From patchwork Wed Jul 19 13:54:50 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ryan Roberts X-Patchwork-Id: 122643 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:c923:0:b0:3e4:2afc:c1 with SMTP id j3csp2472269vqt; Wed, 19 Jul 2023 07:18:24 -0700 (PDT) X-Google-Smtp-Source: APBJJlFVOSkyO4XqAaRdzE3teL3x88NGKnElX5adR24z4+pEROWBCq9vWzRZY2+yIzBOV/UKDtBJ X-Received: by 2002:a17:902:ab56:b0:1b3:fb76:215b with SMTP id ij22-20020a170902ab5600b001b3fb76215bmr2667017plb.48.1689776303974; Wed, 19 Jul 2023 07:18:23 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1689776303; cv=none; d=google.com; s=arc-20160816; b=nvi69Ed6KZpbTkx9HbtSQdOAUCSLU59C7FgTiItFnMqZRmTqsRE63OrQWFBcogzVfL bPFaQNPcN2RY/6dcI/0EgzHHo9VErw5mcl6zp84m4gQ+OCe1QX8KlfPT/kqFL9x5wN2b QkBjVMbCdgKVCywKG48AnYbeaDSdI/SDktb/+btI+/woCcqSCkzLOBVqx7PZ/eiQtayt jcCihQyQ4HdTWcXLsINhTsKMDFInLdHk8UxbiIgPxXQTRmAZ2CAZjJwR8LQXpiKpJtGc 6VZd+v70WItN0UbVnogvgWZad90k0GLvXjhALduvD9p9H9X70z74H1odvQhH/IJTxgC8 WEog== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from; bh=G2GF+BZHvW+OuduMU+juyHwMecPdL/HtveJeza/m3Jw=; fh=THi7eKCjaWcVibUnyL3CTjC3PwRMYqk9JChFkSe1vn0=; b=LWFjp9MRdc45OeVjSvDEe8xgEdGWmoGlXs8mZlEQqFxxBEab9GFNH4IdkHryYrFJJ8 Tj//oYyrooWvQfqQg4ffmeZUhcS0DtYedMCrOMs5Y28ZnAeF8hVnw4T76WTUCzchN6xM /OHeM7WbLd06cZX3TiZ2FnTgq5UqRF0OJmzZsSbdaVV1hWySzC2OI9Hs8n/+HwnJzGUJ MB24PnFdNFi2CRGRSsqjD7eqzzQIkdwQf5JhW/5wOiDlSmtDiYLpiGdz7jtsnYE392Bl kTEdomYiglYIzSsnrWts+yi8/SKtBC40Bm95dUFMXmskUs+adQnJ238PDelCXnBYy4ac urSQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=arm.com Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id lb5-20020a170902fa4500b001b89baba4f6si3417408plb.408.2023.07.19.07.18.10; Wed, 19 Jul 2023 07:18:23 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=arm.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231389AbjGSNzW (ORCPT + 99 others); Wed, 19 Jul 2023 09:55:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37066 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231345AbjGSNzS (ORCPT ); Wed, 19 Jul 2023 09:55:18 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 13A551998 for ; Wed, 19 Jul 2023 06:55:15 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1A0532F4; Wed, 19 Jul 2023 06:55:58 -0700 (PDT) Received: from e125769.cambridge.arm.com (e125769.cambridge.arm.com [10.1.196.26]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3DE203F6C4; Wed, 19 Jul 2023 06:55:08 -0700 (PDT) From: Ryan Roberts To: Andrew Morton , Matthew Wilcox , Yin Fengwei , David Hildenbrand , Yu Zhao , Yang Shi , "Huang, Ying" , Zi Yan Cc: Ryan Roberts , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v2 3/3] mm: Batch-zap large anonymous folio PTE mappings Date: Wed, 19 Jul 2023 14:54:50 +0100 Message-Id: <20230719135450.545227-4-ryan.roberts@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230719135450.545227-1-ryan.roberts@arm.com> References: <20230719135450.545227-1-ryan.roberts@arm.com> MIME-Version: 1.0 X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1771858877693895518 X-GMAIL-MSGID: 1771858877693895518 This allows batching the rmap removal with folio_remove_rmap_range(), which means we avoid spuriously adding a partially unmapped folio to the deferred split queue in the common case, which reduces split queue lock contention. Previously each page was removed from the rmap individually with page_remove_rmap(). If the first page belonged to a large folio, this would cause page_remove_rmap() to conclude that the folio was now partially mapped and add the folio to the deferred split queue. But