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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 7F9B5C388F7 for ; Tue, 10 Nov 2020 13:52:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3DB5E2076E for ; Tue, 10 Nov 2020 13:52:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730629AbgKJNwW (ORCPT ); Tue, 10 Nov 2020 08:52:22 -0500 Received: from mx2.suse.de ([195.135.220.15]:42498 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730059AbgKJNwW (ORCPT ); Tue, 10 Nov 2020 08:52:22 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 2A0BDABD6; Tue, 10 Nov 2020 13:52:20 +0000 (UTC) Date: Tue, 10 Nov 2020 14:52:15 +0100 From: Oscar Salvador To: Muchun Song 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 Subject: Re: [External] Re: [PATCH v3 09/21] mm/hugetlb: Free the vmemmap pages associated with each hugetlb page Message-ID: <20201110135210.GA29463@linux> References: <20201108141113.65450-1-songmuchun@bytedance.com> <20201108141113.65450-10-songmuchun@bytedance.com> <20201109185138.GD17356@linux> <20201110094830.GA25373@linux> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org 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). -- Oscar Salvador SUSE L3