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 23E2AC83F17 for ; Tue, 15 Jul 2025 14:05:12 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ubgFb-0001Ym-7K; Tue, 15 Jul 2025 10:03:19 -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 1ubfe5-0004TV-Jc; Tue, 15 Jul 2025 09:24:33 -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 1ubfe3-0000IV-6e; Tue, 15 Jul 2025 09:24:33 -0400 Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id C5D154086E; Tue, 15 Jul 2025 15:24:18 +0200 (CEST) Message-ID: <0fb6eb67-2ebb-4042-a5d4-8c679baed4ac@proxmox.com> Date: Tue, 15 Jul 2025 15:24:17 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 00/48] block: do not drain while holding the graph lock To: Kevin Wolf Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org, den@virtuozzo.com, andrey.drobyshev@virtuozzo.com, hreitz@redhat.com, stefanha@redhat.com, eblake@redhat.com, jsnow@redhat.com, vsementsov@yandex-team.ru, xiechanglong.d@gmail.com, wencongyang2@huawei.com, berto@igalia.com, fam@euphon.net, ari@tuxera.com References: <20250530151125.955508-1-f.ebner@proxmox.com> Content-Language: en-US From: Fiona Ebner 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, RCVD_IN_MSPIKE_H2=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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 14.07.25 um 15:43 schrieb Kevin Wolf: > Am 01.07.2025 um 19:16 hat Kevin Wolf geschrieben: >> Am 30.05.2025 um 17:10 hat Fiona Ebner geschrieben: >>> This series is an attempt to fix a deadlock issue reported by Andrey >>> here [3]. >>> >>> bdrv_drained_begin() polls and is not allowed to be called with the >>> block graph lock held. Mark the function as GRAPH_UNLOCKED. >>> >>> This alone does not catch the issue reported by Andrey, because there >>> is a bdrv_graph_rdunlock_main_loop() before bdrv_drained_begin() in >>> the function bdrv_change_aio_context(). That unlock is of course >>> ineffective if the exclusive lock is held, but it prevents TSA from >>> finding the issue. >>> >>> Thus the bdrv_drained_begin() call from inside >>> bdrv_change_aio_context() needs to be moved up the call stack before >>> acquiring the locks. This is the bulk of the series. >>> >>> Granular draining is not trivially possible, because many of the >>> affected functions can recursively call themselves. >>> >>> In place where bdrv_drained_begin() calls were removed, assertions >>> are added, checking the quiesced_counter to ensure that the nodes >>> already got drained further up in the call stack. >> >> I finished review for this series. I had some minor comments on patches >> 24, 27 and 41. Once we agree what to do there, I can probably just make >> any changes myself while applying. > > I don't see any objections, so I just applied this and made all the > changes I had suggested. Sorry, for not responding anymore. I was on vacation for a while and will still be busy with other stuff in the coming weeks. The changes you suggested sound good to me, thanks! Best Regards, Fiona