From patchwork Wed Sep 22 10:24:08 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Muchun Song X-Patchwork-Id: 12510019 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=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 A5EF0C433EF for ; Wed, 22 Sep 2021 10:27:10 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 29694611C9 for ; Wed, 22 Sep 2021 10:27:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 29694611C9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=bytedance.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id B2A926B0072; Wed, 22 Sep 2021 06:27:09 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AB4526B0073; Wed, 22 Sep 2021 06:27:09 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8DE37900002; Wed, 22 Sep 2021 06:27:09 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0075.hostedemail.com [216.40.44.75]) by kanga.kvack.org (Postfix) with ESMTP id 7D3546B0072 for ; Wed, 22 Sep 2021 06:27:09 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 2C0221815A83D for ; Wed, 22 Sep 2021 10:27:09 +0000 (UTC) X-FDA: 78614831778.25.7BAA089 Received: from mail-pl1-f180.google.com (mail-pl1-f180.google.com [209.85.214.180]) by imf16.hostedemail.com (Postfix) with ESMTP id EDF9CF00008E for ; Wed, 22 Sep 2021 10:27:08 +0000 (UTC) Received: by mail-pl1-f180.google.com with SMTP id l6so1430931plh.9 for ; Wed, 22 Sep 2021 03:27:08 -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=RHk1GYqIv9c7OsUmXy1N9g9NUo1OgEGcbHl8wQrkV2M=; b=jom0zex6MwCnNc1iytnrbH58SSUt5ZZw+ClfVdn5mczOkMLs5uQotAiulF8J8zLge5 sjX6JAxZbqPJ5MbICX/l3voxBV7N2NPLBRE2D0tjjuI1sR9WQDIjYUt4eV5/f/pTtkk3 J5Vz90m/aHCECzsZV2SsQICZ+cXtcmNFsdlxuSRtEN7Kt5H1Kfwbt3bBMgbX90QNEYns b3Zc7P6VconJ1qowH1bRhGBlS9KOPg1bT7+6gAj5P3NxuwMfhtnDNnKJ/Jd1rnv9Z1FX hdC1hJsAkZ/pf+upLsdKOxUag2PCnD1TOmjUKsAsNGXFmNAA05F7xoNRfj9qwHXtIoPG Fcaw== 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=RHk1GYqIv9c7OsUmXy1N9g9NUo1OgEGcbHl8wQrkV2M=; b=JXZPQdtwJszxl/Ka3uPkavx85gU++1Ykibes1FHVINloH+PgJ0D8tsMio3S3RdOHGC /y9e7mJoC8NRuQG3wyhqPwyAAT4wSK5+iMW+fVb4Ta1jpb48D2Dw28GW2HZeJ3llR3jv 5mCcy2BnXeYhjUb/0AuMemJfV8nqn0Erx4AcxaKPebBHHIumbdiVYy8I7d3GzSf1BgRf ib9y1edtQJpG8MI7v7Z6gQKH0nAdUnJRsGfQDkDfRBs8PwGWADOtHh4AmQZI4Gx0+cEb odkXlm3zgv5TSRWZfWFr9NkL3+kzOgycaEbnCVJ8QtOsejEjYwfdlEhYoWbVJJl3IZ3n 12Gg== X-Gm-Message-State: AOAM533cwJjDG+yQ8tX7Qy2K3qKAqNo2d5xnuMxN5Ep1S6gNgz5jxHfZ j2Ln/L9LefZpCxjUL4Nb4EDzww== X-Google-Smtp-Source: ABdhPJyGqXcFKOX3u5XzyMRMMB9zLxhZZqHHjMJ6ZpZ9sik9K0nwT5neIZ0aZ/WW3E9jJb/fWeZRIg== X-Received: by 2002:a17:902:c149:b0:13d:cbcc:a4d8 with SMTP id 9-20020a170902c14900b0013dcbcca4d8mr2840081plj.42.1632306427844; Wed, 22 Sep 2021 03:27:07 -0700 (PDT) Received: from localhost.localdomain ([139.177.225.255]) by smtp.gmail.com with ESMTPSA id s89sm1821929pjj.43.2021.09.22.03.27.01 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 22 Sep 2021 03:27:07 -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, 21cnbao@gmail.com 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 v3 1/4] mm: hugetlb: free the 2nd vmemmap page associated with each HugeTLB page Date: Wed, 22 Sep 2021 18:24:08 +0800 Message-Id: <20210922102411.34494-2-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20210922102411.34494-1-songmuchun@bytedance.com> References: <20210922102411.34494-1-songmuchun@bytedance.com> MIME-Version: 1.0 Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=bytedance-com.20210112.gappssmtp.com header.s=20210112 header.b=jom0zex6; spf=pass (imf16.hostedemail.com: domain of songmuchun@bytedance.com designates 209.85.214.180 as permitted sender) smtp.mailfrom=songmuchun@bytedance.com; dmarc=pass (policy=none) header.from=bytedance.com X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: EDF9CF00008E X-Stat-Signature: y6hjatbiehscw57gk1hsrb43ydf7s7z4 X-HE-Tag: 1632306428-445534 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: Currently, we only free 6 vmemmap pages associated with a 2MB HugeTLB page. However, we can remap all tail vmemmap pages to the page frame mapped to with the head vmemmap page. Finally, we can free 7 vmemmap pages for a 2MB HugeTLB page. It is a fine gain (e.g. we can save extra 2GB memory when there is 1TB HugeTLB pages in the system compared with the current implementation). But the head vmemmap page is not freed to the buddy allocator and all tail vmemmap pages are mapped to the head vmemmap page frame. So we can see more than one struct page struct with PG_head (e.g. 8 per 2 MB HugeTLB page) associated with each HugeTLB page. We should adjust compound_head() to make it