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Subject: Re: [bug] SLUB & freeing locks [was: Re: 2.6.23-rc1: known
	regressions with patches]
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Christoph Lameter <clameter@sgi.com>
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
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Date: Thu, 26 Jul 2007 20:17:52 +0200
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On Thu, 2007-07-26 at 11:10 -0700, Christoph Lameter wrote:
> 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>

Not something this clean, only my WIP slub-rt. I'll run this and do a
proper post of this fix.