From patchwork Mon May 29 06:11:07 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hugh Dickins X-Patchwork-Id: 9953 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:994d:0:b0:3d9:f83d:47d9 with SMTP id k13csp1310094vqr; Sun, 28 May 2023 23:24:09 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ5xc4xU+cmgcdHoTP2RszFnS4G0uhL4QnMUCj48RyFfBPVPR9dJ+zGLHCKYGTE/c9HPUxb0 X-Received: by 2002:a05:6a21:3282:b0:105:b75e:9df6 with SMTP id yt2-20020a056a21328200b00105b75e9df6mr8533852pzb.26.1685341449172; Sun, 28 May 2023 23:24:09 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1685341449; cv=none; d=google.com; s=arc-20160816; b=QUbVMjEPC2vjEGur5aSdrxDmdbjYGw70EmWJXZfwVFJdBihVHQvBaqKckh+YOt76ax HbOVoo655YABKHF+MFBI3pZmlO6srm8bzUQlWO1dxaHv5nxKf/ZJMt0RpQnec7sA/lDD nOivYApow93V/R80qgGBAH3ymI0/L0gHkwMHyK9uYAio9aTJZrffrwn8qozV4/Ky2z08 1Qs5OpSHeY/rKe/Tmr2qrgArDzWrb7MWoXumXFQPGnPrST0ogJpoYcxBQW/PumPGlqk4 be+m1mP6WMtAdec5aiLHsL6P8lFN13VK2deqeVqCGVnbBIvjJSEAlH+2GawXpmPvf+FR TsjQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:mime-version:message-id:subject:cc:to:from:date :dkim-signature; bh=zliJFPKkBRA/n2GaYWcI8flBsJ+sn1iKXV6efEOvVuc=; b=SDtDKssaH59zWVwDj5OkHOxQ7iYFC8QVWU7qda5IuawGPzPt4wS9P8/pxExau1yU+T u2Gj5m9tVrph0OKHjuvEqTKIDLiIFx6fhrImeODe3eRgdeKAuJNhrNvYoY2udjS51o1l g262SbyRvjS38Kabgmnc+hu9XXOOzG7CdFIcFD2tI77iCcw+38xX7X1twxBfWmt7HVw4 LQE+xunYY/BIwuaAcgwmipNBe2l2zqyOEYQm/iiiDxdGSz+sJ45nRfLuVApa21JYAHyM lXEByxVfaug+3GQPxWJW/hQ4HLSgHIvoi7HkH0HzZQXcsseVg4sF8Mux2IBKlIU4NR4E v/WA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20221208 header.b=7B1W5MLw; 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=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id l194-20020a633ecb000000b005347ed33096si4366227pga.258.2023.05.28.23.23.55; Sun, 28 May 2023 23:24:09 -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; dkim=pass header.i=@google.com header.s=20221208 header.b=7B1W5MLw; 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=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230249AbjE2GLa (ORCPT + 99 others); Mon, 29 May 2023 02:11:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41522 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230160AbjE2GL0 (ORCPT ); Mon, 29 May 2023 02:11:26 -0400 Received: from mail-yb1-xb34.google.com (mail-yb1-xb34.google.com [IPv6:2607:f8b0:4864:20::b34]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0F94BAD for ; Sun, 28 May 2023 23:11:25 -0700 (PDT) Received: by mail-yb1-xb34.google.com with SMTP id 3f1490d57ef6-ba81ded8d3eso4527894276.3 for ; Sun, 28 May 2023 23:11:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1685340684; x=1687932684; h=mime-version:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to; bh=zliJFPKkBRA/n2GaYWcI8flBsJ+sn1iKXV6efEOvVuc=; b=7B1W5MLwR/lNmx3BIWIEBSexKnAAtAeI5OObdohvQtJ0ya6QvwHlgYFcOox2PoWx79 AqTZ5kdBzWLNorOsK4QCVE297PN18hQKAQbCdVGnbvFaS7kyYm3WQLVA/nvW5TUXBwEK caAcy7rQi84u8SNtdxTLyllY4LVN73jaN501s4k727QQrqblWsE0z78z1nbHIMjpBe5J U7bsOrnIMfDvYrfJ38H4/OhgD5cA+Y2quHyXE8xkEJQ1/qi+xCB9+P6Rf/V3USkqhcRr ADhdVtWOZGV+AvVYyI9ulfCMHPe9IScFN/bL7d58cmN+M8/9WGgQpLLoAa3PpgIRJ6V+ lp1g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685340684; x=1687932684; h=mime-version:message-id:subject:cc:to:from:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=zliJFPKkBRA/n2GaYWcI8flBsJ+sn1iKXV6efEOvVuc=; b=KoDx5dVQSKxNgQBmETNhR6XBWDC44QCslbkKyKMJpLcH64HnYUPntWBJF799J8WF2Y C29wykff8A/6TZzZrvw4ovODZs1Yp5/s51W4awmP3RFCC42pn9SMCz+eHYOb9f3xZKn9 zHPSZamv7uc07ZFBSp8PbaN1HMydq/AUc6BnAbpYedMhc+VwwTqzUQl8xLRv/bOqZGmg jRHmbEiyHxNLFYEPMkRI8kGlg/NNPx+nqiEBSWgGBts5nJgdRRTBXQSUn7WhpWIhuE+s kvEId5J0FluIW9kcpWOFPfHWBKWxDqGHXobv+wgqtU/DrW7x0ImEEa5ShCQKAA531vFv PiIQ== X-Gm-Message-State: AC+VfDxgRf5A/JbpGrxDfo9xpTlhW5YqYAUbAtKSP1L1pZEojDt5t2v2 X+ATXpx272zNynAfeVaAM5uA6Q== X-Received: by 2002:a25:d4b:0:b0:ba8:6530:d561 with SMTP id 72-20020a250d4b000000b00ba86530d561mr10306665ybn.30.1685340684077; Sun, 28 May 2023 23:11:24 -0700 (PDT) Received: from ripple.attlocal.net (172-10-233-147.lightspeed.sntcca.sbcglobal.net. [172.10.233.147]) by smtp.gmail.com with ESMTPSA id r63-20020a252b42000000b00b7b0aba5cccsm2703954ybr.22.2023.05.28.23.11.