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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 X-Rspamd-Queue-Id: C574E120010 X-Rspam-User: X-Stat-Signature: 8wbxsjaxwr4wkcutypwj8un54xzxiony X-Rspamd-Server: rspam01 X-HE-Tag: 1685412657-917502 X-HE-Meta: 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 /gyG1s58 TJO5gBLjOBnPc72+H84XHE6kQIyIXK+LWolD8XCYP4Su1C7Bi6SZZM4tuN16H4iFd/JdH2EShA/sjxlUGT5eWml01efscVKmJWN7X9F6EYUka26E/as4YgNx90gH0lbW3aD42gQyIIHACY74OWp4wiW4M5MbKeS/EhsTrDXN1uPeUwVoXKly6bWOCdw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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;