From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 20B86ECDFB8 for ; Tue, 24 Jul 2018 07:22:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D740220856 for ; Tue, 24 Jul 2018 07:22:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D740220856 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388462AbeGXI1n (ORCPT ); Tue, 24 Jul 2018 04:27:43 -0400 Received: from mx2.suse.de ([195.135.220.15]:54076 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2388400AbeGXI1n (ORCPT ); Tue, 24 Jul 2018 04:27:43 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id ABCCEAE83; Tue, 24 Jul 2018 07:22:38 +0000 (UTC) Date: Tue, 24 Jul 2018 09:22:37 +0200 From: Michal Hocko To: David Hildenbrand Cc: Vlastimil Babka , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Baoquan He , Dave Young , Greg Kroah-Hartman , Hari Bathini , Huang Ying , "Kirill A. Shutemov" , =?iso-8859-1?Q?Marc-Andr=E9?= Lureau , Matthew Wilcox , Miles Chen , Pavel Tatashin , Petr Tesarik Subject: Re: [PATCH v1 0/2] mm/kdump: exclude reserved pages in dumps Message-ID: <20180724072237.GA28386@dhcp22.suse.cz> References: <20180720123422.10127-1-david@redhat.com> <9f46f0ed-e34c-73be-60ca-c892fb19ed08@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 23-07-18 19:12:58, David Hildenbrand wrote: > On 23.07.2018 13:45, Vlastimil Babka wrote: > > On 07/20/2018 02:34 PM, David Hildenbrand wrote: > >> Dumping tools (like makedumpfile) right now don't exclude reserved pages. > >> So reserved pages might be access by dump tools although nobody except > >> the owner should touch them. > > > > Are you sure about that? Or maybe I understand wrong. Maybe it changed > > recently, but IIRC pages that are backing memmap (struct pages) are also > > PG_reserved. And you definitely do want those in the dump. > > I proposed a new flag/value to mask pages that are logically offline but > Michal wanted me to go into this direction. > > While we can special case struct pages in dump tools ("we have to > read/interpret them either way, so we can also dump them"), it smells > like my original attempt was cleaner. Michal? But we do not have many page flags spare and even if we have one or two this doesn't look like the use for them. So I still think we should try the PageReserved way. -- Michal Hocko SUSE Labs