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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: Baoquan He CC: Matthew Wilcox , Andrew Morton , , , Mike Rapoport References: <20230529144022.42927-1-wangkefeng.wang@huawei.com> <38ea4ea3-cd7f-abf4-e992-2f748e3b1fcb@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: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: BF06A100009 X-Stat-Signature: qr7es5swo8ndnp1684hfdmi77njkyqhz X-HE-Tag: 1685428820-69390 X-HE-Meta: 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 ZdOwcPRN EPcdkSAmOmVfaW+DMP47kA5oPIYn2SSrMoxkdFFt4scgU9ByLc6SZ/+l+FnObq6VLfyG6mizy9e5TtujLGDXkPfg4UKP4j4tdMde11TFYx88If2q90fp7g4qVFgeEWYs3yqN2jyRoCOQyIcRoOnHB5Ss8U5Qn3iTpdHe7NcR6/PMxCPAu6yko6QI2FTq3TBkf9nMUQtNIZIayjEo= 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 2023/5/30 12:18, Baoquan He wrote: > 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] Oh, it looks strange, but it do occur if firmware report as this way. Thanks Willy and Baoquan, please ignore the patch.