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Subject: Re: [BUG] SLOB's krealloc() seems bust
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Matt Mackall <mpm@selenic.com>
Cc: Christoph Lameter <cl@linux-foundation.org>, linux-mm <linux-mm@kvack.org>,
       Nick Piggin <nickpiggin@yahoo.com.au>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Ingo Molnar <mingo@elte.hu>,
       linux-kernel <linux-kernel@vger.kernel.org>
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Date: Tue, 07 Oct 2008 18:10:45 +0200
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On Tue, 2008-10-07 at 10:00 -0500, Matt Mackall wrote:
> Give this a try, please:
> 
> diff -r 5e32b09a1b2b mm/slob.c
> --- a/mm/slob.c Fri Oct 03 14:04:43 2008 -0500
> +++ b/mm/slob.c Tue Oct 07 10:00:16 2008 -0500
> @@ -515,7 +515,7 @@
>  
>         sp = (struct slob_page *)virt_to_page(block);
>         if (slob_page(sp))
> -               return ((slob_t *)block - 1)->units + SLOB_UNIT;
> +               return (((slob_t *)block - 1)->units - 1) * SLOB_UNIT;
>         else
>                 return sp->page.private;
>  }

That seems to make it work again! (4 reboots, 0 crashes)

Tested-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

Thanks!