linux-kernel - Re: [PATCH v9 00/19] DCD: Add support for Dynamic Capacity Devices (DCD)

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Message-ID: <aYXr9u1Y50MBtEP6@gourry-fedora-PF4VCD3F>
Date: Fri, 6 Feb 2026 08:26:14 -0500
From: Gregory Price <gourry@...rry.net>
To: Alireza Sanaee <alireza.sanaee@...wei.com>
Cc: Jonathan Cameron <jonathan.cameron@...wei.com>,
	Ira Weiny <ira.weiny@...el.com>, Dave Jiang <dave.jiang@...el.com>,
	Fan Ni <fan.ni@...sung.com>,
	Dan Williams <dan.j.williams@...el.com>,
	Davidlohr Bueso <dave@...olabs.net>,
	Alison Schofield <alison.schofield@...el.com>,
	Vishal Verma <vishal.l.verma@...el.com>, linux-cxl@...r.kernel.org,
	nvdimm@...ts.linux.dev, linux-kernel@...r.kernel.org,
	Li Ming <ming.li@...omail.com>
Subject: Re: [PATCH v9 00/19] DCD: Add support for Dynamic Capacity Devices
 (DCD)

On Fri, Feb 06, 2026 at 11:01:30AM +0000, Alireza Sanaee wrote:
> On Thu, 5 Feb 2026 17:48:47 +0000
> Jonathan Cameron <jonathan.cameron@...wei.com> wrote:
> 
> I think both of these approaches are OK, but looking from developers
> perspective, if someone wants a specific memory for their workload, they
> should rather get a fd and play with it in whichever way they want. NUMA may
> not give that much flexibility. As a developer it would prefer 2. Though you
> may say oh dax then? not sure!

DAX or numa-aware memfd

If you want *specific* memory (a particular HPA/DPA range), tagged dax is
probably appropriate.

If you just want any old page from a particular chunk of HPA, then
probably some kind of numa-aware memfd would be simplest (though this
may require new interfaces, since memfd is not currently numa-aware).

We might be able to make private node work specifically with membind
policy on a VMA (not on a task).  That would probably be sufficient.

~Gregory