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=-16.6 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,URIBL_BLOCKED,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 15827C64E8A for ; Mon, 30 Nov 2020 15:20:06 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5B33320719 for ; Mon, 30 Nov 2020 15:20:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=bytedance-com.20150623.gappssmtp.com header.i=@bytedance-com.20150623.gappssmtp.com header.b="epMoITOm" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5B33320719 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=bytedance.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id DDA2A8D000A; Mon, 30 Nov 2020 10:20:04 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id D95898D0002; Mon, 30 Nov 2020 10:20:04 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BB5568D000A; Mon, 30 Nov 2020 10:20:04 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0201.hostedemail.com [216.40.44.201]) by kanga.kvack.org (Postfix) with ESMTP id 9FB458D0002 for ; Mon, 30 Nov 2020 10:20:04 -0500 (EST) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 64CA0181AEF2A for ; Mon, 30 Nov 2020 15:20:04 +0000 (UTC) X-FDA: 77541445128.30.eyes72_1f022ad273a2 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin30.hostedemail.com (Postfix) with ESMTP id 24203180B3C8E for ; Mon, 30 Nov 2020 15:20:04 +0000 (UTC) X-HE-Tag: eyes72_1f022ad273a2 X-Filterd-Recvd-Size: 14573 Received: from mail-pf1-f182.google.com (mail-pf1-f182.google.com [209.85.210.182]) by imf49.hostedemail.com (Postfix) with ESMTP for ; Mon, 30 Nov 2020 15:20:03 +0000 (UTC) Received: by mail-pf1-f182.google.com with SMTP id e8so10611535pfh.2 for ; Mon, 30 Nov 2020 07:20:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=9vdDREmbmInhjdApsMpNN6yHRVfI2DjGpJbOKZ/lZXg=; b=epMoITOmeG5CH4Z4wxEHfhRF2KZrYA9MSwC3V6MgUXw+B8xY/YltjyTJcp49naqMrE KVAwnA8qhKlxpEk0Z1Y5/egH56S6DgbvxhPWRwt0fsKxYBu6mVnkDsR+wlPiKN+b8QCk fUS20mBdGOOmsa7CrGlkUH6DvGJqey5m15PcbXjPH3uKxuDHHwYCXeDJmprURRHpB7SX Bq0e8OOM64KBCXvZXNmy0qckm3ao/2r+rBk9V493coS58NmdxmlWGrOK0uxGN9+sRteo X5eF34RkZwL6ddMpLuUYviRqgGUXGGVSL1YKYUq4mYGbWLQKssPMhtM6ljNljcl5wUTe WsRQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=9vdDREmbmInhjdApsMpNN6yHRVfI2DjGpJbOKZ/lZXg=; b=LIg/nRIeUl0iilm6gbeIw1tR8ZnSKNWiafW0uprQbNNWLDGq2Nepgv4/+xSxowc6j2 y5IpYtNJ5/MwbO0OA7tFfMTrBFMc146iLmx+maDngvTLckkxiZUsFXVo/bJag8LGRUtx fc8KKAirsDYNXmrHds48qrfntVtNh4si52Q/wmno1/7LCW2+9PCHD5OESkMCkpW+XD4Z VvoxVAPrEiGcpYwhQ32YI+mhb4wMjmVZX8wlxY+hNfRnw2GktTQLJeHsN0GglRJ85VTZ bGL8851v2JpYxZaQ6OWeZu2et/xIuxmewuhLfmZaHC7feqWX3JMx8hsb2HeoHe9FnsTK gHqA== X-Gm-Message-State: AOAM532K6XvOLeJuryOz8fO2anEyw9s0AJ3ApFyTo1J/4w8iT5V2hpew zUgeNX52pBU751C23DYhkeLddQ== X-Google-Smtp-Source: ABdhPJy8wd6DEoTVKlaxsLRoxXEZiFbmiJmb9K9qEfnalXvr859l2pIATie6wECmyool3BTsBkzlkw== X-Received: by 2002:a62:75c6:0:b029:18a:d510:ff60 with SMTP id q189-20020a6275c60000b029018ad510ff60mr18879498pfc.35.1606749602318; Mon, 30 Nov 2020 07:20:02 -0800 (PST) Received: from localhost.bytedance.net ([103.136.221.68]) by smtp.gmail.com with ESMTPSA id q12sm16201660pgv.91.2020.11.30.07.19.52 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 30 Nov 2020 07:20:01 -0800 (PST) From: Muchun Song To: corbet@lwn.net, mike.kravetz@oracle.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, paulmck@kernel.org, mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com, rdunlap@infradead.org, oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de, almasrymina@google.com, rientjes@google.com, willy@infradead.org, osalvador@suse.de, mhocko@suse.com, song.bao.hua@hisilicon.com Cc: duanxiongchun@bytedance.