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=-16.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 24376C433F5 for ; Fri, 17 Sep 2021 03:53:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B23B610C9 for ; Fri, 17 Sep 2021 03:53:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244182AbhIQDzH (ORCPT ); Thu, 16 Sep 2021 23:55:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60914 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244137AbhIQDy5 (ORCPT ); Thu, 16 Sep 2021 23:54:57 -0400 Received: from mail-pj1-x102c.google.com (mail-pj1-x102c.google.com [IPv6:2607:f8b0:4864:20::102c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A3238C061756 for ; Thu, 16 Sep 2021 20:53:34 -0700 (PDT) Received: by mail-pj1-x102c.google.com with SMTP id i19so6020995pjv.4 for ; Thu, 16 Sep 2021 20:53:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=0sSF06QuAY7kUNXCT+H8hO7WNAzsL+XHoJo4uKapYUQ=; b=d7oXrFiwLxVl+QDJ45TJCHO5rPPOJ2J06Arj3E0JjwACw0Dzonyj496/iRL70tZEDA EuMPSdakZAHG4X7Asun5/fVzg3bkWJSWwtxDmn5Kum7iE/HjaWn6uT0uMDF+zvs7kFQV Fo+486EroYVFtkeRBIfqdRyaEP/UhMoLjrUflG66vgHfx6hkt2W/XjH3faoPkuqAefDn Ie3bhXqjZ1moLpvRO2MpiVy2lqQ99Eazh0N3zb33Fn6VtvSPYqDDCSC8QqfCeDgMNIAN dK4HcE3O08fpgg1M1uUJ7UISwDj0Bz7ej7N02lZZy3jq2FRa/zKINPHrX9YAQQXNiwQn dqag== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=0sSF06QuAY7kUNXCT+H8hO7WNAzsL+XHoJo4uKapYUQ=; b=LMPi7voQr/KqetGkcGkI0+dl6ItINijp6U3MSsBc9qVxeg8PKrnC7QE6lr3406Zkmi dWSH3WK50xXqJFpTNDLp824UXgzESrFLhiyDE0JNOd6cnYAx7h48I8biaEQ1kIQgPHFy xbndIAEwTUszQutgvrya5Cc7BEbo/EmauUldBDCtZaM7qELcWNb29bBU2WHVHJm4qSZi Y6KMbq2myQ7bLED96/FQPfw59fZonsP8B7cDZMbnNRDESMT95zXh5HBOJop8smKWDFko eCVL/KuHOxYlNbObUV7WFjmNJ6h6qRmUJ2EL5AqRE8IYzJ5C9UEzthzXsR8a9L57gMy9 u/Sg== X-Gm-Message-State: AOAM533Eulj7sE2dg+pcQGI9HZbMoGdbEp8Qtz2i3ywgtc+LP1zCBkoL PTFiy6uvbI3c1XUie71ZZ1qHZQ== X-Google-Smtp-Source: ABdhPJysLWSTpZBBnsGr+SwefgGTH706NuJHGHNEwUSjRTb/TLYCvvsWcEu/i1vl1i9/i/l/6KUu5g== X-Received: by 2002:a17:902:6b0b:b0:13a:18bf:1ece with SMTP id o11-20020a1709026b0b00b0013a18bf1ecemr7744262plk.49.1631850814182; Thu, 16 Sep 2021 20:53:34 -0700 (PDT) Received: from localhost.localdomain ([139.177.225.226]) by smtp.gmail.com with ESMTPSA id g12sm8997704pja.28.2021.09.16.20.53.27 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 16 Sep 2021 20:53:33 -0700 (PDT) From: Muchun Song To: mike.kravetz@oracle.com, akpm@linux-foundation.org, osalvador@suse.de, mhocko@suse.com, song.bao.hua@hisilicon.com, david@redhat.com, chenhuang5@huawei.com, bodeddub@amazon.com, corbet@lwn.net, willy@infradead.org Cc: duanxiongchun@bytedance.com, fam.zheng@bytedance.com, smuchun@gmail.com, zhengqi.arch@bytedance.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Muchun Song Subject: [PATCH RESEND v2 3/4] mm: sparsemem: use page table lock to protect kernel pmd operations Date: Fri, 17 Sep 2021 11:48:14 +0800 Message-Id: <20210917034815.80264-4-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20210917034815.80264-1-songmuchun@bytedance.com> References: <20210917034815.80264-1-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The init_mm.page_table_lock is used to protect kernel page tables, we can use it to serialize splitting vmemmap PMD mappings instead of mmap write lock, which can increase the concurrency of vmemmap_remap_free(). Signed-off-by: Muchun Song --- mm/ptdump.c | 16 ++++++++++++---- mm/sparse-vmemmap.c | 49 ++++++++++++++++++++++++++++++++++--------------- 2 files changed, 46 insertions(+), 19 deletions(-) diff --git a/mm/ptdump.c b/mm/ptdump.c index da751448d0e4..eea3d28d173c 