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=-7.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,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 DDC73C64E69 for ; Fri, 20 Nov 2020 09:16:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7A4C522264 for ; Fri, 20 Nov 2020 09:16:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="T5w64cDb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727417AbgKTJPt (ORCPT ); Fri, 20 Nov 2020 04:15:49 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:30424 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727354AbgKTJPr (ORCPT ); Fri, 20 Nov 2020 04:15:47 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1605863745; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=PwuP1reil3EHDjEAdkxJz3A0u+9v93EU1GsEwtmmEUI=; b=T5w64cDbF+WpAqGA5nDqOz7UhopVcHj5VhxD5C9kx0KcYVTkvz4ztwSC4YOTKRgTRnsIOE 4jT2Lc7O4F2mOmSIXZzkkJeKF/CDGU2ClxV+zFuwIb95XV/wJrN2cO2m6v52Bw52M4Etfc oRGoAbip6lzXoMKMu7cg7LZCZZcFe1c= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-567-XqBTzF7ZPumVNm0YPi5lsg-1; Fri, 20 Nov 2020 04:15:41 -0500 X-MC-Unique: XqBTzF7ZPumVNm0YPi5lsg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 69A038797DA; Fri, 20 Nov 2020 09:15:37 +0000 (UTC) Received: from [10.36.114.78] (ovpn-114-78.ams2.redhat.com [10.36.114.78]) by smtp.corp.redhat.com (Postfix) with ESMTP id 589225D6AD; Fri, 20 Nov 2020 09:15:31 +0000 (UTC) Subject: Re: [PATCH v5 21/21] mm/hugetlb: Disable freeing vmemmap if struct page size is not power of two To: Michal Hocko , Muchun Song Cc: 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, osalvador@suse.de, song.bao.hua@hisilicon.com, duanxiongchun@bytedance.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org References: <20201120064325.34492-1-songmuchun@bytedance.com> <20201120064325.34492-22-songmuchun@bytedance.com> <20201120082552.GI3200@dhcp22.suse.cz> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <9b26c749-3bb6-4b16-d1fc-da7ec5d1e8a5@redhat.com> Date: Fri, 20 Nov 2020 10:15:30 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20201120082552.GI3200@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 20.11.20 09:25, Michal Hocko wrote: > On Fri 20-11-20 14:43:25, Muchun Song wrote: >> We only can free the unused vmemmap to the buddy system when the >> size of struct page is a power of two. > > Can we actually have !power_of_2 struct pages? AFAIK multiples of 8 bytes (56, 64, 72) are possible. -- Thanks, David / dhildenb