subsequent calls would cause the folio to become fully unmapped, meaning there is no value to adding it to the split queue. Signed-off-by: Ryan Roberts --- mm/memory.c | 120 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 120 insertions(+) diff --git a/mm/memory.c b/mm/memory.c index 01f39e8144ef..189b1cfd823d 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1391,6 +1391,94 @@ zap_install_uffd_wp_if_needed(struct vm_area_struct *vma, pte_install_uffd_wp_if_needed(vma, addr, pte, pteval); } +static inline unsigned long page_cont_mapped_vaddr(struct page *page, + struct page *anchor, unsigned long anchor_vaddr) +{ + unsigned long offset; + unsigned long vaddr; + + offset = (page_to_pfn(page) - page_to_pfn(anchor)) << PAGE_SHIFT; + vaddr = anchor_vaddr + offset; + + if (anchor > page) { + if (vaddr > anchor_vaddr) + return 0; + } else { + if (vaddr < anchor_vaddr) + return ULONG_MAX; + } + + return vaddr; +} + +static int folio_nr_pages_cont_mapped(struct folio *folio, + struct page *page, pte_t *pte, + unsigned long addr, unsigned long end) +{ + pte_t ptent; + int floops; + int i; + unsigned long pfn; + struct page *folio_end; + + if (!folio_test_large(folio)) + return 1; + + folio_end = &folio->page + folio_nr_pages(folio); + end = min(page_cont_mapped_vaddr(folio_end, page, addr), end); + floops = (end - addr) >> PAGE_SHIFT; + pfn = page_to_pfn(page); + pfn++; + pte++; + + for (i = 1; i < floops; i++) { + ptent = ptep_get(pte); + + if (!pte_present(ptent) || pte_pfn(ptent) != pfn) + break; + + pfn++; + pte++; + } + + return i; +} + +static unsigned long try_zap_anon_pte_range(struct mmu_gather *tlb, + struct vm_area_struct *vma, + struct folio *folio, + struct page *page, pte_t *pte, + unsigned long addr, int nr_pages, + struct zap_details *details) +{ + struct mm_struct *mm = tlb->mm; + pte_t ptent; + bool full; + int i; + + for (i = 0; i < nr_pages;) { + ptent = ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm); + tlb_remove_tlb_entry(tlb, pte, addr); + zap_install_uffd_wp_if_needed(vma, addr, pte, details, ptent); + full = __tlb_remove_page(tlb, page, 0); + + if (unlikely(page_mapcount(page) < 1)) + print_bad_pte(vma, addr, ptent, page); + + i++; + page++; + pte++; + addr += PAGE_SIZE; + + if (unlikely(full)) + break; + } + + folio_remove_rmap_range(folio, page - i, i, vma); + + return i; +} + static unsigned long zap_pte_range(struct mmu_gather *tlb, struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr, unsigned long end, @@ -1428,6 +1516,38 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, page = vm_normal_page(vma, addr, ptent); if (unlikely(!should_zap_page(details, page))) continue; + + /* + * Batch zap large anonymous folio mappings. This allows + * batching the rmap removal, which means we avoid + * spuriously adding a partially unmapped folio to the + * deferrred split queue in the common case, which + * reduces split queue lock contention. + */ + if (page && PageAnon(page)) { + struct folio *folio = page_folio(page); + int nr_pages_req, nr_pages; + + nr_pages_req = folio_nr_pages_cont_mapped( + folio, page, pte, addr, end); + + nr_pages = try_zap_anon_pte_range(tlb, vma, + folio, page, pte, addr, + nr_pages_req, details); + + rss[mm_counter(page)] -= nr_pages; + nr_pages--; + pte += nr_pages; + addr += nr_pages << PAGE_SHIFT; + + if (unlikely(nr_pages < nr_pages_req)) { + force_flush = 1; + addr += PAGE_SIZE; + break; + } + continue; + } + ptent = ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm); tlb_remove_tlb_entry(tlb, pte, addr);