linux-kernel - Re: [PATCH v2 00/11] Remove device private pages from physical address space

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Message-ID: <20260107205404.GI293394@nvidia.com>
Date: Wed, 7 Jan 2026 16:54:04 -0400
From: Jason Gunthorpe <jgg@...dia.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Jordan Niethe <jniethe@...dia.com>, linux-mm@...ck.org,
	balbirs@...dia.com, matthew.brost@...el.com,
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
	david@...hat.com, ziy@...dia.com, apopple@...dia.com,
	lorenzo.stoakes@...cle.com, lyude@...hat.com, dakr@...nel.org,
	airlied@...il.com, simona@...ll.ch, rcampbell@...dia.com,
	mpenttil@...hat.com, willy@...radead.org,
	linuxppc-dev@...ts.ozlabs.org, intel-xe@...ts.freedesktop.org,
	Felix.Kuehling@....com
Subject: Re: [PATCH v2 00/11] Remove device private pages from physical
 address space

On Wed, Jan 07, 2026 at 12:06:08PM -0800, Andrew Morton wrote:

> >   2) Attempting to add the device private pages to the linear map at
> >      addresses beyond the actual physical memory causes issues on
> >      architectures like aarch64  - meaning the feature does not work there [0].
> 
> Can you better help us understand the seriousness of these problems? 
> How much are our users really hurting from this?

We think it is pretty serious, in the future HW support sense, as it
means real systems being built do not work :)

Also Willy and others were cheering this work on at LPC. I think the
possible followup to move DEVICE_PRIVATE from struct page and reduce
the memory allocation would be well celebrated.

The Intel Xe and AMD GPU teams are the two drivers most important to
be testing this as they consume the feature.

Jason