linux-kernel - Re: [PATCH 3/4] ACPI/MRRM: Add "node" symlink to /sys/devices/system/memory/rangeX

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <2025021231-panhandle-stonewall-ba3e@gregkh>
Date: Wed, 12 Feb 2025 08:48:41 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: "Luck, Tony" <tony.luck@...el.com>
Cc: "Moore, Robert" <robert.moore@...el.com>,
	"Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
	Len Brown <lenb@...nel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"acpica-devel@...ts.linux.dev" <acpica-devel@...ts.linux.dev>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"x86@...nel.org" <x86@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
	David Hildenbrand <david@...hat.com>,
	Oscar Salvador <osalvador@...e.de>,
	Danilo Krummrich <dakr@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/4] ACPI/MRRM: Add "node" symlink to
 /sys/devices/system/memory/rangeX

On Tue, Feb 11, 2025 at 05:02:11PM +0000, Luck, Tony wrote:
> >> +	if (node)
> >> +		ret = sysfs_create_link(&entry->dev.kobj, &node->dev.kobj, "node");
> >
> > What is going to remove this symlink if the memory goes away?  Or do
> > these never get removed?
> 
> There's currently no method for runtime changes to these memory ranges. They
> are described by a static ACPI table.  I need to poke the folks that came up
> with this to ask how memory hotplug will be handled (since CXL seems to be
> making that fashionable again).

ACPI should be supporting memory hotplug today, at the very least
"memory add", so surely you have some old boxes to test this with?

> > symlinks in sysfs created like this always worry me.  What is going to
> > use it?
> 
> <hand waves>User space tools that want to understand what the "per-region"
> monitoring and control features are actually operating on.</hand waves>

If you don't have a real user today, please don't include it now.  Wait
until it is actually needed.

thanks,

greg k-h