From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 83A82C43331 for ; Fri, 3 Apr 2020 11:29:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4079F2073B for ; Fri, 3 Apr 2020 11:29:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=shutemov-name.20150623.gappssmtp.com header.i=@shutemov-name.20150623.gappssmtp.com header.b="HxR/QJ/L" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390724AbgDCL3k (ORCPT ); Fri, 3 Apr 2020 07:29:40 -0400 Received: from mail-lj1-f196.google.com ([209.85.208.196]:40475 "EHLO mail-lj1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727944AbgDCL3h (ORCPT ); Fri, 3 Apr 2020 07:29:37 -0400 Received: by mail-lj1-f196.google.com with SMTP id 19so6539095ljj.7 for ; Fri, 03 Apr 2020 04:29:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=LuEy02dea2Id4xDMDSGK8RSYYGNAW5A/0ZkDN1BjR34=; b=HxR/QJ/L4Z6HP93x/D6CzjyRFeUboWgvzTyMgbZfnDaxgUHZN6tIaAcsHiEasuYhNH 5r/gCVehKDpxFiqtwJBjsLp0fDkEwMPG6M75u/aBZAg5RRr+kUJ1t7528sN06um6s34e +HarAoZzw6ob0Q+4xbBLr9YCpuByc629A8SomBymWKozj0ezCagw540mUpvay83YJQ8G ZOrHUWhr3kKtVIeOh6Nh+2Epm9gBMwcqjcnNUmXczD9YUlg+ON1QX840ur06fbbEHvi6 ecRCHW4hgy3PbS/LvDAPkBfCAl8BIFXGMj++xMLy2Iy8e7YIAQ4H158yqwpl8FWaC9Yh Dftg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=LuEy02dea2Id4xDMDSGK8RSYYGNAW5A/0ZkDN1BjR34=; b=oMvDlY/RqSWvPcdI9AcDr3iTsh4CK3js823i6Ae2xqWrYAR64q0DxNrLlV1K5F84iU 1FUlaQzSmh9LKOgBR0tTzNR9IVh9d0df13KAmtBqIwaeMhaYvwT2HGJFuS9CWFHellVS AAJ+tST4nWTDlJWMav4TuNNdpJbc1DCraF6hAvXgD20HguWjKPUy4gfdwu8KpUIF2/9Z 93IhWaEkdnVNVuwAdqcOtudLFeL+PqzcKtVKN/Pgp9bn7uGzWeD6Qj3dcLRRSaqb6VWU p7prCLx/4rrVaQ+hNgbYKfqH42NBN9BDS/iZa3aVZGMCxQsVKr0i6TP2TjVhzhIQGrl9 tssA== X-Gm-Message-State: AGi0PuZkXm++zfvze51kCI0TtgaTE/6q9qjnaHMMfz1byOMtdmbMXF1I ebK3ZvHuSTSS59t6XWbEyY/pWA== X-Google-Smtp-Source: APiQypJx19H3PKA94XWdS8fRP37nmflFSLxOtZfO5fJK+nPnKT5g2EYx9/vmKNzWDSlNFpPCBSsWsw== X-Received: by 2002:a2e:8850:: with SMTP id z16mr4499348ljj.284.1585913375878; Fri, 03 Apr 2020 04:29:35 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id n23sm4708341lji.59.2020.04.03.04.29.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Apr 2020 04:29:34 -0700 (PDT) From: "Kirill A. Shutemov" X-Google-Original-From: "Kirill A. Shutemov" Received: by box.localdomain (Postfix, from userid 1000) id 86739101334; Fri, 3 Apr 2020 14:29:31 +0300 (+03) To: akpm@linux-foundation.org, Andrea Arcangeli Cc: Zi Yan , Yang Shi , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCHv2 6/8] khugepaged: Allow to collapse PTE-mapped compound pages Date: Fri, 3 Apr 2020 14:29:26 +0300 Message-Id: <20200403112928.19742-7-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.26.0 In-Reply-To: <20200403112928.19742-1-kirill.shutemov@linux.intel.com> References: <20200403112928.19742-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We can collapse PTE-mapped compound pages. We only need to avoid handling them more than once: lock/unlock page only once if it's present in the PMD range multiple times as it handled on compound level. The same goes for LRU isolation and putback. Signed-off-by: Kirill A. Shutemov --- mm/khugepaged.c | 103 ++++++++++++++++++++++++++++++++---------------- 1 file changed, 68 insertions(+), 35 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 1e7e6543ebca..49e56e4e30d1 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -515,23 +515,37 @@ void __khugepaged_exit(struct mm_struct *mm) static void release_pte_page(struct page *page) { - dec_node_page_state(page, NR_ISOLATED_ANON + page_is_file_cache(page)); + mod_node_page_state(page_pgdat(page), + NR_ISOLATED_ANON + page_is_file_cache(page), + -compound_nr(page)); unlock_page(page); putback_lru_page(page); } -static void release_pte_pages(pte_t *pte, pte_t *_pte) +static void release_pte_pages(pte_t *pte, pte_t *_pte, + struct list_head *compound_pagelist) { + struct page *page, *tmp; + while (--_pte >= pte) { pte_t pteval = *_pte; - if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval))) - release_pte_page(pte_page(pteval)); + + page = pte_page(pteval); + if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval)) && + !PageCompound(page)) + release_pte_page(page); + } + + list_for_each_entry_safe(page, tmp, compound_pagelist, lru) { + list_del(&page->lru); + release_pte_page(page); } } static int __collapse_huge_page_isolate(struct vm_area_struct *vma, unsigned long address, - pte_t *pte) + pte_t *pte, + struct list_head *compound_pagelist) { struct page *page = NULL; pte_t *_pte; @@ -561,13 +575,21 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, goto out; } - /* TODO: teach khugepaged to collapse THP mapped with pte */ + VM_BUG_ON_PAGE(!PageAnon(page), page); + if (PageCompound(page)) { - result = SCAN_PAGE_COMPOUND; - goto out; - } + struct page *p; + page = compound_head(page); - VM_BUG_ON_PAGE(!PageAnon(page), page); + /* + * Check if we have dealt with the compound page + * already + */ + list_for_each_entry(p, compound_pagelist, lru) { + if (page == p) + goto next; + } + } /* * We can do it before isolate_lru_page because the @@ -597,19 +619,15 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, result = SCAN_PAGE_COUNT; goto out; } - if (pte_write(pteval)) { - writable = true; - } else { - if (PageSwapCache(page) && - !reuse_swap_page(page, NULL)) { - unlock_page(page); - result = SCAN_SWAP_CACHE_PAGE; - goto out; - } + if (!pte_write(pteval) && PageSwapCache(page) && + !reuse_swap_page(page, NULL)) { /* - * Page is not in the swap cache. It can be collapsed - * into a THP. + * Page is in the swap cache and cannot be re-used. + * It cannot be collapsed into a THP. */ + unlock_page(page); + result = SCAN_SWAP_CACHE_PAGE; + goto out; } /* @@ -621,16 +639,23 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, result = SCAN_DEL_PAGE_LRU; goto out; } - inc_node_page_state(page, - NR_ISOLATED_ANON + page_is_file_cache(page)); + mod_node_page_state(page_pgdat(page), + NR_ISOLATED_ANON + page_is_file_cache(page), + compound_nr(page)); VM_BUG_ON_PAGE(!PageLocked(page), page); VM_BUG_ON_PAGE(PageLRU(page), page); + if (PageCompound(page)) + list_add_tail(&page->lru, compound_pagelist); +next: /* There should be enough young pte to collapse the page */ if (pte_young(pteval) || page_is_young(page) || PageReferenced(page) || mmu_notifier_test_young(vma->vm_mm, address)) referenced++; + + if (pte_write(pteval)) + writable = true; } if (likely(writable)) { if (likely(referenced)) { @@ -644,7 +669,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, } out: - release_pte_pages(pte, _pte); + release_pte_pages(pte, _pte, compound_pagelist); trace_mm_collapse_huge_page_isolate(page, none_or_zero, referenced, writable, result); return 0; @@ -653,13 +678,14 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, static void __collapse_huge_page_copy(pte_t *pte, struct page *page, struct vm_area_struct *vma, unsigned long address, - spinlock_t *ptl) + spinlock_t *ptl, + struct list_head *compound_pagelist) { + struct page *src_page, *tmp; pte_t *_pte; for (_pte = pte; _pte < pte + HPAGE_PMD_NR; _pte++, page++, address += PAGE_SIZE) { pte_t pteval = *_pte; - struct page *src_page; if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { clear_user_highpage(page, address); @@ -679,7 +705,6 @@ static void __collapse_huge_page_copy(pte_t *pte, struct page *page, } else { src_page = pte_page(pteval); copy_user_highpage(page, src_page, address, vma); - release_pte_page(src_page); /* * ptl mostly unnecessary, but preempt has to * be disabled to update the per-cpu stats @@ -693,9 +718,18 @@ static void __collapse_huge_page_copy(pte_t *pte, struct page *page, pte_clear(vma->vm_mm, address, _pte); page_remove_rmap(src_page, false); spin_unlock(ptl); - free_page_and_swap_cache(src_page); + if (!PageCompound(src_page)) { + release_pte_page(src_page); + free_page_and_swap_cache(src_page); + } } } + + list_for_each_entry_safe(src_page, tmp, compound_pagelist, lru) { + list_del(&src_page->lru); + release_pte_page(src_page); + free_page_and_swap_cache(src_page); + } } static void khugepaged_alloc_sleep(void) @@ -960,6 +994,7 @@ static void collapse_huge_page(struct mm_struct *mm, struct page **hpage, int node, int referenced) { + LIST_HEAD(compound_pagelist); pmd_t *pmd, _pmd; pte_t *pte; pgtable_t pgtable; @@ -1059,7 +1094,8 @@ static void collapse_huge_page(struct mm_struct *mm, mmu_notifier_invalidate_range_end(&range); spin_lock(pte_ptl); - isolated = __collapse_huge_page_isolate(vma, address, pte); + isolated = __collapse_huge_page_isolate(vma, address, pte, + &compound_pagelist); spin_unlock(pte_ptl); if (unlikely(!isolated)) { @@ -1084,7 +1120,8 @@ static void collapse_huge_page(struct mm_struct *mm, */ anon_vma_unlock_write(vma->anon_vma); - __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl); + __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl, + &compound_pagelist); pte_unmap(pte); __SetPageUptodate(new_page); pgtable = pmd_pgtable(_pmd); @@ -1181,11 +1218,7 @@ static int khugepaged_scan_pmd(struct mm_struct *mm, goto out_unmap; } - /* TODO: teach khugepaged to collapse THP mapped with pte */ - if (PageCompound(page)) { - result = SCAN_PAGE_COMPOUND; - goto out_unmap; - } + page = compound_head(page); /* * Record which node the original page is from and save this -- 2.26.0