From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S3000321AbdEALdL (ORCPT ); Mon, 1 May 2017 07:33:11 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36412 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S969302AbdEALci (ORCPT ); Mon, 1 May 2017 07:32:38 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com B7A8E7F4A9 Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=bhe@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com B7A8E7F4A9 Date: Mon, 1 May 2017 19:32:32 +0800 From: Baoquan He To: Jeff Moyer Cc: thgarnie@google.com, mingo@kernel.org, dan.j.williams@intel.com, linux-kernel@vger.kernel.org, linux-nvdimm@ml01.01.org, keescook@chromium.org, dyoung@redhat.com Subject: Re: KASLR causes intermittent boot failures on some systems Message-ID: <20170501113232.GA24218@x1> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.7.0 (2016-08-17) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Mon, 01 May 2017 11:32:37 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, The root cause has been found out finally. It's caused by code bug in sync_global_pgds which is wrong for loop count calculation. Will post patch. Thanks Baoquan On 04/07/17 at 10:41am, Jeff Moyer wrote: > Hi, > > commit 021182e52fe01 ("x86/mm: Enable KASLR for physical mapping memory > regions") causes some of my systems with persistent memory (whether real > or emulated) to fail to boot with a couple of different crash > signatures. The first signature is a NMI watchdog lockup of all but 1 > cpu, which causes much difficulty in extracting useful information from > the console. The second variant is an invalid paging request, listed > below. > > On some systems, I haven't hit this problem at all. Other systems > experience a failed boot maybe 20-30% of the time. To reproduce it, > configure some emulated pmem on your system. You can find directions > for that here: https://nvdimm.wiki.kernel.org/ > > Install ndctl (https://github.com/pmem/ndctl). > Configure the namespace: > # ndctl create-namespace -f -e namespace0.0 -m memory > > Then just reboot several times (5 should be enough), and hopefully > you'll hit the issue. > > I've attached both my .config and the dmesg output from a successful > boot at the end of this mail. >