returns the real head struct page when the parameter is the tail struct page but with PG_head flag. Signed-off-by: Muchun Song --- Documentation/admin-guide/kernel-parameters.txt | 2 +- include/linux/page-flags.h | 77 +++++++++++++++++++++++-- mm/hugetlb_vmemmap.c | 60 ++++++++++--------- mm/sparse-vmemmap.c | 21 +++++++ 4 files changed, 128 insertions(+), 32 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 91ba391f9b32..5aaf2f271980 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1617,7 +1617,7 @@ [KNL] Reguires CONFIG_HUGETLB_PAGE_FREE_VMEMMAP enabled. Allows heavy hugetlb users to free up some more - memory (6 * PAGE_SIZE for each 2MB hugetlb page). + memory (7 * PAGE_SIZE for each 2MB hugetlb page). Format: { on | off (default) } on: enable the feature diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index a68af80649a4..b47a7f51d2c3 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -184,13 +184,68 @@ enum pageflags { #ifndef __GENERATING_BOUNDS_H +#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP +extern bool hugetlb_free_vmemmap_enabled; + +/* + * If the feature of freeing some vmemmap pages associated with each HugeTLB + * page is enabled, the head vmemmap page frame is reused and all of the tail + * vmemmap addresses map to the head vmemmap page frame (furture details can + * refer to the figure at the head of the mm/hugetlb_vmemmap.c). In other + * words, there are more than one page struct with PG_head associated with each + * HugeTLB page. We __know__ that there is only one head page struct, the tail + * page structs with PG_head are fake head page structs. We need an approach + * to distinguish between those two different types of page structs so that + * compound_head() can return the real head page struct when the parameter is + * the tail page struct but with PG_head. + * + * The page_fixed_fake_head() returns the real head page struct if the @page is + * fake page head, otherwise, returns @page which can either be a true page + * head or tail. + */ +static __always_inline const struct page *page_fixed_fake_head(const struct page *page) +{ + if (!hugetlb_free_vmemmap_enabled) + return page; + /* + * Only addresses aligned with PAGE_SIZE of struct page may be fake head + * struct page. The alignment check aims to avoid access the fields ( + * e.g. compound_head) of the @page[1]. It can avoid touch a (possibly) + * cold cacheline in some cases. + */ + if (IS_ALIGNED((unsigned long)page, PAGE_SIZE) && + test_bit(PG_head, &page->flags)) { + /* + * We can safely access the field of the @page[1] with PG_head + * because the @page is a compound page composed with at least + * two contiguous pages. + */ + unsigned long head = READ_ONCE(page[1].compound_head); + + if (likely(head & 1)) + return (const struct page *)(head - 1); + } + return page; +} +#else +static __always_inline const struct page *page_fixed_fake_head(const struct page *page) +{ + return page; +} +#endif + +static __always_inline int page_is_fake_head(struct page *page) +{ + return page_fixed_fake_head(page) != page; +} + static inline unsigned long _compound_head(const struct page *page) { unsigned long head = READ_ONCE(page->compound_head); if (unlikely(head & 1)) return head - 1; - return (unsigned long)page; + return (unsigned long)page_fixed_fake_head(page); } #define compound_head(page) ((typeof(page))_compound_head(page)) @@ -225,12 +280,13 @@ static inline unsigned long _compound_head(const struct page *page) static __always_inline int PageTail(struct page *page) { - return READ_ONCE(page->compound_head) & 1; + return READ_ONCE(page->compound_head) & 1 || page_is_fake_head(page); } static __always_inline int PageCompound(struct page *page) { - return test_bit(PG_head, &page->flags) || PageTail(page); + return test_bit(PG_head, &page->flags) || + READ_ONCE(page->compound_head) & 1; } #define PAGE_POISON_PATTERN -1l @@ -675,7 +731,20 @@ static inline bool test_set_page_writeback(struct page *page) return set_page_writeback(page); } -__PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY) +static __always_inline bool folio_test_head(struct folio *folio) +{ + return test_bit(PG_head, folio_flags(folio, FOLIO_PF_ANY)); +} + +static __always_inline int PageHead(struct page *page) +{ + PF_POISONED_CHECK(page); + return test_bit(PG_head, &page->flags) && !page_is_fake_head(page); +} + +__SETPAGEFLAG(Head, head, PF_ANY) +__CLEARPAGEFLAG(Head, head, PF_ANY) +CLEARPAGEFLAG(Head, head, PF_ANY) /* Whether there are one or multiple pages in a folio */ static inline bool