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,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 2E9F4C56202 for ; Wed, 25 Nov 2020 18:47:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B489E20679 for ; Wed, 25 Nov 2020 18:47:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="LMgh6+Kx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732127AbgKYSrb (ORCPT ); Wed, 25 Nov 2020 13:47:31 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:45393 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730520AbgKYSra (ORCPT ); Wed, 25 Nov 2020 13:47:30 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1606330049; 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: in-reply-to:in-reply-to:references:references; bh=k3kz6C4a6AtRNaq6oY0n9BienKaRknyUdLMKhNfj96A=; b=LMgh6+KxQdKRIw9OWXw57bLXQTGOB5pli+jXW+0ylj2cUYqNwFaCiblj4ZzHG5VEReMSLQ uExT9h6tGc+Rv8YdPVMEt8KC5iSaFuh2VLNPqXY1YQKYsIzwmzrdbGj38Akw6jcz9KGxyY yOON2xGrMiaLomHoEwH8L9mbsrtoELI= 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-191-K57xygSzMzm_0lK3RSXoQw-1; Wed, 25 Nov 2020 13:47:27 -0500 X-MC-Unique: K57xygSzMzm_0lK3RSXoQw-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 9EEFE1E7C7; Wed, 25 Nov 2020 18:47:25 +0000 (UTC) Received: from mail (ovpn-112-118.rdu2.redhat.com [10.10.112.118]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 417525D71B; Wed, 25 Nov 2020 18:47:22 +0000 (UTC) Date: Wed, 25 Nov 2020 13:47:21 -0500 From: Andrea Arcangeli To: David Hildenbrand Cc: Mel Gorman , Vlastimil Babka , