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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 3955DC43461 for ; Tue, 15 Sep 2020 22:44:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 02DA920795 for ; Tue, 15 Sep 2020 22:44:16 +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="NvD9FH7j" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727327AbgIOPzF (ORCPT ); Tue, 15 Sep 2020 11:55:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47294 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727449AbgIOPxp (ORCPT ); Tue, 15 Sep 2020 11:53:45 -0400 Received: from mail-pf1-x442.google.com (mail-pf1-x442.google.com [IPv6:2607:f8b0:4864:20::442]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 12CFDC06178A for ; Tue, 15 Sep 2020 08:28:38 -0700 (PDT) Received: by mail-pf1-x442.google.com with SMTP id z19so2124450pfn.8 for ; Tue, 15 Sep 2020 08:28:38 -0700 (PDT) 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=3hFA+AYRcOFg15m1pODeTESDGf29GxzkowTbH/0FwhE=; b=NvD9FH7jzHdmmVqx2+B3GaZyyb7SzVJCGbxcurxADdLywqS4prFZe+m15IKNLz/lZb uufZgZRL5fc24zy97GUZiwuSjWy5SmkECf811W3pWN5ZmcZNLUppvpAj0LRvDeW5fg15 oxG0UXwRhqo/E0iSVuDLvwhhwAx6ZwjTAngSWBzPBAbBn+umSmm1DTYlDuAIMdMnoQTv 0Ffe/ORg2/b1UkMDmEKFU7XkXQUBqYfUZk1WNhhn6lDem+yq/j1f+uzz1zHXTBjRU+yO 2GqP9m9QdmD7dghZrVk93zAxLCXvJeT4QxQrEIhB4kRwR81ZyPu3Ikwm8LeaqyvlVhxo MssA== 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=3hFA+AYRcOFg15m1pODeTESDGf29GxzkowTbH/0FwhE=; b=iVaeUMq7Ks1VHSW9F+JwV4m+/a7bVy+0XjTrYRkMET+PMUle61n4FSrcB0mKxaRLVx RIO6yAjKHBPtXDgRH8BFPR6zKSyEb9AhwXTxm1QK6xPfv0MUveDENbxPjT8VyLnn3DYz DGN6EDv+2hAbTo+c+NRKlfClSCtX9JBoNYAQBB0heJZ7bKAZ86Kh2wNq15DgkiuEiUUb lQMPsj4G/QuUh+ZcavRmq6gi/6kN8lVjPvijnQDDVBSXnHJQAHfdNkND9oZ0F/3ggGwF 41YqGXmvk+aaI7ftQZqu4rxcdxw0xMXF5wPPhbUqv6KWckcYX+8BGcFthAwryLikOztw s5AQ== X-Gm-Message-State: AOAM530SZ6zVM7c1L0Tgd6s26sQd/WYyLEhxJaj3mr0UwgorU5OuUkA7 awSC/Os6tRJ2j21BYFces7fJ14wNRCBmabsRB7dMfw== X-Google-Smtp-Source: ABdhPJxqFxl0ezhOPvlUoXv87DU4ARGU0sUArN1IhU04uIEVn+Sze3RMVgqCcwOmxVDT3336+MmXOQXZxq6T9WdXFms= X-Received: by 2002:aa7:8287:0:b029:142:2501:39ec with SMTP id s7-20020aa782870000b0290142250139ecmr2349117pfm.59.1600183717500; Tue, 15 Sep 2020 08:28:37 -0700 (PDT) MIME-Version: 1.0 References: <20200915125947.26204-1-songmuchun@bytedance.com> <20200915143241.GH5449@casper.infradead.org> In-Reply-To: <20200915143241.GH5449@casper.infradead.org> From: Muchun Song Date: Tue, 15 Sep 2020 23:28:01 +0800 Message-ID: Subject: Re: [External] Re: [RFC PATCH 00/24] mm/hugetlb: Free some vmemmap pages of hugetlb page To: Matthew Wilcox 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, almasrymina@google.com, David Rientjes , linux-doc@vger.kernel.org, LKML , Linux Memory Management List , linux-fsdevel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Sep 15, 2020 at 10:32 PM Matthew Wilcox wrote: > > On Tue, Sep 15, 2020 at 08:59:23PM +0800, Muchun Song wrote: > > This patch series will free some vmemmap pages(struct page structures) > > associated with each hugetlbpage when preallocated to save memory. > > It would be lovely to be able to do this. Unfortunately, it's completely > impossible right now. Consider, for example, get_user_pages() called > on the fifth page of a hugetlb page. Can you elaborate on the problem? Thanks so much. > > I've spent a lot of time thinking about this, and there's a lot of work > that needs to happen before we can do this, mostly in device drivers. > Do you want to help? It's a multi-year project. Welcome, we can work together. -- Yours, Muchun