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=-5.3 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 B3A9EC433E0 for ; Tue, 26 Jan 2021 14:59:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 77361230FD for ; Tue, 26 Jan 2021 14:59:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390955AbhAZO71 (ORCPT ); Tue, 26 Jan 2021 09:59:27 -0500 Received: from mx2.suse.de ([195.135.220.15]:55792 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391635AbhAZO7J (ORCPT ); Tue, 26 Jan 2021 09:59:09 -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 5FA2DAB9F; Tue, 26 Jan 2021 14:58:27 +0000 (UTC) Date: Tue, 26 Jan 2021 15:58:19 +0100 From: Oscar Salvador To: David Hildenbrand Cc: Muchun Song , corbet@lwn.net, mike.kravetz@oracle.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, paulmck@kernel.org, mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com, rdunlap@infradead.org, oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de, almasrymina@google.com, rientjes@google.com, willy@infradead.org, mhocko@suse.com, song.bao.hua@hisilicon.com, naoya.horiguchi@nec.com, duanxiongchun@bytedance.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v13 05/12] mm: hugetlb: allocate the vmemmap pages associated with each HugeTLB page Message-ID: <20210126145819.GB16870@linux> References: <20210117151053.24600-1-songmuchun@bytedance.com> <20210117151053.24600-6-songmuchun@bytedance.com> <20210126092942.GA10602@linux> <6fe52a7e-ebd8-f5ce-1fcd-5ed6896d3797@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6fe52a7e-ebd8-f5ce-1fcd-5ed6896d3797@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Jan 26, 2021 at 10:36:21AM +0100, David Hildenbrand wrote: > I think either keep it completely simple (only free vmemmap of hugetlb > pages allocated early during boot - which is what's not sufficient for > some use cases) or implement the full thing properly (meaning, solve > most challenging issues to get the basics running). > > I don't want to have some easy parts of complex features merged (e.g., > breaking other stuff as you indicate below), and later finding out "it's > not that easy" again and being stuck with it forever. Well, we could try to do an optimistic allocation, without tricky loopings. If that fails, refuse to shrink the pool at that moment. The user could always try to shrink it later via /proc/sys/vm/nr_hugepages interface. But I am just thinking out loud.. > > Of course, this means that e.g: memory-hotplug (hot-remove) will not fully work > > when this in place, but well. > > Can you elaborate? Are we're talking about having hugepages in > ZONE_MOVABLE that are not migratable (and/or dissolvable) anymore? Than > a clear NACK from my side. Pretty much, yeah. -- Oscar Salvador SUSE L3