From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752919AbYKKQmr (ORCPT ); Tue, 11 Nov 2008 11:42:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751458AbYKKQmj (ORCPT ); Tue, 11 Nov 2008 11:42:39 -0500 Received: from ogre.sisk.pl ([217.79.144.158]:54216 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751486AbYKKQmi (ORCPT ); Tue, 11 Nov 2008 11:42:38 -0500 From: "Rafael J. Wysocki" To: Pavel Machek Subject: Re: CONFIG_NUMA breaks hibernation on x86-32 with PAE Date: Tue, 11 Nov 2008 17:47:27 +0100 User-Agent: KMail/1.9.9 Cc: Andi Kleen , Ingo Molnar , kernel list , "H. Peter Anvin" References: <20081109140726.GB1786@ucw.cz> <200811111520.22386.rjw@sisk.pl> <20081111150342.GB1648@ucw.cz> In-Reply-To: <20081111150342.GB1648@ucw.cz> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200811111747.28347.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday, 11 of November 2008, Pavel Machek wrote: > > > > > It is. However, the problem is 100% reproducible on any 32-bit single-node > > > > system with CONFIG_NUMA set, from what I can tell. > > > > > > > > It doesn't happen if the kernel is booted with highmem=0, so it looks like > > > > the code that saves highmem causes the problem to happen. However, this > > > > same code works well for all of the !CONFIG_NUMA cases and practically only > > > > the only non-open-coded it uses is kmap_atomic(). > > > > > > > > > One possibility would be to bisect if it ever worked? > > > > > > > > Not sure it did, probably not. :-( > > > > > > Well, interesting point would be just before this commit: > > > > > > > > > commit 8357376d3df21b7d6f857931a57ac50da9c66e26 > > > tree daf2c369e9b79d24c1666323b3ae75189e482a4a > > > parent bf73bae6ba0dc4bd4f1e570feb34a06b72725af6 > > > author Rafael J. Wysocki Wed, 06 Dec 2006 20:34:18 -0800 > > > committer Linus Torvalds Thu, 07 Dec 2006 > > > 08:39:27 -0800 > > > > > > [PATCH] swsusp: Improve handling of highmem > > > > > > Currently swsusp saves the contents of highmem pages by copying > > > them to the > > > normal zone which is quite inefficient (eg. it requires two > > > normal pages > > > to be used for saving one highmem page). This may be improved by > > > using > > > highmem for saving the contents of saveable highmem pages. > > > > > > ...highmem handling was way simpler in those good old days ;-) > > > > Please stop kidding, this is a serious issue. > > > > The hibernation code _works_ with all kinds of highmem when CONFIG_NUMA is > > unset. > > And it does not work with single highmem page when NUMA is set... I > went through the highmem saving code, and it depends on highmem not > changing from under it (right?) and is generally quite tricky ('if > they are both in highmem do this, else if one of them is do that, else > do something else') It actually is quite simple, if you know the idea. > and it changes page protections on the fly, etc. No, it doesn't do that, at least for pages it hasn't allocated itself. I don't think it changes anything like page protections at all, though. > I'm not saying the bug is in that code, but before that commit we had > very stupid --- but very robust -- code. I'll try if that one works > with config_numa, perhaps we can get some debug info that way. if you can do that, it actually may be valuable information. Thanks, Rafael