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From: Nathan Lynch <nathanl@linux.ibm.com>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
 Michael Ellerman <mpe@ellerman.id.au>
Subject: Re: [PATCH 1/2] powerpc/numa: Limit possible nodes to within
 num_possible_nodes
In-Reply-To: <20200715120534.3673-1-srikar@linux.vnet.ibm.com>
References: <871rljfet9.fsf@linux.ibm.com>
 <20200715120534.3673-1-srikar@linux.vnet.ibm.com>
Date: Tue, 21 Jul 2020 22:14:14 -0500
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Cc: Tyrel Datwyler <tyreld@linux.ibm.com>,
 linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
 Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
 Michael Ellerman <michaele@au1.ibm.com>
Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org
Sender: "Linuxppc-dev"
 <linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org>

Srikar Dronamraju <srikar@linux.vnet.ibm.com> writes:
> MAX_NUMNODES is a theoretical maximum number of nodes thats is supported
> by the kernel. Device tree properties exposes the number of possible
> nodes on the current platform. The kernel would detected this and would
> use it for most of its resource allocations.  If the platform now
> increases the nodes to over what was already exposed, then it may lead
> to inconsistencies. Hence limit it to the already exposed nodes.
>
> Suggested-by: Nathan Lynch <nathanl@linux.ibm.com>
> Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
> Cc: Michael Ellerman <michaele@au1.ibm.com>
> Cc: Nathan Lynch <nathanl@linux.ibm.com>
> Cc: Tyrel Datwyler <tyreld@linux.ibm.com>
> Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> ---
>  arch/powerpc/mm/numa.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> index 8ec7ff05ae47..a2c5fe0d0cad 100644
> --- a/arch/powerpc/mm/numa.c
> +++ b/arch/powerpc/mm/numa.c
> @@ -221,7 +221,7 @@ static void initialize_distance_lookup_table(int nid,
>  	}
>  }
>  
> -/* Returns nid in the range [0..MAX_NUMNODES-1], or -1 if no useful numa
> +/* Returns nid in the range [0..num_possible_nodes()-1], or -1 if no useful numa
>   * info is found.
>   */
>  static int associativity_to_nid(const __be32 *associativity)
> @@ -235,7 +235,7 @@ static int associativity_to_nid(const __be32 *associativity)
>  		nid = of_read_number(&associativity[min_common_depth], 1);
>  
>  	/* POWER4 LPAR uses 0xffff as invalid node */
> -	if (nid == 0xffff || nid >= MAX_NUMNODES)
> +	if (nid == 0xffff || nid >= num_possible_nodes())
>  		nid = NUMA_NO_NODE;
>  
>  	if (nid > 0 &&
> @@ -448,7 +448,7 @@ static int of_drconf_to_nid_single(struct drmem_lmb *lmb)
>  		index = lmb->aa_index * aa.array_sz + min_common_depth - 1;
>  		nid = of_read_number(&aa.arrays[index], 1);
>  
> -		if (nid == 0xffff || nid >= MAX_NUMNODES)
> +		if (nid == 0xffff || nid >= num_possible_nodes())
>  			nid = default_nid;
>  
>  		if (nid > 0) {

Yes, looks fine to me.

Reviewed-by: Nathan Lynch <nathanl@linux.ibm.com>