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[2003:cb:c705:1e00:8d67:f75a:a8ae:dc02]) by smtp.gmail.com with ESMTPSA id bg18-20020a05600c3c9200b0037c2ef07493sm14954074wmb.3.2022.03.07.02.12.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 07 Mar 2022 02:12:45 -0800 (PST) Message-ID: Date: Mon, 7 Mar 2022 11:12:44 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH RFC 0/3] MAP_POPULATE for device memory Content-Language: en-US To: Jarkko Sakkinen , linux-mm@kvack.org Cc: Dave Hansen , Nathaniel McCallum , Reinette Chatre , Andrew Morton , linux-sgx@vger.kernel.org, linux-kernel@vger.kernel.org, Florian Fainelli , Thomas Bogendoerfer , Matthew Auld , =?UTF-8?Q?Thomas_Hellstr=c3=b6m?= , Daniel Vetter , Jason Ekstrand , Chris Wilson , Maarten Lankhorst , Greg Kroah-Hartman , Tvrtko Ursulin , Vasily Averin , Shakeel Butt , Michal Hocko , zhangyiru , Alexey Gladkov , Alexander Mikhalitsyn , linux-mips@vger.kernel.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, codalist@coda.cs.cmu.edu, linux-unionfs@vger.kernel.org, linux-fsdevel@vger.kernel.org References: <20220306053211.135762-1-jarkko@kernel.org> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20220306053211.135762-1-jarkko@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-unionfs@vger.kernel.org On 06.03.22 06:32, Jarkko Sakkinen wrote: > For device memory (aka VM_IO | VM_PFNMAP) MAP_POPULATE does nothing. Allow > to use that for initializing the device memory by providing a new callback > f_ops->populate() for the purpose. > > SGX patches are provided to show the callback in context. > > An obvious alternative is a ioctl but it is less elegant and requires > two syscalls (mmap + ioctl) per memory range, instead of just one > (mmap). What about extending MADV_POPULATE_READ | MADV_POPULATE_WRITE to support VM_IO | VM_PFNMAP (as well?) ? -- Thanks, David / dhildenb