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 DDDA0C433B4 for ; Tue, 6 Apr 2021 16:34:02 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 878BC613C0 for ; Tue, 6 Apr 2021 16:34:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 878BC613C0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 1DC116B007D; Tue, 6 Apr 2021 12:34:02 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 18D286B0080; Tue, 6 Apr 2021 12:34:02 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 053846B0081; Tue, 6 Apr 2021 12:34:01 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0153.hostedemail.com [216.40.44.153]) by kanga.kvack.org (Postfix) with ESMTP id DC6836B007D for ; Tue, 6 Apr 2021 12:34:01 -0400 (EDT) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 946DA8249980 for ; Tue, 6 Apr 2021 16:34:01 +0000 (UTC) X-FDA: 78002489082.08.458A974 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf18.hostedemail.com (Postfix) with ESMTP id F02382000250 for ; Tue, 6 Apr 2021 16:34:00 +0000 (UTC) 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 X-Rspamd-Queue-Id: F02382000250 X-Stat-Signature: qx3xms7u4tx1wjdz3n1buwqt8fzemmoi X-Rspamd-Server: rspam02 Received-SPF: none (suse.de>: No applicable sender policy available) receiver=imf18; identity=mailfrom; envelope-from=""; helo=mx2.suse.de; client-ip=195.135.220.15 X-HE-DKIM-Result: none/none X-HE-Tag: 1617726840-643946 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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