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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 0A59CC19759 for ; Thu, 1 Aug 2019 07:40:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D116F2173E for ; Thu, 1 Aug 2019 07:40:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564645211; bh=pWNHnvJa+JKrZaUJesTc4QvrVQAOwyEb/9hXofZd7BI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=ZyUpzOj6UJjjiA/mk+P334oGZDm/D8KK/qRgVGbIzqDRtQGCEnu2a5vUP8yZ219q8 5Dkawb0JjR+fLwU2YodwPVr1/LWJl0Tl62Z3E3n+IQB6U29iJO8ZXPzcdGiDv10Zbo k0HOGkVTkdo9lJnaCcXFgBKJ2wncYZ7pHx1NaSXs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729621AbfHAHkK (ORCPT ); Thu, 1 Aug 2019 03:40:10 -0400 Received: from mx2.suse.de ([195.135.220.15]:59984 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725804AbfHAHkK (ORCPT ); Thu, 1 Aug 2019 03:40:10 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 55B34B11C; Thu, 1 Aug 2019 07:40:09 +0000 (UTC) Date: Thu, 1 Aug 2019 09:39:57 +0200 From: Michal Hocko To: David Hildenbrand Cc: Rashmica Gupta , Oscar Salvador , Andrew Morton , Dan Williams , pasha.tatashin@soleen.com, Jonathan.Cameron@huawei.com, anshuman.khandual@arm.com, Vlastimil Babka , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 0/5] Allocate memmap from hotadded memory Message-ID: <20190801073957.GH11627@dhcp22.suse.cz> References: <9143f64391d11aa0f1988e78be9de7ff56e4b30b.camel@gmail.com> <20190702074806.GA26836@linux> <20190731120859.GJ9330@dhcp22.suse.cz> <4ddee0dd719abd50350f997b8089fa26f6004c0c.camel@gmail.com> <20190801071709.GE11627@dhcp22.suse.cz> <9bcbd574-7e23-5cfe-f633-646a085f935a@redhat.com> <20190801072430.GF11627@dhcp22.suse.cz> <5e6137c9-5269-5756-beaa-d116652be8b9@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5e6137c9-5269-5756-beaa-d116652be8b9@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 01-08-19 09:31:09, David Hildenbrand wrote: > On 01.08.19 09:26, David Hildenbrand wrote: [...] > > I am not sure about the implications of having > > pfn_valid()/pfn_present()/pfn_online() return true but accessing it > > results in crashes. (suspend, kdump, whatever other technology touches > > online memory) > > (oneidea: we could of course go ahead and mark the pages PG_offline > before unmapping the pfn range to work around these issues) PG_reserved and an elevated reference count should be enough to drive any pfn walker out. Pfn walkers shouldn't touch any page unless they know and recognize their type. -- Michal Hocko SUSE Labs