From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DDD71C4332F for ; Fri, 3 Nov 2023 13:22:03 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qyu6a-0004MK-Uv; Fri, 03 Nov 2023 09:20:56 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qyu6Z-0004M5-Su; Fri, 03 Nov 2023 09:20:55 -0400 Received: from proxmox-new.maurer-it.com ([94.136.29.106]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qyu6Y-0001gy-1a; Fri, 03 Nov 2023 09:20:55 -0400 Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id 63657442A9; Fri, 3 Nov 2023 14:20:51 +0100 (CET) Message-ID: <7534e14e-df32-4772-99d2-335c486ddd72@proxmox.com> Date: Fri, 3 Nov 2023 14:20:50 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: deadlock when using iothread during backup_clean() Content-Language: en-US From: Fiona Ebner To: Kevin Wolf Cc: Vladimir Sementsov-Ogievskiy , Paolo Bonzini , QEMU Developers , Hanna Reitz , John Snow , "open list:Network Block Dev..." , Thomas Lamprecht References: <44ff810b-8ec6-0f11-420a-6efa2c7c2475@proxmox.com> <2ca4eb06-75c3-7bd8-972b-b37af47743dc@yandex-team.ru> <71e3112d-3d3f-fd55-4099-6765d4f22205@proxmox.com> <76f9678d-ed92-418e-8d1e-c6dc55f83279@proxmox.com> <3e1c941b-2b76-4f85-88cb-4a2a968eb3e6@proxmox.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=94.136.29.106; envelope-from=f.ebner@proxmox.com; helo=proxmox-new.maurer-it.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Am 20.10.23 um 15:52 schrieb Fiona Ebner: > And I found that with drive-mirror, the issue during starting seems to > manifest with the bdrv_open() call. Adding a return before it, the guest > IO didn't get stuck in my testing, but adding a return after it, it can > get stuck. I'll try to see if I can further narrow it down next week, > but maybe that's already a useful hint? > In the end, I was able to find a reproducer that just does draining and bisected the issue (doesn't seem related to the graph lock after all). I replied there, to avoid all the overhead from this thread: https://lists.nongnu.org/archive/html/qemu-devel/2023-11/msg00681.html Best Regards, Fiona