From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752758AbcLLVex (ORCPT ); Mon, 12 Dec 2016 16:34:53 -0500 Received: from mail.skyhub.de ([78.46.96.112]:40736 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751702AbcLLVev (ORCPT ); Mon, 12 Dec 2016 16:34:51 -0500 Date: Mon, 12 Dec 2016 22:34:46 +0100 From: Borislav Petkov To: Josh Poimboeuf Cc: x86-ml , lkml , Andy Lutomirski Subject: Re: WARNING: kernel stack frame pointer at ffffffff82e03f40 in swapper:0 has bad value (null) Message-ID: <20161212213446.imd3hpt3nudomu7r@pd.tnic> References: <20161210161749.gvboowyhtffvpoo3@pd.tnic> <20161210170444.trpnnq4gtkx5djqm@treble> <20161210172802.gpgjjndo56d43mi4@pd.tnic> <20161212154542.ul6cnzjtkbvooluh@treble> <20161212175023.455mlwhmnqfew2nu@pd.tnic> <20161212181025.uz3gk3jasuskqfmf@treble> <20161212211627.yuodrw35xwq3hmn7@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20161212211627.yuodrw35xwq3hmn7@treble> User-Agent: NeoMutt/20161014 (1.7.1) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 12, 2016 at 03:16:27PM -0600, Josh Poimboeuf wrote: > I still can't figure out what could cause this, nor can I recreate it. Want my .config? > Andy, any idea? I'm trying to figure out why a stack trace of the > initial task, early in start_kernel(), would show start_cpu() on the > stack *twice*. The start_cpu() entry on the stack at ffffffffbce03f50 > is right where it's supposed to be. But then there's another > start_cpu() entry at 0xffffffffbce03f48 which is pointed to by the frame > pointer chain. I can't figure out where that one came from and why the > stack is offset by a word, compared to all the other idle task stacks > I've seen. Btw, why do you have: call 1f # put return address on stack for unwinder there in start_cpu() instead of push $start_cpu or so? That CALL looks strange there. If you want to put the return address, just push start_cpu's address and that's it. Or am I missing something? > Boris, what kind of CPU is it? [ 0.169371] smpboot: CPU0: Intel(R) Xeon(R) CPU E5-1620 0 @ 3.60GHz (family: 0x6, model: 0x2d, stepping: 0x7) Sandybridge. The model 0x2d corresponds to that INTEL_FAM6_SANDYBRIDGE_X define in intel-family.h. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.