From patchwork Mon Oct 26 14:51:03 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Muchun Song X-Patchwork-Id: 11857469 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9897892C for ; Mon, 26 Oct 2020 14:54:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6A40A20773 for ; Mon, 26 Oct 2020 14:54:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=bytedance-com.20150623.gappssmtp.com header.i=@bytedance-com.20150623.gappssmtp.com header.b="1XUbgX6F" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1782293AbgJZOy2 (ORCPT ); Mon, 26 Oct 2020 10:54:28 -0400 Received: from mail-pf1-f195.google.com ([209.85.210.195]:39502 "EHLO mail-pf1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1782288AbgJZOy2 (ORCPT ); Mon, 26 Oct 2020 10:54:28 -0400 Received: by mail-pf1-f195.google.com with SMTP id e15so6324926pfh.6 for ; Mon, 26 Oct 2020 07:54:27 -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=EcJtKWN8O9Qodyyp13/1PkKx/cUbDB95Z/x259AJSBY=; b=1XUbgX6FaLFoZU9pI23pS8o0DXUp9yNPArHW3McFT9vzwsmyVy3VL5DSA5BQr5PXZC SH1tkTSrwA18hKOIXTamspmxj/sSHIqZaB9weP8mImesc0/JLZCcDkRBHVWZM2q6qUI6 XvEf1fqxB4298oGy3OeVf6URDdEDexEwtqrvW9ejyUmmQlH9lc9g0wGELvcmZES97qLz NRXfV9xH3UWl9feO5kuPAplRtr+0yGBeLnCIMA6Y19dbhm+DqD1+gq3Ej8hLwSXOy0lv SVuFYrmUP9+AOig7GImjG/LUzRccGtxnuzPpdIdopxj8MGUXCQC1eC6gIlM+Nrl88uc1 u5xQ== 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=EcJtKWN8O9Qodyyp13/1PkKx/cUbDB95Z/x259AJSBY=; b=q1kKbuXcpXl6rmeO8oUndY1K7/kBEL6fRJNVO+NxbtRQXOLsr0FyUDvgGRUWwpzfs+ RA50cK0e1fwVRisLsB06yUJ2Mxf7eNUznqbZ/IIPD+KMZR4DNtZSi+y3aErE92rhk2wH tQRY689rKVJzFJnLUIDj0DgdxdHIZCe2Gq9Igss/yt8t0JCXEji/X5JneW22+BMHyY9O sX2KeLVtMEaro/zX1lO5gOjeIGsMBnQdrssO8PBMENKW+rXwSaSuUQ+I4PXSsmMb7qw7 V5TbjUrBfwboRBLAjecoF7/q/a5Ff7P6Eb69W3031BX+9zstcmfGjtmL009xRslTX2aH OJ1w== X-Gm-Message-State: AOAM531UcsalrhddJD9e0U/MS4tNHtR6S4WAQ1Tpv/RPlkOIRQvoV+rP /pMchq3XfEmV+6ImqwoiuNKNJw== X-Google-Smtp-Source: ABdhPJx37UPgiI/VapjlHMmbDWY5Gek8UN494n0cx2H6I0fWbAXFRnr7QVt+RJebYAaHfgT+SjyS5A== X-Received: by 2002:a63:2406:: with SMTP id k6mr13751141pgk.366.1603724067420; Mon, 26 Oct 2020 07:54:27 -0700 (PDT) Received: from localhost.localdomain ([103.136.220.89]) by smtp.gmail.com with ESMTPSA id x123sm12042726pfb.212.2020.10.26.07.54.18 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 26 Oct 2020 07:54:26 -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, 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 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 v2 08/19] mm/hugetlb: Defer freeing of hugetlb pages Date: Mon, 26 Oct 2020 22:51:03 +0800 Message-Id: <20201026145114.59424-9-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20201026145114.59424-1-songmuchun@bytedance.com> References: <20201026145114.59424-1-songmuchun@bytedance.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org In the subsequent patch, we will allocate the vmemmap pages when free huge pages. But update_and_free_page() is be called from a non-task context(and hold hugetlb_lock), we can defer the actual freeing in a workqueue to prevent use GFP_ATOMIC to allocate the vmemmap pages. Signed-off-by: Muchun Song --- mm/hugetlb.c | 94 +++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 85 insertions(+), 9 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index aa012d603e06..a5500c79e2df 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1292,6 +1292,8 @@ static inline void destroy_compound_gigantic_page(struct