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Date: Thu, 26 Jul 2007 11:10:29 -0700 (PDT)
From: Christoph Lameter <clameter@sgi.com>
X-X-Sender: clameter@schroedinger.engr.sgi.com
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
cc: Ingo Molnar <mingo@elte.hu>,
       Michal Piotrowski <michal.k.k.piotrowski@gmail.com>,
       Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org
Subject: Re: [bug] SLUB & freeing locks [was: Re: 2.6.23-rc1: known regressions
 with patches]
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On Thu, 26 Jul 2007, Peter Zijlstra wrote:

> > Index: linux-2.6/mm/slub.c
> > ===================================================================
> > --- linux-2.6.orig/mm/slub.c
> > +++ linux-2.6/mm/slub.c
> > @@ -1131,6 +1131,7 @@ static void __free_slab(struct kmem_cach
> >  		slab_pad_check(s, page);
> >  		for_each_object(p, s, page_address(page))
> >  			check_object(s, page, p, 0);
> > +		ClearSlabDebug(page);
> >  	}
> >  
> >  	mod_zone_page_state(page_zone(page),
> > @@ -1169,7 +1170,6 @@ static void discard_slab(struct kmem_cac
> >  
> >  	atomic_long_dec(&n->nr_slabs);
> >  	reset_page_mapcount(page);
> > -	ClearSlabDebug(page);
> >  	__ClearPageSlab(page);
> >  	free_slab(s, page);
> >  }
> > 
> 
> Christoph, how about this bit, it looks to me like we clear SlabDebug()
> before we hit the last check in __free_slab().

Looks right. Have you tried to run a kernel with this change and 
"slub_debug"?

Acked-by: Christoph Lameter <clameter@sgi.com>