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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 E4837C433DF for ; Fri, 14 Aug 2020 07:29:44 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9BB9120639 for ; Fri, 14 Aug 2020 07:29:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="R3lBnAZp" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9BB9120639 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 39B276B0003; Fri, 14 Aug 2020 03:29:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 324126B0005; Fri, 14 Aug 2020 03:29:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1C5446B0008; Fri, 14 Aug 2020 03:29:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 0532D6B0003 for ; Fri, 14 Aug 2020 03:29:44 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id BA8974DDD for ; Fri, 14 Aug 2020 07:29:43 +0000 (UTC) X-FDA: 77148349446.02.robin99_4c10b0926ffb Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin02.hostedemail.com (Postfix) with ESMTP id 8C28B10097ABC for ; Fri, 14 Aug 2020 07:29:43 +0000 (UTC) X-HE-Tag: robin99_4c10b0926ffb X-Filterd-Recvd-Size: 3420 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf37.hostedemail.com (Postfix) with ESMTP for ; Fri, 14 Aug 2020 07:29:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=AfrMrkrA2HZxTkg5Cv0NWjTzaYh5Z28RiUGGto0tVJU=; b=R3lBnAZpajlKS+ZYCmzCTpzXZE WGskKYnrQlnWOI08brF1QFByRNy9vewCqurBe8Sf7S6fS7hkYLfKSbxupKlE9RPQT9NbuzcWIwtfe +5b6TguaGGXn5Lcg34eWFhwMbYdHtbmQAHk8+UgjKsuOR5zYxZthbEqKTZgd7Q+IXKUIaTDTTy6hi EKm9u0BgGFiEAtjVzo/4P5mO2SjqiAw7Pb8SEMSUEqUKekpbo6VERpfF1Eai1/PwpiNTcC7tdq8M2 5DDK5kk5wuflH/Kkdc/b25Aln3IQ3Kt2ErsOFEzjpFNp7ioD/PZIfZc2H1Ob+lJhV/YbogoRFnlP0 SXuEMMGw==; Received: from hch by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1k6U9Q-0001lh-7m; Fri, 14 Aug 2020 07:29:20 +0000 Date: Fri, 14 Aug 2020 08:29:20 +0100 From: Christoph Hellwig To: Roger Pau Monn?? Cc: Christoph Hellwig , linux-kernel@vger.kernel.org, Oleksandr Andrushchenko , David Airlie , Daniel Vetter , Boris Ostrovsky , Juergen Gross , Stefano Stabellini , Dan Carpenter , Wei Liu , Yan Yankovskyi , dri-devel@lists.freedesktop.org, xen-devel@lists.xenproject.org, linux-mm@kvack.org, David Hildenbrand , Michal Hocko , Dan Williams Subject: Re: [PATCH v4 2/2] xen: add helpers to allocate unpopulated memory Message-ID: <20200814072920.GA6126@infradead.org> References: <20200811094447.31208-1-roger.pau@citrix.com> <20200811094447.31208-3-roger.pau@citrix.com> <20200813073337.GA16160@infradead.org> <20200813075420.GC975@Air-de-Roger> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200813075420.GC975@Air-de-Roger> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html X-Rspamd-Queue-Id: 8C28B10097ABC X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Aug 13, 2020 at 09:54:20AM +0200, Roger Pau Monn?? wrote: > On Thu, Aug 13, 2020 at 08:33:37AM +0100, Christoph Hellwig wrote: > > On Tue, Aug 11, 2020 at 11:44:47AM +0200, Roger Pau Monne wrote: > > > If enabled (because ZONE_DEVICE is supported) the usage of the new > > > functionality untangles Xen balloon and RAM hotplug from the usage of > > > unpopulated physical memory ranges to map foreign pages, which is the > > > correct thing to do in order to avoid mappings of foreign pages depend > > > on memory hotplug. > > > > So please just select ZONE_DEVICE if this is so much better rather > > than maintaining two variants. > > We still need to other variant for Arm at least, so both need to be > maintained anyway, even if we force ZONE_DEVICE on x86. Well, it still really helps reproducability if you stick to one implementation of x86. The alternative would be an explicit config option to opt into it, but just getting a different implementation based on a random kernel option is strange.