linux-kernel - Re: [RFC PATCH v3 0/8] mm,numa: N_PRIVATE node isolation for device-managed memory

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Message-ID: <91015dcc-6164-4728-a512-1486333d7275@nvidia.com>
Date: Tue, 13 Jan 2026 14:24:40 +1100
From: Balbir Singh <balbirs@...dia.com>
To: Gregory Price <gourry@...rry.net>, dan.j.williams@...el.com
Cc: Yury Norov <ynorov@...dia.com>, linux-mm@...ck.org,
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Subject: Re: [RFC PATCH v3 0/8] mm,numa: N_PRIVATE node isolation for
 device-managed memory

On 1/13/26 12:30, Gregory Price wrote:
> On Mon, Jan 12, 2026 at 05:17:53PM -0800, dan.j.williams@...el.com wrote:
>>
>> I think what Balbir is saying is that the _PUBLIC is implied and can be
>> omitted. It is true that N_MEMORY[_PUBLIC] already indicates multi-zone
>> support. So N_MEMORY_PRIVATE makes sense to me as something that it is
>> distinct from N_{HIGH,NORMAL}_MEMORY which are subsets of N_MEMORY.
>> Distinct to prompt "go read the documentation to figure out why this
>> thing looks not like the others".
> 
> Ah, ack.  Will update for v4 once i give some thought to the compression
> stuff and the cgroups notes.
> 
> I would love if the ZONE_DEVICE folks could also chime in on whether the
> callback structures for pgmap and hmm might be re-usable here, but might
> take a few more versions to get the attention of everyone.
> 

I see ZONE_DEVICE as a parallel construct to N_MEMORY_PRIVATE. ZONE_DEVICE
is memory managed by devices and already isolated from the allocator. Do you
see a need for both? I do see the need for migration between the two, but
I suspect you want to have ZONE_DEVICE as a valid zone inside of N_MEMORY_PRIVATE?

Balbir