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, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 8B5E4C43461 for ; Tue, 6 Apr 2021 16:34:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4B336613C0 for ; Tue, 6 Apr 2021 16:34:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238181AbhDFQeU (ORCPT ); Tue, 6 Apr 2021 12:34:20 -0400 Received: from mx2.suse.de ([195.135.220.15]:55950 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346415AbhDFQeI (ORCPT ); Tue, 6 Apr 2021 12:34:08 -0400 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 C7249B26B; Tue, 6 Apr 2021 16:33:59 +0000 (UTC) MIME-Version: 1.0 Date: Tue, 06 Apr 2021 18:33:59 +0200 From: Oscar Salvador To: David Hildenbrand Cc: Andrew Morton , Michal Hocko , Anshuman Khandual , Pavel Tatashin , Vlastimil Babka , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v6 2/8] mm,memory_hotplug: Relax fully spanned sections check In-Reply-To: References: <20210406111115.8953-1-osalvador@suse.de> <20210406111115.8953-3-osalvador@suse.de> User-Agent: Roundcube Webmail Message-ID: X-Sender: osalvador@suse.de Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021-04-06 17:32, David Hildenbrand wrote: > I'd only relax start_pfn. That way the function is pretty much > impossible to abuse for sub-section onlining/offlining. > > if (WARN_ON_ONCE(!nr_pages || > !IS_ALIGNED(start_pfn, pageblock_nr_pages)) > !IS_ALIGNED(start_pfn + nr_pages, PAGES_PER_SECTION))) But this is not going to work. When using memmap_on_memory, the nr of pages that online_pages() and offline_pages() get might be less than PAGES_PER_SECTION, so this check will always blow us up. -- Oscar Salvador SUSE L3