From patchwork Wed Aug 30 09:50:07 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ryan Roberts X-Patchwork-Id: 13370143 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C8502C6FA8F for ; Wed, 30 Aug 2023 09:50:34 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 357368E0009; Wed, 30 Aug 2023 05:50:34 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2B76828004E; Wed, 30 Aug 2023 05:50:34 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 109468E004E; Wed, 30 Aug 2023 05:50:34 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 0054E8E0009 for ; Wed, 30 Aug 2023 05:50:33 -0400 (EDT) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id B7BB0A028B for ; Wed, 30 Aug 2023 09:50:33 +0000 (UTC) X-FDA: 81180301146.04.47E5E35 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf07.hostedemail.com (Postfix) with ESMTP id 119334000C for ; Wed, 30 Aug 2023 09:50:31 +0000 (UTC) Authentication-Results: imf07.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf07.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1693389032; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=rg768vUtzYQIWfRK/vocg9s9AsOKLD8pS52LGJ1MyoA=; b=CEHS0TRVo0H0x8kIAMo+xUY1pb3/HaZuKCryXMZzT0GM16Z2ZyxQt2tOR0EQM2zrlQhfSX S0FsZpRW6lNFxtfUT1cSnwzptQqZmo49VQTQShY6eKQkFiF6/oFgnr9W+/HbTA5Pev3mjh zQV+V+pv5J2dpmm3Ctjr0Z6T7vGx+RY= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf07.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1693389032; a=rsa-sha256; cv=none; b=K4x9IryTndIXwXeXQkJWpJRn2VAz1eMOUAKsmih1HMwcSlaOaFAcYooPg57zrOy0tCWMvZ Q7uwcw9Bvj0T//NhlK3zXt9+jDiN/iAp2T6aCxF+VHsXmt5eDQn+GCGtpfqJ+BBQjzOJ5/ HxaNLiGbRmTbnWJeR6IvIfpocljs8hY= 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 9D1C1FEC; Wed, 30 Aug 2023 02:51:10 -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 9E2F23F64C; Wed, 30 Aug 2023 02:50:28 -0700 (PDT) From: Ryan Roberts To: Will Deacon , "Aneesh Kumar K.V" , Andrew Morton , Nick Piggin , Peter Zijlstra , Christian Borntraeger , Sven Schnelle , Arnd Bergmann , "Matthew Wilcox (Oracle)" , David Hildenbrand , Yu Zhao , "Kirill A. Shutemov" , Yin Fengwei , Yang Shi , "Huang, Ying" , Zi Yan Cc: Ryan Roberts , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/5] mm: Implement folio_remove_rmap_range() Date: Wed, 30 Aug 2023 10:50:07 +0100 Message-Id: <20230830095011.1228673-2-ryan.roberts@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230830095011.1228673-1-ryan.roberts@arm.com> References: <20230830095011.1228673-1-ryan.roberts@arm.com> MIME-Version: 1.0 X-Rspamd-Queue-Id: 119334000C X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: ahehe69ha9xw9s9xgu6afopgz6n8wo38 X-HE-Tag: 1693389031-364789 X-HE-Meta: U2FsdGVkX1/17wSrd8iuWfCs44ggA5ArKHrbClzYd/lenxdmiCvxTjjYmgS8ZV0Oo1h1aWrTTzCuoRWeaED6EBAM3Fr1HU6xZuQbXRWxzV06jU8DBIMD2jW4JeLWoEigMCuMclm7CGd9f+8ic+Ib+LsGdEmmmBMp20IFicWmlES9lHKuAJQ1EPxBh5tqoWDV9WZUIrW6WPYuo2x9L106YWuLhqFIlyvnNN7OW1yjNaYLvthWww7pmg1TGlUmj/ud73xvxa7P0bW/bQ1xhrldWmTBeCm5mrUVspFmh6gjwdrvzNqu2kxH900pYmE1DxtabWNrycUMc0w+auk7dIuN6c4u0M9KtbeQ+gFm7gLqXfFsNbe5Q15xAmrvyFPv+NyzmWe0q//CAH3Zlpb/rKmROiN9C/xQgbzSg14p6TjOKkgCDQfTeUP0O64mDT61PY1YoCvkw6X721I70+yX7NNbjSkBW6ofkO71xUt8hx4f9HtIXwqVrrishXt1LSKFRE4l52HVv2FWTM2RR4SGvpUcO7ptwjvEAKxQZJwPPr8uTHFf71Jf8+BCi8qQVUv+kk0UAXpl1kcG4Cc1+A49Z258BC95CFn1asG38RYIvvNgx8R3Ax0guy9co9SfDX1uNXaPKZkW8cKqwWk/X5GT9JUCS1fY5R1LVv6MtowGQ9kOkZELnrDD8JyG7hbFhYbRYVxAwKLrrfUaHQi99zmM+e5Wco0AvPb9Mvh6lx3EDa/dss0nmlW1RVkM7R7IYnQ7MeQ4XNEFMPCdHhDuc2m15QjrBKmTLFxRZ+fiylnmcyxZ7V9SJL9813W339vq67/k99M0XgawXg5jDL1fJNhjMIWbfXM0Gmm+oObIVWIHmLPUtbiiZJdv+TteaPTl+X4+rWBVrqyTZjkQWnhIWlPbljC5kqHMz4243/6g080h/IV7NxEMKtBIKmvHpGVkPyAp9eET3DwMMHX5ul5XTNB3y0i