linux-kernel - Re: [PATCH] ACPI: NUMA: debug invalid unused PXM value for CFMWs

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Message-ID: <Z88rzKHrqlCXQOTb@aschofie-mobl2.lan>
Date: Mon, 10 Mar 2025 11:13:32 -0700
From: Alison Schofield <alison.schofield@...el.com>
To: Yuquan Wang <wangyuquan1236@...tium.com.cn>
Cc: rafael@...nel.org, lenb@...nel.org, Jonathan.Cameron@...wei.com,
	dan.j.williams@...el.com, rrichter@....com, bfaccini@...dia.com,
	haibo1.xu@...el.com, dave.jiang@...el.com, rppt@...nel.org,
	gourry@...rry.net, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-cxl@...r.kernel.org,
	chenbaozi@...tium.com.cn
Subject: Re: [PATCH] ACPI: NUMA: debug invalid unused PXM value for CFMWs

On Mon, Mar 10, 2025 at 05:39:10PM +0800, Yuquan Wang wrote:
> The absence of SRAT would cause the fake_pxm to be -1 and increment
> to 0, then send to acpi_parse_cfmws(). If there exists CXL memory
> ranges that are defined in the CFMWS and not already defined in the
> SRAT, the new node (node0) for the CXL memory would be invalid, as
> node0 is already in "used".


If no SRAT or bad SRAT, then all memory is at node:0, and first fake
node for CFMWs should start at 1. Right?

If so, might it be safest to always start the the CFMWS fake nodes at
at a minimum of node[1]. Maybe srat_disabled() can be used to decide.

> 
> Signed-off-by: Yuquan Wang <wangyuquan1236@...tium.com.cn>
> ---
>  drivers/acpi/numa/srat.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/acpi/numa/srat.c b/drivers/acpi/numa/srat.c
> index 00ac0d7bb8c9..eb8628e217fa 100644
> --- a/drivers/acpi/numa/srat.c
> +++ b/drivers/acpi/numa/srat.c
> @@ -646,6 +646,9 @@ int __init acpi_numa_init(void)
>  		if (node_to_pxm_map[i] > fake_pxm)
>  			fake_pxm = node_to_pxm_map[i];
>  	}
> +	if (fake_pxm == PXM_INVAL)
> +		pr_warn("Failed to find the next unused PXM value for CFMWs\n");
> +

How come it is sufficient to just warn?
As per my comment above, can we adjust?



>  	last_real_pxm = fake_pxm;
>  	fake_pxm++;
>  	acpi_table_parse_cedt(ACPI_CEDT_TYPE_CFMWS, acpi_parse_cfmws,
> -- 
> 2.34.1
>