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(p200300d82f250700d84615f36ca08029.dip0.t-ipconnect.de. [2003:d8:2f25:700:d846:15f3:6ca0:8029]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-45dd0595af9sm100737155e9.2.2025.09.08.08.50.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 08 Sep 2025 08:50:20 -0700 (PDT) Message-ID: <3229ac90-943f-4574-a9b8-bd4f5fa6cf03@redhat.com> Date: Mon, 8 Sep 2025 17:50:18 +0200 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 03/16] mm: add vma_desc_size(), vma_desc_pages() helpers From: David Hildenbrand To: Jason Gunthorpe Cc: Lorenzo Stoakes , Andrew Morton , Jonathan Corbet , Matthew Wilcox , Guo Ren , Thomas Bogendoerfer , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , "David S . 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So we should check exactly that, not >>> whether we might have a cow mapping. >> >> secretmem is checking shared for a different reason than many other places.. > > I think many cases just don't want any private mappings. > > After all, you need a R/O file (VM_MAYWRITE cleared) mapped MAP_PRIVATE > to make is_cow_mapping() == false. Sorry, was confused there. R/O file does not matter with MAP_PRIVATE. I think we default to VM_MAYWRITE with MAP_PRIVATE unless someone explicitly clears it. So in practice there is indeed not a big difference between a private and cow mapping. -- Cheers David / dhildenb