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Wed, 24 Jun 2026 00:12:32 -0700 (PDT) Received: from localhost ([212.73.77.104]) by smtp.gmail.com with UTF8SMTPSA id ffacd0b85a97d-46c1ee0189esm4296531f8f.9.2026.06.24.00.12.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 24 Jun 2026 00:12:32 -0700 (PDT) From: Askar Safin To: avagin@gmail.com Cc: akpm@linux-foundation.org, alexander@mihalicyn.com, axboe@kernel.dk, bernd@bsbernd.com, brauner@kernel.org, criu@lists.linux.dev, david@kernel.org, dhowells@redhat.com, fuse-devel@lists.linux.dev, hch@infradead.org, jack@suse.cz, joannelkoong@gmail.com, 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, rostedt@goodmis.org, safinaskar@gmail.com, torvalds@linux-foundation.org, val@packett.cool, viro@zeniv.linux.org.uk, willy@infradead.org Subject: Re: [PATCH 0/3] vmsplice: make vmsplice a trivial wrapper for preadv2/pwritev2 Date: Wed, 24 Jun 2026 10:12:26 +0300 Message-ID: <20260624071226.2272209-1-safinaskar@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 65E73100003 X-Rspam-User: X-Stat-Signature: h7zu8iksrmmbc538aauob93ssi939wwj X-HE-Tag: 1782285154-125635 X-HE-Meta: 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 04xFafVT 6vvZn2ck26qc7uL4HhptnW43FXi+CLQFUpc66k2NGZVsD6fJFMSRV8yUFm0T/qt2k6O502S2cBOifoGKqPM1FPA38EdvrN3agfN/YEv7hv1V5HHiOqhLvzT+5QMCKk6zH+J1GrhGAfsWzOhjzyb14cZCSVVyB1H31hReOnMEk1kXoOMKBBvXLvollHsUrpmuuduBnFRqVKf5sws7/Z5TL6iZRf1CN5TunoSkHj8DGyj2GZYPilkKNwsp69IHaEu1VEmSRX9zUQ0VYqmJuLvpYNsBiGewt3hyEDpdH1OsF1+HIR89qzG0aXekCf28fU213B8mfItHRDZLX2mIYM8TJoyWyxs4hJxGKuXEIyvwHJq7ix0pYZP/2EE/Z2PaTXHlOO2cL6guqBCF3SK1abLA02esW4Akel8QE4wXG Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Andrei Vagin : > The CRIU fifo test fails with this change. The problem is that vmsplice > with SPLICE_F_NONBLOCK to a fifo file descriptor fails with -EOPNOTSUPP. > > It seems we need a fix like this one: > > diff --git a/fs/pipe.c b/fs/pipe.c > index 429b0714ec57..6fc49e933727 100644 > --- a/fs/pipe.c > +++ b/fs/pipe.c > @@ -1253,6 +1253,7 @@ static int fifo_open(struct inode *inode, struct > file *filp) > > /* We can only do regular read/write on fifos */ > stream_open(inode, filp); > + filp->f_mode |= FMODE_NOWAIT; > > switch (filp->f_mode & (FMODE_READ | FMODE_WRITE)) { > case FMODE_READ: Does CRIU actually rely on ability to do SPLICE_F_NONBLOCK vmsplice into named fifos? Or this is merely a test? If this is just a test, I think we need not to preserve this behavior. I did debian code search with regex "vmsplice.*SPLICE_F_NONBLOCK" and I found very few packages. And it seems all them use pipes, not named fifos. (On speed: I still think that my vmsplice patches are good thing, despite performance regressions in CRIU.) -- Askar Safin