From patchwork Wed Jul 19 13:54:48 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ryan Roberts X-Patchwork-Id: 122645 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:c923:0:b0:3e4:2afc:c1 with SMTP id j3csp2473452vqt; Wed, 19 Jul 2023 07:20:11 -0700 (PDT) X-Google-Smtp-Source: APBJJlGVDVm5RVZRy0y3PeLHFLQcsinDrbvXO3A7PosoZY61AZKIPhowdCP/glJDm58u350sLdTn X-Received: by 2002:a17:90a:db0f:b0:263:f3ad:64af with SMTP id g15-20020a17090adb0f00b00263f3ad64afmr1686719pjv.45.1689776410994; Wed, 19 Jul 2023 07:20:10 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1689776410; cv=none; d=google.com; s=arc-20160816; b=XMftQwd+2W5QfVOlRKHgMgVe8qJYBRfRAXhRZFKWJihWu9LPGV7KBeFytiHN19hUQg GE6gcTWWnVo3GBhT82ed6Ke7JLYB7rDxeDBeIJaSyYLGRG+zMd62g65Ipm5u+yNDi8Ly t8SNC2iwYpjriiaWkze6yeJ07TJubWPGpxkUWFCnR2UijXVJvolmvLo/png0POBjQ6ws OR00GAPiMm0mDfb7z0uFJReZt6/ziEg37AuF9B95fFrzw/Af9Del6iiFoM7pX4J1ZBhT IdSPy3i7JM2kdJSgpoXB44LW2BNrIhe4eqiEAqnH0f9CCJuUULBKin5oGj8di8Mk/IMR Hz2w== 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=hNL1y3SfunmfxSUTvIEH48/V1tE9GSr47MXZQeskAHk=; fh=THi7eKCjaWcVibUnyL3CTjC3PwRMYqk9JChFkSe1vn0=; b=A4fKiuPKHrcW+iiFnnS/kXDhBXAXmRAl8qpDTLtl8HWC5KMD4ePNlRYPv/1Awn0M05 Q+ulon+xt5VZYuKIBD65mbEO59IrA+AlOAhFDNLsg0z4RPsmuZA4+KY2k4znOigwB8Fi zD+C0+iNv44LdPZaok1AubtaqG8Q4CkNSCS7gzfGSw4MBK97eUNxh5zEpv1EfYkWAB7U 6MczlVpgpQriSA6Sx9lXEpuneMRSFZdt6Hm9FcBAlT5B0mcu2B1UafsSeHFk4JZs47nb f/Nrl8jkm1X8xiapSAgO/NfAM9UrzzldV1JpTJZjc6HW5bRHsxfVrKs3KSQSd2kLU8Ml 6cTQ== 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 rm2-20020a17090b3ec200b0025653dc2881si1592032pjb.23.2023.07.19.07.19.57; Wed, 19 Jul 2023 07:20:10 -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 S230349AbjGSNzK (ORCPT + 99 others); Wed, 19 Jul 2023 09:55:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37010 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230020AbjGSNzH (ORCPT ); Wed, 19 Jul 2023 09:55:07 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 64BC312C for ; Wed, 19 Jul 2023 06:55:06 -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 6CEF3D75; Wed, 19 Jul 2023 06:55:49 -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 90B6C3F6C4; Wed, 19 Jul 2023 06:55:04 -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 1/3] mm: Allow deferred splitting of arbitrary large anon folios Date: Wed, 19 Jul 2023 14:54:48 +0100 Message-Id: <20230719135450.545227-2-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: 1771858989892782652 X-GMAIL-MSGID: 1771858989892782652 In preparation for the introduction of large folios for anonymous memory, we would like to be able to split them when they have unmapped subpages, in order to free those unused pages under memory pressure. So remove the artificial requirement that the large folio needed to be at least PMD-sized. Reviewed-by: Yu Zhao Reviewed-by: Yin Fengwei Reviewed-by: Matthew Wilcox (Oracle) Reviewed-by: David Hildenbrand Signed-off-by: Ryan Roberts --- mm/rmap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index 0c0d8857dfce..eb0bb00dae34 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1426,11 +1426,11 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma, __lruvec_stat_mod_folio(folio, idx, -nr); /* - * Queue anon THP for deferred split if at least one + * Queue anon large 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_pmd_mappable(folio) && folio_test_anon(folio)) + if (folio_test_large(folio) && folio_test_anon(folio)) if (!compound || nr < nr_pmdmapped) deferred_split_folio(folio); } From patchwork Wed Jul 19 13:54:49 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ryan Roberts