folio_test_single(struct folio *folio) diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index c540c21e26f5..527bcaa44a48 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -124,9 +124,9 @@ * page of page structs (page 0) associated with the HugeTLB page contains the 4 * page structs necessary to describe the HugeTLB. The only use of the remaining * pages of page structs (page 1 to page 7) is to point to page->compound_head. - * Therefore, we can remap pages 2 to 7 to page 1. Only 2 pages of page structs + * Therefore, we can remap pages 1 to 7 to page 0. Only 1 pages of page structs * will be used for each HugeTLB page. This will allow us to free the remaining - * 6 pages to the buddy allocator. + * 7 pages to the buddy allocator. * * Here is how things look after remapping. * @@ -134,30 +134,30 @@ * +-----------+ ---virt_to_page---> +-----------+ mapping to +-----------+ * | | | 0 | -------------> | 0 | * | | +-----------+ +-----------+ - * | | | 1 | -------------> | 1 | - * | | +-----------+ +-----------+ - * | | | 2 | ----------------^ ^ ^ ^ ^ ^ - * | | +-----------+ | | | | | - * | | | 3 | ------------------+ | | | | - * | | +-----------+ | | | | - * | | | 4 | --------------------+ | | | - * | PMD | +-----------+ | | | - * | level | | 5 | ----------------------+ | | - * | mapping | +-----------+ | | - * | | | 6 | ------------------------+ | - * | | +-----------+ | - * | | | 7 | --------------------------+ + * | | | 1 | ---------------^ ^ ^ ^ ^ ^ ^ + * | | +-----------+ | | | | | | + * | | | 2 | -----------------+ | | | | | + * | | +-----------+ | | | | | + * | | | 3 | -------------------+ | | | | + * | | +-----------+ | | | | + * | | | 4 | ---------------------+ | | | + * | PMD | +-----------+ | | | + * | level | | 5 | -----------------------+ | | + * | mapping | +-----------+ | | + * | | | 6 | -------------------------+ | + * | | +-----------+ | + * | | | 7 | ---------------------------+ * | | +-----------+ * | | * | | * | | * +-----------+ * - * When a HugeTLB is freed to the buddy system, we should allocate 6 pages for + * When a HugeTLB is freed to the buddy system, we should allocate 7 pages for * vmemmap pages and restore the previous mapping relationship. * * For the HugeTLB page of the pud level mapping. It is similar to the former. - * We also can use this approach to free (PAGE_SIZE - 2) vmemmap pages. + * We also can use this approach to free (PAGE_SIZE - 1) vmemmap pages. * * Apart from the HugeTLB page of the pmd/pud level mapping, some architectures * (e.g. aarch64) provides a contiguous bit in the translation table entries @@ -166,7 +166,13 @@ * * The contiguous bit is used to increase the mapping size at the pmd and pte * (last) level. So this type of HugeTLB page can be optimized only when its - * size of the struct page structs is greater than 2 pages. + * size of the struct page structs is greater than 1 pages. + * + * Notice: The head vmemmap page is not freed to the buddy allocator and all + * tail vmemmap pages are mapped to the head vmemmap page frame. So we can see + * more than one struct page struct with PG_head (e.g. 8 per 2 MB HugeTLB page) + * associated with each HugeTLB page. The compound_head() can handle this + * correctly (more details refer to the comment above compound_head()). */ #define pr_fmt(fmt) "HugeTLB: " fmt @@ -175,14 +181,16 @@ /* * There are a lot of struct page structures associated with each HugeTLB page. * For tail pages, the value of compound_head is the same. So we can reuse first - * page of tail page structures. We map the virtual addresses of the remaining - * pages of tail page structures to the first tail page struct, and then free - * these page frames. Therefore, we need to reserve two pages as vmemmap areas. + * page of head page structures. We map the virtual addresses of all the pages + * of tail page structures to the head page struct, and then free these page + * frames. Therefore, we need to reserve one pages as vmemmap areas. */ -#define RESERVE_VMEMMAP_NR 2U +#define RESERVE_VMEMMAP_NR 1U #define RESERVE_VMEMMAP_SIZE (RESERVE_VMEMMAP_NR << PAGE_SHIFT) -bool hugetlb_free_vmemmap_enabled = IS_ENABLED(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON); +bool hugetlb_free_vmemmap_enabled __read_mostly = + IS_ENABLED(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON); +EXPORT_SYMBOL(hugetlb_free_vmemmap_enabled); static int __init early_hugetlb_free_vmemmap_param(char *buf) { @@ -236,7 +244,6 @@ int alloc_huge_page_vmemmap(struct hstate *h, struct page *head) */ ret = vmemmap_remap_alloc(vmemmap_addr, vmemmap_end, vmemmap_reuse, GFP_KERNEL | __GFP_NORETRY | __GFP_THISNODE); - if (!ret) ClearHPageVmemmapOptimized(head); @@ -282,9 +289,8 @@ void __init hugetlb_vmemmap_init(struct hstate *h) vmemmap_pages = (nr_pages * sizeof(struct page)) >> PAGE_SHIFT; /* - * The head page and the first tail page are not to be freed to buddy - * allocator, the other pages will map to the first tail page, so they - * can be freed. + * The head page is not to be freed to buddy allocator, the other tail + * pages will map to the head page, so they can be freed. * * Could RESERVE_VMEMMAP_NR be greater than @vmemmap_pages? It is true * on some architectures (e.g. aarch64). See Documentation/arm64/ diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c index bdce883f9286..62e3d20648ce 100644 --- a/mm/sparse-vmemmap.c +++ b/mm/sparse-vmemmap.c @@ -53,6 +53,17 @@ struct vmemmap_remap_walk { struct list_head *vmemmap_pages; }; +/* + * How many struct page structs need to be reset. When we reuse the head + * struct page, the special metadata (e.g. page->flags or page->mapping) + * cannot copy to the tail struct page structs. The invalid value will be + * checked in the free_tail_pages_check(). In order to avoid the message + * of "corrupted mapping in tail page". We need to reset at least 3 (one + * head struct page struct and two tail struct page structs) struct page + * structs. + */ +#define NR_RESET_STRUCT_PAGE 3 + static int split_vmemmap_huge_pmd(pmd_t *pmd, unsigned long start, struct vmemmap_remap_walk *walk) { @@ -245,6 +256,15 @@ static void vmemmap_remap_pte(pte_t *pte, unsigned long addr, set_pte_at(&init_mm, addr, pte, entry); } +static inline void reset_struct_pages(struct page *start) +{ + int i; + struct page *from = start + NR_RESET_STRUCT_PAGE; + + for (i = 0; i < NR_RESET_STRUCT_PAGE; i++) + memcpy(start + i, from, sizeof(*from)); +} + static void vmemmap_restore_pte(pte_t *pte, unsigned long addr, struct vmemmap_remap_walk *walk) { @@ -258,6 +278,7 @@ static void vmemmap_restore_pte(pte_t *pte, unsigned long addr, list_del(&page->lru); to = page_to_virt(page); copy_page(to, (void *)walk->reuse_addr); + reset_struct_pages(to); set_pte_at(&init_mm, addr, pte, mk_pte(page, pgprot)); } From patchwork Wed Sep 22 10:24:09 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Muchun Song X-Patchwork-Id: 12510021 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=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 A3AF3C433F5 for ; Wed, 22 Sep 2021 10:27:16 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 20D52611C9 for ; Wed, 22 Sep 2021 10:27:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 20D52611C9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=bytedance.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id B76E76B0073; Wed, 22 Sep 2021 06:27:15 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AFFEE900002; Wed, 22 Sep 2021 06:27:15 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 97B006B0075; Wed, 22 Sep 2021 06:27:15 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0241.hostedemail.com [216.40.44.241]) by kanga.kvack.org (Postfix) with ESMTP id 8763D6B0073 for ; Wed, 22 Sep 2021 06:27:15 -0400 (EDT) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 3E398180357C2 for ; Wed, 22 Sep 2021 10:27:15 +0000 (UTC) X-FDA: 78614832030.11.211D864 Received: from mail-pf1-f169.google.com (mail-pf1-f169.google.com [209.85.210.169]) by imf03.hostedemail.com (Postfix) with ESMTP id 061B130000A4 for ; Wed, 22 Sep 2021 10:27:14 +0000 (UTC) Received: by mail-pf1-f169.google.com with SMTP id e16so2333370pfc.6 for ; Wed, 22 Sep 2021 03:27:14 -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=z9Y75SXjQ4OjFnf6AL18GnX+kpqvEJUigzCibLGNWc0=; b=GoaNh0eyBtI0BAqbHw0AIPyMRmRMogyXs6ENtuhJGZRh7QLB6qZhAYmlhRt3JpTkmg w+FjzBOWFidlgTJxxCS1rlaNtWkqw9hU8SIgyItfljjyCa6vLtSpriQ/VDeRt7FHf2Ju P4yVKFidSEWAYw2n4yMjkX8Ry9IX/tvlbBZ2l+/C61KUcldmySBCsVL2S65jZFVPNOKo q5z4V9kz6d12molI4J1Q7OB3ZpjEXV0Sr1JZL5LXOVOikW/niitVMPYeW5l0l6P1KRfl zVG34ggd/XbKZoP34T11Le4LU7XbyNHtnHWUEksOrEJ996dvlTq6gFCEDK8WbtuQbh6+ qqbQ== 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=z9Y75SXjQ4OjFnf6AL18GnX+kpqvEJUigzCibLGNWc0=; b=fUJQPXUS0z3LOcakCKk6HIYGOUnlfK0LOX2F7GeZ+oUgCiLOuiCtBgqlx31ubX71Ja 2eqk0WiYMNxTJPBpOVdRluKP08VHsfaIJo7UwlgetGicRUKHopxCYrMoQZ1QwPG1zf1Q P+Vo+nMkWrwdynInVd7z0ct6Md5X9ua2qIigjIZByBKfLHIjjte9R6Z9YtU9EpjS8vwJ UHwzN39+4V1ZcNlViG0xTbZgSv3VGrQbgNQSBF15EPXY2TbSUdh/+ibDB/WFU9f+Xz8R 4Htalpq6QOcGalVIX7hxFOqqcQLTVM+o5UkE1DuuPPrnlKceEHVDEobSkHj6WCS6AQ/e V9dw== X-Gm-Message-State: