From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]) by casper.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1cyDag-0000iL-CY for kexec@lists.infradead.org; Wed, 12 Apr 2017 08:25:28 +0000 Date: Wed, 12 Apr 2017 16:24:33 +0800 From: Dave Young Subject: Re: KASLR causes intermittent boot failures on some systems Message-ID: <20170412082433.GA3546@dhcp-128-65.nay.redhat.com> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Jeff Moyer Cc: bhe@redhat.com, linux-nvdimm@lists.01.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, mingo@kernel.org, dan.j.williams@intel.com, thgarnie@google.com 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. > [snip] I did some tests about emulated pmem via memmap=, kdump kernel hangs or just reboots early during compressing kernel, no clue how to handle it. Since for kdump kernel kaslr is pointless a workaround is use "nokaslr" In Fedora or RHEL, just add "nokaslr" in KDUMP_COMMANDLINE_APPEND in /etc/sysconfig/kdump Can you try if this works? Thanks Dave _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec