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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 1E4DDC282C2 for ; Thu, 7 Feb 2019 21:25:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E668821721 for ; Thu, 7 Feb 2019 21:25:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726718AbfBGVZU (ORCPT ); Thu, 7 Feb 2019 16:25:20 -0500 Received: from shards.monkeyblade.net ([23.128.96.9]:52998 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726512AbfBGVZU (ORCPT ); Thu, 7 Feb 2019 16:25:20 -0500 Received: from localhost (unknown [IPv6:2601:601:9f80:35cd::bf5]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id D7249146D8BE1; Thu, 7 Feb 2019 13:25:19 -0800 (PST) Date: Thu, 07 Feb 2019 13:25:19 -0800 (PST) Message-Id: <20190207.132519.1698007650891404763.davem@davemloft.net> To: ilias.apalodimas@linaro.org Cc: willy@infradead.org, brouer@redhat.com, tariqt@mellanox.com, toke@redhat.com, netdev@vger.kernel.org, mgorman@techsingularity.net, linux-mm@kvack.org Subject: Re: [RFC, PATCH] net: page_pool: Don't use page->private to store dma_addr_t From: David Miller In-Reply-To: <20190207152034.GA3295@apalos> References: <1549550196-25581-1-git-send-email-ilias.apalodimas@linaro.org> <20190207150745.GW21860@bombadil.infradead.org> <20190207152034.GA3295@apalos> X-Mailer: Mew version 6.8 on Emacs 26.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Thu, 07 Feb 2019 13:25:20 -0800 (PST) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Ilias Apalodimas Date: Thu, 7 Feb 2019 17:20:34 +0200 > Well updating struct page is the final goal, hence the comment. I am mostly > looking for opinions here since we are trying to store dma addresses which are > irrelevant to pages. Having dma_addr_t definitions in mm-related headers is a > bit controversial isn't it ? If we can add that, then yes the code would look > better I fundamentally disagree. One of the core operations performed on a page is mapping it so that a device and use it. Why have ancillary data structure support for this all over the place, rather than in the common spot which is the page. A page really is not just a 'mm' structure, it is a system structure.