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[209.85.128.53]) by smtp.gmail.com with ESMTPSA id 6sm3037174ejj.164.2021.12.17.12.46.12 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 17 Dec 2021 12:46:12 -0800 (PST) Received: by mail-wm1-f53.google.com with SMTP id b73so2432163wmd.0 for ; Fri, 17 Dec 2021 12:46:12 -0800 (PST) X-Received: by 2002:a05:600c:1d97:: with SMTP id p23mr4080563wms.144.1639773961365; Fri, 17 Dec 2021 12:46:01 -0800 (PST) MIME-Version: 1.0 References: <20211217113049.23850-1-david@redhat.com> <20211217113049.23850-7-david@redhat.com> <54c492d7-ddcd-dcd0-7209-efb2847adf7c@redhat.com> <17bfb2fd-da51-1264-513f-f9e928ec36c6@redhat.com> In-Reply-To: <17bfb2fd-da51-1264-513f-f9e928ec36c6@redhat.com> From: Linus Torvalds Date: Fri, 17 Dec 2021 12:45:45 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v1 06/11] mm: support GUP-triggered unsharing via FAULT_FLAG_UNSHARE (!hugetlb) To: David Hildenbrand Cc: Linux Kernel Mailing List , Andrew Morton , Hugh Dickins , David Rientjes , Shakeel Butt , John Hubbard , Jason Gunthorpe , Mike Kravetz , Mike Rapoport , Yang Shi , "Kirill A . Shutemov" , Matthew Wilcox , Vlastimil Babka , Jann Horn , Michal Hocko , Nadav Amit , Rik van Riel , Roman Gushchin , Andrea Arcangeli , Peter Xu , Donald Dutile , Christoph Hellwig , Oleg Nesterov , Jan Kara , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , "open list:DOCUMENTATION" Content-Type: text/plain; charset="UTF-8" Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b=TiDJROI9; spf=pass (imf05.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.208.49 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org; dmarc=none X-Rspamd-Queue-Id: 75A46100037 X-Stat-Signature: 3ec6tnnfpgm6duy9rsg44xmx45frpwg5 X-Rspamd-Server: rspam04 X-HE-Tag: 1639773974-281463 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: On Fri, Dec 17, 2021 at 12:42 PM David Hildenbrand wrote: > > > Then somebody else modified that page, and you got exactly what you > > asked for - a COW event. The original R/O pin has the original page > > that it asked for, and can read it just fine. > > Where in the code did I ask for a COW event? I asked for a R/O pin, not > any kind of memory protection. Why didn't you ask for a shared pin, if that is what you want? We already support that. If you don't like the read-only pins, don't use them. It's that simple. Linus