AOAM532xgr8d4zQ7FPGHdtwbrln61Q440GMSBCKxOhm1EmoQUlbF5YyZ 8YgMli/sqz2LHnVAq6iURjq9mg== X-Google-Smtp-Source: ABdhPJwj+m8/3Sco/DMCLFXrMXDs8yZjN0k1vj0JTznwjQRew1gI7Jr5pVDALF/DRfwJHuGQAjB39w== X-Received: by 2002:a63:1f24:: with SMTP id f36mr32764347pgf.6.1632306434072; Wed, 22 Sep 2021 03:27:14 -0700 (PDT) Received: from localhost.localdomain ([139.177.225.255]) by smtp.gmail.com with ESMTPSA id s89sm1821929pjj.43.2021.09.22.03.27.08 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 22 Sep 2021 03:27:13 -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, 21cnbao@gmail.com 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 v3 2/4] mm: hugetlb: replace hugetlb_free_vmemmap_enabled with a static_key Date: Wed, 22 Sep 2021 18:24:09 +0800 Message-Id: <20210922102411.34494-3-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20210922102411.34494-1-songmuchun@bytedance.com> References: <20210922102411.34494-1-songmuchun@bytedance.com> MIME-Version: 1.0 X-Stat-Signature: p7oyezwi9u1mxbyc19iy7qhtsw7wagd3 Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=bytedance-com.20210112.gappssmtp.com header.s=20210112 header.b=GoaNh0ey; dmarc=pass (policy=none) header.from=bytedance.com; spf=pass (imf03.hostedemail.com: domain of songmuchun@bytedance.com designates 209.85.210.169 as permitted sender) smtp.mailfrom=songmuchun@bytedance.com X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 061B130000A4 X-HE-Tag: 1632306434-750205 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: The page_head_if_fake() is used throughout memory management and the conditional check requires checking a global variable, although the overhead of this check may be small, it increases when the memory cache comes under pressure. Also, the global variable will not be modified after system boot, so it is very appropriate to use static key machanism. Signed-off-by: Muchun Song --- include/linux/hugetlb.h | 10 ++++++++-- include/linux/page-flags.h | 6 ++++-- mm/hugetlb_vmemmap.c | 12 ++++++------ mm/memory_hotplug.c | 2 +- 4 files changed, 19 insertions(+), 11 deletions(-) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 1faebe1cd0ed..4cc647a5dbf8 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -1066,9 +1066,15 @@ static inline void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr #endif /* CONFIG_HUGETLB_PAGE */ #ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP -extern bool hugetlb_free_vmemmap_enabled; +static inline bool hugetlb_free_vmemmap_enabled(void) +{ + return static_key_enabled(&hugetlb_free_vmemmap_enabled_key); +} #else -#define hugetlb_free_vmemmap_enabled false +static inline bool hugetlb_free_vmemmap_enabled(void) +{ + return false; +} #endif static inline spinlock_t *huge_pte_lock(struct hstate *h, diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index b47a7f51d2c3..54e119e44496 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -185,7 +185,8 @@ enum pageflags { #ifndef __GENERATING_BOUNDS_H #ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP -extern bool hugetlb_free_vmemmap_enabled; +DECLARE_STATIC_KEY_MAYBE(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON, + hugetlb_free_vmemmap_enabled_key); /* * If the feature of freeing some vmemmap pages associated with each HugeTLB @@ -205,7 +206,8 @@ extern bool hugetlb_free_vmemmap_enabled; */ static __always_inline const struct page *page_fixed_fake_head(const struct page *page) { - if (!hugetlb_free_vmemmap_enabled) + if (!static_branch_maybe(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON, + &hugetlb_free_vmemmap_enabled_key)) return page; /* * Only addresses aligned with PAGE_SIZE of struct page may be fake head diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index 527bcaa44a48..47517e878ed5 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -188,9 +188,9 @@ #define RESERVE_VMEMMAP_NR 1U #define RESERVE_VMEMMAP_SIZE (RESERVE_VMEMMAP_NR << PAGE_SHIFT) -bool hugetlb_free_vmemmap_enabled __read_mostly = - IS_ENABLED(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON); -EXPORT_SYMBOL(hugetlb_free_vmemmap_enabled); +DEFINE_STATIC_KEY_MAYBE(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON, + hugetlb_free_vmemmap_enabled_key); +EXPORT_SYMBOL(hugetlb_free_vmemmap_enabled_key); static int __init early_hugetlb_free_vmemmap_param(char *buf) { @@ -204,9 +204,9 @@ static int __init early_hugetlb_free_vmemmap_param(char *buf) return -EINVAL; if (!strcmp(buf, "on")) - hugetlb_free_vmemmap_enabled = true; + static_branch_enable(&hugetlb_free_vmemmap_enabled_key); else if (!strcmp(buf, "off")) - hugetlb_free_vmemmap_enabled = false; + static_branch_disable(&hugetlb_free_vmemmap_enabled_key); else return -EINVAL; @@ -284,7 +284,7 @@ void __init hugetlb_vmemmap_init(struct hstate *h) BUILD_BUG_ON(__NR_USED_SUBPAGE >= RESERVE_VMEMMAP_SIZE / sizeof(struct page)); - if (!hugetlb_free_vmemmap_enabled) + if (!hugetlb_free_vmemmap_enabled()) return; vmemmap_pages = (nr_pages * sizeof(struct page)) >> PAGE_SHIFT; diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 0488eed3327c..89c1fde02162 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1341,7 +1341,7 @@ bool mhp_supports_memmap_on_memory(unsigned long size) * populate a single PMD. */ return memmap_on_memory && - !hugetlb_free_vmemmap_enabled && + !hugetlb_free_vmemmap_enabled() && IS_ENABLED(CONFIG_MHP_MEMMAP_ON_MEMORY) && size == memory_block_size_bytes() && IS_ALIGNED(vmemmap_size, PMD_SIZE) && From patchwork Wed Sep 22 10:24:10 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Muchun Song X-Patchwork-Id: 12510023 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=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 AFBA7C433EF for ; Wed, 22 Sep 2021 10:27:22 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 54DC161209 for ; Wed, 22 Sep 2021 10:27:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 54DC161209 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=bytedance.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id E84586B0074; Wed, 22 Sep 2021 06:27:21 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E0DD76B0075; Wed, 22 Sep 2021 06:27:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C38ED6B0078; Wed, 22 Sep 2021 06:27:21 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0253.hostedemail.com [216.40.44.253]) by kanga.kvack.org (Postfix) with ESMTP id B5B5E6B0074 for ; Wed, 22 Sep 2021 06:27:21 -0400 (EDT) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 7BCA0181B10E2 for ; Wed, 22 Sep 2021 10:27:21 +0000 (UTC) X-FDA: 78614832282.11.1B1670A Received: from mail-pl1-f171.google.com (mail-pl1-f171.google.com [209.85.214.171]) by imf01.hostedemail.com (Postfix) with ESMTP id 40862505BD2D for ; Wed, 22 Sep 2021 10:27:21 +0000 (UTC) Received: by mail-pl1-f171.google.com with SMTP id j15so23491plh.7 for ; Wed, 22 Sep 2021 03:27:21 -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=4dXtWvh0hz8AcEkJtaCmZCNKq+swCjTc/s3IW/xzmY0=; b=iY1pxp/2LjuDMZjmTZVAm7zcKIrGCkGDzB8F60/vWyJhBG5OcZHTnCVHmQ3RK7R2Bt FFLnNjzE9DjpjGDHrYEMi59CeaVszgVi/h+w79XXPo51qdU/iWCogjk/3z0yHWmiW+84 uPemc83b+vwRqo1cGqWQbgzc4CamH74Cq5foB+wUHiTeS48b10l4tzL4nHUMZ5Q/QHJH 9XFvlg96N6gmgQXCaZTsPganY668ZQvB5F+R3tif8zFXelLPKbHfkYebnNXrFVMTjAGn XiWwgmCpsoIeKXqf17NPnrIEloRe90Aarlv0+8gKhzjnzgyNgmU6dBk30xxHujB9m1zo l90g== 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=4dXtWvh0hz8AcEkJtaCmZCNKq+swCjTc/s3IW/xzmY0=; b=w0Sv1KsMbyJd39o0mosQE1DODQOi6YKd+Qm2jnI6abziLbtGb8fzNelknXz5LLL/0e qHKoQlKCQnQteANLTxHbBm7B05yMrGMmjYO0dq6KlzsvkXhsWQuHSUwcbpS0qGe+QtmT ItYi7dTg5+EVN1Bs8/dWXWdpBt7Iji3+9IS4MRC+eYEwGXlfInSTuTiQwLruMwrn+eOu Ut8MaBUDSyv1/9810Ga0OVAelNvRa/xo+mlgaub3++rY3KEPASqu8A26aON92ytGJHa+ IUaQsQLjojmXUFWF4OThq75SaHbKNQMNG5cCEMNTbzSAMwXf2TEKQHtdTdX0SsOHVHeV 4xfA== X-Gm-Message-State: AOAM530wqqI7FF02x9isJ6pvpfhKsL6EF3HEc/3UoJhP1svHfngCzM2H p+cc5LCtT5c5wEahi0uvv2SOSQ== X-Google-Smtp-Source: ABdhPJxC+8sPcMCYb0LCoNN2Yblp/Tq/ZoiWIgS7Vo0HeqiB0K1B/lTrvFsHWyH/3dUXCrgzLLFZfg== X-Received: by 2002:a17:90b:4b4b:: with SMTP id mi11mr10255208pjb.41.1632306440284; Wed, 22 Sep 2021 03:27:20 -0700 (PDT) Received: from localhost.localdomain ([139.177.225.255]) by smtp.gmail.com with ESMTPSA id s89sm1821929pjj.43.2021.09.22.03.27.14 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 22 Sep 2021 03:27:20 -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, 21cnbao@gmail.com 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 v3 3/4] mm: sparsemem: use page table lock to protect kernel pmd operations Date: Wed, 22 Sep 2021 18:24:10 +0800 Message-Id: <20210922102411.34494-4-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20210922102411.34494-1-songmuchun@bytedance.com> References: <20210922102411.34494-1-songmuchun@bytedance.com> MIME-Version: 1.0 Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=bytedance-com.20210112.gappssmtp.com header.s=20210112 header.b="iY1pxp/2"; spf=pass (imf01.hostedemail.com: domain of songmuchun@bytedance.com designates 209.85.214.171 as permitted sender) smtp.mailfrom=songmuchun@bytedance.com; dmarc=pass (policy=none) header.from=bytedance.com X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 40862505BD2D X-Stat-Signature: 96skh5ffnx3buk4qqe7cd4ck7bcswt8b X-HE-Tag: 1632306441-454047 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: 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(). Actually, It increase the concurrency between allocations of HugeTLB pages. But it is not the only benefit. There are a lot of users of mmap read lock of init_mm. The mmap write lock is holding through vmemmap_remap_free(), removing mmap write lock usage to make it does not affect other users of mmap read lock. It is not making anything worse and always a win to move. 