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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: Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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