[RFC PATCH 4/8] arch_numa: Avoid onlining empty NUMA nodes

[Yuquan Wang]

On Wed, May 29, 2024 at 06:12:32PM +0100, Jonathan Cameron wrote:
> ACPI can declare NUMA nodes for memory that will be along later.
> CXL Fixed Memory Windows may also be assigned NUMA nodes that
> are initially empty.  Currently the generic arch_numa handling will
> online these empty nodes. This is both inconsistent with x86 and
> with itself as if we add memory and remove it again the node goes
> away.
> 
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron at huawei.com>
> ---
>  drivers/base/arch_numa.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/base/arch_numa.c b/drivers/base/arch_numa.c
> index 5b59d133b6af..0630efb696ab 100644
> --- a/drivers/base/arch_numa.c
> +++ b/drivers/base/arch_numa.c
> @@ -363,6 +363,11 @@ static int __init numa_register_nodes(void)
>  		unsigned long start_pfn, end_pfn;
>  
>  		get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);
> +		if (start_pfn >= end_pfn &&
> +		    !node_state(nid, N_CPU) &&
> +		    !node_state(nid, N_GENERIC_INITIATOR))
> +			continue;
> +
>  		setup_node_data(nid, start_pfn, end_pfn);
>  		node_set_online(nid);
>  	}
> -- 
> 2.39.2
>

Tested-off-by: Yuquan Wang <wangyuquan1236 at phytium.com.cn>