linux-kernel - Re: [PATCH 3/3] x86/numa_emulation: restructures numa_nodes

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Date:   Mon, 10 Apr 2017 17:36:25 -0700 (PDT)
From:   David Rientjes <rientjes@...gle.com>
To:     Wei Yang <richard.weiyang@...il.com>
cc:     kirill@...temov.name, bp@...en8.de, tglx@...utronix.de,
        mingo@...hat.com, hpa@...or.com, tj@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] x86/numa_emulation: restructures numa_nodes_parsed
 from emulated nodes

On Tue, 11 Apr 2017, Wei Yang wrote:

> By emulating numa, it may contains more or less nodes than physical nodes.
> In numa_emulation(), numa_meminfo/numa_distance/__apicid_to_node is
> restructured according to emulated nodes, except numa_nodes_parsed.
> 
> This patch restructures numa_nodes_parsed from emulated nodes.
> 
> Signed-off-by: Wei Yang <richard.weiyang@...il.com>

Acked-by: David Rientjes <rientjes@...gle.com>

although there's a small nit: NODE_MASK_NONE is only used for 
initialization, this should be nodes_clear(numa_nodes_parsed) instead, but 
that would be up to the x86 maintainers to allow it.

> ---
>  arch/x86/mm/numa_emulation.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/arch/x86/mm/numa_emulation.c b/arch/x86/mm/numa_emulation.c
> index a6d01931b9a1..14f075fc4cc5 100644
> --- a/arch/x86/mm/numa_emulation.c
> +++ b/arch/x86/mm/numa_emulation.c
> @@ -391,6 +391,13 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt)
>  	/* commit */
>  	*numa_meminfo = ei;
>  
> +	/* Make sure numa_nodes_parsed only contains emulated nodes */
> +	numa_nodes_parsed = NODE_MASK_NONE;
> +	for (i = 0; i < ARRAY_SIZE(ei.blk); i++)
> +		if (ei.blk[i].start != ei.blk[i].end &&
> +		    ei.blk[i].nid != NUMA_NO_NODE)
> +			node_set(ei.blk[i].nid, numa_nodes_parsed);
> +
>  	/*
>  	 * Transform __apicid_to_node table to use emulated nids by
>  	 * reverse-mapping phys_nid.  The maps should always exist but fall