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[85.214.156.166]) by gmr-mx.google.com with ESMTPS id n9si10767ljj.8.2021.08.17.06.02.23 for (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Tue, 17 Aug 2021 06:02:23 -0700 (PDT) Received-SPF: pass (google.com: domain of amikan@ilbers.de designates 85.214.156.166 as permitted sender) client-ip=85.214.156.166; Authentication-Results: gmr-mx.google.com; spf=pass (google.com: domain of amikan@ilbers.de designates 85.214.156.166 as permitted sender) smtp.mailfrom=amikan@ilbers.de Received: from [192.168.67.164] (mm-146-26-214-37.mgts.dynamic.pppoe.byfly.by [37.214.26.146] (may be forged)) (authenticated bits=0) by shymkent.ilbers.de (8.15.2/8.15.2/Debian-8) with ESMTPSA id 17HD2LuK008491 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 17 Aug 2021 15:02:22 +0200 Subject: Re: [PATCH v1 3/5] dpkg: Remove unmount loop To: Jan Kiszka , isar-users@googlegroups.com References: <20210707163851.204296-1-amikan@ilbers.de> <20210707163851.204296-4-amikan@ilbers.de> <18078814-c9c0-b46b-af32-17058c39f036@siemens.com> From: Anton Mikanovich Message-ID: <96a7a839-7b1e-61a9-1aed-184aafcfd6ba@ilbers.de> Date: Tue, 17 Aug 2021 16:02:16 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <18078814-c9c0-b46b-af32-17058c39f036@siemens.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Spam-Status: No, score=-1.0 required=5.0 tests=ALL_TRUSTED autolearn=unavailable autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on shymkent.ilbers.de X-TUID: zvlT28qmYRuX 08.07.2021 15:21, Jan Kiszka wrote: > On 07.07.21 18:38, Anton Mikanovich wrote: >> Remove while loop when trying to unmount WORKDIR. Any failures of >> umount should be investigated to fix the root cause. >> Also make dpkg_undo_mounts do not fail if dpkg_do_mounts was not >> called or it was called twice. >> > This is very likely wrong: We know from the past (should be in the git > history, e.g 17d0842d) that not all subprocesses started inside the > chroot may have been terminated when we left it. That can cause > significant delays between returning from chroot and finding non-busy > mount points to complete all umounts. Now, if you silently fail umounts, > you may find inconsistently mounted chroots on the next recipe that > tries to remount them. Big fat warning sign...! > > Jan We've reproduced the issue fixed by 17d0842d on the old code (pre-17d0842d). The issue was caused by unmounting buildchroot mounts without care of their usage. The latest v5 patchset is not affected, because there is no global task fail handling, and per-task unmount is protected by the reference counting. Moreover, buildchroot_undo_mounts was moved after the while loop in dpkg_undo_mounts in v5, so it will not fail immediately like we had it with '/sys/fs/cgroups is busy' failures (the real fix of '/sys/fs/cgroups is busy' is still in progress). -- Anton Mikanovich Promwad Ltd. External service provider of ilbers GmbH Maria-Merian-Str. 8 85521 Ottobrunn, Germany +49 (89) 122 67 24-0 Commercial register Munich, HRB 214197 General Manager: Baurzhan Ismagulov