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=-3.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 45E2FC352A2 for ; Fri, 7 Feb 2020 08:54:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 174D82082E for ; Fri, 7 Feb 2020 08:54:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="KtUCSeXn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726674AbgBGIyK (ORCPT ); Fri, 7 Feb 2020 03:54:10 -0500 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:54939 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726417AbgBGIyK (ORCPT ); Fri, 7 Feb 2020 03:54:10 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1581065649; 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=0USnf3hBn92ifbh7P2D9fosqj0oQrhEhCYDRgIDXfoE=; b=KtUCSeXnu4vcZuxCbtH2LyuDPy3dbhTYCSdMa7p55sF3EDZjMOs2G7GmRA5PrFqVn6eOUr T2spddgHEny2fdSombbK6YZz2TX/nlXApBcYvWiC0wNfRXYuAc3vMx9QFpdOuMFdHVj3ZW ouxSQhcVJHzc7XmHZpCK1Dl3Bpp2YEo= 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-389-wGf86mQwOcWZfWagUhSSDA-1; Fri, 07 Feb 2020 03:54:08 -0500 X-MC-Unique: wGf86mQwOcWZfWagUhSSDA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EF06810CE783; Fri, 7 Feb 2020 08:54:06 +0000 (UTC) Received: from gondolin (ovpn-117-112.ams2.redhat.com [10.36.117.112]) by smtp.corp.redhat.com (Postfix) with ESMTP id 82683857BF; Fri, 7 Feb 2020 08:53:56 +0000 (UTC) Date: Fri, 7 Feb 2020 09:53:53 +0100 From: Cornelia Huck To: Christian Borntraeger Cc: "Michael S. Tsirkin" , eperezma@redhat.com, "virtualization@lists.linux-foundation.org" , Stephen Rothwell , Linux Next Mailing List , "linux-kernel@vger.kernel.org" , kvm list , Halil Pasic Subject: Re: vhost changes (batched) in linux-next after 12/13 trigger random crashes in KVM guests after reboot Message-ID: <20200207095353.08bc91e4.cohuck@redhat.com> In-Reply-To: <97c93d38-ef07-e321-d133-18483d54c0c0@de.ibm.com> References: <20200107042401-mutt-send-email-mst@kernel.org> <20200107065434-mutt-send-email-mst@kernel.org> <20200120012724-mutt-send-email-mst@kernel.org> <2a63b15f-8cf5-5868-550c-42e2cfd92c60@de.ibm.com> <1ade56b5-083f-bb6f-d3e0-3ddcf78f4d26@de.ibm.com> <20200206171349-mutt-send-email-mst@kernel.org> <5c860fa1-cef5-b389-4ebf-99a62afa0fe8@de.ibm.com> <20200207025806-mutt-send-email-mst@kernel.org> <97c93d38-ef07-e321-d133-18483d54c0c0@de.ibm.com> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: linux-next-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-next@vger.kernel.org On Fri, 7 Feb 2020 09:13:14 +0100 Christian Borntraeger wrote: > On 07.02.20 08:58, Michael S. Tsirkin wrote: > > On Fri, Feb 07, 2020 at 08:47:14AM +0100, Christian Borntraeger wrote: > >> Also adding Cornelia. > >> > >> > >> On 06.02.20 23:17, Michael S. Tsirkin wrote: > >>> On Thu, Feb 06, 2020 at 04:12:21PM +0100, Christian Borntraeger wrote: > >>>> > >>>> > >>>> On 06.02.20 15:22, eperezma@redhat.com wrote: > >>>>> Hi Christian. > >>>>> > >>>>> Could you try this patch on top of ("38ced0208491 vhost: use batched version by default")? > >>>>> > >>>>> It will not solve your first random crash but it should help with the lost of network connectivity. > >>>>> > >>>>> Please let me know how does it goes. > >>>> > >>>> > >>>> 38ced0208491 + this seem to be ok. > >>>> > >>>> Not sure if you can make out anything of this (and the previous git bisect log) > >>> > >>> Yes it does - that this is just bad split-up of patches, and there's > >>> still a real bug that caused worse crashes :) > >>> > >>> So I just pushed batch-v4. > >>> I expect that will fail, and bisect to give us > >>> vhost: batching fetches > >>> Can you try that please? > >>> > >> > >> yes. > >> > >> eccb852f1fe6bede630e2e4f1a121a81e34354ab is the first bad commit > >> commit eccb852f1fe6bede630e2e4f1a121a81e34354ab > >> Author: Michael S. Tsirkin > >> Date: Mon Oct 7 06:11:18 2019 -0400 > >> > >> vhost: batching fetches > >> > >> With this patch applied, new and old code perform identically. > >> > >> Lots of extra optimizations are now possible, e.g. > >> we can fetch multiple heads with copy_from/to_user now. > >> We can get rid of maintaining the log array. Etc etc. > >> > >> Signed-off-by: Michael S. Tsirkin > >> > >> drivers/vhost/test.c | 2 +- > >> drivers/vhost/vhost.c | 39 ++++++++++++++++++++++++++++++++++----- > >> drivers/vhost/vhost.h | 4 +++- > >> 3 files changed, 38 insertions(+), 7 deletions(-) > >> > > > > > > And the symptom is still the same - random crashes > > after a bit of traffic, right? > > random guest crashes after a reboot of the guests. As if vhost would still > write into now stale buffers. > I'm late to the party; but where is that commit located? Or has it been dropped again already?