Re: [PATCH] ACPI: add a boot parameter to disable parsing CFMWS during NUMA init

[Gregory Price]

On Thu, Mar 05, 2026 at 12:18:05PM +0800, Haifeng Xu wrote:
> On 2026/3/5 01:16, Gregory Price wrote:
> > On Wed, Mar 04, 2026 at 04:06:47PM +0800, Haifeng Xu wrote:
> 
> Every memcg records shrinker info for each possible node. If we use online node
> instead of possible node，then during memory hotplug, we must tarverse all memcgs
> and shrinkers to check whether corresponding node has allocated the shrinker_info.
> This way introduces more complexity.
>

Right, but some systems might actually WANT this many nodes, and this
does not scale well at all as-is.  I also don't think it's as complex as
you think, most of the infrastructure is already there.

> > If you're not actually using CXL, can't you just disable CXL in the
> > BIOS?  Then you shouldn't even emit CFMWS at all.
> 
> I have asked our Intel Support Engineer, he saied that cxl can't be disabled
> in BIOS.
> 

Huh, this is surprising.

If this is the case then see Dan's patch here:
https://lore.kernel.org/linux-cxl/1f5074979a58803ec875dd10c9234c7b1a17192d.camel@xxxxxxxxx/T/#m0d64b723a63ca7faf44311c52c1ebd5f280ae626

That should deal with your issue more cleanly.

Otherwise, the problem you're describing here really should really be
fixed with either better lock scoping or lazy-allocation.

(Already poking at the issue a bit)

~Gregory