vFYZ0W1Q GkLv9kDyRfb6kIYHDwOaFbnPYaikXk2p6QOTCCVfNjluqUM7s83M70BB/yOUNyBy/hle6U3gpYvMkfCKNv7agBWg1EVKhtsRG+sSd1/XTYlDJrUEs1FMaJvWT5c85/v10nvBkv0Dh1PTibASRUErgjvBfJ+oTdobPjM4M5hiaRbIFhjQL4706eH6eE+j5tHQmuKAgxmEfs0UMxiQ= 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: Like page_remove_rmap() but batch-removes the rmap for a range of pages belonging to a folio. This can provide a small speedup due to less manipuation of the various counters. But more crucially, if removing the rmap for all pages of a folio in a batch, there is no need to (spuriously) add it to the deferred split list, which saves significant cost when there is contention for the split queue lock. All contained pages are accounted using the order-0 folio (or base page) scheme. page_remove_rmap() is refactored so that it forwards to folio_remove_rmap_range() for !compound cases, and both functions now share a common epilogue function. The intention here is to avoid duplication of code. Signed-off-by: Ryan Roberts --- include/linux/rmap.h | 2 + mm/rmap.c | 125 ++++++++++++++++++++++++++++++++----------- 2 files changed, 97 insertions(+), 30 deletions(-) diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 51cc21ebb568..f2e5af3c0e7f 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -202,6 +202,8 @@ void folio_add_file_rmap_range(struct folio *, struct page *, unsigned int nr, struct vm_area_struct *, bool compound); void page_remove_rmap(struct page *, struct vm_area_struct *, bool compound); +void folio_remove_rmap_range(struct folio *folio, struct page *page, + int nr, struct vm_area_struct *vma); void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long address, rmap_t flags); diff --git a/mm/rmap.c b/mm/rmap.c index ec7f8e6c9e48..5ea51c70ecd6 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1379,6 +1379,94 @@ void page_add_file_rmap(struct page *page, struct vm_area_struct *vma, folio_add_file_rmap_range(folio, page, nr_pages, vma, compound); } +/** + * __remove_rmap_finish - common operations when taking down a mapping. + * @folio: Folio containing all pages taken down. + * @vma: The VM area containing the range. + * @compound: True if pages were taken down from PMD or false if from PTE(s). + * @nr_unmapped: Number of pages within folio that are now unmapped. + * @nr_mapped: Number of pages within folio that are still mapped. + */ +static void __remove_rmap_finish(struct folio *folio, + struct vm_area_struct *vma, bool compound, + int nr_unmapped, int nr_mapped) +{ + enum node_stat_item idx; + + if (nr_unmapped) { + idx = folio_test_anon(folio) ? NR_ANON_MAPPED : NR_FILE_MAPPED; + __lruvec_stat_mod_folio(folio, idx, -nr_unmapped); + + /* + * Queue large anon folio for deferred split if at least one + * page of the folio is unmapped and at least one page is still + * mapped. + */ + if (folio_test_large(folio) && + folio_test_anon(folio) && nr_mapped) + deferred_split_folio(folio); + } + + /* + * It would be tidy to reset folio_test_anon mapping when fully + * unmapped, but that might overwrite a racing page_add_anon_rmap + * which increments mapcount