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

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Message-ID: <Z8+yggwrcYZXmnd0@phytium.com.cn>
Date: Tue, 11 Mar 2025 11:48:18 +0800
From: Yuquan Wang <wangyuquan1236@...tium.com.cn>
To: Alison Schofield <alison.schofield@...el.com>
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 11:13:32AM -0700, Alison Schofield wrote:
> 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?
Yes.
> 
> 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?
>
Sure. Thanks for your suggestion.
> 
> 
> >  	last_real_pxm = fake_pxm;
> >  	fake_pxm++;
> >  	acpi_table_parse_cedt(ACPI_CEDT_TYPE_CFMWS, acpi_parse_cfmws,
> > -- 
> > 2.34.1
> >