From nobody Thu Mar 28 23:01:10 2024 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org ARC-Seal: i=1; a=rsa-sha256; t=1585151519; cv=none; d=zohomail.com; s=zohoarc; b=Rn8UBJOFIi9CeR6w26I+EfHPK8il942jynNW12gP7CqaRRI8dJklqKsgInSKiP/7sDy0W78ef2vcnm1wicgu8QLrieVC00YV6iD8df+YfjT6UBwgbgmTqMv6JpyLruvgO+0Tir47fGDyOBjLYHsp/3LpMD/Ku7htTRpDaP/CzP0= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1585151519; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=7jBRC1vMo4Q/NJb/WlUanDtLBlvfrbxGI66wkLxKq00=; b=dzxXFWQVPgf1lW/iArp+ki9JaZXwEQddEk5nkZanXvvX/u39ZArHxN7j91LrqzU+7tpy50cI/WRwOl+tPEdbIbWm1FN04aC6ELXrwPYASGKyqbG1BYaaRRCksNa5wRL8GRyLhQev+zUMksQOpiVcwsPlE/M1zoc9k0xPJgQ+w5U= ARC-Authentication-Results: i=1; mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1585151519172117.45470718248703; Wed, 25 Mar 2020 08:51:59 -0700 (PDT) Received: from localhost ([::1]:38666 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jH8Jx-0003lG-2E for importer@patchew.org; Wed, 25 Mar 2020 11:51:57 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:46791) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jH8JL-0003IE-I3 for qemu-devel@nongnu.org; Wed, 25 Mar 2020 11:51:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jH8JK-0006OR-Ez for qemu-devel@nongnu.org; Wed, 25 Mar 2020 11:51:19 -0400 Received: from proxmox-new.maurer-it.com ([212.186.127.180]:62947) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1jH8JH-0006Em-VF; Wed, 25 Mar 2020 11:51:16 -0400 Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id 9FA8242E95; Wed, 25 Mar 2020 16:51:11 +0100 (CET) From: Stefan Reiter To: qemu-devel@nongnu.org, qemu-block@nongnu.org Subject: [PATCH] backup: don't acquire aio_context in backup_clean Date: Wed, 25 Mar 2020 16:50:55 +0100 Message-Id: <20200325155055.730633-1-s.reiter@proxmox.com> X-Mailer: git-send-email 2.25.2 In-Reply-To: <76edbead-7ccf-833b-a3f2-15dff7f0748c@virtuozzo.com> References: <76edbead-7ccf-833b-a3f2-15dff7f0748c@virtuozzo.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 212.186.127.180 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, vsementsov@virtuozzo.com, mreitz@redhat.com, stefanha@redhat.com, jsnow@redhat.com, dietmar@proxmox.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" backup_clean is only ever called as a handler via job_exit, which already acquires the job's context. The job's context is guaranteed to be the same as the one used by backup_top via backup_job_create. Since the previous logic effectively acquired the lock twice, this broke cleanup of backups for disks using IO threads, since the BDRV_POLL_WH= ILE in bdrv_backup_top_drop -> bdrv_do_drained_begin would only release the lock once, thus deadlocking with the IO thread. Signed-off-by: Stefan Reiter --- This is a fix for the issue discussed in this part of the thread: https://lists.gnu.org/archive/html/qemu-devel/2020-03/msg07639.html ...not the original problem (core dump) posted by Dietmar. I've still seen it occasionally hang during a backup abort. I'm trying to f= igure out why that happens, stack trace indicates a similar problem with the main thread hanging at bdrv_do_drained_begin, though I have no clue why as of ye= t. block/backup.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/block/backup.c b/block/backup.c index 7430ca5883..a7a7dcaf4c 100644 --- a/block/backup.c +++ b/block/backup.c @@ -126,11 +126,7 @@ static void backup_abort(Job *job) static void backup_clean(Job *job) { BackupBlockJob *s =3D container_of(job, BackupBlockJob, common.job); - AioContext *aio_context =3D bdrv_get_aio_context(s->backup_top); - - aio_context_acquire(aio_context); bdrv_backup_top_drop(s->backup_top); - aio_context_release(aio_context); } =20 void backup_do_checkpoint(BlockJob *job, Error **errp) --=20 2.25.2