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 768EBFD8FCA for ; Thu, 26 Feb 2026 15:26:15 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vvdFI-0006Jc-Cq; Thu, 26 Feb 2026 10:25:44 -0500 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 1vvdFD-0006J9-Kw for qemu-devel@nongnu.org; Thu, 26 Feb 2026 10:25:40 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vvdF5-0005Kk-LK for qemu-devel@nongnu.org; Thu, 26 Feb 2026 10:25:36 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1772119530; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=P6T4+eVfHVZJh/RAPggWQOSXbIgtrPWNcXlWAC5T1zQ=; b=Sja5aka0jSTTkOZgpv5x7GWCjTVTND5Tw3ZD/QozvxzspO+IdZlpc34cn6udkJUyFt/3tc 3ZPztEs0bbZlYnFxwq+Yh/wIutWwW/P3FAR7EkPLJxC+L8fzpg6IG8brz/bm8mhQZLsCv5 QBFRbx6gu+2JYNrWiVxp8GA4tRUYwXk= Received: from mail-qk1-f199.google.com (mail-qk1-f199.google.com [209.85.222.199]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-447-zXa8h25QNPmczaX_70KiDA-1; Thu, 26 Feb 2026 10:25:28 -0500 X-MC-Unique: zXa8h25QNPmczaX_70KiDA-1 X-Mimecast-MFC-AGG-ID: zXa8h25QNPmczaX_70KiDA_1772119528 Received: by mail-qk1-f199.google.com with SMTP id af79cd13be357-8cb6291d95aso924909285a.1 for ; Thu, 26 Feb 2026 07:25:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1772119528; x=1772724328; darn=nongnu.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=P6T4+eVfHVZJh/RAPggWQOSXbIgtrPWNcXlWAC5T1zQ=; b=Hx9TQw0ZnwZAyG30N6n+t9RqpeelDkrPjj5KMY7Kb9AT1Iff0UIvEw3PCgB7l3iYdW K3F45BuOISt367q0K6+rGIdrYrr8DLmtKSeDYZD9cI16IlBdi9bqM/JKcCBkwQnXTtDz MGGHv7wMvqVj1cK6JNv4gS10nazEoI4ujBVFA9Y63fR1Dtj6hQIY5RbhviIcBWuLiEwI +ZxA66jAWEVgXIMHM1AYEGjo1bb9c0N9726JxWSDcMoZqjdmiTP87Y0xJci83+QuVWOw 7AA+HJjXzhducZdshshldKNJyt5q1RBfF/SlvGn9+JGdKfr3dUxEeuSipwpz47fWZxBc nTAQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1772119528; x=1772724328; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=P6T4+eVfHVZJh/RAPggWQOSXbIgtrPWNcXlWAC5T1zQ=; b=qfaNgtsxnNSM1MTk8Np2MXQEeDcsYgkNMqGG40lHgekva3N3bqEWG28fhIlG9yl/bj 75gGVTrB4YdCpeWtbO0GtTEVsq1okih/CxFdPAYSVMZ9f4tnCnYT9lVr+KQps/j0WyeB 0kEfq9+uFSIJ8ZcUFL1cEa1i5jgCko+Zo1pGybqYGxk5SHUnAX0hEHvSQ+8RigU66PIu 2ZSca2W67b2zAWw6CRS+6EynYXWcX+2dUv16jnikmLXVY+hZ4ocaslwAylglmcnOYhmD vSj9/WHf3DwO3QN7qZt31vqZrEjN/c9xmx7l8kAGpLnqqMxQLTGjKoRfyWfZsHjBnhkL 6JyA== X-Gm-Message-State: AOJu0YzAb8yA65u8mAdVCGAj0Qx/cNO5whykNanWvOSowW2I9wsZAO9w pvZdGqYou+juqcCfNR4lmc6tVrltn5cIgahofp2sz5goKBWmcfaEuQ2dRXd7cxRx3IjgXLKsRCV y9lj5CvDEkrr3DXFz+fSJv3uEl9QAs4h+4PinJaOiOb/5oUW4JjZ20Wdu X-Gm-Gg: ATEYQzzyF1cmkq/Wp1CCPiCIB09mkXtw3EsGG/J2zKdbDFGOrYAKxxW+XT9NhvXJvDc A2iPRbX6POsZqOuE8Vg1ieo+REeFKgTEfYYa5i5e1SRoIkfNhZwDjmWHd49/JTzrnfgFidp/rG3 99BPyy2rHuHf+Ciu9CcOkEt/BoE6R5P/UkLxBVqSubFG/fhBXc1tnO8CRQ4PwOg3daFFZiftLKV WyEGBFQtPmaJhJUXdZz9/ieJFuaGf20N5xktzPx7BQNk4KWj6Mt1UyZFC/RVNvga0QDmmmu4ikl yM3FP9zUmkgjbC9XVYnYrvcl5Vet0TNMNPF6PEuH/GRCiob4ZgVHHHAH8YScaC3HyXkkcI5qun2 IYNynGs+pXReSjA/8kZHwAvpLTbW8EReLJYgRRFz7f3QTrxseJSb7+VSvCvSu0aK9bAhIh2YCrd 88wdDuhQ== X-Received: by 2002:a05:620a:46a6:b0:8c6:e579:a81f with SMTP id af79cd13be357-8cbbcf77cb0mr598302185a.23.1772119527415; Thu, 26 Feb 2026 07:25:27 -0800 (PST) X-Received: by 2002:a05:620a:46a6:b0:8c6:e579:a81f with SMTP id af79cd13be357-8cbbcf77cb0mr598297485a.23.1772119526876; Thu, 26 Feb 2026 07:25:26 -0800 (PST) Received: from x1.local (bras-vprn-aurron9134w-lp130-03-174-91-117-149.dsl.bell.ca. [174.91.117.149]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-899c7159c15sm20937726d6.2.2026.02.26.07.25.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 Feb 2026 07:25:26 -0800 (PST) Date: Thu, 26 Feb 2026 10:25:24 -0500 From: Peter Xu To: Lukas Straub Cc: qemu-devel@nongnu.org, Fabiano Rosas , Laurent Vivier , Paolo Bonzini , Zhang Chen , Hailiang Zhang , Markus Armbruster , Li Zhijian , "Dr. David Alan Gilbert" Subject: Re: [PATCH v10 18/19] multifd: Fix hang if send thread errors during sync Message-ID: References: <20260220-colo_unit_test_multifd-v10-0-bfe67d422ef1@web.de> <20260220-colo_unit_test_multifd-v10-18-bfe67d422ef1@web.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260220-colo_unit_test_multifd-v10-18-bfe67d422ef1@web.de> Received-SPF: pass client-ip=170.10.129.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -10 X-Spam_score: -1.1 X-Spam_bar: - X-Spam_report: (-1.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.306, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.668, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development 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 On Fri, Feb 20, 2026 at 08:51:40PM +0100, Lukas Straub wrote: > When a send thread encounters an error (as is the case with yank), > it sets multifd_send_state->exiting and the other threads exit too. > This races with multifd_send_sync_main() which now hangs at > qemu_sem_wait(&p->sem_sync) in multifd_send_sync_main() line 647 > as it waits for threads that have exited. > > Fix this by kicking the semaphores when exiting the send threads. > > I encountered this hang when stress testing the colo unit test, > though I was unable to write a migration test to reliably hit this. > > Signed-off-by: Lukas Straub Reviewed-by: Peter Xu -- Peter Xu