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[47.55.120.4]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8b52a1b7d99sm342498985a.28.2025.11.28.09.51.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 28 Nov 2025 09:51:09 -0800 (PST) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1vP2ce-00000003Vf9-1jsT; Fri, 28 Nov 2025 13:51:08 -0400 Date: Fri, 28 Nov 2025 13:51:08 -0400 From: Jason Gunthorpe To: Jordan Niethe Cc: linux-mm@kvack.org, balbirs@nvidia.com, matthew.brost@intel.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, david@redhat.com, ziy@nvidia.com, apopple@nvidia.com, lorenzo.stoakes@oracle.com, lyude@redhat.com, dakr@kernel.org, airlied@gmail.com, simona@ffwll.ch, rcampbell@nvidia.com, mpenttil@redhat.com, willy@infradead.org Subject: Re: [RFC PATCH 6/6] mm: Remove device private pages from the physical address space Message-ID: <20251128175108.GG812105@ziepe.ca> References: <20251128044146.80050-1-jniethe@nvidia.com> <20251128044146.80050-7-jniethe@nvidia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251128044146.80050-7-jniethe@nvidia.com> On Fri, Nov 28, 2025 at 03:41:46PM +1100, Jordan Niethe wrote: > Introduce helpers: > > - device_private_page_to_offset() > - device_private_folio_to_offset() > > to take a given device private page / folio and return its offset within > the device private address space (this is essentially a PFN within the > device private address space). It would be nice if we rarely/never needed to see number space outside the pte itself or the internal helpers.. Like, I don't think there should be stuff like this: > entry = make_writable_migration_device_private_entry( > - page_to_pfn(page)); > + device_private_page_to_offset(page)); make_writable_migration_device_private_entry() should accept the struct page as the handle? If it really is needed I think it should have its own dedicated type and not be intermixed with normal pfns.. Jason