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Tue, 30 May 2023 00:18:49 -0400 X-MC-Unique: rxs9tmbgPDaDSRJNcMrZWg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 047F0101A52C; Tue, 30 May 2023 04:18:49 +0000 (UTC) Received: from localhost (ovpn-12-192.pek2.redhat.com [10.72.12.192]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4319340CFD45; Tue, 30 May 2023 04:18:47 +0000 (UTC) Date: Tue, 30 May 2023 12:18:44 +0800 From: Baoquan He To: Kefeng Wang Cc: Matthew Wilcox , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Rapoport Subject: Re: [PATCH -next] mm: page_alloc: simplify has_managed_dma() Message-ID: References: <20230529144022.42927-1-wangkefeng.wang@huawei.com> <38ea4ea3-cd7f-abf4-e992-2f748e3b1fcb@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <38ea4ea3-cd7f-abf4-e992-2f748e3b1fcb@huawei.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 X-Rspamd-Queue-Id: BD7B51C000B X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: 75knftdfwyk67ntpftf6izs7kxbirkh1 X-HE-Tag: 1685420333-520773 X-HE-Meta: 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 hDR+AlZk aUdIy3KRFrDqDJETYjiW755BBM7kJwbkcNGwm6f+2MVTwjZ8ubD3ucaoIPHRe7VrAq2r3puMH44wukwWQMhNCKdOW/F4Gk5ZN4OiTPlZTwJ7YJ0FifBc11lbYjkh/XoK3SviyEzVR7/PDjBdDyh0ENm8+t7KWtbPAvQoMjxosaqAXvPydZwiTcn+wSG5WgpDAZw2R2j/Rl+0PjCeWtp+oCgHtlDn93VRBHCDZCWuQ8m1zyd1DW0z0IydLdLYR8NHT3sAXlYsuS9ffEHE= 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 05/30/23 at 10:10am, Kefeng Wang wrote: > > > 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/' willy is right. max_zone_pfn can only limit the range of zone, but can't decide which zone is put on which node. The memory layout is decided by firmware. I searched commit log to get below commit which can give a good example. commit c1d0da83358a2316d9be7f229f26126dbaa07468 Author: Laurent Dufour Date: Fri Sep 25 21:19:28 2020 -0700 mm: replace memmap_context by meminit_context Patch series "mm: fix memory to node bad links in sysfs", v3. Sometimes, firmware may expose interleaved memory layout like this: Early memory node ranges node 1: [mem 0x0000000000000000-0x000000011fffffff] node 2: [mem 0x0000000120000000-0x000000014fffffff] node 1: [mem 0x0000000150000000-0x00000001ffffffff] node 0: [mem 0x0000000200000000-0x000000048fffffff] node 2: [mem 0x0000000490000000-0x00000007ffffffff] > > 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; >