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Received: from authenticated user by stravinsky.debian.org with esmtpsa (TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.94.2) (envelope-from ) id 1sClGN-003Mdp-CQ; Thu, 30 May 2024 19:16:36 +0000 Date: Thu, 30 May 2024 21:16:32 +0200 From: Emanuele Rocca To: David Howells Cc: Andrea Righi , Jeff Layton , Steve French , Matthew Wilcox , Paulo Alcantara , Dominique Martinet , Eric Van Hensbergen , Christian Brauner , linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, v9fs@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Latchesar Ionkov , Christian Schoenebeck , Luca Boccassi Subject: Re: [PATCH v5 40/40] 9p: Use netfslib read/write_iter Message-ID: References: <20231221132400.1601991-1-dhowells@redhat.com> <20231221132400.1601991-41-dhowells@redhat.com> <531994.1716450257@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <531994.1716450257@warthog.procyon.org.uk> X-Debian-User: ema X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 0E52F40014 X-Stat-Signature: apkmyrijoyzrk9znod6pt3y4uwf6y3zn X-HE-Tag: 1717096619-237818 X-HE-Meta: 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 YqJeAWpr keXAGRKse6w87VSgIBoUull1zR4hFdBrOlIOPa2vTBX8AS686bJrAAtD76Kskl4NK1apjzRJ6EN71eru1Vec4/GZ+6LhhNmLGz5AJcb2xswf5lV0RqgpX5uCmjX9Hp3l8sYlUJcdmj5EZLoiEN0qRPU++vEOZNL/KnRwN0xF+WI2lM2o28mCx/fkBjeMG92lcR4xjZ0tGRvY/VyLXmp7GOUXEqBNNosfyhFUfTxCygZuIU/ttbTftr5gCOuCY8kBlIM7s 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: List-Subscribe: List-Unsubscribe: Hi David, On 2024-05-23 08:44, David Howells wrote: > In https://bugs.launchpad.net/ubuntu/+source/autopkgtest/+bug/2056461 you say: > > | It seems that kernel 6.8 introduced a regression in the 9pfs related to > | caching and netfslib, that can cause some user-space apps to read content > | from files that is not up-to-date (when they are used in a producer/consumer > | fashion). > > Can you clarify how these files are being used? I don't know the details of the 9pfs operations involved, but still I wanted to mention that to reliably reproduce the issue on a Debian system one can run: autopkgtest-build-qemu unstable /tmp/sid.img autopkgtest -ddd -B dpdk -- autopkgtest-virt-qemu --debug --show-boot /tmp/sid.img If the kernel installed in the guest VM is affected by this problem, after a while the test hangs with something like: autopkgtest-virt-qemu: DBG: executing copydown /tmp/alog/tests-tree/ /tmp/autopkgtest.uG6tsJ/build.6QA/src/ [...] autopkgtest-virt-qemu: DBG: +>? Full logs at https://people.debian.org/~ema/1072004-6.10-rc1.log Part of the code mounting the 9pfs in case it helps is at: https://salsa.debian.org/ci-team/autopkgtest/-/blob/master/virt/autopkgtest-virt-qemu#L290 I could reproduce the issue with both 6.9.2 and 6.10-rc1.