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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1ucltU-00000007NL5-3jwd; Fri, 18 Jul 2025 14:17:00 +0000 Date: Fri, 18 Jul 2025 15:17:00 +0100 From: Matthew Wilcox To: Yonatan Maman Cc: =?iso-8859-1?B?Suly9G1l?= Glisse , Andrew Morton , Jason Gunthorpe , Leon Romanovsky , Lyude Paul , Danilo Krummrich , David Airlie , Simona Vetter , Alistair Popple , Ben Skeggs , Michael Guralnik , Or Har-Toov , Daisuke Matsuda , Shay Drory , linux-mm@kvack.org, linux-rdma@vger.kernel.org, dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org, linux-kernel@vger.kernel.org, Gal Shalom Subject: Re: [PATCH v2 1/5] mm/hmm: HMM API to enable P2P DMA for device private pages Message-ID: References: <20250718115112.3881129-1-ymaman@nvidia.com> <20250718115112.3881129-2-ymaman@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250718115112.3881129-2-ymaman@nvidia.com> X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 1CF6440010 X-Stat-Signature: g7t3sta9t167584od64tccwoib9dwfns X-Rspam-User: X-HE-Tag: 1752848226-920967 X-HE-Meta: U2FsdGVkX1+t5YDzqr+DI+lecDY4AbkBeNfRd9vJz68cLDSPlCn3TvJqhlIDfxvaoXjcAQpotwZdKFKp/sZ4HnIo3q0nthTpckXZsO0k3U5eQMc67xEkd8I2f784YrHmZXXZgIvu/UNQMYZugVnvoO+d6pk0ojG+WVJWQ25/PotxJ2eDUb0WhyHDwcMaM2YIwEBB3YZ91RqwHMTr1s+0hM6uNg9sF8e1tieii3a3UgT+jGnAhb0Bty9N2GLFrq+786Q9s0Pyby/nHT99QtQxDVEJoH4Cl215IIm7w2ye71p41MapgNT8tkVQqoHRuDQsLPTRXEi41qdDVkR5Tg4qOrs53S58/k9Yx83lIIgwIro0Lo89vzrsa6No3fbTK4zN1DlMiFjZqvFWG5QfyvBvq+7ertqFfqs88DUmEeIPlRlFL8UQXhU6ZGFwPG+fcnDkVFdiStbbNPag7pCXaSCvLzr5ZGojvTNkaW3IC1966E9rfZzhpaK7USYZdLeYhoCvP1ZODDsr2/ZRRJpvcFUhMGDfjl74nWj4wXOs3CxDaeGWY1a1kyB88wW3jnJGoxKwujZ1rbGWW5hKGCO7/6wCth36nTV5U2Z5/lFtZP1+lbUUAM0DVhxI+HBipFk8pcX7d0rRmf2+HLD3Ma0bL62QtK7zVTs1rkxRWxvE8SCqpePkqSz4dJL7nJUcCt8aZmdwci3Q5TFORXDQFbarmGjcbjsICgWG39pctBInaoJFlopT7E0l5jPdO8Nk9AFPkuLg3R1XkDJ9L+3AGO5SgeR96q738MTnAQ0tFduXmxOyJD+M7ZZthZc8u157OUUJ228nitWmXyhjF4EdBdbl8DLCmOHVI1KplBwK3tpdCM6RMoq7MkvXJ7I2cplKe7NPopW5/vxLFcmnoXoSsyfxvjVYM70nB466fOsii7p3ZnuvzWTtz5KtBHuA/6v1et1OjTNQ+1VJyTaAcH6ItCbMqZg RZsp9kuf L7Myjb0aOiYsaNM1cYnEun504Mmniz3bVlYzYFgh+SRurgR1N25JU4U8lh1E29tMjmOJxz+MshPxBPVj+7C+kSt6qDYDoTfttF8pYt+g+ACtha10OLvTKzLP+mosICRYnS9JLhay9xWCQSmQ= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Jul 18, 2025 at 02:51:08PM +0300, Yonatan Maman wrote: > +++ b/include/linux/memremap.h > @@ -89,6 +89,14 @@ struct dev_pagemap_ops { > */ > vm_fault_t (*migrate_to_ram)(struct vm_fault *vmf); > > + /* > + * Used for private (un-addressable) device memory only. Return a > + * corresponding PFN for a page that can be mapped to device > + * (e.g using dma_map_page) > + */ > + int (*get_dma_pfn_for_device)(struct page *private_page, > + unsigned long *dma_pfn); This makes no sense. If a page is addressable then it has a PFN. If a page is not addressable then it doesn't have a PFN.