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 28 May 2023 23:11:23 -0700 (PDT) Date: Sun, 28 May 2023 23:11:07 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@ripple.attlocal.net To: Andrew Morton cc: Mike Kravetz , Mike Rapoport , "Kirill A. Shutemov" , Matthew Wilcox , David Hildenbrand , Suren Baghdasaryan , Qi Zheng , Yang Shi , Mel Gorman , Peter Xu , Peter Zijlstra , Will Deacon , Yu Zhao , Alistair Popple , Ralph Campbell , Ira Weiny , Steven Price , SeongJae Park , Naoya Horiguchi , Christophe Leroy , Zack Rusin , Jason Gunthorpe , Axel Rasmussen , Anshuman Khandual , Pasha Tatashin , Miaohe Lin , Minchan Kim , Christoph Hellwig , Song Liu , Thomas Hellstrom , Russell King , "David S. Miller" , Michael Ellerman , "Aneesh Kumar K.V" , Heiko Carstens , Christian Borntraeger , Claudio Imbrenda , Alexander Gordeev , Jann Horn , linux-arm-kernel@lists.infradead.org, sparclinux@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 00/12] mm: free retracted page table by RCU Message-ID: <35e983f5-7ed3-b310-d949-9ae8b130cdab@google.com> MIME-Version: 1.0 X-Spam-Status: No, score=-17.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, ENV_AND_HDR_SPF_MATCH,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE,USER_IN_DEF_DKIM_WL,USER_IN_DEF_SPF_WL 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: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1767208595177748780?= X-GMAIL-MSGID: =?utf-8?q?1767208595177748780?= Here is the third series of patches to mm (and a few architectures), based on v6.4-rc3 with the preceding two series applied: in which khugepaged takes advantage of pte_offset_map[_lock]() allowing for pmd transitions. This follows on from the "arch: allow pte_offset_map[_lock]() to fail" https://lore.kernel.org/linux-mm/77a5d8c-406b-7068-4f17-23b7ac53bc83@google.com/ series of 23 posted on 2023-05-09, and the "mm: allow pte_offset_map[_lock]() to fail" https://lore.kernel.org/linux-mm/68a97fbe-5c1e-7ac6-72c-7b9c6290b370@google.com/ series of 31 posted on 2023-05-21. Those two series were "independent": neither depending for build or correctness on the other, but both series needed before this third one can safely make the effective changes. I'll send v2 of those two series in a couple of days, incorporating Acks and Revieweds and the minor fixes. What is it all about? Some mmap_lock avoidance i.e. latency reduction. Initially just for the case of collapsing shmem or file pages to THPs: the usefulness of MADV_COLLAPSE on shmem is being limited by that mmap_write_lock it currently requires. Likely to be relied upon later in other contexts e.g. freeing of empty page tables (but that's not work I'm doing). mmap_write_lock avoidance when collapsing to anon THPs? Perhaps, but again that's not work I've done: a quick attempt was not as easy as the shmem/file case. These changes (though of course not these exact patches) have been in Google's data centre kernel for three years now: we do rely upon them. Based on the preceding two series over v6.4-rc3, but good over v6.4-rc[1-4], current mm-everything or current linux-next. 01/12 mm/pgtable: add rcu_read_lock() and rcu_read_unlock()s 02/12 mm/pgtable: add PAE safety to __pte_offset_map() 03/12 arm: adjust_pte() use pte_offset_map_nolock() 04/12 powerpc: assert_pte_locked() use pte_offset_map_nolock() 05/12 powerpc: add pte_free_defer() for pgtables sharing page 06/12 sparc: add pte_free_defer() for pgtables sharing page 07/12 s390: add pte_free_defer(), with use of mmdrop_async() 08/12 mm/pgtable: add pte_free_defer() for pgtable as page 09/12 mm/khugepaged: retract_page_tables() without mmap or vma lock 10/12 mm/khugepaged: collapse_pte_mapped_thp() with mmap_read_lock() 11/12 mm/khugepaged: delete khugepaged_collapse_pte_mapped_thps() 12/12 mm: delete mmap_write_trylock() and vma_try_start_write() arch/arm/mm/fault-armv.c | 3 +- arch/powerpc/include/asm/pgalloc.h | 4 + arch/powerpc/mm/pgtable-frag.c | 18 ++ arch/powerpc/mm/pgtable.c | 16 +- arch/s390/include/asm/pgalloc.h | 4 + arch/s390/mm/pgalloc.c | 34 +++ arch/sparc/include/asm/pgalloc_64.h | 4 + arch/sparc/mm/init_64.c | 16 ++ include/linux/mm.h | 17 -- include/linux/mm_types.h | 2 +- include/linux/mmap_lock.h | 10 - include/linux/pgtable.h | 6 +- include/linux/sched/mm.h | 1 + kernel/fork.c | 2 +- mm/khugepaged.c | 425 ++++++++---------------------- mm/pgtable-generic.c | 44 +++- 16 files changed, 253 insertions(+), 353 deletions(-) Hugh