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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 E75ECC7618F for ; Wed, 17 Jul 2019 17:50:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BCAD921849 for ; Wed, 17 Jul 2019 17:50:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="CV5RjjFY" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727528AbfGQRu0 (ORCPT ); Wed, 17 Jul 2019 13:50:26 -0400 Received: from hqemgate16.nvidia.com ([216.228.121.65]:12191 "EHLO hqemgate16.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727255AbfGQRu0 (ORCPT ); Wed, 17 Jul 2019 13:50:26 -0400 Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqemgate16.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Wed, 17 Jul 2019 10:50:23 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Wed, 17 Jul 2019 10:50:25 -0700 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Wed, 17 Jul 2019 10:50:25 -0700 Received: from rcampbell-dev.nvidia.com (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Wed, 17 Jul 2019 17:50:21 +0000 Subject: Re: [PATCH 1/3] mm: document zone device struct page reserved fields To: Christoph Hellwig , John Hubbard CC: , , , Vlastimil Babka , Christoph Lameter , Dave Hansen , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , "Kirill A . Shutemov" , Lai Jiangshan , Martin Schwidefsky , Pekka Enberg , Randy Dunlap , Andrey Ryabinin , Jason Gunthorpe , Andrew Morton , Linus Torvalds References: <20190717001446.12351-1-rcampbell@nvidia.com> <20190717001446.12351-2-rcampbell@nvidia.com> <26a47482-c736-22c4-c21b-eb5f82186363@nvidia.com> <20190717042233.GA4529@lst.de> <20190717043824.GA4755@lst.de> X-Nvconfidentiality: public From: Ralph Campbell Message-ID: <4295112b-e5ff-f9ad-defc-597ad3bc49a1@nvidia.com> Date: Wed, 17 Jul 2019 10:50:20 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190717043824.GA4755@lst.de> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL105.nvidia.com (172.20.187.12) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1563385823; bh=SWBqWTLtRGRFAUZCgh3lTPUjJRJ6jQ100pAZoV0UM5g=; h=X-PGP-Universal:Subject:To:CC:References:X-Nvconfidentiality:From: Message-ID:Date:User-Agent:MIME-Version:In-Reply-To: X-Originating-IP:X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=CV5RjjFYrtxJBPx50YvgVwuu37aXkSWSWDX7gZc9Perx7pREk/ltNltuoF01N12nF fbcGNahPv9Pu7cj2VWx7kgYouKXYLs74/GvanmWlQgzAEpDd+r92oWoAmxifsQSOjY IZCfGm6yu8dITo783GAtU7Q+sH2EPk3XJuBReBiHhao9nODGOnDHYbAxPp59+502lb 1vSZkgb7BwefFsx24B8sNYTUZW17BtBCGEjl7ecTuX83NvLUYsDv8AWDDqHZBPf1J2 lV2g4EFQ6YMntYjOwT54R0Kw2q3EvgtT+HYCrx1u69MVIzVv+IMtetkOAJZcos5+bY UxIthrioLOHeQ== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/16/19 9:38 PM, Christoph Hellwig wrote: > On Tue, Jul 16, 2019 at 09:31:33PM -0700, John Hubbard wrote: >> OK, so just delete all the _zd_pad_* fields? Works for me. It's misleading to >> calling something padding, if it's actually unavailable because it's used >> in the other union, so deleting would be even better than commenting. >> >> In that case, it would still be nice to have this new snippet, right?: > > I hope willy can chime in a bit on his thoughts about how the union in > struct page should look like. The padding at the end of the sub-structs > certainly looks pointless, and other places don't use it either. But if > we are using the other fields it almost seems to me like we only want to > union the lru field in the first sub-struct instead of overlaying most > of it. > I like this approach. I'll work on an updated patch that makes "struct list_head lru" part of a union with the ZONE_DEVICE struct without the padding and update the comments and change log. I will also wait a day or two for others to add their comments.