From mboxrd@z Thu Jan 1 00:00:00 1970 From: joeyli Subject: Re: [PATCH v2] Hibernate: check unsafe page should not in e820 reserved region Date: Thu, 7 Aug 2014 16:52:03 +0800 Message-ID: <20140807085203.GF26210@linux-rxt1.site> References: <1407165801-24648-1-git-send-email-jlee@suse.com> <20140807040543.GE26210@linux-rxt1.site> <20140807080025.GA24700@amd.pavel.ucw.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from smtp.nue.novell.com ([195.135.221.5]:41730 "EHLO smtp.nue.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754363AbaHGIwT (ORCPT ); Thu, 7 Aug 2014 04:52:19 -0400 Content-Disposition: inline In-Reply-To: <20140807080025.GA24700@amd.pavel.ucw.cz> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Pavel Machek Cc: "Lee, Chun-Yi" , "Rafael J. Wysocki" , Len Brown , Takashi Iwai , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org On Thu, Aug 07, 2014 at 10:00:25AM +0200, Pavel Machek wrote: > Hi! > > > > When the machine doesn't well handle the e820 persistent when hibernate > > > resuming, then it may causes page fault when writing image to snapshot > > > buffer: > > > > > > [ 17.929495] BUG: unable to handle kernel paging request at ffff880069d4f000 > > > [ 17.933469] IP: [] load_image_lzo+0x810/0xe40 > > > [ 17.933469] PGD 2194067 PUD 77ffff067 PMD 2197067 PTE 0 > > > [ 17.933469] Oops: 0002 [#1] SMP [...] > > > [ 8.933534] PM: Failed to load hibernation image, recovering. > > > > > > v2: > > > + removed empty check of nosave_regions list. > > > + fixed the typo of "region" in code for error message and patch comment. > > > > > > Cc: "Rafael J. Wysocki" > > > Cc: Len Brown > > > Cc: Takashi Iwai > > > Acked-by: Pavel Machek > > > Signed-off-by: Lee, Chun-Yi > > > > I discussed with Vojtech Pavlik for this patch, he raised a situation is: > > > > Maybe e820 changed but image kernel original pages do not fall into new e820 region. > > Then the hibernate will recovery success, but later kernel drivers may got problem > > when accessing memory. > > > > My idea is hashing the start/end pfn of each nosave region sequentially, put this > > nosave region digest to hibernate header then compare e820 digest in check_header() > > when hibernate resuming. > > > > I am developing patch, then we don't need check unsafe page should not in unsave(e820) > > regions. > > Actually, if you are doing such a check... it makes sense to check for > _all_ the regions, nosave or not. If e820 map changed at all, it is > not safe to resume. > Pavel Currently nosave region only called register by e820 code, so hibernate's nosave region included e820 reserved, ACPI data and ACPI NVS region. I thought hashing the start/end pfn of above regions is enough. Regards Joey Lee