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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Christian Brauner , Richard Cochran , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , linux-fsdevel@vger.kernel.org, linux-perf-users@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, Oleg Nesterov , Jason Gunthorpe Subject: Re: [PATCH v2] mm/gup: disallow GUP writing to file-backed mappings by default Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 88DCB16001D X-Stat-Signature: 4cz3fyjug6arifh7di34dbn5np44si5k X-HE-Tag: 1682329442-134972 X-HE-Meta: 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 Mq6T5MHO NJ+PeD4BR9+3Qi/wXCFcCOjbjbk2I6+WLJBl+1ePU6iln/H6F+0HQ98UvFyC18nttGJeS7rvgp1uerG7vQMq6cqxmbolWZH8zONYjvGv5v8WZe8Tlro4RfoJ23HD9AV7TogQiCjdCXMfI5AlVCTXe/iFdc41cqa3sqPeQQTcVQGLEhcXkjyR+WbOMvyslpybPY1Wt6oEINvmMfKnDTBnEAEEyrSvM2Ek2vtJJTU4hv/PU17habxixYCRe3FITHGmG0HXj6eRVW+SvvjyjNxaqsQFWBwf3V6q/+YdB7n26ST6hXZd2MUHofABWKtyTU45moZOIdj5vMQi1bxta61bqEd+L9AWgXMjQWRvzif9XhKH3MGKY3trxzKi8Exziz4XHLl7UpKayenlFxz9+y88EQ6TJJ31VYtEI2XwIQVl23gq9g49HBY5KcGrS2AAwCvwEbnSzBI0V+g1CxrY= 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: I'm pretty sure DIRECT I/O reads that write into file backed mappings are out there in the wild. So while I wish we had never allowed this, the exercise seems futile and instead we need to work on supporting this usecase, with the FOLL_PIN infrastructure being a big step toward that.