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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D951FC7EE23 for ; Tue, 30 May 2023 02:11:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229966AbjE3CLD (ORCPT ); Mon, 29 May 2023 22:11:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51496 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229673AbjE3CK5 (ORCPT ); Mon, 29 May 2023 22:10:57 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DE4A1F1 for ; Mon, 29 May 2023 19:10:55 -0700 (PDT) Received: from dggpemm500001.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4QVbNS2DTgzqTTd; Tue, 30 May 2023 10:06:16 +0800 (CST) Received: from [10.174.177.243] (10.174.177.243) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.23; Tue, 30 May 2023 10:10:53 +0800 Message-ID: <38ea4ea3-cd7f-abf4-e992-2f748e3b1fcb@huawei.com> Date: Tue, 30 May 2023 10:10:52 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.10.1 Subject: Re: [PATCH -next] mm: page_alloc: simplify has_managed_dma() Content-Language: en-US To: Matthew Wilcox CC: Andrew Morton , , , Baoquan He , Mike Rapoport References: <20230529144022.42927-1-wangkefeng.wang@huawei.com> From: Kefeng Wang In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2023/5/29 22:26, Matthew Wilcox wrote: > On Mon, May 29, 2023 at 10:40:22PM +0800, Kefeng Wang wrote: >> The ZONE_DMA should only exists on Node 0, only check NODE_DATA(0) >> is enough, so simplify has_managed_dma() and make it inline. > > That's true on x86, but is it true on all architectures? There is no document about numa node info for the DMA_ZONE, + Mike I used 'git grep -w ZONE_DMA arch/' 1) the following archs without NUMA support, so it's true for them, arch/alpha/mm/init.c: max_zone_pfn[ZONE_DMA] = dma_pfn; arch/arm/mm/init.c: max_zone_pfn[ZONE_DMA] = min(arm_dma_pfn_limit, max_low); arch/m68k/mm/init.c: max_zone_pfn[ZONE_DMA] = end_mem >> PAGE_SHIFT; arch/m68k/mm/mcfmmu.c: max_zone_pfn[ZONE_DMA] = PFN_DOWN(_ramend); arch/m68k/mm/motorola.c: max_zone_pfn[ZONE_DMA] = memblock_end_of_DRAM(); arch/m68k/mm/sun3mmu.c: max_zone_pfn[ZONE_DMA] = ((unsigned long)high_memory) >> PAGE_SHIFT; arch/microblaze/mm/init.c: zones_size[ZONE_DMA] = max_low_pfn; arch/microblaze/mm/init.c: zones_size[ZONE_DMA] = max_pfn; 2) Simple check following archs, it seems that it is yes to them too. arch/mips/mm/init.c: max_zone_pfns[ZONE_DMA] = MAX_DMA_PFN; arch/powerpc/mm/mem.c: max_zone_pfns[ZONE_DMA] = min(max_low_pfn, arch/s390/mm/init.c: max_zone_pfns[ZONE_DMA] = PFN_DOWN(MAX_DMA_ADDRESS); arch/sparc/mm/srmmu.c: max_zone_pfn[ZONE_DMA] = max_low_pfn; arch/x86/mm/init.c: max_zone_pfns[ZONE_DMA] = min(MAX_DMA_PFN, max_low_pfn); arch/arm64/mm/init.c: max_zone_pfns[ZONE_DMA] = PFN_DOWN(arm64_dma_phys_limit); arch/loongarch/mm/init.c: max_zone_pfns[ZONE_DMA] = MAX_DMA_PFN;