X-Patchwork-Id: 122641 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:c923:0:b0:3e4:2afc:c1 with SMTP id j3csp2471471vqt; Wed, 19 Jul 2023 07:17:12 -0700 (PDT) X-Google-Smtp-Source: APBJJlFzTWq8Xaw2IU5d7If1CnzRfce9c24dPchbVe/iC8WGMk9FH9cNIYus72QSYdcoN3q15lhP X-Received: by 2002:a17:90b:3901:b0:261:1141:b70d with SMTP id ob1-20020a17090b390100b002611141b70dmr4073317pjb.45.1689776232291; Wed, 19 Jul 2023 07:17:12 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1689776232; cv=none; d=google.com; s=arc-20160816; b=GMMprt995ourpXzBzRb+5JnxPsYkRmonhMaSJiD8XOo5FQwbeshYEqnvteQVsFXbu1 VCsrkgqmcv1jBT/1YhxEBppqGp7uu7xAo/dv2c4mnQFGvBLNlMwwMXZyfwljEajCfJdq 0rGdNwA4yXnSBArxYoCZbIhOEeKTNKFRjSg7/+yQ/xsMMscHyGAyS6LEPfOzOzs5h9zB RB14yOrJFWmtMEU3a428wb0h5b9DVLiAg9zOAupKZw5BZiB5LuJw086+I1nibF/tzUT7 gh1gR8ssGwMGbjsmW7cKbEf18IH8g0krc7U1IsYrDG84rnbq8X6Nk8bB2rWo3ZX8ASgA xwKg== 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=2dqIz3C526jfk09wr8sX5z1Ztv6RWuu5WBWCEVsOmTA=; fh=THi7eKCjaWcVibUnyL3CTjC3PwRMYqk9JChFkSe1vn0=; b=lmOh19PKxa2+pF7XSCfq/rni+nBfFWHlm2CGDloxrlOXOphJJgDvl0Bc520AtNEQ/r F9irzvwWP/0Y6JOPf/H5Ze8wL0wJEwS8e1+3hNfzWL9O1XR1objpouAZaLw0RW2PI7TM Y+G8LY2I/syA60QLJJb6eY077ncekcNFU+Gr436hYBALo9wAwUwvANwON2LbKMpe/rTL 9jxTZ/NWmeEDY0zxhlBGJ+sU83K8vtnNNTcBv5i+sv/dgg1yg6rSpIpk+TyzetKqbVe7 tbGYa+u3K/Jw4hz2rk75xtssDwRw7VGhMUngNny52Oi7j9ghOrhS28mLkvS5YGIPolqi sJ/A== 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 rm2-20020a17090b3ec200b0025653dc2881si1592032pjb.23.2023.07.19.07.16.58; Wed, 19 Jul 2023 07:17:12 -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 S231216AbjGSNzN (ORCPT + 99 others); Wed, 19 Jul 2023 09:55:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37016 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229539AbjGSNzJ (ORCPT ); Wed, 19 Jul 2023 09:55:09 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 3F0B112C for ; Wed, 19 Jul 2023 06:55:08 -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 4238512FC; Wed, 19 Jul 2023 06:55:51 -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 672B43F6C4; Wed, 19 Jul 2023 06:55:06 -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 2/3] mm: Implement folio_remove_rmap_range() Date: Wed, 19 Jul 2023 14:54:49 +0100 Message-Id: <20230719135450.545227-3-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: 1771858802254952565 X-GMAIL-MSGID: 1771858802254952565 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. Reviewed-by: Yin Fengwei Reviewed-by: Zi Yan Signed-off-by: Ryan Roberts --- include/linux/rmap.h | 2 ++ mm/rmap.c | 72 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 74 insertions(+) diff --git a/include/linux/rmap.h b/include/linux/rmap.h index b87d01660412..f578975c12c0 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -200,6 +200,8 @@ void page_add_file_rmap(struct page *, 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 eb0bb00dae34..4022a3ab73a8 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1359,6 +1359,78 @@ void page_add_file_rmap(struct page *page, struct vm_area_struct *vma, mlock_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; + bool last; + enum node_stat_item idx; + + 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; + } + + if (nr_unmapped) { + idx = folio_test_anon(folio) ? NR_ANON_MAPPED : NR_FILE_MAPPED; + __lruvec_stat_mod_folio(folio, idx, -nr_unmapped); + + /* + * Queue anon large 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, false); +} + /** * page_remove_rmap - take down pte mapping from a page * @page: page to remove mapping from 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);