From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from stravinsky.debian.org (stravinsky.debian.org [82.195.75.108]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 577D37C6D5; Thu, 30 May 2024 19:17:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=82.195.75.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717096626; cv=none; b=IwzJW+fd+uhE5kNfsL2paDgAV/7X69UteQWjw/9huyaYPaMfHAfttfZrkakJSg6Mb3xbpQjLkY5XSThqK7Bnzyib4DJZ+GknaVN3SOLgeJUhwGk5GLIi3z/s9JHwGOYtyeG3nMc7RQTjEhqwOHBUk3PgaSfqGjvsZp3yAbwNntI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717096626; c=relaxed/simple; bh=x633Xo1sPJ/fWXz66nCdmoq39u/bEbd6iBe4RlJ3CZM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=owfkQFvRXgAEOmLVYRE1aaUMn4/cvMbo17bH1tvEJF0Ym3QjwHTShYJMh3VcIDmWR/CpTOeGDNFOxMMvVfgYe7TpgZ2gwB+cDaf8l+RL76KaadS+98OwlZMHTWNK2i0e3s9oxiF2Oz5pXgV0Cc+lqQhOQMuJpnMajGPEPkN4l5o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=debian.org; spf=none smtp.mailfrom=debian.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b=wO80Z9JT; arc=none smtp.client-ip=82.195.75.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=debian.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b="wO80Z9JT" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=debian.org; s=smtpauto.stravinsky; h=X-Debian-User:In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=lfx+tTR93fLZk+8tmXgXmXPxooSXIgmr48RKZPv6Tx8=; b=wO80Z9JTrWaFPPaW5/fAiO+04F BToKUsjARfJGAANPPESgc4Urtp+BdaJ42vrqQk/a15MbHLGOqiC+fVpq/V1PstuRp5EF6QKr+lT2Q R/91OnQ3slwCNyIO6YITdTReRNyjQlwPCHs/hdUUjY99jrEq9AZJyHjonKPYT5nk918UdT+AZNPSx LlENIvWRW1+gT6t0cTJC1OrcuivS7Up9UuLgJvolGY6ZX0uOpmX1KiXOOBXSEIeFZKJNAUgJFehaR jPl1uBsGeYn4+Ug7PskSxbcbB93JbCbveUiECqN9PgcNjtSHljt2oj4JP/A0VFrNSjvcf3Rm2aheD CWa0ybhQ==; 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> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 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.