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Wed, 03 Jun 2026 16:01:27 -0700 (PDT) Received: from localhost ([212.73.77.104]) by smtp.gmail.com with UTF8SMTPSA id 5b1f17b1804b1-490b7e6c6a4sm45890145e9.2.2026.06.03.16.01.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 03 Jun 2026 16:01:26 -0700 (PDT) From: Askar Safin To: luto@amacapital.net Cc: akpm@linux-foundation.org, axboe@kernel.dk, brauner@kernel.org, david@kernel.org, dhowells@redhat.com, hch@infradead.org, jack@suse.cz, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, miklos@szeredi.hu, netdev@vger.kernel.org, patches@lists.linux.dev, pfalcato@suse.de, safinaskar@gmail.com, torvalds@linux-foundation.org, viro@zeniv.linux.org.uk, willy@infradead.org Subject: Re: [PATCH 0/3] vmsplice: make vmsplice a trivial wrapper for preadv2/pwritev2 Date: Thu, 4 Jun 2026 02:00:25 +0300 Message-ID: <20260603230122.851517-1-safinaskar@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 1A11A40012 X-Stat-Signature: 5qpfn7euyfjisypgrjqbr93cqqfqypho X-Rspam-User: X-HE-Tag: 1780527688-992844 X-HE-Meta: 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 y2cEud8D 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Andy Lutomirski : > On Wed, Jun 3, 2026 at 3:43 PM Askar Safin wrote: > > Finally, we can degrade tee(2) to copy, and hopefully this will > > allow us to always be sure that pipe buffers are not shared with anything. > > This is possible future direction. > > I'm a bit nervous that, if I've read the code correctly (a big if), > then iscsi and nvme will still send *shared* buffers via > MSG_SPLICE_PAGES, but that normal user code will not be able to do > this, and that something will bitrot. As well as I understand you correctly, you mean that if we remove tee(2), then there still will be subsystems, which will be able to send shared pages. Yes, I totally agree. So, if we remove tee(2), then we will probably need to remove all non-standard implementations of pipe_buf_operations. -- Askar Safin