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=-8.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 7CC79C4332B for ; Tue, 26 Jan 2021 19:12:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4F30822CE3 for ; Tue, 26 Jan 2021 19:12:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729916AbhAZF4d (ORCPT ); Tue, 26 Jan 2021 00:56:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49426 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728012AbhAYMkc (ORCPT ); Mon, 25 Jan 2021 07:40:32 -0500 Received: from mail-pl1-x629.google.com (mail-pl1-x629.google.com [IPv6:2607:f8b0:4864:20::629]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7B8B1C06178A for ; Mon, 25 Jan 2021 04:31:09 -0800 (PST) Received: by mail-pl1-x629.google.com with SMTP id j21so2890847pls.7 for ; Mon, 25 Jan 2021 04:31:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=QW8QHydhaLv2kCU+6eTvr2welYmg+FLV/r+/koJuoLk=; b=xjDsgoFJfGSx+QNEJsDoPpI6efmJI7cXx1rArOBkvxtD5CI8yASxFFYDVnqLbfElBp aLK4FtgR+15ZVnswDysdST3r8KI85QituFeOZJYVdcr8YztK0VXzUEZS8kWbBK1bHUoP S305pTMQi8NXQ4QW/MLiaG+nkJK0HgJb0gd7hWR+K0hSfaOpDfCx4XKA/wSM6NKSJX6N 7BWmQaIN1x1BQ+m9UeMPWDTk+2eY7wqW6BGtJsdjC1Mpl6p4DL+hgAo3reOxHMiQK9Ij Guuma2LpY+FkUSohEtdd9l3WTiP6AWVR4A2xM/CNxhjGd6u94DEW8dTpSSE4V818Ey53 xtiw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=QW8QHydhaLv2kCU+6eTvr2welYmg+FLV/r+/koJuoLk=; b=I7k6uO8V8wD8cFZOqHJNjviq0BTq8KFq87MStdyn4g/n8R20ajERtXWFUWr+Kqai+b HEB5Flr6zFAlmM+/QPKkc0KG5ewd8iJUsmRPicuhetKBJjrxbswOG6xXWjipCJmGuQwC t/d5qZhtQK8QQbASohJ3yVppD0tZap3IS6dXikoAQRGpir0PcykJ5wQl8K/AYcMsgAY5 qwgDCOVZYSIwxRZrnMUR4ivIihiDFwXgpuNFdQ+Sw2kwGN3bHUWa2AUguH5b8S4CibhR F0EwGa9+2yymeYhmgYtWdU7/MsnEa90Hr/q5onExcvpAcz/BRV3Vz3hpt5L98tyU+8sw 6a5w== X-Gm-Message-State: AOAM5305yWEqQ/PS6SXxzFoEq2PHO+aikv0sOE+craxAViV7rWvej1Me o9Mxy3X25L9FBT4EnVwkwbFkH3s4RPUq0F1eOOg8ow== X-Google-Smtp-Source: ABdhPJyY+tByzJR/2m5cQEXW38XAGhEuuitjV3/Wk3nuW0Q0nL5BLsXF/owMsdW62WXyPcjcnj/9dBD1hUwTOTMdINg= X-Received: by 2002:a17:90a:3e81:: with SMTP id k1mr179973pjc.13.1611577869029; Mon, 25 Jan 2021 04:31:09 -0800 (PST) MIME-Version: 1.0 References: <20210117151053.24600-1-songmuchun@bytedance.com> <20210117151053.24600-10-songmuchun@bytedance.com> <7550ebba-fdb5-0dc9-a517-dda56bd105d9@redhat.com> In-Reply-To: <7550ebba-fdb5-0dc9-a517-dda56bd105d9@redhat.com> From: Muchun Song Date: Mon, 25 Jan 2021 20:30:32 +0800 Message-ID: Subject: Re: [External] Re: [PATCH v13 09/12] mm: hugetlb: add a kernel parameter hugetlb_free_vmemmap To: David Hildenbrand Cc: Jonathan Corbet , Mike Kravetz , Thomas Gleixner , mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, Peter Zijlstra , viro@zeniv.linux.org.uk, Andrew Morton , paulmck@kernel.org, mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com, Randy Dunlap , oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de, Mina Almasry , David Rientjes , Matthew Wilcox , Oscar Salvador , Michal Hocko , "Song Bao Hua (Barry Song)" , =?UTF-8?B?SE9SSUdVQ0hJIE5BT1lBKOWggOWPoyDnm7TkuZ8p?= , Xiongchun duan , linux-doc@vger.kernel.org, LKML , Linux Memory Management List , linux-fsdevel Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 25, 2021 at 7:43 PM David Hildenbrand wrote: > > On 17.01.21 16:10, Muchun Song wrote: > > Add a kernel parameter hugetlb_free_vmemmap to enable the feature of > > freeing unused vmemmap pages associated with each hugetlb page on boot. > > The description completely lacks a description of the changes performed > in arch/x86/mm/init_64.c. Will update. Thanks. > > [...] > > > --- a/arch/x86/mm/init_64.c > > +++ b/arch/x86/mm/init_64.c > > @@ -34,6 +34,7 @@ > > #include > > #include > > #include > > +#include > > > > #include > > #include > > @@ -1557,7 +1558,8 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node, > > { > > int err; > > > > - if (end - start < PAGES_PER_SECTION * sizeof(struct page)) > > + if (is_hugetlb_free_vmemmap_enabled() || > > + end - start < PAGES_PER_SECTION * sizeof(struct page)) > > This looks irresponsible. You ignore any altmap, even though current > altmap users (ZONE_DEVICE) will not actually result in applicable > vmemmaps that huge pages could ever use. > > Why do you ignore the altmap completely? This has to be properly > documented, but IMHO it's not even the right approach to mess with > altmap here. Thanks for reminding me of this. Sorry I also did not notice that. > > -- > Thanks, > > David / dhildenb >