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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 DA586C4321D for ; Fri, 17 Aug 2018 17:01:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9410C208E4 for ; Fri, 17 Aug 2018 17:01:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9410C208E4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728020AbeHQUFm (ORCPT ); Fri, 17 Aug 2018 16:05:42 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:55780 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727828AbeHQUFl (ORCPT ); Fri, 17 Aug 2018 16:05:41 -0400 Received: from localhost (unknown [194.244.16.108]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id BD17ACBF; Fri, 17 Aug 2018 17:01:32 +0000 (UTC) Date: Fri, 17 Aug 2018 19:01:29 +0200 From: Greg Kroah-Hartman To: Jinpu Wang Cc: Thomas Gleixner , stable , linux-kernel@vger.kernel.org, Ingo Molnar , konrad.wilk@oracle.com Subject: Re: [BUG]smt sysfs dir missing on 4.4.148 and 4.14.63 Message-ID: <20180817170129.GE24945@kroah.com> References: <20180816155126.GA18296@kroah.com> <20180816163937.GA5105@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 17, 2018 at 02:39:00PM +0200, Jinpu Wang wrote: > On Thu, Aug 16, 2018 at 6:48 PM Jinpu Wang wrote: > > > > On Thu, Aug 16, 2018 at 6:39 PM Greg Kroah-Hartman > > wrote: > > > > > > On Thu, Aug 16, 2018 at 06:28:59PM +0200, Jinpu Wang wrote: > > > > On Thu, Aug 16, 2018 at 5:51 PM Greg Kroah-Hartman > > > > wrote: > > > > > > > > > > On Thu, Aug 16, 2018 at 05:43:23PM +0200, Jinpu Wang wrote: > > > > > > Hi Greg, hi Thomas, > > > > > > > > > > > > I noticed /sys/devices/system/cpu/smt dir is missing on 4.4.148 and > > > > > > 4.14.63, default setting. > > > > > > > > > > For 4.4, I would be amazed if anything was there, the backport was done > > > > > only to handle the local user issue, not the "full" protection. So > > > > > please try 4.9 or 4.14. > > > > Thanks for quick reply. Right, just checked. the patch for create the > > > > sysfs entry is missing. > > > > > > What patch is that? What is the git commit id that we missed? > > > > > > > > How about 4.17 and 4.18, do those trees work properly for you? > > > > I guess it's the same. > > > > > > > > > > > Tried stable/master branch 31130a16d459 ("Merge tag > > > > > > 'for-linus-4.19-rc1-tag' of > > > > > > git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip") > > > > > > It's the same there. > > > > > > > > > > Ah, so we are bug compatible, good :) > > > > I will try test stable master a bit more to gather the full log. > > > > > > > > > > > When boot with 'nosmt' kernel paramter kernel 4.14.63 panic during > > > > > > boot, 4.4.148 boot fine. > > > > > > The call trace seem irq related, is it known bug? > > > > > > > > > > You are not giving us much to go on here sorry. We need full details, > > > > > and also please cc: lkml and the other developers who worked on this. > > > > > THomas is on vacation this week. > > > > Now, add more developers to cc, also lkml. > > > > > > > > I have the config and boot dmesg attached for default setting. > > > > > > I see no error in your boot log, what exactly are you worried about? > > 2 problems here: > > 1 According to https://www.kernel.org/doc/html/latest/admin-guide/l1tf.html > > I expect /sys/devices/system/cpu/smt/, but it's not. > > 2 kernel 4.14.63 panic when I boot with 'nosmt' or 'l1tf=full', I > > attached the picture here again, > > I will try to get the full log tomorrow, also test with linus tree. > > > > > > confused, > > > > > > greg k-h > > > > Thanks > I found the problem, CONFIG_HOTPLUG_SMT is enable due to CONFIG_SMP, > but I did explicitly enable CONFIG_HOTPLUG_CPU. > > That's why the smt dir is missing, and kernel panic when I boot with > 'nosmt' or 'l1tf=full' probably also other combination. > > With CONFIG_HOTPLUG_CPU=y, it works fine so far. So do we need a new configuration dependancy here to resolve this problem? Why is this not an issue in Linus's tree? confused, greg k-h