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[99.254.144.39]) by smtp.gmail.com with ESMTPSA id w13-20020ae9e50d000000b0077407e3d68asm729062qkf.111.2023.10.03.13.21.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Oct 2023 13:21:44 -0700 (PDT) Date: Tue, 3 Oct 2023 16:21:41 -0400 From: Peter Xu To: Suren Baghdasaryan Cc: Lokesh Gidra , David Hildenbrand , Jann Horn , akpm@linux-foundation.org, viro@zeniv.linux.org.uk, brauner@kernel.org, shuah@kernel.org, aarcange@redhat.com, hughd@google.com, mhocko@suse.com, axelrasmussen@google.com, rppt@kernel.org, willy@infradead.org, Liam.Howlett@oracle.com, zhangpeng362@huawei.com, bgeffon@google.com, kaleshsingh@google.com, ngeoffray@google.com, jdduke@google.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH v2 2/3] userfaultfd: UFFDIO_REMAP uABI Message-ID: References: <85e5390c-660c-ef9e-b415-00ee71bc5cbf@redhat.com> <9434ef94-15e8-889c-0c31-3e875060a2f7@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspamd-Queue-Id: 4E71A40026 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: x1k7tezshkzqicwpiwidmcpsndcu8ggc X-HE-Tag: 1696364508-932627 X-HE-Meta: U2FsdGVkX19DzqI3ZrYLajFRCqfvhlhBZfxA29JKFu49gmbuFVEDbq2UUl5otQT3vR/J7xfZLW+sgzRKcHh0yDO8D+ZrqGMKC1/MLL1mV8SQB98bnBFwrBDRC5OxZ88nOl/EoIJ8vCEHwmhnBXwbMFLZf1yTAUV38ARI4Jw2hKc37vOM8fOWoBeC84KmxdUnYRP+lx0+a5d2jNCykXehT9+SOBZtfG/lLM2ubU2JwTRiqyFQjQkEH64trUhysfmUIZYGlXZ6jnkZscVm24WBf1ZVzIYEODW+ewvyp095Z0VnfKcCRBeTMp/jB9UyBwFpY+g66+b1fjRS9k1gnZSju6o/dIeDc+0HjWmAGj3SHjrexFoSIIfhrHpEAXN3WYJ2RC3sV0/N5xn1XCfw4TPtwDXpkVjWsjZbAI/Wc7lqQakjraDmd3QCqqBtKEsY4qgjv8XwHNh6p7w721xm3A2Mk7gAZdQgJ3/X/6o2UnuRtsrsKgaHhARg6Sr3be9KtKgrMQy37BLznNCoHvP8t6sW0pALLwlTNbrf92ryUusumJT6ycYqjfCYJD9JqZ4l/6p9lzLxux1OIlaAIae7zHelgxUXVHAgySt6SmQw5wG6ZtYVpjs9im1Z4N5SGwzCSGQMN7d9jTjLJRy/tZtljVfiRk1MUXe/gyx4kxMxBExjUU5czgZJAnE/DLdJFuOC8KMondD3Sh3QLHHbN0IOT0flFXEJoX0wWg9QpjRXga1fTlC4xdJE0aKiFpBQl2CgkxQiIn9144xAbE5PPdHesTZWAnfFWc7Ov+ceSGCp1Iz9KNwGo/Lxv2ckrA9xwU4jrGcqGvVgjepExg1hWaHmk1lD16i+LadqxwD/KIswz/sU43DayqTpRQUjKXUM9eKNs0IyrHAmyGE5Ud04nfJULE8MGGCIWpRwbc9kiw2PM01Vixw/YHG+em7rgX7LvpUSZnLE+TpKr/eD3qJ5oKs2zIq K56gA9JT xHVu3ho9rp2Y8eYOPhHDQ706lZhJw3nKelDYu+S+Erc0Ox3+vhJTsnwaJkqE8Dwe9CCTWTyHHHFVvdxrhKBFOV79GXDmlO8+DSedF8zhGO+H8gUc2GNjzuIckaXbplyy734MIiaIZEdnOE23v+j4B5xtnscCrgq906U499wpGYxvSPMzB8LtM060nx6ik+LognS12OeS7BClX6PtMQQhXe9K/wDTm390oxrW4hdyeMbDr/YNxxYi/n6i7SK32q8qGVpALp1pKWW3k3UabUUMASA/PyxNlq+8Whvfl94UXTrZ+cppEc6uXwG0u/eyVeCNiZix/83L30llyq6OzR7gVD385NthPdlifrWZ3OctMQjfB1INvRQE1RbUBoZddg3TzewAkHW0+Xl9pj0X+JNXhZILkXge7B5gnOuJB X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Oct 03, 2023 at 01:04:44PM -0700, Suren Baghdasaryan wrote: > Ok, I think it makes sense to implement the strict remap logic but in > a way that we can easily add copy fallback if that's needed in the > future. So, I'll change UFFDIO_REMAP to UFFDIO_MOVE and will return > some unique error, like EBUSY when the page is not PAE. If we need to > add a copy fallback in the future, we will add a > UFFDIO_MOVE_MODE_ALLOW_COPY flag and will implement the copy > mechanism. Does that sound good? For the clear failing approach, sounds all good here. For the name, no strong opinion, but is there any strong one over MOVE? MOVE is a fine name, however considering UFFDIO_REMAP's long history.. I tend to prefer keeping it called as REMAP - it still sounds sane, and anyone who knows REMAP will know this is exactly that. Thanks, -- Peter Xu