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Wed, 3 Jan 2024 14:23:14 +0800 Message-ID: <8d941161-6433-44c4-9064-b3bb346edf2c@huawei.com> Date: Wed, 3 Jan 2024 14:23:14 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: memory: use nth_page() in clear/copy_subpage() Content-Language: en-US To: David Hildenbrand , Matthew Wilcox CC: Andrew Morton , , References: <20231229082207.60235-1-wangkefeng.wang@huawei.com> <9bb17dcd-4651-41d2-9982-4632147a82f8@huawei.com> <747e1c4e-6339-4b11-aaf9-9f8c4a428d66@redhat.com> From: Kefeng Wang In-Reply-To: <747e1c4e-6339-4b11-aaf9-9f8c4a428d66@redhat.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpemm100001.china.huawei.com (7.185.36.93) X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 0FCE31A0003 X-Stat-Signature: cwrs3iqd5d7g41xj3qtc1q4yy7pyucns X-HE-Tag: 1704263003-55398 X-HE-Meta: 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 a0KfIxT9 EIceQ3jmTU1l43KlL54x1nTYznN3iyAR3ujvgLEr3Zo7BckqajLGwF3y8wYzs0aRGMx19INkNL+iqyxmfD/eiNqgAkVANPJtzNJPIAk1c2wUm3Ixv5ex+n3WoSWbzgRVmyBBtP8n6knxx6uSmL27gDrZMMqi7XO7okKRth7uKOjHsPGSknwuxgTr0JvwTeHYDURsp/+/a1s5Cr94Dh9Vur2rpNg== 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: List-Subscribe: List-Unsubscribe: On 2024/1/3 0:11, David Hildenbrand wrote: > On 02.01.24 07:53, Kefeng Wang wrote: >> >> >> On 2023/12/29 19:15, David Hildenbrand wrote: >>> On 29.12.23 09:49, Matthew Wilcox wrote: >>>> On Fri, Dec 29, 2023 at 04:22:07PM +0800, Kefeng Wang wrote: >>>>> The clear and copy of huge gigantic page has converted to use >>>>> nth_page() >>>>> to handle the possible discontinuous struct page(SPARSEMEM without >>>>> VMEMMAP), >>>>> but not change for the non-gigantic part, fix it too. >>>> >>>> Can there be discontiguities within a non-gigantic huge page?  My >>>> impression was that you can't have a discontiguity at such a small >>>> boundary. >>> >>> No, we can't. MAX_ORDER allocations from the buddy always completely fit >>> into a memory section. >> >> On ARM64, we have 32M(16*2M) HugeTLB, it maybe not within a mem section, >> right? > > I recall the mem sections are always at least 128 MiB on arm64. > > Note that anything > MAX_ORDER is called a "gigantic huge page" in > hugetlb code. Yes, we already check MAX_ORDER, please ignore this one, thanks. > >