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Tue, 21 Oct 2025 21:36:41 +0800 (CST) Received: from dggpemf100008.china.huawei.com (unknown [7.185.36.138]) by mail.maildlp.com (Postfix) with ESMTPS id CE2B41A016C; Tue, 21 Oct 2025 21:37:04 +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; Tue, 21 Oct 2025 21:37:03 +0800 Message-ID: <8ffb441a-d9a5-451f-ad39-5689acea13df@huawei.com> Date: Tue, 21 Oct 2025 21:37:02 +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 From: Kefeng Wang 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> <2436956a-d5d2-476d-9117-a06fae5d788d@huawei.com> Content-Language: en-US In-Reply-To: <2436956a-d5d2-476d-9117-a06fae5d788d@huawei.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: kwepems100001.china.huawei.com (7.221.188.238) To dggpemf100008.china.huawei.com (7.185.36.138) X-Rspamd-Server: rspam05 X-Stat-Signature: 58by8crix6pfz7yz5q6ektb6juym81ou X-Rspam-User: X-Rspamd-Queue-Id: E2D721C000C X-HE-Tag: 1761053833-867301 X-HE-Meta: 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 E8GG0cJu idMA09bVNphK9eA4q4v18PP3gvhfioDNNqUHho9CByXf0YZo1ewnNRQMkze/A4SPsULShzpWWXui4Foi+xpc97t7AbRxxaUf7wpk5QSJDtMBM4DA8UEp6ddHb5BrkPSu9I147TVbDmUN4iRYDaX4aPIYKbc5lyK9Lf3memPM2E4LFL3knhdQipYJVBqB5GrXZHW1THkWOHb3A0aIPezOj1wA4rIBInzcJLF8RKHj6k6D78B/QBwJLj5NNm7fOsflp6oiaODXE9fpHaP2R+unAanSwicdFauKbyENRV3hp5dM0Re/X8ZAr2mRfEaJbv7z6S4losYLI28tgdYSxIvL3FH67mioQPhaWQ3iwzZG1LWQsG7MfAVDmAmZ0o1ugyJnuiZvhTOW3swtH8HU= 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 23:18, Kefeng Wang wrote: > > > 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. > If no objection, I won't change this and will send a new version with 1) kerneldoc refresh for folio_need_prot_numa, per Lorenzo 2) update the changelog of this one, per David Thanks