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; /* From patchwork Wed Sep 22 10:24:11 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Muchun Song X-Patchwork-Id: 12510025 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=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 6D247C433EF for ; Wed, 22 Sep 2021 10:27:29 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2200C611C9 for ; Wed, 22 Sep 2021 10:27:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 2200C611C9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=bytedance.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id BECCF6B0075; Wed, 22 Sep 2021 06:27:28 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B75846B0078; Wed, 22 Sep 2021 06:27:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9EFFA6B007B; Wed, 22 Sep 2021 06:27:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0065.hostedemail.com [216.40.44.65]) by kanga.kvack.org (Postfix) with ESMTP id 8E1E96B0075 for ; Wed, 22 Sep 2021 06:27:28 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 3702382499A8 for ; Wed, 22 Sep 2021 10:27:28 +0000 (UTC) X-FDA: 78614832576.14.FD340D8 Received: from mail-pj1-f41.google.com (mail-pj1-f41.google.com [209.85.216.41]) by imf12.hostedemail.com (Postfix) with ESMTP id E948610000A3 for ; Wed, 22 Sep 2021 10:27:27 +0000 (UTC) Received: by mail-pj1-f41.google.com with SMTP id me1so1682803pjb.4 for ; Wed, 22 Sep 2021 03:27:27 -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=2WShyFWb04L9WEAJIMbiQ1oAuqmUubIidKcAA6z6qHc=; b=cmX7TscVl7FShFFSBOdOXLSIvnSRAK2+duMaOxUohUqToHBQ4DZTIo8CNMXeSIcXCh QlbB3FsrvQ+luQXw0SxtwUvA2Jh/CS10+n+7p6uQj7YLQDwSgDQZYO7oqJxRMcmD2JDB tpyL9E4o0GqjwEGdPz5Fg8CL8URUpWBI4KefN/Mgz8HjQDFe510Ix2aazYtQjUWFqdzJ nrIHZxfacZX995iYpQbwxAM6f9SjeIH5XvhBRLhsiiAPPybW2b3eP1R7osUTLWfxGrAW nSYPCLmEml+3OcrnZriVdgIOAGCE8crbypeYn/lgHwyj5+Xe6OtrCfkNq/d2HKhaV/g0 fnhg== 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=2WShyFWb04L9WEAJIMbiQ1oAuqmUubIidKcAA6z6qHc=; b=rweuFfMM/7qqmS1uA6fVJBfgF6Ugg9/ipQmKMmOECiOe1qbDvnJN8BF98QLJoMZSIz 97tUAw9gxutOMnb9EUylHm6VnQbcmYaPaAIZfx6BZ2eXJ4apNFx/OMXwzforGx4RAO2y 85/zLMg8lM0W025btHc/PKhoMCxOIUIIBqToHSioGH4eI/hGPbv1LxuVDfkH+6M2qXls dqFe/xKgZZsm8UxmgCQd608HxqMzzn2Vyg0FwceaYsJzej+5UUkwlZnrjkioh2BGAfo4 Li2YpsjtIvwE983+HPMak8eK6+sDFB9cwCQ9IuZAAxTxLcFFGGQzhQBvxHtLPmaSycwW YyWg== X-Gm-Message-State: AOAM533zpSsG715QoCeCjb42tnCgm0dz8F1Y7gQ8w+Z+AnBXMLzXmGzK FtZs7Jh7uRjbD7aBNJFh0teM6Q== X-Google-Smtp-Source: ABdhPJwdS5Kmj5jx1TOgHHJcAJ4Oj6w5rtx3g+FopqrNg7Ovjt492uI9o2342vDaynECyHxNmd9l8w== X-Received: by 2002:a17:90a:345:: with SMTP id 5mr10185110pjf.189.1632306446871; Wed, 22 Sep 2021 03:27:26 -0700 (PDT) Received: from localhost.localdomain ([139.177.225.255]) by smtp.gmail.com with ESMTPSA id s89sm1821929pjj.43.2021.09.22.03.27.20 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 22 Sep 2021 03:27:26 -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, 21cnbao@gmail.com 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 v3 4/4] selftests: vm: add a hugetlb test case Date: Wed, 22 Sep 2021 18:24:11 +0800 Message-Id: <20210922102411.34494-5-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20210922102411.34494-1-songmuchun@bytedance.com> References: <20210922102411.34494-1-songmuchun@bytedance.com> MIME-Version: 1.0 Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=bytedance-com.20210112.gappssmtp.com header.s=20210112 header.b=cmX7TscV; spf=pass (imf12.hostedemail.com: domain of songmuchun@bytedance.com designates 209.85.216.41 as permitted sender) smtp.mailfrom=songmuchun@bytedance.com; dmarc=pass (policy=none) header.from=bytedance.com X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: E948610000A3 X-Stat-Signature: nsm3epcq3o78n6q5648ep6qdhbo6o8pp X-HE-Tag: 1632306447-484198 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: Since the head vmemmap page frame associated with each HugeTLB page is reused, we should hide the PG_head flag of tail struct page from the user. Add a tese case to check whether it is work properly. The test steps are as follows. 