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=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 1FDB0C433B4 for ; Sun, 25 Apr 2021 07:13:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F1691613C2 for ; Sun, 25 Apr 2021 07:13:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230073AbhDYHOZ (ORCPT ); Sun, 25 Apr 2021 03:14:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60982 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230037AbhDYHOY (ORCPT ); Sun, 25 Apr 2021 03:14:24 -0400 Received: from mail-pf1-x431.google.com (mail-pf1-x431.google.com [IPv6:2607:f8b0:4864:20::431]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3C0FFC061756 for ; Sun, 25 Apr 2021 00:13:45 -0700 (PDT) Received: by mail-pf1-x431.google.com with SMTP id i190so36880289pfc.12 for ; Sun, 25 Apr 2021 00:13:45 -0700 (PDT) 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=8JtmIUu8YXtS47iFe6zG44KZB01vXFzyHRHrIOUs08s=; b=FEWrRkk2sBgBM6FC8NIrFUH2cB6e4xN7N4J+8g78W2KIun4XLprsU5tFl7i0ZOpzwp g3Yl2ZPa1FeDgwbXRvdqUkUp8ldd8f+pKHWdZEAT/wVQiHRI+KyLA68jaKMZM59TnS4n AOMLOL7l/S7UKURFoF+RKFLyqxIDpvy9MVy7TzaHjssyU1U0YV/Kw+uJnYlpQPlrFr0G EOrCn5NqXDzDSRgIoJ5pWycEWb0ExeTIGGALMVA3Mj2yIFz1N4MpWVI056KGyE4ealNm lMe7vkrRHFrMBbGy3+JITCQWpa5Avt/tSeNeMpwxAEdZn5wxbyrNa48Ve47qCCUp/z+Y Qq5A== 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=8JtmIUu8YXtS47iFe6zG44KZB01vXFzyHRHrIOUs08s=; b=TB+BtLerS5pzjSiVSpwrTvhdOHBFXYx3cB08Wy2ROWvbadpnsLMyyZ97+SWPcVWtkO fd4qf3W2UYjRiD8PuWbHyUE2bw7bzINzM3WazYG3OJLX7YtkvLw17/iQikGkztkChKId krG0t/1Qp0dVDam7Ht1bXgZhxu94eWQD6tiGE7jx+HGrwcee/Mz2Sci6aaSvQlk1dPUR gin9kGuei8E/GHFlREXQxoZIB2f8dWiHK0VZrqaaRP7bBLXGQP4HsFmZkO2qH6SM28iO qnnmotgsWABcNgcCk9kOMVIMFmJSob4TNIFwMrUENAdUPPtZ1IKTmhofaGXHzvj2KhE4 lIyA== X-Gm-Message-State: AOAM531BLDDk/dMoNtcjfgV/Yh7zsJVgMkl6SIzzRtArTnIqlRZrcm6V LxiYdLfP4VoH8kfm91kmjEKAOw== X-Google-Smtp-Source: ABdhPJw+kgjbbKW3Ph57udTG0bmmdlEASR/KwZWLPBJgVkwMLnrgTjjgWF0AAk+8F1wwLOAdYhDicw== X-Received: by 2002:aa7:9f5d:0:b029:265:e8b5:ecd0 with SMTP id h29-20020aa79f5d0000b0290265e8b5ecd0mr11726727pfr.26.1619334824750; Sun, 25 Apr 2021 00:13:44 -0700 (PDT) Received: from localhost.localdomain ([139.177.225.255]) by smtp.gmail.com with ESMTPSA id h8sm8767125pjt.17.2021.04.25.00.13.33 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Sun, 25 Apr 2021 00:13:44 -0700 (PDT) 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, 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, david@redhat.com, naoya.horiguchi@nec.com, joao.m.martins@oracle.com Cc: duanxiongchun@bytedance.com, fam.zheng@bytedance.com, zhengqi.arch@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 v21 5/9] mm: hugetlb: defer freeing of HugeTLB pages Date: Sun, 25 Apr 2021 15:07:48 +0800 Message-Id: <20210425070752.17783-6-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20210425070752.17783-1-songmuchun@bytedance.com> References: <20210425070752.17783-1-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org In the subsequent patch, we should allocate the vmemmap pages when freeing a HugeTLB page. But update_and_free_page() can be called under any context, so we cannot use GFP_KERNEL to allocate vmemmap pages. However, we can defer the actual freeing in a kworker to prevent from using GFP_ATOMIC to allocate the vmemmap pages. The __update_and_free_page() is where the call to allocate vmemmmap pages will be inserted. Signed-off-by: Muchun Song --- mm/hugetlb.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++++---- mm/hugetlb_vmemmap.c | 12 -------- mm/hugetlb_vmemmap.h | 17 +++++++++++ 3 files changed, 92 insertions(+), 18 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 61dd653a2c66..72ce4d28441a 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1376,7 +1376,7 @@ static void remove_hugetlb_page(struct hstate *h, struct page *page, h->nr_huge_pages_node[nid]--; } -static void update_and_free_page(struct hstate *h, struct page *page) +static void __update_and_free_page(struct hstate *h, struct page *page) { int i; struct page *subpage = page; @@ -1399,12 +1399,79 @@ static void update_and_free_page(struct hstate *h, struct page *page) } } +/* + * As update_and_free_page() can be called under any context, so we cannot + * use GFP_KERNEL to allocate vmemmap pages. However, we can defer the + * actual freeing in a workqueue to prevent from using GFP_ATOMIC to allocate + * the vmemmap pages. + * + * free_hpage_workfn() locklessly retrieves the linked list of pages to be + * freed and frees them one-by-one. As the page->mapping pointer is going + * to be cleared in free_hpage_workfn() anyway, it is reused as the llist_node + * structure of a lockless linked list of huge pages to be freed. + */ +static LLIST_HEAD(hpage_freelist); + +static void free_hpage_workfn(struct work_struct *work) +{ + struct llist_node *node; + + node = llist_del_all(&hpage_freelist); + + while (node) { + struct page *page; + struct hstate *h; + + page = container_of((struct address_space **)node, + struct page, mapping); + node = node->next; + page->mapping = NULL; + /* + * The VM_BUG_ON_PAGE(!PageHuge(page), page) in page_hstate() + * is going to trigger because a previous call to + * remove_hugetlb_page() will set_compound_page_dtor(page, + * NULL_COMPOUND_DTOR), so do not use page_hstate() directly. + */ + h = size_to_hstate(page_size(page)); + + __update_and_free_page(h, page); + + cond_resched(); + } +} +static DECLARE_WORK(free_hpage_work, free_hpage_workfn); + +static inline void flush_free_hpage_work(struct hstate *h) +{ + if (free_vmemmap_pages_per_hpage(h)) + flush_work(&free_hpage_work); +} + +static void update_and_free_page(struct hstate *h, struct page *page, + bool atomic) +{ + if (!free_vmemmap_pages_per_hpage(h) || !atomic) { + __update_and_free_page(h, page); + return; + } + + /* + * Defer freeing to avoid using GFP_ATOMIC to allocate vmemmap pages. + * + * Only call schedule_work() if hpage_freelist is previously + * empty. Otherwise, schedule_work() had been called but the workfn + * hasn't retrieved the list yet. + */ + if (llist_add((struct llist_node *)&page->mapping, &hpage_freelist)) + schedule_work(&free_hpage_work); +} + static void update_and_free_pages_bulk(struct hstate *h, struct list_head *list) { struct page *page, *t_page; list_for_each_entry_safe(page, t_page, list, lru) { - update_and_free_page(h, page); + update_and_free_page(h, page, false); cond_resched(); } } @@ -1471,12 +1538,12 @@ void free_huge_page(struct page *page) if (HPageTemporary(page)) { remove_hugetlb_page(h, page, false); spin_unlock_irqrestore(&hugetlb_lock, flags); - update_and_free_page(h, page); + update_and_free_page(h, page, true); } else if (h->surplus_huge_pages_node[nid]) { /* remove the page from active list */ remove_hugetlb_page(h, page, true); spin_unlock_irqrestore(&hugetlb_lock, flags); - update_and_free_page(h, page); + update_and_free_page(h, page, true); } else { arch_clear_hugepage_flags(page); enqueue_huge_page(h, page); @@ -1798,7 +1865,7 @@ int dissolve_free_huge_page(struct page *page) remove_hugetlb_page(h, page, false); h->max_huge_pages--; spin_unlock_irq(&hugetlb_lock); - update_and_free_page(h, head); + update_and_free_page(h, head, false); return 0; } out: @@ -2347,7 +2414,7 @@ static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page, * Pages have been replaced, we can safely free the old one. */ spin_unlock_irq(&hugetlb_lock); - update_and_free_page(h, old_page); + update_and_free_page(h, old_page, false); } return ret; @@ -2768,6 +2835,7 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid, * pages in hstate via the proc/sysfs interfaces. */ mutex_lock(&h->resize_lock); + flush_free_hpage_work(h); spin_lock_irq(&hugetlb_lock); /* @@ -2877,6 +2945,7 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid, /* free the pages after dropping lock */ spin_unlock_irq(&hugetlb_lock); update_and_free_pages_bulk(h, &page_list); + flush_free_hpage_work(h); spin_lock_irq(&hugetlb_lock); while (count < persistent_huge_pages(h)) { diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index e45a138a7f85..cb28c5b6c9ff 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -180,18 +180,6 @@ #define RESERVE_VMEMMAP_NR 2U #define RESERVE_VMEMMAP_SIZE (RESERVE_VMEMMAP_NR << PAGE_SHIFT) -/* - * How many vmemmap pages associated with a HugeTLB page that can be freed - * to the buddy allocator. - * - * Todo: Returns zero for now, which means the feature is disabled. We will - * enable it once all the infrastructure is there. - */ -static inline unsigned int free_vmemmap_pages_per_hpage(struct hstate *h) -{ - return 0; -} - static inline unsigned long free_vmemmap_pages_size_per_hpage(struct hstate *h) { return (unsigned long)free_vmemmap_pages_per_hpage(h) << PAGE_SHIFT; diff --git a/mm/hugetlb_vmemmap.h b/mm/hugetlb_vmemmap.h index 6923f03534d5..01f8637adbe0 100644 --- a/mm/hugetlb_vmemmap.h +++ b/mm/hugetlb_vmemmap.h @@ -12,9 +12,26 @@ #ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP void free_huge_page_vmemmap(struct hstate *h, struct page *head); + +/* + * How many vmemmap pages associated with a HugeTLB page that can be freed + * to the buddy allocator. + * + * Todo: Returns zero for now, which means the feature is disabled. We will + * enable it once all the infrastructure is there. + */ +static inline unsigned int free_vmemmap_pages_per_hpage(struct hstate *h) +{ + return 0; +} #else static inline void free_huge_page_vmemmap(struct hstate *h, struct page *head) { } + +static inline unsigned int free_vmemmap_pages_per_hpage(struct hstate *h) +{ + return 0; +} #endif /* CONFIG_HUGETLB_PAGE_FREE_VMEMMAP */ #endif /* _LINUX_HUGETLB_VMEMMAP_H */ -- 2.11.0