From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751587Ab1I0RBD (ORCPT ); Tue, 27 Sep 2011 13:01:03 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:59396 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750978Ab1I0RBC (ORCPT ); Tue, 27 Sep 2011 13:01:02 -0400 From: "Rafael J. Wysocki" To: Yinghai Lu Subject: Re: S4 resume broken since 2.6.39 (3.1, too) Date: Tue, 27 Sep 2011 19:03:14 +0200 User-Agent: KMail/1.13.6 (Linux/3.1.0-rc4+; KDE/4.6.0; x86_64; ; ) Cc: Takashi Iwai , linux-kernel@vger.kernel.org, "H. Peter Anvin" , oneukum@suse.de, x86@kernel.org, Linux PM mailing list , Ingo Molnar , Linus Torvalds References: <201109270024.55418.rjw@sisk.pl> <4E813639.10907@oracle.com> In-Reply-To: <4E813639.10907@oracle.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201109271903.14694.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday, September 27, 2011, Yinghai Lu wrote: > On 09/26/2011 03:24 PM, Rafael J. Wysocki wrote: > > > On Thursday, September 22, 2011, Yinghai Lu wrote: > >> On Wed, Sep 21, 2011 at 11:48 AM, Rafael J. Wysocki wrote: > >>> It looks like init_memory_mapping() is sometimes called with "end" > >>> beyond the last mapped PFN and it explodes when we try to write stuff to > >>> that address during image restoration. > >>> > >>> IOW, the Yinghai's assumption that init_memory_mapping() would always be > >>> called with a "good end" on x86_64 was overomptimistic. > >> > >> for 64bit x86, kernel_physical_mapping_init() will use > >> map_low_page()/call early_memmap() to access ram for page_table that is above > >> rather last mapped PFN. > >> > >> the point is: > >> on system with 64g, usable ram will be [0,2048m), [4g, 64g) > >> init_memory_mapping will be called two times for them. > >> before putting page_table high, > >> page table will be two parts: one is just below 512M, and one below 2048m. > >> after putting page_table high, > >> page table will be two parts: one is just below 2048M, and one below 64G. > >> > >> one of the purposes is finding biggest continuous big range under > >> 1024m for kdump. > > > > This is all fine so long as we can ensure that the "end" value we're > > passing to init_memory_mapping() will always be a valid address, which > > evidently is not the case sometimes. > > > I don't understand why end is not valid could happen. > > end should be always valid address. one is max_low_pfn under 4g, and another one is max_pfn... > > > > > > So, in my opinion we should simply apply the Takashi's patch at this > > point and revisit the kdump issue later, when we actually know how to do > > the right thing. > > > Takashi said: 2.6.37 with that commit is ok, only 2.6.39 somehow has the 1/20 chance has the reset problem. > > so that commit should not the cause. could be some hidden assumption from > restore code ? Quite frankly, I doubt it. The only remotely related change between 2.6.37 and 2.6.37 seems to be commit d1ee433 (x86, trampoline: Use the unified trampoline setup for ACPI wakeup). Thanks, Rafael