after us but sets mapping before us: + * so leave the reset to free_pages_prepare, and remember that + * it's only reliable while mapped. + */ + + munlock_vma_folio(folio, vma, compound); +} + +/** + * folio_remove_rmap_range - Take down PTE mappings from a range of pages. + * @folio: Folio containing all pages in range. + * @page: First page in range to unmap. + * @nr: Number of pages to unmap. + * @vma: The VM area containing the range. + * + * All pages in the range must belong to the same VMA & folio. They must be + * mapped with PTEs, not a PMD. + * + * Context: Caller holds the pte lock. + */ +void folio_remove_rmap_range(struct folio *folio, struct page *page, + int nr, struct vm_area_struct *vma) +{ + atomic_t *mapped = &folio->_nr_pages_mapped; + int nr_unmapped = 0; + int nr_mapped = 0; + bool last; + + if (unlikely(folio_test_hugetlb(folio))) { + VM_WARN_ON_FOLIO(1, folio); + return; + } + + VM_WARN_ON_ONCE(page < &folio->page || + page + nr > (&folio->page + folio_nr_pages(folio))); + + if (!folio_test_large(folio)) { + /* Is this the page's last map to be removed? */ + last = atomic_add_negative(-1, &page->_mapcount); + nr_unmapped = last; + } else { + for (; nr != 0; nr--, page++) { + /* Is this the page's last map to be removed? */ + last = atomic_add_negative(-1, &page->_mapcount); + if (last) + nr_unmapped++; + } + + /* Pages still mapped if folio mapped entirely */ + nr_mapped = atomic_sub_return_relaxed(nr_unmapped, mapped); + if (nr_mapped >= COMPOUND_MAPPED) + nr_unmapped = 0; + } + + __remove_rmap_finish(folio, vma, false, nr_unmapped, nr_mapped); +} + /** * page_remove_rmap - take down pte mapping from a page * @page: page to remove mapping from @@ -1405,15 +1493,13 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma, return; } - /* Is page being unmapped by PTE? Is this its last map to be removed? */ + /* Is page being unmapped by PTE? */ if (likely(!compound)) { - last = atomic_add_negative(-1, &page->_mapcount); - nr = last; - if (last && folio_test_large(folio)) { - nr = atomic_dec_return_relaxed(mapped); - nr = (nr < COMPOUND_MAPPED); - } - } else if (folio_test_pmd_mappable(folio)) { + folio_remove_rmap_range(folio, page, 1, vma); + return; + } + + if (folio_test_pmd_mappable(folio)) { /* That test is redundant: it's for safety or to optimize out */ last = atomic_add_negative(-1, &folio->_entire_mapcount); @@ -1441,29 +1527,8 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma, idx = NR_FILE_PMDMAPPED; __lruvec_stat_mod_folio(folio, idx, -nr_pmdmapped); } - if (nr) { - idx = folio_test_anon(folio) ? NR_ANON_MAPPED : NR_FILE_MAPPED; - __lruvec_stat_mod_folio(folio, idx, -nr); - - /* - * Queue anon THP for deferred split if at least one - * page of the folio is unmapped and at least one page - * is still mapped. - */ - if (folio_test_pmd_mappable(folio) && folio_test_anon(folio)) - if (!compound || nr < nr_pmdmapped) - deferred_split_folio(folio); - } - - /* - * It would be tidy to reset folio_test_anon mapping when fully - * unmapped, but that might overwrite a racing page_add_anon_rmap - * which increments mapcount after us but sets mapping before us: - * so leave the reset to free_pages_prepare, and remember that - * it's only reliable while mapped. - */ - munlock_vma_folio(folio, vma, compound); + __remove_rmap_finish(folio, vma, compound, nr, nr_pmdmapped - nr); } /*