From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758159Ab0LBXzL (ORCPT ); Thu, 2 Dec 2010 18:55:11 -0500 Received: from smtp1.linux-foundation.org ([140.211.169.13]:51143 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757895Ab0LBXzK (ORCPT ); Thu, 2 Dec 2010 18:55:10 -0500 Date: Thu, 2 Dec 2010 15:54:53 -0800 From: Andrew Morton To: "Rafael J. Wysocki" Cc: Hugh Dickins , KAMEZAWA Hiroyuki , KOSAKI Motohiro , Kernel development list , Ondrej Zary , "Linux-pm mailing list" Subject: Re: [PATCH] PM / Hibernate: Fix memory corruption related to swap Message-Id: <20101202155453.92e8ca57.akpm@linux-foundation.org> In-Reply-To: <201012030040.37273.rjw@sisk.pl> References: <201012030040.37273.rjw@sisk.pl> X-Mailer: Sylpheed 3.0.2 (GTK+ 2.20.1; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 3 Dec 2010 00:40:36 +0100 "Rafael J. Wysocki" wrote: > From: Rafael J. Wysocki > > There is a problem that swap pages allocated before the creation of > a hibernation image can be released and used for storing the contents > of different memory pages while the image is being saved. Since the > kernel stored in the image doesn't know of that, it causes memory > corruption to occur after resume from hibernation, especially on > systems with relatively small RAM that need to swap often. > > This issue can be addressed by keeping the GFP_IOFS bits clear > in gfp_allowed_mask during the entire hibernation, including the > saving of the image, until the system is finally turned off or > the hibernation is aborted. Unfortunately, for this purpose > it's necessary to rework the way in which the hibernate and > suspend code manipulates gfp_allowed_mask. > > This change is based on an earlier patch from Hugh Dickins. > > Signed-off-by: Rafael J. Wysocki > Reported-by: Ondrej Zary > Acked-by: Hugh Dickins > --- > > Hi, > > This patch is a fix for a regression and nasty memory corruption, so I'd like > to push it to Linus for 2.6.37 if there are no objections. > It looks OK to me for 2.6.37 but for 2.6.38 please let's make everything here a 100% no-op for CONFIG_PM_SLEEP=n builds. Specifically the slight overhead in __alloc_pages_nodemask. Because given the global nature of saved_gfp_mask and the unlocked way in which it is accessed, this facility won't be at all useful for anything other than suspend.