100644 --- a/mm/ptdump.c +++ b/mm/ptdump.c @@ -40,8 +40,10 @@ static int ptdump_pgd_entry(pgd_t *pgd, unsigned long addr, if (st->effective_prot) st->effective_prot(st, 0, pgd_val(val)); - if (pgd_leaf(val)) + if (pgd_leaf(val)) { st->note_page(st, addr, 0, pgd_val(val)); + walk->action = ACTION_CONTINUE; + } return 0; } @@ -61,8 +63,10 @@ static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr, if (st->effective_prot) st->effective_prot(st, 1, p4d_val(val)); - if (p4d_leaf(val)) + if (p4d_leaf(val)) { st->note_page(st, addr, 1, p4d_val(val)); + walk->action = ACTION_CONTINUE; + } return 0; } @@ -82,8 +86,10 @@ static int ptdump_pud_entry(pud_t *pud, unsigned long addr, if (st->effective_prot) st->effective_prot(st, 2, pud_val(val)); - if (pud_leaf(val)) + if (pud_leaf(val)) { st->note_page(st, addr, 2, pud_val(val)); + walk->action = ACTION_CONTINUE; + } return 0; } @@ -101,8 +107,10 @@ static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr, if (st->effective_prot) st->effective_prot(st, 3, pmd_val(val)); - if (pmd_leaf(val)) + if (pmd_leaf(val)) { st->note_page(st, addr, 3, pmd_val(val)); + walk->action = ACTION_CONTINUE; + } return 0; } diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c index 62e3d20648ce..e636943ccfc4 100644 --- a/mm/sparse-vmemmap.c +++ b/mm/sparse-vmemmap.c @@ -64,8 +64,8 @@ struct vmemmap_remap_walk { */ #define NR_RESET_STRUCT_PAGE 3 -static int split_vmemmap_huge_pmd(pmd_t *pmd, unsigned long start, - struct vmemmap_remap_walk *walk) +static int __split_vmemmap_huge_pmd(pmd_t *pmd, unsigned long start, + struct vmemmap_remap_walk *walk) { pmd_t __pmd; int i; @@ -87,15 +87,37 @@ static int split_vmemmap_huge_pmd(pmd_t *pmd, unsigned long start, set_pte_at(&init_mm, addr, pte, entry); } - /* Make pte visible before pmd. See comment in __pte_alloc(). */ - smp_wmb(); - pmd_populate_kernel(&init_mm, pmd, pgtable); + spin_lock(&init_mm.page_table_lock); + if (likely(pmd_leaf(*pmd))) { + /* Make pte visible before pmd. See comment in __pte_alloc(). */ + smp_wmb(); + pmd_populate_kernel(&init_mm, pmd, pgtable); + flush_tlb_kernel_range(start, start + PMD_SIZE); + spin_unlock(&init_mm.page_table_lock); - flush_tlb_kernel_range(start, start + PMD_SIZE); + return 0; + } + spin_unlock(&init_mm.page_table_lock); + pte_free_kernel(&init_mm, pgtable); return 0; } +static int split_vmemmap_huge_pmd(pmd_t *pmd, unsigned long start, + struct vmemmap_remap_walk *walk) +{ + int ret; + + spin_lock(&init_mm.page_table_lock); + ret = pmd_leaf(*pmd); + spin_unlock(&init_mm.page_table_lock); + + if (ret) + ret = __split_vmemmap_huge_pmd(pmd, start, walk); + + return ret; +} + static void vmemmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, struct vmemmap_remap_walk *walk) @@ -132,13 +154,12 @@ static int vmemmap_pmd_range(pud_t *pud, unsigned long addr, pmd = pmd_offset(pud, addr); do { - if (pmd_leaf(*pmd)) { - int ret; + int ret; + + ret = split_vmemmap_huge_pmd(pmd, addr & PMD_MASK, walk); + if (ret) + return ret; - ret = split_vmemmap_huge_pmd(pmd, addr & PMD_MASK, walk); - if (ret) - return ret; - } next = pmd_addr_end(addr, end); vmemmap_pte_range(pmd, addr, next, walk); } while (pmd++, addr = next, addr != end); @@ -321,10 +342,8 @@ int vmemmap_remap_free(unsigned long start, unsigned long end, */ BUG_ON(start - reuse != PAGE_SIZE); - mmap_write_lock(&init_mm); + mmap_read_lock(&init_mm); ret = vmemmap_remap_range(reuse, end, &walk); - mmap_write_downgrade(&init_mm); - if (ret && walk.nr_walked) { end = reuse + walk.nr_walked * PAGE_SIZE; /* -- 2.11.0