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 1B81EC49ED9 for ; Tue, 10 Sep 2019 18:00:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EC50F21479 for ; Tue, 10 Sep 2019 18:00:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568138434; bh=zol/Jw0oSCFl4O2QYN4xe8B2UqECSwFKVlUV7QcKGF0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=ODotjze1k1+RSECtJHvEvTHvSAlMw9/UwxL0zxiC9oYAGj4Bm4m6oOgVvWa1njrLA kFrcF7HX0ggXbQAAqQ6HYDJqRCMMF53SStgF+Wm7c5DRdMHcoUFM5a1zFk7OtR0RPY nhHK2YkCLmgEUfR0dTwLfswobu4ENeOxSPKae2gc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726731AbfIJSAa (ORCPT ); Tue, 10 Sep 2019 14:00:30 -0400 Received: from mx2.suse.de ([195.135.220.15]:50772 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726421AbfIJSAa (ORCPT ); Tue, 10 Sep 2019 14:00:30 -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 0FCC7AF8D; Tue, 10 Sep 2019 18:00:28 +0000 (UTC) Date: Tue, 10 Sep 2019 20:00:26 +0200 From: Michal Hocko To: Alexander Duyck Cc: virtio-dev@lists.oasis-open.org, kvm list , "Michael S. Tsirkin" , Catalin Marinas , David Hildenbrand , Dave Hansen , LKML , Matthew Wilcox , linux-mm , Andrew Morton , will@kernel.org, linux-arm-kernel@lists.infradead.org, Oscar Salvador , Yang Zhang , Pankaj Gupta , Konrad Rzeszutek Wilk , Nitesh Narayan Lal , Rik van Riel , lcapitulino@redhat.com, "Wang, Wei W" , Andrea Arcangeli , ying.huang@intel.com, Paolo Bonzini , Dan Williams , Fengguang Wu , Alexander Duyck , "Kirill A. Shutemov" Subject: Re: [PATCH v9 0/8] stg mail -e --version=v9 \ Message-ID: <20190910180026.GE4023@dhcp22.suse.cz> References: <20190907172225.10910.34302.stgit@localhost.localdomain> <20190910124209.GY2063@dhcp22.suse.cz> <20190910144713.GF2063@dhcp22.suse.cz> <20190910175213.GD4023@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190910175213.GD4023@dhcp22.suse.cz> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue 10-09-19 19:52:13, Michal Hocko wrote: > On Tue 10-09-19 09:05:43, Alexander Duyck wrote: [...] > > All this is providing is just a report and it is optional if the > > hypervisor will act on it or not. If the hypervisor takes some sort of > > action on the page, then the expectation is that the hypervisor will > > use some sort of mechanism such as a page fault to discover when the > > page is used again. > > OK so the baloon driver is in charge of this metadata and the allocator > has to live with that. Isn't that a layer violation? Another thing that is not clear to me is how these marked pages are different from any other free pages. All of them are unused and you are losing your metadata as soon as the page gets allocated because the page changes its owner and the struct page belongs to it. -- Michal Hocko SUSE Labs