From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755618AbbJ1Jxg (ORCPT ); Wed, 28 Oct 2015 05:53:36 -0400 Received: from smtp53.i.mail.ru ([94.100.177.113]:48884 "EHLO smtp53.i.mail.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750980AbbJ1Jxe (ORCPT ); Wed, 28 Oct 2015 05:53:34 -0400 Subject: Re: [PATCH v2 0/4] x86: sigcontext fixes, again To: Toshi Kani , Linus Torvalds , Andrew Morton , Toshi Kani , Ingo Molnar References: <562E126E.6030300@list.ru> <562F84AE.1030500@list.ru> <1445990693.20657.98.camel@hpe.com> Cc: Andy Lutomirski , Andy Lutomirski , X86 ML , "linux-kernel@vger.kernel.org" , Brian Gerst , Denys Vlasenko , Borislav Petkov , Stas Sergeev From: Stas Sergeev X-Enigmail-Draft-Status: N1110 Message-ID: <56309B10.50706@list.ru> Date: Wed, 28 Oct 2015 12:53:20 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <1445990693.20657.98.camel@hpe.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Mras: Ok Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 28.10.2015 03:04, Toshi Kani пишет: > On Wed, 2015-10-28 at 07:37 +0900, Linus Torvalds wrote: >> On Tue, Oct 27, 2015 at 11:05 PM, Stas Sergeev wrote: >>> >>> I can't easily post an Oops: under X it doesn't even appear - >>> machine freezes immediately, and under non-KMS console it is >>> possible to get one, but difficult to screen-shot (using bare >>> metal, not VM). Also the Oops was seemingly unrelated. >>> And if you run "dosemu -s" under non-KMS console, you'll also >>> reproduce this one: >>> https://bugzilla.kernel.org/show_bug.cgi?id=97321 >> >> Hmm. Andrew Morton responded to that initially, but then nothing >> happened, and now it's been another six months. Andrew? >> >> The arch/x86/mm/pat.c error handling does seem to be suspect. This is >> all code several years old, so none of this is new, and I think Suresh >> is gone. Adding a few other people with recent sign-offs to that >> file, in the hope that somebody feels like they own it.. > > In the case of PFNMAP, the range should always be mapped. So, I wonder why > follow_phys() failed with the !pte_present() check. > > Stas, do you have a test program that can reproduce 97321? Get dosemu2 from here: https://github.com/stsp/dosemu2/releases or from git, or get dosemu1. Then boot your kernel with "nomodeset=1" to get a text console. Run dosemu -s and you'll get the bug. You don't even need to mess with FreeDOS or whatever, because the problem happens on a very start. And since it is WARN_OCNCE, you'll need to reboot to get it again. You will probably need to adjust /etc/sudoers because -s means that dosemu (a wrapper script for dosemu.bin) will try sudo so that dosemu.bin can grab /dev/mem as root. If it is too complicated, let me know and I'll try to code up a reduced test-case (but can't promise to get to that quickly). Thanks to everyone (esp Linus of course :-) who got involved in finally supporting dosemu again - it was rather ill for the last years.