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Muchun Song Subject: [PATCH v7 04/15] mm/hugetlb: Introduce nr_free_vmemmap_pages in the struct hstate Date: Mon, 30 Nov 2020 23:18:27 +0800 Message-Id: <20201130151838.11208-5-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20201130151838.11208-1-songmuchun@bytedance.com> References: <20201130151838.11208-1-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable 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: Every HugeTLB has more than one struct page structure. The 2M HugeTLB has 512 struct page structure and 1G HugeTLB has 4096 struct page structures. We __know__ that we only use the first 4(HUGETLB_CGROUP_MIN_O= RDER) struct page structures to store metadata associated with each HugeTLB. There are a lot of struct page structures(8 page frames for 2MB HugeTLB page and 4096 page frames for 1GB HugeTLB page) 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. So we introduce a new nr_free_vmemmap_pages field in the hstate to indicate how many vmemmap pages associated with a HugeTLB page that we can free to buddy system. Signed-off-by: Muchun Song Acked-by: Mike Kravetz --- include/linux/hugetlb.h | 3 ++ mm/Makefile | 1 + mm/hugetlb.c | 3 ++ mm/hugetlb_vmemmap.c | 129 ++++++++++++++++++++++++++++++++++++++++++= ++++++ mm/hugetlb_vmemmap.h | 20 ++++++++ 5 files changed, 156 insertions(+) create mode 100644 mm/hugetlb_vmemmap.c create mode 100644 mm/hugetlb_vmemmap.h diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index ebca2ef02212..4efeccb7192c 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -492,6 +492,9 @@ struct hstate { unsigned int nr_huge_pages_node[MAX_NUMNODES]; unsigned int free_huge_pages_node[MAX_NUMNODES]; unsigned int surplus_huge_pages_node[MAX_NUMNODES]; +#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP + unsigned int nr_free_vmemmap_pages; +#endif #ifdef CONFIG_CGROUP_HUGETLB /* cgroup control files */ struct cftype cgroup_files_dfl[7]; diff --git a/mm/Makefile b/mm/Makefile index ed4b88fa0f5e..056801d8daae 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -71,6 +71,7 @@ obj-$(CONFIG_FRONTSWAP) +=3D frontswap.o obj-$(CONFIG_ZSWAP) +=3D zswap.o obj-$(CONFIG_HAS_DMA) +=3D dmapool.o obj-$(CONFIG_HUGETLBFS) +=3D hugetlb.o +obj-$(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP) +=3D hugetlb_vmemmap.o obj-$(CONFIG_NUMA) +=3D mempolicy.o obj-$(CONFIG_SPARSEMEM) +=3D sparse.o obj-$(CONFIG_SPARSEMEM_VMEMMAP) +=3D sparse-vmemmap.o diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 1f3bf1710b66..25f9e8e9fc4a 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -42,6 +42,7 @@ #include #include #include "internal.h" +#include "hugetlb_vmemmap.h" =20 int hugetlb_max_hstate __read_mostly; unsigned int default_hstate_idx; @@ -3206,6 +3207,8 @@ void __init hugetlb_add_hstate(unsigned int order) snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB", huge_page_size(h)/1024); =20 + hugetlb_vmemmap_init(h); + parsed_hstate =3D h; } =20 diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c new file mode 100644 index 000000000000..51152e258f39 --- /dev/null +++ b/mm/hugetlb_vmemmap.c @@ -0,0 +1,129 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Free some vmemmap pages of HugeTLB + * + * Copyright (c) 2020, Bytedance. All rights reserved. + * + * Author: Muchun Song + * + * The struct page structures (page structs) are used to describe a phys= ical + * page frame. By default, there is a one-to-one mapping from a page fra= me to + * it's corresponding page struct. + * + * The HugeTLB pages consist of multiple base page size pages and is sup= ported + * by many architectures. See hugetlbpage.rst in the Documentation direc= tory + * for more details. On the x86 architecture, HugeTLB pages of size 2MB = and 1GB + * are currently supported. Since the base page size on x86 is 4KB, a 2M= B + * HugeTLB page consists of 512 base pages and a 1GB HugeTLB page consis= ts of + * 4096 base pages. For each base page, there is a corresponding page st= ruct. + * + * Within the HugeTLB subsystem, only the first 4 page structs are used = to + * contain unique information about a HugeTLB page. HUGETLB_CGROUP_MIN_O= RDER + * provides this upper limit. The only 'useful' information in the remai= ning + * page structs is the compound_head field, and this field is the same f= or all + * tail pages. + * + * By removing redundant page structs for HugeTLB pages, memory can retu= rned to + * the buddy allocator for other uses. + * + * When the system boot up, every 2M HugeTLB has 512 struct page structs= which + * size is 8 pages(sizeof(struct page) * 512 / PAGE_SIZE). + * + * HugeTLB struct pages(8 pages) page frame(= 8 pages) + * +-----------+ ---virt_to_page---> +-----------+ mapping to +-----= ------+ + * | | | 0 | -------------> | = 0 | + * | | +-----------+ +-----= ------+ + * | | | 1 | -------------> | = 1 | + * | | +-----------+ +-----= ------+ + * | | | 2 | -------------> | = 2 | + * | | +-----------+ +-----= ------+ + * | | | 3 | -------------> | = 3 | + * | | +-----------+ +-----= ------+ + * | | | 4 | -------------> | = 4 | + * | 2MB | +-----------+ +-----= ------+ + * | | | 5 | -------------> | = 5 | + * | | +-----------+ +-----= ------+ + * | | | 6 | -------------> | = 6 | + * | | +-----------+ +-----= ------+ + * | | | 7 | -------------> | = 7 | + * | | +-----------+ +-----= ------+ + * | | + * | | + * | | + * +-----------+ + * + * The value of page->compound_head is the same for all tail pages. The = first + * page of page structs (page 0) associated with the HugeTLB page contai= ns the 4 + * page structs necessary to describe the HugeTLB. The only use of the r= emaining + * pages of page structs (page 1 to page 7) is to point to page->compoun= d_head. + * Therefore, we can remap pages 2 to 7 to page 1. Only 2 pages of page = structs + * will be used for each HugeTLB page. This will allow us to free the re= maining + * 6 pages to the buddy allocator. + * + * Here is how things look after remapping. + * + * HugeTLB struct pages(8 pages) page frame(= 8 pages) + * +-----------+ ---virt_to_page---> +-----------+ mapping to +-----= ------+ + * | | | 0 | -------------> | = 0 | + * | | +-----------+ +-----= ------+ + * | | | 1 | -------------> | = 1 | + * | | +-----------+ +-----= ------+ + * | | | 2 | ----------------^ ^ ^= ^ ^ ^ + * | | +-----------+ | |= | | | + * | | | 3 | ------------------+ |= | | | + * | | +-----------+ |= | | | + * | | | 4 | --------------------+= | | | + * | 2MB | +-----------+ = | | | + * | | | 5 | ---------------------= -+ | | + * | | +-----------+ = | | + * | | | 6 | ---------------------= ---+ | + * | | +-----------+ = | + * | | | 7 | ---------------------= -----+ + * | | +-----------+ + * | | + * | | + * | | + * +-----------+ + * + * When a HugeTLB is freed to the buddy system, we should allocate 6 pag= es for + * vmemmap pages and restore the previous mapping relationship. + * + * Apart from 2MB HugeTLB page, we also have 1GB HugeTLB page. It is sim= ilar + * to the 2MB HugeTLB page. We also can use this approach to free the vm= emmap + * pages. + */ +#define pr_fmt(fmt) "HugeTLB vmemmap: " fmt + +#include "hugetlb_vmemmap.h" + +/* + * There are a lot of struct page structures(8 page frames for 2MB HugeT= LB page + * and 4096 page frames for 1GB HugeTLB page) associated with each HugeT= LB page. + * For tail pages, the value of compound_head is the same. So we can reu= se first + * page of tail page structures. We map the virtual addresses of the rem= aining + * 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. + */ +#define RESERVE_VMEMMAP_NR 2U + +void __init hugetlb_vmemmap_init(struct hstate *h) +{ + unsigned int nr_pages =3D pages_per_huge_page(h); + unsigned int vmemmap_pages; + + vmemmap_pages =3D (nr_pages * sizeof(struct page)) >> PAGE_SHIFT; + /* + * The head page and the first tail page are not to be freed to buddy + * system, the others page will map to the first tail page. So there + * are the remaining pages that can be freed. + * + * Could RESERVE_VMEMMAP_NR be greater than @vmemmap_pages? It is true + * on some architectures (e.g. aarch64). See Documentation/arm64/ + * hugetlbpage.rst for more details. + */ + if (likely(vmemmap_pages > RESERVE_VMEMMAP_NR)) + h->nr_free_vmemmap_pages =3D vmemmap_pages - RESERVE_VMEMMAP_NR; + + pr_debug("can free %d vmemmap pages for %s\n", h->nr_free_vmemmap_pages= , + h->name); +} diff --git a/mm/hugetlb_vmemmap.h b/mm/hugetlb_vmemmap.h new file mode 100644 index 000000000000..40c0c7dfb60d --- /dev/null +++ b/mm/hugetlb_vmemmap.h @@ -0,0 +1,20 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Free some vmemmap pages of HugeTLB + * + * Copyright (c) 2020, Bytedance. All rights reserved. + * + * Author: Muchun Song + */ +#ifndef _LINUX_HUGETLB_VMEMMAP_H +#define _LINUX_HUGETLB_VMEMMAP_H +#include + +#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP +void __init hugetlb_vmemmap_init(struct hstate *h); +#else +static inline void hugetlb_vmemmap_init(struct hstate *h) +{ +} +#endif /* CONFIG_HUGETLB_PAGE_FREE_VMEMMAP */ +#endif /* _LINUX_HUGETLB_VMEMMAP_H */ --=20 2.11.0