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=-6.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 A7625C433E2 for ; Mon, 13 Jul 2020 11:41:47 +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 7145820738 for ; Mon, 13 Jul 2020 11:41:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="KTxO1gVO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7145820738 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:43964 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1juwqA-0003ra-IY for qemu-devel@archiver.kernel.org; Mon, 13 Jul 2020 07:41:46 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:47758) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1juwon-0002ga-Dq for qemu-devel@nongnu.org; Mon, 13 Jul 2020 07:40:21 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:32161 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1juwoe-0002KI-P9 for qemu-devel@nongnu.org; Mon, 13 Jul 2020 07:40:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1594640410; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5btOSnoodjFBjezWJA6lx/RJBkRf2VDFeTOIWsvz5aI=; b=KTxO1gVOx+K/GMrRkWWSCEiB5n0CNurRNgcIeT8IfbfwENsWYIImCkwxBXn6gCNkzI56PU daronzzySGrorsCAzvyY5Ib3ZkbrFzdoSwNoSoAkw0zszyF0adYdxZlca4Wn+9QJF/v8dP wATaSJUo8rLeMuiOfwnbgtOCGv/BL08= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-373-A7iTE2jeM7mezrak1KW_yQ-1; Mon, 13 Jul 2020 07:40:09 -0400 X-MC-Unique: A7iTE2jeM7mezrak1KW_yQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 909A380040A; Mon, 13 Jul 2020 11:40:07 +0000 (UTC) Received: from gondolin (ovpn-113-13.ams2.redhat.com [10.36.113.13]) by smtp.corp.redhat.com (Postfix) with ESMTP id E39F45C1D0; Mon, 13 Jul 2020 11:39:59 +0000 (UTC) Date: Mon, 13 Jul 2020 13:39:57 +0200 From: Cornelia Huck To: "Dr. David Alan Gilbert" Subject: Re: migration: broken snapshot saves appear on s390 when small fields in migration stream removed Message-ID: <20200713133957.148716a7.cohuck@redhat.com> In-Reply-To: <20200713110333.GE3122@work-vm> References: <8bbafdec-836d-b7de-cab8-7a325b6e238d@suse.de> <20200713110333.GE3122@work-vm> Organization: Red Hat GmbH MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=207.211.31.81; envelope-from=cohuck@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/13 02:19:41 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, 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_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, 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 , Thomas Huth , Juan Quintela , Peter Maydell , qemu-devel , Claudio Fontana , Stefan Hajnoczi , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, 13 Jul 2020 12:03:33 +0100 "Dr. David Alan Gilbert" wrote: > * Claudio Fontana (cfontana@suse.de) wrote: > > The following workarounds hide the problem (make the test pass): > > > > 1) always including the icount field in the (unrelated) timers field that are sent before in the migration stream (ie not applying the reproducer patch). > > > > 2) increasing the IO_BUF_SIZE also hides the problem: > > > > ----------------------cut-------------------------- > > diff --git a/migration/qemu-file.c b/migration/qemu-file.c > > index be21518c57..f81d1272eb 100644 > > --- a/migration/qemu-file.c > > +++ b/migration/qemu-file.c > > @@ -30,7 +30,7 @@ > > #include "trace.h" > > #include "qapi/error.h" > > > > -#define IO_BUF_SIZE 32768 > > +#define IO_BUF_SIZE 65536 > > #define MAX_IOV_SIZE MIN_CONST(IOV_MAX, 64) > > > > struct QEMUFile { > > ----------------------cut-------------------------- > > > > 3) adding a qemu_fflush in hw/s390x/s390-skeys.c after EOS also "fixes" the problem: > > > > ----------------------cut-------------------------- > > diff --git a/hw/s390x/s390-skeys.c b/hw/s390x/s390-skeys.c > > index 1e036cc602..47c9a015af 100644 > > --- a/hw/s390x/s390-skeys.c > > +++ b/hw/s390x/s390-skeys.c > > @@ -252,6 +252,8 @@ static const TypeInfo qemu_s390_skeys_info = { > > .class_size = sizeof(S390SKeysClass), > > }; > > > > +extern void qemu_fflush(QEMUFile *f); > > + > > static void s390_storage_keys_save(QEMUFile *f, void *opaque) > > { > > S390SKeysState *ss = S390_SKEYS(opaque); > > @@ -302,6 +304,7 @@ static void s390_storage_keys_save(QEMUFile *f, void *opaque) > > g_free(buf); > > end_stream: > > qemu_put_be64(f, eos); > > + qemu_fflush(f); > > } > > > > static int s390_storage_keys_load(QEMUFile *f, void *opaque, int version_id) > > ----------------------cut-------------------------- > > > > Do any of you with better understanding of migration/, block and s390 have a suggestion on what could be the issue here, > > and what could be the next step in the investigation? > > > > Is the fact that migration/ram.c always does fflush after writing the EOS have any relevance here? why does it do it, > > and should s390 code also follow the same pattern? > > I didn't think it was required. > And qemu_put_buffer loops if needed and calls qemu_fflush internally. > It's possible here that the storage key code is just the canary - the > first thing that detects that the stream is invalid after it all goes > wrong. Yes, that seems possible. Especially as we end up with all zeroes after the skeys section in the bad case -- it seems like weird problem to have to be cured by an individual device. No good idea *what* actually goes wrong, though.