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_PASS,USER_AGENT_MUTT autolearn=unavailable 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 29DAEC10F06 for ; Wed, 3 Apr 2019 10:46:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EC4E820700 for ; Wed, 3 Apr 2019 10:46:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554288370; bh=LYcMB2ThWS8TiTb2sdQZtFtuxTkNgYOkY5ZRF0bVuu0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=ve/8C7Fl/TJx9GUVDMMxKPd5psMDviC36g2eDo0a0mM9ooGQUFVz4Hk6bURRwgMJz Q2zWZj7Mmlos3DvaCefwVOds2zwasYROA8WLWTdTwzSj2Mhv4jCI5omhNCquRUAUdM Wj+uCn/huDwCJL/zKmkZk9AEBwBobKZv87SEcCAw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726656AbfDCKqI (ORCPT ); Wed, 3 Apr 2019 06:46:08 -0400 Received: from mx2.suse.de ([195.135.220.15]:49372 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725935AbfDCKqF (ORCPT ); Wed, 3 Apr 2019 06:46:05 -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 E6B22AF4C; Wed, 3 Apr 2019 10:46:03 +0000 (UTC) Date: Wed, 3 Apr 2019 12:46:02 +0200 From: Michal Hocko To: Oscar Salvador Cc: David Hildenbrand , akpm@linux-foundation.org, dan.j.williams@intel.com, Jonathan.Cameron@huawei.com, anshuman.khandual@arm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 0/4] mm,memory_hotplug: allocate memmap from hotadded memory Message-ID: <20190403104602.GJ15605@dhcp22.suse.cz> References: <20190329134243.GA30026@dhcp22.suse.cz> <20190401075936.bjt2qsrhw77rib77@d104.suse.de> <20190401115306.GF28293@dhcp22.suse.cz> <20190402082812.fefamf7qlzulb7t2@d104.suse.de> <20190402124845.GD28293@dhcp22.suse.cz> <20190403080113.adj2m3szhhnvzu56@d104.suse.de> <20190403081232.GB15605@dhcp22.suse.cz> <20190403083757.GC15605@dhcp22.suse.cz> <20190403094054.jdr7lxm45htgcsk7@d104.suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190403094054.jdr7lxm45htgcsk7@d104.suse.de> 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 Wed 03-04-19 11:40:54, Oscar Salvador wrote: > On Wed, Apr 03, 2019 at 10:37:57AM +0200, Michal Hocko wrote: > > That being said it should be the caller of the hotplug code to tell > > the vmemmap allocation strategy. For starter, I would only pack vmemmaps > > for "regular" kernel zone memory. Movable zones should be more careful. > > We can always re-evaluate later when there is a strong demand for huge > > pages on movable zones but this is not the case now because those pages > > are not really movable in practice. > > I agree that makes sense to let the caller specify if it wants to allocate > vmemmaps per memblock or per memory-range, so we are more flexible when it > comes to granularity in hot-add/hot-remove operations. And just to be more specific. The api shouldn't really care about this implementation detail. So ideally the caller of add_pages just picks up the proper allocator and the rest is completely transparent. > But the thing is that the zones are picked at onling stage, while > vmemmaps are created at hot-add stage, so I am not sure we can define > the strategy depending on the zone. THis is a good point. We do have means to tell a default zone for the regular memory hotplug so this can be reused based on the pfn range (default_zone_for_pfn). -- Michal Hocko SUSE Labs