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=-7.5 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 E18B8C433E9 for ; Wed, 17 Mar 2021 09:49:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B798E64F51 for ; Wed, 17 Mar 2021 09:49:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229905AbhCQJs4 (ORCPT ); Wed, 17 Mar 2021 05:48:56 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:20454 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229903AbhCQJsj (ORCPT ); Wed, 17 Mar 2021 05:48:39 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1615974518; 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=Cy/a1Z/HUF5zY1QTMNBd7dixVMe1UxNpkW4BGe5sLnY=; b=bY9lTsaFf0lRBs1jV5dBUnbtFQQ7IlGph5UyzWywWy4A0unkV+UVkWA/cWSHTX48qLqqOf yQsf/uTHisiUV+fFSMPA24sHPK9WxN+OQ0sgXH+wks6coaSOonzw7aEouKjOns/Y7I1NwF bVeW1XjjTKo39GOzZWsAjpln9lc6y1k= 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-280-o_sZjHjVPY2itaVRMayfqg-1; Wed, 17 Mar 2021 05:48:37 -0400 X-MC-Unique: o_sZjHjVPY2itaVRMayfqg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 627FC1922023; Wed, 17 Mar 2021 09:48:35 +0000 (UTC) Received: from [10.36.112.124] (ovpn-112-124.ams2.redhat.com [10.36.112.124]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0F472690F6; Wed, 17 Mar 2021 09:48:32 +0000 (UTC) Subject: Re: [PATCH v4 0/4] Make alloc_contig_range handle Hugetlb pages To: Oscar Salvador Cc: Andrew Morton , Vlastimil Babka , Michal Hocko , Muchun Song , Mike Kravetz , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Anshuman Khandual References: <20210310150853.13541-1-osalvador@suse.de> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <01d2ee6a-f0aa-4580-b1f4-f0e8a2ded4f8@redhat.com> Date: Wed, 17 Mar 2021 10:48:31 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17.03.21 10:43, Oscar Salvador wrote: > On 2021-03-15 10:06, David Hildenbrand wrote: >> BTW, I stumbled yesterday over >> >> alloc_contig_pages()->pfn_range_valid_contig(): >> >> if (page_count(page) > 0) >> rerurn false; >> if (PageHuge(page)) >> return false; >> >> As used by memtrace and for gigantic pages. We can now >> >> a) Drop these check completely, as it's best-effort only and racy. >> alloc_contig_pages()/alloc_contig_range() will handle it properly. > > I was preparing v5, and I wanted to be sure I understood you here. > > Right you are that the in-use page check can be dropped, as those pages > can > be migrated away, and the Hugetlb page check can also be dropped since > isolate_migratepages_range is now capable of dealing with those kind of > pages. > >> b) Similarly, check for gigantic pages and/or movability/migratability. > > I lost you here. > > isolate_or_dissolve_huge_page() already bails out on hugetlb-gigantic > pages. > > Or do you mean to place an upfront check here? (hstate_is_gigantic())? Yes. But I prefer a) and keeping it simple here -- just doing basic sanity checks (online, zone, PageReserved()) that are absolutely necessary. -- Thanks, David / dhildenb