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=-15.4 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 D5416C433E0 for ; Thu, 4 Feb 2021 11:45:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9497864E35 for ; Thu, 4 Feb 2021 11:45:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235889AbhBDLpL (ORCPT ); Thu, 4 Feb 2021 06:45:11 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:12075 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235586AbhBDLpE (ORCPT ); Thu, 4 Feb 2021 06:45:04 -0500 Received: from DGGEMS408-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4DWc9W6SRBzMV3b; Thu, 4 Feb 2021 19:42:39 +0800 (CST) Received: from [10.174.179.241] (10.174.179.241) by DGGEMS408-HUB.china.huawei.com (10.3.19.208) with Microsoft SMTP Server id 14.3.498.0; Thu, 4 Feb 2021 19:44:13 +0800 Subject: Re: [PATCH v14 2/8] mm: hugetlb: introduce a new config HUGETLB_PAGE_FREE_VMEMMAP To: Muchun Song CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , References: <20210204035043.36609-1-songmuchun@bytedance.com> <20210204035043.36609-3-songmuchun@bytedance.com> From: Miaohe Lin Message-ID: <7349db78-9eeb-86e2-b5de-9ebbcba85e1d@huawei.com> Date: Thu, 4 Feb 2021 19:44:12 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210204035043.36609-3-songmuchun@bytedance.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.179.241] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi: On 2021/2/4 11:50, Muchun Song wrote: > The option HUGETLB_PAGE_FREE_VMEMMAP allows for the freeing of > some vmemmap pages associated with pre-allocated HugeTLB pages. > For example, on X86_64 6 vmemmap pages of size 4KB each can be > saved for each 2MB HugeTLB page. 4094 vmemmap pages of size 4KB > each can be saved for each 1GB HugeTLB page. > > When a HugeTLB page is allocated or freed, the vmemmap array > representing the range associated with the page will need to be > remapped. When a page is allocated, vmemmap pages are freed > after remapping. When a page is freed, previously discarded > vmemmap pages must be allocated before remapping. > > The config option is introduced early so that supporting code > can be written to depend on the option. The initial version of > the code only provides support for x86-64. > > Like other code which frees vmemmap, this config option depends on > HAVE_BOOTMEM_INFO_NODE. The routine register_page_bootmem_info() is > used to register bootmem info. Therefore, make sure > register_page_bootmem_info is enabled if HUGETLB_PAGE_FREE_VMEMMAP > is defined. > > Signed-off-by: Muchun Song > Reviewed-by: Oscar Salvador > Acked-by: Mike Kravetz LGTM. Thanks. Reviewed-by: Miaohe Lin > --- > arch/x86/mm/init_64.c | 2 +- > fs/Kconfig | 6 ++++++ > 2 files changed, 7 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c > index 0a45f062826e..0435bee2e172 100644 > --- a/arch/x86/mm/init_64.c > +++ b/arch/x86/mm/init_64.c > @@ -1225,7 +1225,7 @@ static struct kcore_list kcore_vsyscall; > > static void __init register_page_bootmem_info(void) > { > -#ifdef CONFIG_NUMA > +#if defined(CONFIG_NUMA) || defined(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP) > int i; > > for_each_online_node(i) > diff --git a/fs/Kconfig b/fs/Kconfig > index 97e7b77c9309..de87f234f1e9 100644 > --- a/fs/Kconfig > +++ b/fs/Kconfig > @@ -237,6 +237,12 @@ config HUGETLBFS > config HUGETLB_PAGE > def_bool HUGETLBFS > > +config HUGETLB_PAGE_FREE_VMEMMAP > + def_bool HUGETLB_PAGE > + depends on X86_64 > + depends on SPARSEMEM_VMEMMAP > + depends on HAVE_BOOTMEM_INFO_NODE > + > config MEMFD_CREATE > def_bool TMPFS || HUGETLBFS > >