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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 79452C43218 for ; Tue, 11 Jun 2019 14:36:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5B350206BB for ; Tue, 11 Jun 2019 14:36:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390988AbfFKOg5 (ORCPT ); Tue, 11 Jun 2019 10:36:57 -0400 Received: from foss.arm.com ([217.140.110.172]:34522 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387551AbfFKOg5 (ORCPT ); Tue, 11 Jun 2019 10:36:57 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 093FC346; Tue, 11 Jun 2019 07:36:56 -0700 (PDT) Received: from [10.1.29.141] (e121487-lin.cambridge.arm.com [10.1.29.141]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 187C33F557; Tue, 11 Jun 2019 07:36:54 -0700 (PDT) Subject: Re: [PATCH 02/17] mm: stub out all of swapops.h for !CONFIG_MMU To: Christoph Hellwig Cc: Palmer Dabbelt , Damien Le Moal , linux-riscv@lists.infradead.org, uclinux-dev@uclinux.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20190610221621.10938-1-hch@lst.de> <20190610221621.10938-3-hch@lst.de> <516c8def-22db-027c-873d-a943454e33af@arm.com> <20190611141841.GA29151@lst.de> From: Vladimir Murzin Message-ID: <80d01a1d-b6b0-18e8-811c-71af14cba3b9@arm.com> Date: Tue, 11 Jun 2019 15:36:53 +0100 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: <20190611141841.GA29151@lst.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/11/19 3:18 PM, Christoph Hellwig wrote: > On Tue, Jun 11, 2019 at 11:15:44AM +0100, Vladimir Murzin wrote: >> On 6/10/19 11:16 PM, Christoph Hellwig wrote: >>> The whole header file deals with swap entries and PTEs, none of which >>> can exist for nommu builds. >> >> Although I agree with the patch, I'm wondering how you get into it? > > Without that the RISC-V nommu blows up like this: > > > In file included from mm/vmscan.c:58: > ./include/linux/swapops.h: In function ‘pte_to_swp_entry’: > ./include/linux/swapops.h:71:15: error: implicit declaration of function ‘__pte_to_swp_entry’; did you mean ‘pte_to_swp_entry’? [-Werror=implicit-function-declaration] > arch_entry = __pte_to_swp_entry(pte); > ^~~~~~~~~~~~~~~~~~ > pte_to_swp_entry > ./include/linux/swapops.h:71:13: error: incompatible types when assigning to type ‘swp_entry_t’ {aka ‘struct ’} from type ‘int’ > arch_entry = __pte_to_swp_entry(pte); > ^ > ./include/linux/swapops.h:72:19: error: implicit declaration of function ‘__swp_type’; did you mean ‘swp_type’? [-Werror=implicit-function-declaration] > return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry)); > ^~~~~~~~~~ > swp_type > ./include/linux/swapops.h:72:43: error: implicit declaration of function ‘__swp_offset’; did you mean ‘swp_offset’? [-Werror=implicit-function-declaration] > return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry)); > ^~~~~~~~~~~~ > swp_offset > ./include/linux/swapops.h: In function ‘swp_entry_to_pte’: > ./include/linux/swapops.h:83:15: error: implicit declaration of function ‘__swp_entry’; did you mean ‘swp_entry’? [-Werror=implicit-function-declaration] > arch_entry = __swp_entry(swp_type(entry), swp_offset(entry)); > ^~~~~~~~~~~ > swp_entry > ./include/linux/swapops.h:83:13: error: incompatible types when assigning to type ‘swp_entry_t’ {aka ‘struct ’} from type ‘int’ > arch_entry = __swp_entry(swp_type(entry), swp_offset(entry)); > ^ > ./include/linux/swapops.h:84:9: error: implicit declaration of function ‘__swp_entry_to_pte’; did you mean ‘swp_entry_to_pte’? [-Werror=implicit-function-declaration] > return __swp_entry_to_pte(arch_entry); > ^~~~~~~~~~~~~~~~~~ > swp_entry_to_pte > ./include/linux/swapops.h:84:9: error: incompatible types when returning type ‘int’ but ‘pte_t’ {aka ‘struct ’} was expected > return __swp_entry_to_pte(arch_entry); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > cc1: some warnings being treated as errors > make[1]: *** [scripts/Makefile.build:278: mm/vmscan.o] Error 1 > make: *** [Makefile:1071: mm] Error 2 > make: *** Waiting for unfinished jobs.... > It looks like NOMMU ports tend to define those. For ARM they are: #define __swp_type(x) (0) #define __swp_offset(x) (0) #define __swp_entry(typ,off) ((swp_entry_t) { ((typ) | ((off) << 7)) }) #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) }) #define __swp_entry_to_pte(x) ((pte_t) { (x).val }) Anyway, I have no strong opinion on which is better :) Cheers Vladimir