1) alloc 2MB hugeTLB 2) get each page frame 3) apply those APIs in each page frame 4) Those APIs work completely the same as before. Reading the flags of a page by /proc/kpageflags is done in stable_page_flags(), which has invoked PageHead(), PageTail(), PageCompound() and compound_head(). If those APIs work properly, the head page must have 15 and 17 bits set. And tail pages must have 16 and 17 bits set but 15 bit unset. Those flags are checked in check_page_flags(). Signed-off-by: Muchun Song Reviewed-by: Barry Song --- tools/testing/selftests/vm/vmemmap_hugetlb.c | 144 +++++++++++++++++++++++++++ 1 file changed, 144 insertions(+) create mode 100644 tools/testing/selftests/vm/vmemmap_hugetlb.c diff --git a/tools/testing/selftests/vm/vmemmap_hugetlb.c b/tools/testing/selftests/vm/vmemmap_hugetlb.c new file mode 100644 index 000000000000..4cc74dd4c333 --- /dev/null +++ b/tools/testing/selftests/vm/vmemmap_hugetlb.c @@ -0,0 +1,144 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * A test case of using hugepage memory in a user application using the + * mmap system call with MAP_HUGETLB flag. Before running this program + * make sure the administrator has allocated enough default sized huge + * pages to cover the 2 MB allocation. + * + * For ia64 architecture, Linux kernel reserves Region number 4 for hugepages. + * That means the addresses starting with 0x800000... will need to be + * specified. Specifying a fixed address is not required on ppc64, i386 + * or x86_64. + */ +#include +#include +#include +#include +#include + +#define MAP_LENGTH (2UL * 1024 * 1024) + +#ifndef MAP_HUGETLB +#define MAP_HUGETLB 0x40000 /* arch specific */ +#endif + +#define PAGE_SIZE 4096 + +#define PAGE_COMPOUND_HEAD (1UL << 15) +#define PAGE_COMPOUND_TAIL (1UL << 16) +#define PAGE_HUGE (1UL << 17) + +#define HEAD_PAGE_FLAGS (PAGE_COMPOUND_HEAD | PAGE_HUGE) +#define TAIL_PAGE_FLAGS (PAGE_COMPOUND_TAIL | PAGE_HUGE) + +#define PM_PFRAME_BITS 55 +#define PM_PFRAME_MASK ~((1UL << PM_PFRAME_BITS) - 1) + +/* Only ia64 requires this */ +#ifdef __ia64__ +#define MAP_ADDR (void *)(0x8000000000000000UL) +#define MAP_FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED) +#else +#define MAP_ADDR NULL +#define MAP_FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB) +#endif + +static void write_bytes(char *addr, size_t length) +{ + unsigned long i; + + for (i = 0; i < length; i++) + *(addr + i) = (char)i; +} + +static unsigned long virt_to_pfn(void *addr) +{ + int fd; + unsigned long pagemap; + + fd = open("/proc/self/pagemap", O_RDONLY); + if (fd < 0) + return -1UL; + + lseek(fd, (unsigned long)addr / PAGE_SIZE * sizeof(pagemap), SEEK_SET); + read(fd, &pagemap, sizeof(pagemap)); + close(fd); + + return pagemap & ~PM_PFRAME_MASK; +} + +static int check_page_flags(unsigned long pfn) +{ + int fd, i; + unsigned long pageflags; + + fd = open("/proc/kpageflags", O_RDONLY); + if (fd < 0) + return -1; + + lseek(fd, pfn * sizeof(pageflags), SEEK_SET); + + read(fd, &pageflags, sizeof(pageflags)); + if ((pageflags & HEAD_PAGE_FLAGS) != HEAD_PAGE_FLAGS) { + close(fd); + printf("Head page flags (%lx) is invalid\n", pageflags); + return -1; + } + + /* + * pages other than the first page must be tail and shouldn't be head; + * this also verifies kernel has correctly set the fake page_head to tail + * while hugetlb_free_vmemmap is enabled. + */ + for (i = 1; i < MAP_LENGTH / PAGE_SIZE; i++) { + read(fd, &pageflags, sizeof(pageflags)); + if ((pageflags & TAIL_PAGE_FLAGS) != TAIL_PAGE_FLAGS || + (pageflags & HEAD_PAGE_FLAGS) == HEAD_PAGE_FLAGS) { + close(fd); + printf("Tail page flags (%lx) is invalid\n", pageflags); + return -1; + } + } + + close(fd); + + return 0; +} + +int main(int argc, char **argv) +{ + void *addr; + unsigned long pfn; + + addr = mmap(MAP_ADDR, MAP_LENGTH, PROT_READ | PROT_WRITE, MAP_FLAGS, -1, 0); + if (addr == MAP_FAILED) { + perror("mmap"); + exit(1); + } + + /* Trigger allocation of HugeTLB page. */ + write_bytes(addr, MAP_LENGTH); + + pfn = virt_to_pfn(addr); + if (pfn == -1UL) { + munmap(addr, MAP_LENGTH); + perror("virt_to_pfn"); + exit(1); + } + + printf("Returned address is %p whose pfn is %lx\n", addr, pfn); + + if (check_page_flags(pfn) < 0) { + munmap(addr, MAP_LENGTH); + perror("check_page_flags"); + exit(1); + } + + /* munmap() length of MAP_HUGETLB memory must be hugepage aligned */ + if (munmap(addr, MAP_LENGTH)) { + perror("munmap"); + exit(1); + } + + return 0; +}