page *page, unsigned int order) { } #endif +static void __free_hugepage(struct hstate *h, struct page *page); + #ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP #include @@ -1601,6 +1603,64 @@ static void free_huge_page_vmemmap(struct hstate *h, struct page *head) free_vmemmap_page_list(&free_pages); } + +/* + * As update_and_free_page() is be called from a non-task context(and hold + * hugetlb_lock), we can defer the actual freeing in a workqueue to prevent + * use GFP_ATOMIC to allocate a lot of vmemmap pages. + * + * update_hpage_vmemmap_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 update_hpage_vmemmap_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_update_freelist); + +static void update_hpage_vmemmap_workfn(struct work_struct *work) +{ + struct llist_node *node; + struct page *page; + + node = llist_del_all(&hpage_update_freelist); + + while (node) { + page = container_of((struct address_space **)node, + struct page, mapping); + node = node->next; + page->mapping = NULL; + __free_hugepage(page_hstate(page), page); + + cond_resched(); + } +} +static DECLARE_WORK(hpage_update_work, update_hpage_vmemmap_workfn); + +static inline void __update_and_free_page(struct hstate *h, struct page *page) +{ + /* No need to allocate vmemmap pages */ + if (!nr_free_vmemmap(h)) { + __free_hugepage(h, page); + return; + } + + /* + * Defer freeing to avoid using GFP_ATOMIC to allocate vmemmap + * pages. + * + * Only call schedule_work() if hpage_update_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_update_freelist)) + schedule_work(&hpage_update_work); +} + +static inline void free_gigantic_page_comm(struct hstate *h, struct page *page) +{ + free_gigantic_page(page, huge_page_order(h)); +} #else static inline void hugetlb_vmemmap_init(struct hstate *h) { @@ -1618,17 +1678,39 @@ static inline void vmemmap_pgtable_free(struct hstate *h, struct page *page) static inline void free_huge_page_vmemmap(struct hstate *h, struct page *head) { } + +static inline void __update_and_free_page(struct hstate *h, struct page *page) +{ + __free_hugepage(h, page); +} + +static inline void free_gigantic_page_comm(struct hstate *h, struct page *page) +{ + /* + * Temporarily drop the hugetlb_lock, because + * we might block in free_gigantic_page(). + */ + spin_unlock(&hugetlb_lock); + free_gigantic_page(page, huge_page_order(h)); + spin_lock(&hugetlb_lock); +} #endif static void update_and_free_page(struct hstate *h, struct page *page) { - int i; - if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported()) return; h->nr_huge_pages--; h->nr_huge_pages_node[page_to_nid(page)]--; + + __update_and_free_page(h, page); +} + +static void __free_hugepage(struct hstate *h, struct page *page) +{ + int i; + for (i = 0; i < pages_per_huge_page(h); i++) { page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced | 1 << PG_dirty | @@ -1640,14 +1722,8 @@ static void update_and_free_page(struct hstate *h, struct page *page) set_compound_page_dtor(page, NULL_COMPOUND_DTOR); set_page_refcounted(page); if (hstate_is_gigantic(h)) { - /* - * Temporarily drop the hugetlb_lock, because - * we might block in free_gigantic_page(). - */ - spin_unlock(&hugetlb_lock); destroy_compound_gigantic_page(page, huge_page_order(h)); - free_gigantic_page(page, huge_page_order(h)); - spin_lock(&hugetlb_lock); + free_gigantic_page_comm(h, page); } else { __free_pages(page, huge_page_order(h)); }