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Mon, 20 Oct 2025 14:19:11 +0800 (CST) Received: from dggpemf100008.china.huawei.com (unknown [7.185.36.138]) by mail.maildlp.com (Postfix) with ESMTPS id 8D6D9180488; Mon, 20 Oct 2025 14:20:02 +0800 (CST) Received: from localhost.localdomain (10.50.87.83) 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 14:20:01 +0800 From: Kefeng Wang To: Andrew Morton , David Hildenbrand , Lorenzo Stoakes , CC: Zi Yan , Baolin Wang , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , , Kefeng Wang , Sidhartha Kumar Subject: [PATCH v4 2/4] mm: mprotect: avoid unnecessary struct page accessing if pte_protnone() Date: Mon, 20 Oct 2025 14:18:43 +0800 Message-ID: <20251020061845.3347258-3-wangkefeng.wang@huawei.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20251020061845.3347258-1-wangkefeng.wang@huawei.com> References: <20251020061845.3347258-1-wangkefeng.wang@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.50.87.83] X-ClientProxiedBy: kwepems100001.china.huawei.com (7.221.188.238) To dggpemf100008.china.huawei.com (7.185.36.138) X-Stat-Signature: d5hsoa8wugrjjn6r6asg68qi5mscto3z X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 725CD20008 X-HE-Tag: 1760941206-158974 X-HE-Meta: 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 BsrD5sUR JSLPQo1ZtueA0XKu5Fngb+sg4UQlGUB6JypIkZ6XnPxt7TDw= 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: If the pte_protnone() is true, we could avoid unnecessary struct page accessing and reduce cache footprint when scanning page tables for prot numa, there was a similar change before, see more commit a818f5363a0e ("autonuma: reduce cache footprint when scanning page tables"). Acked-by: Zi Yan Reviewed-by: Dev Jain Reviewed-by: Sidhartha Kumar Signed-off-by: Kefeng Wang --- mm/mprotect.c | 29 +++++++++++++---------------- 1 file changed, 13 insertions(+), 16 deletions(-) diff --git a/mm/mprotect.c b/mm/mprotect.c index 056986d9076a..6236d120c8e6 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -118,18 +118,13 @@ static int mprotect_folio_pte_batch(struct folio *folio, pte_t *ptep, return folio_pte_batch_flags(folio, NULL, ptep, &pte, max_nr_ptes, flags); } -static bool prot_numa_skip(struct vm_area_struct *vma, unsigned long addr, - pte_t oldpte, pte_t *pte, int target_node, - struct folio *folio) +static bool prot_numa_skip(struct vm_area_struct *vma, int target_node, + struct folio *folio) { bool ret = true; bool toptier; int nid; - /* Avoid TLB flush if possible */ - if (pte_protnone(oldpte)) - goto skip; - if (!folio) goto skip; @@ -307,23 +302,25 @@ static long change_pte_range(struct mmu_gather *tlb, struct page *page; pte_t ptent; + /* Already in the desired state. */ + if (prot_numa && pte_protnone(oldpte)) + continue; + page = vm_normal_page(vma, addr, oldpte); if (page) folio = page_folio(page); + /* * Avoid trapping faults against the zero or KSM * pages. See similar comment in change_huge_pmd. */ - if (prot_numa) { - int ret = prot_numa_skip(vma, addr, oldpte, pte, - target_node, folio); - if (ret) { + if (prot_numa && + prot_numa_skip(vma, target_node, folio)) { - /* determine batch to skip */ - nr_ptes = mprotect_folio_pte_batch(folio, - pte, oldpte, max_nr_ptes, /* flags = */ 0); - continue; - } + /* determine batch to skip */ + nr_ptes = mprotect_folio_pte_batch(folio, + pte, oldpte, max_nr_ptes, /* flags = */ 0); + continue; } nr_ptes = mprotect_folio_pte_batch(folio, pte, oldpte, max_nr_ptes, flags); -- 2.27.0