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 405B1C49ED7 for ; Mon, 23 Sep 2019 12:30:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0D70420835 for ; Mon, 23 Sep 2019 12:30:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1569241812; bh=HU4yCx8g3ABx9yqFacDsRh1eEPwGKuumX+bTsstzbzc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=mmuQx/flSkDrt/yts8sh3V92m5R6ZMxm3Lrkm2/ZBEBWnIyrXwcodioUZZ5miLQZW /EDV0tZQJuTrRQRzGNLD529prNnn/96NirI3BlaFrstBl4dniTpj2ekC1GqNXPOfur hMMC3UEKBOvWTcgPaYEal2suCW2An6f8H/mdF5Q0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2393840AbfIWMaL (ORCPT ); Mon, 23 Sep 2019 08:30:11 -0400 Received: from mx2.suse.de ([195.135.220.15]:51226 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2388199AbfIWMaL (ORCPT ); Mon, 23 Sep 2019 08:30:11 -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 316D9AF16; Mon, 23 Sep 2019 12:30:09 +0000 (UTC) Date: Mon, 23 Sep 2019 14:30:08 +0200 From: Michal Hocko To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Souptick Joarder , linux-hyperv@vger.kernel.org, Andrew Morton , Dan Williams , Haiyang Zhang , "K. Y. Srinivasan" , Oscar Salvador , Pavel Tatashin , Qian Cai , Sasha Levin , Stephen Hemminger , Wei Yang Subject: Re: [PATCH v1 0/3] mm/memory_hotplug: Export generic_online_page() Message-ID: <20190923123008.GP6016@dhcp22.suse.cz> References: <20190909114830.662-1-david@redhat.com> <20190923085807.GD6016@dhcp22.suse.cz> <20190923111559.GK6016@dhcp22.suse.cz> <88ac3511-4ad8-d5c8-8e6a-0cca0a0f0989@redhat.com> <20190923120719.GM6016@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Mon 23-09-19 14:20:05, David Hildenbrand wrote: > On 23.09.19 14:07, Michal Hocko wrote: > > On Mon 23-09-19 13:34:18, David Hildenbrand wrote: > >> On 23.09.19 13:15, Michal Hocko wrote: > > [...] > >>> I am wondering why those pages get onlined when they are, in fact, > >>> supposed to be offline. > >>> > >> > >> It's the current way of emulating sub-memory-block hotplug on top of the > >> memory bock device API we have. Hyper-V and XEN have been using that for > >> a long time. > > > > Do they really have to use the existing block interface when they in > > fact do not operate on the block granularity? Zone device memory already > > acts on sub section/block boundaries. > > > > Yes, we need memory blocks, especially for user space to properly online > them (as we discussed a while back, to decide on a zone) and for udev > events, to e.g., properly reload kexec when memory blocks get > added/removed/onlined/offlined. Just to make sure I really follow. We need a user interface to control where the memory gets onlined but it is the driver which determines which part of the block really gets onlined, right? -- Michal Hocko SUSE Labs