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 X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3D239C4361A for ; Wed, 15 Jul 2020 11:11:03 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 1777120658 for ; Wed, 15 Jul 2020 11:11:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1777120658 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:48392 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jvfJW-0002wv-C3 for qemu-devel@archiver.kernel.org; Wed, 15 Jul 2020 07:11:02 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:35290) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jvfIw-0002RC-JP for qemu-devel@nongnu.org; Wed, 15 Jul 2020 07:10:26 -0400 Received: from [195.135.220.15] (port=39296 helo=mx2.suse.de) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jvfIu-0002OM-JD for qemu-devel@nongnu.org; Wed, 15 Jul 2020 07:10:26 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 125E4B59E; Wed, 15 Jul 2020 11:10:26 +0000 (UTC) Subject: Re: migration: broken snapshot saves appear on s390 when small fields in migration stream removed To: Thomas Huth , Paolo Bonzini , Juan Quintela , "Dr. David Alan Gilbert" , Kevin Wolf , Max Reitz References: <8bbafdec-836d-b7de-cab8-7a325b6e238d@suse.de> <55c406cd-b9ca-4e9b-0acd-d33cfe2a70e3@redhat.com> <8125b1ff-373a-aadc-eccf-27c567007a27@redhat.com> From: Claudio Fontana Message-ID: <8ff7eeab-bef1-0957-a95c-72819680c431@suse.de> Date: Wed, 15 Jul 2020 13:10:22 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <8125b1ff-373a-aadc-eccf-27c567007a27@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Host-Lookup-Failed: Reverse DNS lookup failed for 195.135.220.15 (failed) Received-SPF: pass client-ip=195.135.220.15; envelope-from=cfontana@suse.de; helo=mx2.suse.de X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/14 23:03:40 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x (no timestamps) [generic] X-Spam_score_int: -33 X-Spam_score: -3.4 X-Spam_bar: --- X-Spam_report: (-3.4 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, RDNS_NONE=0.793, 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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Jason J. Herne" , Fam Zheng , Liang Yan , Peter Maydell , Cornelia Huck , qemu-devel , Stefan Hajnoczi Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Thomas, On 7/14/20 4:35 PM, Thomas Huth wrote: > On 14/07/2020 16.29, Claudio Fontana wrote: >> Hello, >> >> I have some tiny progress in narrowing down this issue, possibly a qcow2 issue, still unclear, >> but involving Kevin Wolf and Max Reitz. >> >> >> The reproducer again: >> >>> --------------------------------------------cut------------------------------------------- >>> diff --git a/cpus.c b/cpus.c >>> index 41d1c5099f..443b88697a 100644 >>> --- a/cpus.c >>> +++ b/cpus.c >>> @@ -643,7 +643,7 @@ static void qemu_account_warp_timer(void) >>> >>> static bool icount_state_needed(void *opaque) >>> { >>> - return use_icount; >>> + return 0; >>> } >>> >>> static bool warp_timer_state_needed(void *opaque) >>> --------------------------------------------cut------------------------------------------- >> >> This issue for now appears on s390 only: >> >> On s390 hardware, test 267 fails (both kvm and tcg) in the qcow2 backing file part, with broken migration stream data in the s390-skeys vmsave (old style). > [...] >> If someone has a good idea let me know - first attempts to reproduce on x86 failed, but maybe more work could lead to it. > small update: in the GOOD case (enough padding added) a qcow_merge() is triggered for the last write of 16202 bytes. In the BAD case (not enough padding added) a qcow_merge() is not triggered for the last write of 16201 bytes. Note: manually flushing with qemu_fflush in s390-skeys vmsave also works (maybe got lost in the noise). > Two questions: > > 1) Can you also reproduce the issue manually, without running iotest > 267? ... I tried, but so far I failed. Thanks for the suggestion, will try. > > 2) Since all the information so far sounds like the problem could be > elsewhere in the code, and the skeys just catch it by accident ... have > you tried running with valgrind? Maybe it catches something useful? Nothing yet, but will fiddle with the options a bit more. > > Thomas > Ciao, Claudio