....com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: 2.6.21-rc5-mm4 (SLUB)

On Wed, 2007-04-04 at 11:22 -0700, Christoph Lameter wrote:
> On Wed, 4 Apr 2007, Christoph Lameter wrote:
> 
> > Yes. slub_debug=U. But user tracking may need to increase the slab 
> > size (depends on the padding available in the slab) to store the 
> > tracking information, so you may not get the same corruption.
> 
> Hummm U is switching off merging and you may need merging to trigger the 
> discovery of the overwrite.
> 
> Here is a patch to enable merging even while tracking slabs. This patch 
> should not be applied to mm. In general tracking requires knowing which
> slab the objects come from and merging looses that information.
> 
> Index: linux-2.6.21-rc5-mm4/mm/slub.c
> ===================================================================
> --- linux-2.6.21-rc5-mm4.orig/mm/slub.c	2007-04-04 11:19:29.000000000 -0700
> +++ linux-2.6.21-rc5-mm4/mm/slub.c	2007-04-04 11:19:35.000000000 -0700
> @@ -86,7 +86,7 @@
>  /*
>   * Set of flags that will prevent slab merging
>   */
> -#define SLUB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
> +#define SLUB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | \
>  		SLAB_TRACE | SLAB_DESTROY_BY_RCU)
>  
>  #define SLUB_MERGE_SAME (SLAB_DEBUG_FREE | SLAB_RECLAIM_ACCOUNT | \
> 

Here is the slub_debug=FU output with the above patch.

Thanks,
Badari



View attachment "slub_debug=FU" of type "text/plain" (36123 bytes)