linux-kernel - Re: [PATCH v4 1/7] mm/zone_device: Add order argument to folio

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Message-ID: <aWQlsyIVVGpCvB3y@casper.infradead.org>
Date: Sun, 11 Jan 2026 22:35:31 +0000
From: Matthew Wilcox <willy@...radead.org>
To: Francois Dugast <francois.dugast@...el.com>
Cc: intel-xe@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
	Matthew Brost <matthew.brost@...el.com>, Zi Yan <ziy@...dia.com>,
	Madhavan 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>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Logan Gunthorpe <logang@...tatee.com>,
	David Hildenbrand <david@...nel.org>,
	Oscar Salvador <osalvador@...e.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jason Gunthorpe <jgg@...pe.ca>, Leon Romanovsky <leon@...nel.org>,
	Balbir Singh <balbirs@...dia.com>,
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	Vlastimil Babka <vbabka@...e.cz>, Mike Rapoport <rppt@...nel.org>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Michal Hocko <mhocko@...e.com>,
	Alistair Popple <apopple@...dia.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-pci@...r.kernel.org, linux-mm@...ck.org,
	linux-cxl@...r.kernel.org
Subject: Re: [PATCH v4 1/7] mm/zone_device: Add order argument to folio_free
 callback

On Sun, Jan 11, 2026 at 09:55:40PM +0100, Francois Dugast wrote:
> The core MM splits the folio before calling folio_free, restoring the
> zone pages associated with the folio to an initialized state (e.g.,
> non-compound, pgmap valid, etc...). The order argument represents the
> folio’s order prior to the split which can be used driver side to know
> how many pages are being freed.

This really feels like the wrong way to fix this problem.

I think someone from the graphics side really needs to take the lead on
understanding what the MM is doing (both currently and in the future).
I'm happy to work with you, but it feels like there's a lot of churn right
now because there's a lot of people working on this without understanding
the MM side of things (and conversely, I don't think (m)any people on the
MM side really understand what graphics cards are trying to accomplish).

Who is that going to be?  I'm happy to get on the phone with someone.