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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B05B7EB64D8 for ; Wed, 14 Jun 2023 15:08:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343537AbjFNPIN (ORCPT ); Wed, 14 Jun 2023 11:08:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47680 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343523AbjFNPIK (ORCPT ); Wed, 14 Jun 2023 11:08:10 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 39B41189 for ; Wed, 14 Jun 2023 08:07:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1686755240; 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=wGHMe8IA6mAo0HMH3lZ/8EExV+cg7D2Uq+MQfhPcyas=; b=et+NrPcIWnIxy5/Lqr5LOYhTfqlyfz74RNPIeFcedeQKy9m3RxwwCKunIUmbwRFmF4tVW/ BEJ/JIn/GSKEOMpH589smidNTk4oYhFCBPglj01Mu4uSf0gipeh/GBBWEm4ugjmh5XrQ7Z Pas7hnAnX52XhvIQnOVMmFYkWt/jW9k= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-66-7l4Ipb7wPzmenxHuK39-gw-1; Wed, 14 Jun 2023 11:07:18 -0400 X-MC-Unique: 7l4Ipb7wPzmenxHuK39-gw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 29D573806706; Wed, 14 Jun 2023 15:07:18 +0000 (UTC) Received: from localhost (unknown [10.39.192.206]) by smtp.corp.redhat.com (Postfix) with ESMTP id DF96C9E9F; Wed, 14 Jun 2023 15:07:17 +0000 (UTC) Date: Wed, 14 Jun 2023 16:07:17 +0100 From: "Richard W.M. Jones" To: Peter Zijlstra Cc: Aaron Thompson , linux-kernel@vger.kernel.org Subject: Re: printk.time causes rare kernel boot hangs Message-ID: <20230614150717.GG7636@redhat.com> References: <20230613134105.GA10301@redhat.com> <20230614092158.GF1639749@hirez.programming.kicks-ass.net> <20230614094522.GA7636@redhat.com> <20230614103011.GL7912@redhat.com> <20230614103953.GM7912@redhat.com> <20230614113536.GJ1639749@hirez.programming.kicks-ass.net> <20230614125320.GA1640563@hirez.programming.kicks-ass.net> <20230614130348.GF7636@redhat.com> <20230614130945.GK1639749@hirez.programming.kicks-ass.net> <20230614145348.GB1640563@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230614145348.GB1640563@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 14, 2023 at 04:53:48PM +0200, Peter Zijlstra wrote: > On Wed, Jun 14, 2023 at 03:09:45PM +0200, Peter Zijlstra wrote: > > On Wed, Jun 14, 2023 at 02:03:48PM +0100, Richard W.M. Jones wrote: > > > On Wed, Jun 14, 2023 at 02:53:20PM +0200, Peter Zijlstra wrote: > > > > Ooooh, what qemu version do you have? There were some really dodgy > > > > reports all around self modifying code, all reported on 7.2, that seems > > > > to have gone away with 8. > > > > > > > Now, all of them were using TCG, and I think you're using KVM. > > > > > > I'm using qemu-system-x86-8.0.0-4.fc39.x86_64 with KVM. The host > > > kernel is 6.4.0-0.rc5.41.fc39.x86_64. > > > > > > > I've at least 36000 cycles and still nothing :-(, let me go try your > > > > .config. > > > > > > I can definitely reproduce this with your config (but AMD host), so > > > that's odd. Let me try with Intel hardware and your config. You > > > really should see this with only a few thousands iterations. > > > > Yeah, I'm running on some ancient ivb-ep, let me try on the alderlake. I > > don't really have AMD machines at hand :-/ > > Using v6.4-rc6-37-gb6dad5178cea, and 36000+ cycles on the ADL (affine to > big cores) later and nothing :-( So I have just this minute reproduced it on Intel, after around ~2000 iterations. On this machine I am using: Host kernel: 6.3.7-200.fc38.x86_64 Guest kernel: git commit fb054096aea0576f0c0a61c598e5e9676443ee86 Guest config: defconfig + kvm_guest.config + CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y QEMU: qemu-system-x86-8.0.0-4.fc39.x86_64 (using kvm_intel) Hardware: Intel(R) Core(TM) i7-10850H CPU @ 2.70GHz > Clearly I'm doing something wrong. I'm suspecting version of qemu may have something to do with it, but honestly I don't know. Which qemu are you using? I'll now try with upstream qemu from git in case there's something about the Fedora qemu. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com Fedora Windows cross-compiler. Compile Windows programs, test, and build Windows installers. Over 100 libraries supported. http://fedoraproject.org/wiki/MinGW