linux-kernel - Re: [PATCH v6 1/5] mm/zone_device: Reinitialize large zone device private folios

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Message-ID: <20260122142959.GA1569362@nvidia.com>
Date: Thu, 22 Jan 2026 10:29:59 -0400
From: Jason Gunthorpe <jgg@...dia.com>
To: Matthew Brost <matthew.brost@...el.com>
Cc: Zi Yan <ziy@...dia.com>, Balbir Singh <balbirs@...dia.com>,
	Matthew Wilcox <willy@...radead.org>,
	Alistair Popple <apopple@...dia.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Francois Dugast <francois.dugast@...el.com>,
	intel-xe@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
	adhavan Srinivasan <maddy@...ux.ibm.com>,
	Nicholas Piggin <npiggin@...il.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	"Christophe Leroy (CS GROUP)" <chleroy@...nel.org>,
	Felix Kuehling <Felix.Kuehling@....com>,
	Alex Deucher <alexander.deucher@....com>,
	Christian König <christian.koenig@....com>,
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	Lyude Paul <lyude@...hat.com>, Danilo Krummrich <dakr@...nel.org>,
	David Hildenbrand <david@...nel.org>,
	Oscar Salvador <osalvador@...e.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Leon Romanovsky <leon@...nel.org>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	"Liam R . Howlett" <Liam.Howlett@...cle.com>,
	Mike Rapoport <rppt@...nel.org>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Michal Hocko <mhocko@...e.com>, linuxppc-dev@...ts.ozlabs.org,
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
	amd-gfx@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
	linux-mm@...ck.org, linux-cxl@...r.kernel.org
Subject: Re: [PATCH v6 1/5] mm/zone_device: Reinitialize large zone device
 private folios

On Wed, Jan 21, 2026 at 11:19:45PM -0800, Matthew Brost wrote:
> - Why is Intel the only one proving this stuff works? We can debate all
>   day about what should or should not work — but someone else needs to
>   actually prove it.i, rather than type hypotheticals.

Oh come on, NVIDIA has done an *enormous* amount of work to get these
things to this point where they are actually getting close to
functional and usable.

Don't "Oh poor intel" me :P

> - Intel has demonstrated that this works and is still getting blocked.

We generally don't merge patches because they "works for me". The
issue is the thing you presented is very ugly and inefficient, and
when we start talking about the right way to do it you get all
defensive and disappear.

> - Given the current state of the discussion, I don’t think large device
>   pages should be in 6.19. And if so, why didn’t the entire device pages
>   series receive this level of scrutiny earlier? It’s my mistake for not
>   saying “no” until the reallocation at different sizes issue was resolved.

It did, nobody noticed this bug or post something so obviously ugly :P

> @Andrew. - I'd revert large device pages in 6.19 as it doesn't work and
> we seemly cannot close on this.

What's the issue here? You said you were going to go ahead with the
ugly thing, go do it and come back with something better. That's what
you wanted, right?

Jason