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Mon, 20 Oct 2025 23:17:21 +0800 (CST) Received: from dggpemf100008.china.huawei.com (unknown [7.185.36.138]) by mail.maildlp.com (Postfix) with ESMTPS id 519F2140257; Mon, 20 Oct 2025 23:18:29 +0800 (CST) Received: from [10.174.177.243] (10.174.177.243) by dggpemf100008.china.huawei.com (7.185.36.138) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Mon, 20 Oct 2025 23:18:28 +0800 Message-ID: <2436956a-d5d2-476d-9117-a06fae5d788d@huawei.com> Date: Mon, 20 Oct 2025 23:18:27 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 4/4] mm: huge_memory: use folio_needs_prot_numa() for pmd folio To: David Hildenbrand , Lorenzo Stoakes CC: Andrew Morton , , Zi Yan , Baolin Wang , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , , Sidhartha Kumar References: <20251020061845.3347258-1-wangkefeng.wang@huawei.com> <20251020061845.3347258-5-wangkefeng.wang@huawei.com> <4d9b5a05-5e1a-4a99-b8df-bd61b336392f@lucifer.local> Content-Language: en-US From: Kefeng Wang In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: kwepems500002.china.huawei.com (7.221.188.17) To dggpemf100008.china.huawei.com (7.185.36.138) X-Rspam-User: X-Stat-Signature: 6jkyg56fijrkf3gi4ui8tpogaktics13 X-Rspamd-Queue-Id: 2AC99160017 X-Rspamd-Server: rspam09 X-HE-Tag: 1760973516-291492 X-HE-Meta: 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 EQa98ojA X5AKFl80MVf/1FRrej90wleCPZX1MunY6AMfUVeIlE5UvteuI3YVJz8hBoTr+Iqc+saN44r1BsJGUXnGTJAkFiDSr10OWOMj3drjI8Kt2utznlJ1LHHgcOvaEPeQ3658SJC/NoKICuMekH2TGyGoQThUnof9+tT7sx4bMBtEoQ0fHQiAiO+omYxIk7/a2tcBb1ewS/E5TQjfZSGi4/7GqyFNBD53DPLiLVvndwJvo5pFifB0PdJj9JfWQhE/YDIZkbR3HXhCtAZyWeXkfGv1dawVHga2r/RTBsjWQig/vzfYxPTHGrdk1Z+A1j8DK8KHManz9jWrEgqwNjRJQwncBnO91H1AFilSkuzGrVlbnTOn1OA0f9gxqW2hAESKPqcFzDdMttlhN08ReRxc= 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 2025/10/20 21:23, David Hildenbrand wrote: > >>>           /* >>>            * Avoid trapping faults against the zero page. The read-only >>>            * data is likely to be read-cached on the local CPU and >>> @@ -2490,19 +2490,13 @@ int change_huge_pmd(struct mmu_gather *tlb, >>> struct vm_area_struct *vma, >>>           if (pmd_protnone(*pmd)) >>>               goto unlock; >>> >>> -        folio = pmd_folio(*pmd); >>> -        toptier = node_is_toptier(folio_nid(folio)); >>> -        /* >>> -         * Skip scanning top tier node if normal numa >>> -         * balancing is disabled >>> -         */ >>> -        if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && >>> -            toptier) >>> -            goto unlock; >>> +        /* Get target node for single threaded private VMAs */ >>> +        if (!(vma->vm_flags & VM_SHARED) && >>> +            atomic_read(&vma->vm_mm->mm_users) == 1) >>> +            target_node = numa_node_id(); >> >> This is duplicated in both callers, and only used by >> folio_needs_prot_numa(), >> why not abstract this to the function also? > > There was a discussion on that in v3 I think where I asked the same > question. > Yes, it is in v1, for pte, we could avoid 512 times check and the numa_node_id(), so we leave it as is.