From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932436AbcIHVP6 (ORCPT ); Thu, 8 Sep 2016 17:15:58 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:57522 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753520AbcIHVP4 (ORCPT ); Thu, 8 Sep 2016 17:15:56 -0400 Date: Thu, 8 Sep 2016 23:15:52 +0200 From: Pavel Machek To: "Rafael J. Wysocki" Cc: joeyli , Borislav Petkov , Chen Yu , linux-pm@vger.kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org, Lee@nazgul.tnic Subject: Re: [PATCH][v8] PM / hibernate: Verify the consistent of e820 memory map by md5 value Message-ID: <20160908211552.GA12651@amd> References: <1472402140-959-1-git-send-email-yu.c.chen@intel.com> <20160829134123.GA28806@nazgul.tnic> <20160830083505.GG10967@linux-rxt1.site> <6348002.9YHCcajBsl@vostro.rjw.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6348002.9YHCcajBsl@vostro.rjw.lan> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 2016-08-30 13:54:44, Rafael J. Wysocki wrote: > On Tuesday, August 30, 2016 04:35:05 PM joeyli wrote: > > On Mon, Aug 29, 2016 at 03:41:23PM +0200, Borislav Petkov wrote: > > > On Mon, Aug 29, 2016 at 09:15:00AM +0200, Pavel Machek wrote: > > > > Sounds about as easy as hot unplugging arbitrary memory address. IOW > > > > "not easy". > > > > > > Regardless, forcibly panicking the system more is still the wrong > > > approach IMO. > > > > > > Instead, I'd try to issue a big fat warning that BIOS corrupts E820 and > > > that the user should disable hibernation on that box and never ever > > > enable it again. > > > > > > After that, the kernel should *disable* hibernation for the current boot > > > so any further hibernation runs don't even happen. Maybe even taint > > > itself. > > > > > > > I support this idea to disable hibernation when kernel detected e820 layout > > was changed by BIOS. If system resume luckily then kernel should warn to user > > and refuse to hibernate again. User must to know that's better to reboot > > system when he saw the warning message after lucky resume. > > > > Not just BIOS doesn't fix e820 layout. There have some machines doesn't provide > > _S4_ function, so the hibernation fallbacks to "shutdown" mode because "platform" > > mode unavailable. In this situation, user is just lucky to run the hibernation. > > Kernel should warn to user and disable hibernation when detected e820 layout > > changed. > > Well, please see my reply to Boris. > > Pavel is right that running after detecting an e820 mismatch is generally risky, > so why don't we shut down the system (but try to do that cleanly instead of > causing it to panic right away) on an e820 mismatch? I don't think that's good idea. Anything involving userspace is risky at that point, and clean shutdown means a _lot_ of userspace. We know the filesystems are reasonably clean as we sync-ed them; I believe right solution is to panic -- on-disk state is pretty good and we don't want to do anything risky. Best regards, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html