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=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 23FF9C433DB for ; Tue, 2 Mar 2021 18:06:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E68DA64F1F for ; Tue, 2 Mar 2021 18:06:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350026AbhCBRym (ORCPT ); Tue, 2 Mar 2021 12:54:42 -0500 Received: from hqnvemgate26.nvidia.com ([216.228.121.65]:2477 "EHLO hqnvemgate26.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348007AbhCBAW3 (ORCPT ); Mon, 1 Mar 2021 19:22:29 -0500 Received: from hqmail.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, AES256-SHA) id ; Mon, 01 Mar 2021 16:21:41 -0800 Received: from nvdebian.localnet (172.20.145.6) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Tue, 2 Mar 2021 00:21:37 +0000 From: Alistair Popple To: Jason Gunthorpe CC: , , , , , , , , , , , Subject: Re: [PATCH v3 1/8] mm: Remove special swap entry functions Date: Tue, 2 Mar 2021 11:21:35 +1100 Message-ID: <3156280.dJpzq75PnV@nvdebian> In-Reply-To: <20210301174642.GP4247@nvidia.com> References: <20210226071832.31547-1-apopple@nvidia.com> <20210226071832.31547-2-apopple@nvidia.com> <20210301174642.GP4247@nvidia.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Originating-IP: [172.20.145.6] X-ClientProxiedBy: HQMAIL111.nvidia.com (172.20.187.18) To HQMAIL107.nvidia.com (172.20.187.13) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1614644501; bh=azDUrxm78xZYK+HMnHGyx9Cls7mv6No8+tEzyjhqkY4=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Transfer-Encoding:Content-Type: X-Originating-IP:X-ClientProxiedBy; b=OWpxffKeP4tRIYOnIzWmKU2ko4OneFNOwVj+FyTqa4wUuAyUq/G035xSN96rL3s4U CA2Le5hOQkxj09JDqjwtL+dcVozOjVJOqsAP/77YPxoAGDgKoCS+uC44nuPIHShHJu AQcoFQv2I5HrVxcpLUdaEYX96qs+Fbn+H4WH6IiNhxMuJse6m0q6LImPEePfGXcqS3 y8rWRlSZ6kxZv7XVJ05BMWPXBFERIbAwCPh/cbO3qmpQiPSlkeCWEOdT2cGGNX3CKM xj85TG9o7jkYYmeYx1sJ/KOkEFDUPRj2HB/Euue8YPgbHDP8xnwpiiRC88gPjPdE07 Dv/DTQIp44Jsg== Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Tuesday, 2 March 2021 4:46:42 AM AEDT Jason Gunthorpe wrote: > > I wish you could come up with a more descriptive word that special > here > > What I understand is this is true when the swap_offset is a pfn? Correct, and that points to a better name. Maybe is_pfn_swap_entry()? In which case adding a helper as Christoph suggested makes some more sense. Eg: pfn_swap_entry_to_page() > > -static inline struct page *migration_entry_to_page(swp_entry_t entry) > > -{ > > - struct page *p = pfn_to_page(swp_offset(entry)); > > - /* > > - * Any use of migration entries may only occur while the > > - * corresponding page is locked > > - */ > > - BUG_ON(!PageLocked(compound_head(p))); > > - return p; > > And this constraint has been completely lost? Yes, sorry I should have called that out. I didn't think loosing the check was a big deal, but I can add some checks to some of the call sites which would catch a page being incorrectly unlocked. > A comment in front of the is_special_entry explaining all the rule > would help alot Will add one. > Transformation looks fine otherwise Thanks. - Alistair > Jason >