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=-3.7 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 7621EC388F7 for ; Tue, 10 Nov 2020 14:01:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 26D6A2076E for ; Tue, 10 Nov 2020 14:01:38 +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="KUTCW6u4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730473AbgKJOBf (ORCPT ); Tue, 10 Nov 2020 09:01:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56158 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730070AbgKJOBe (ORCPT ); Tue, 10 Nov 2020 09:01:34 -0500 Received: from mail-pf1-x443.google.com (mail-pf1-x443.google.com [IPv6:2607:f8b0:4864:20::443]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C8102C0613D1 for ; Tue, 10 Nov 2020 06:01:32 -0800 (PST) Received: by mail-pf1-x443.google.com with SMTP id g7so11519965pfc.2 for ; Tue, 10 Nov 2020 06:01:32 -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=Jw4xoyFdbdHuyEb63lDnIpWG8CFdqBLB9T72UopL8mM=; b=KUTCW6u4yJgzk/3g97x8JENk0StNEPh+Ev3Tbja/6QsmlHWhyUmBLM15CC5JCckM4p Thg486qv7XBHc73yt3G8SOJLuxaMj6LfKEznKD1HQjgWMEFl5hCZoW6oWkgBmLbzyrlb lhdjGAdtXxYfRyYCA/MDASkkV7GE8Bfnw4rfeD0w3VZohQ5l/4krYQejJIVRnjP36ao3 VBzN2ZY+YVwG9fNU8Ij42g4dtLtGm8hBIzh5EX/VOKuBv/DALtVPZfBPlp/PnY47kjKE EIxmHdeZFvVaL+GgwfYOk1aagoY+DfWPfDzotkVBCAgTL/GtvpgvVvviGlSPQMO78L5w 2Wuw== 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=Jw4xoyFdbdHuyEb63lDnIpWG8CFdqBLB9T72UopL8mM=; b=jTlgUsuVpS4Xtaj5xge9DZ/i7T+RauuopWyTWj3oHxZYZZpnmJFWlziQ2wTHIRu5L+ qr87EpOyWsnMJCSQ/PB00Y6RvlEGvqoKs70+6xj8eyuzlhYRHnVNor3cA3wEFncD5TQ+ kZ4adBTVyMk0Lb8/lHMF1Qf5GR0/REgobfvXSRg4Mr4ktGZWsqAwqNVvb/CYoz8CgJpd 4w887kwUIrI0bOlUcaIDBSe0FQj47z8Ack5Le0wZqoz08WbVVEiZNhiTaHLAfnLItWz5 sJBwSEGN3+VkfIjTdUdBSulofUBw9FE03gcuMsd5dV+Co+DP7uIGtdmXfQk43O/trTZg ZG1A== X-Gm-Message-State: AOAM532/zB2fH96Ayua7Z7wedpfJ+qeCicEJZY+0MDP9KrshLgWNmRMP jXRXeInPS8tHPT6FvLQTs2vAVDZN94hObuA0xneeLQ== X-Google-Smtp-Source: ABdhPJwU5QwCR2xxeNCT+mxLPbRxLxEnLOBux7J6tk0BgWSB9XQhZ9lxcE9XknqXnntajm6hRB/D3w3Tu4YYTa6PF2o= X-Received: by 2002:a62:e116:0:b029:18b:d325:153f with SMTP id q22-20020a62e1160000b029018bd325153fmr13323150pfh.2.1605016892290; Tue, 10 Nov 2020 06:01:32 -0800 (PST) MIME-Version: 1.0 References: <20201108141113.65450-1-songmuchun@bytedance.com> <20201108141113.65450-10-songmuchun@bytedance.com> <20201109185138.GD17356@linux> <20201110094830.GA25373@linux> <20201110135210.GA29463@linux> In-Reply-To: <20201110135210.GA29463@linux> From: Muchun Song Date: Tue, 10 Nov 2020 22:00:55 +0800 Message-ID: Subject: Re: [External] Re: [PATCH v3 09/21] mm/hugetlb: Free the vmemmap pages associated with each hugetlb page To: Oscar Salvador 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 , Michal Hocko , 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-fsdevel@vger.kernel.org On Tue, Nov 10, 2020 at 9:52 PM Oscar Salvador wrote: > > On Tue, Nov 10, 2020 at 06:47:08PM +0800, Muchun Song wrote: > > > That only refers to gigantic pages, right? > > > > Yeah, now it only refers to gigantic pages. Originally, I also wanted to merge > > vmemmap PTE to PMD for normal 2MB HugeTLB pages. So I introduced > > those macros(e.g. freed_vmemmap_hpage). For 2MB HugeTLB pages, I > > haven't found an elegant solution. Hopefully, when you or someone have > > read all of the patch series, we can come up with an elegant solution to > > merge PTE. > > Well, it is quite a lot of "tricky" code, so it takes some time. > > > > > > > +static void free_huge_page_vmemmap(struct hstate *h, struct page *head) > > > > > > +{ > > > > > > + pmd_t *pmd; > > > > > > + spinlock_t *ptl; > > > > > > + LIST_HEAD(free_pages); > > > > > > + > > > > > > + if (!free_vmemmap_pages_per_hpage(h)) > > > > > > + return; > > > > > > + > > > > > > + pmd = vmemmap_to_pmd(head); > > > > > > + ptl = vmemmap_pmd_lock(pmd); > > I forgot about this one. > You might want to check whether vmemmap_to_pmd returns NULL or not. > If it does means that something went wrong anyways, but still we should handle > such case (and print a fat warning or something like that). Yeah, maybe add a BUG_ON or WARN_ON. Do you think which one would be more suitable? > > > -- > Oscar Salvador > SUSE L3 -- Yours, Muchun