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Date: Wed, 01 Apr 2015 15:07:13 +0530
From: Preeti U Murthy <preeti@linux.vnet.ibm.com>
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To: Jan Stancek <jstancek@redhat.com>, linuxppc-dev@lists.ozlabs.org,
 mpe@ellerman.id.au
Subject: Re: [PATCH] powerpc: fix memory corruption by
 pnv_alloc_idle_core_states
References: <67174f780b3615749546d5a6d5bfba4c4f26a855.1427818011.git.jstancek@redhat.com>
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On 03/31/2015 09:41 PM, Jan Stancek wrote:
> Space allocated for paca is based off nr_cpu_ids,
> but pnv_alloc_idle_core_states() iterates paca with
> cpu_nr_cores()*threads_per_core, which is using NR_CPUS.
> 
> This causes pnv_alloc_idle_core_states() to write over memory,
> which is outside of paca array and may later lead to various panics.
> 
> Fixes: 7cba160ad789 (powernv/cpuidle: Redesign idle states management)
> Signed-off-by: Jan Stancek <jstancek@redhat.com>
> ---
>  arch/powerpc/include/asm/cputhreads.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/include/asm/cputhreads.h b/arch/powerpc/include/asm/cputhreads.h
> index 2bf8e93..4c8ad59 100644
> --- a/arch/powerpc/include/asm/cputhreads.h
> +++ b/arch/powerpc/include/asm/cputhreads.h
> @@ -55,7 +55,7 @@ static inline cpumask_t cpu_thread_mask_to_cores(const struct cpumask *threads)
> 
>  static inline int cpu_nr_cores(void)
>  {
> -	return NR_CPUS >> threads_shift;
> +	return nr_cpu_ids >> threads_shift;
>  }

Thanks for the patch!

Reviewed-by: Preeti U. Murthy <preeti@linux.vnet.ibm.com>
> 
>  static inline cpumask_t cpu_online_cores_map(void)
>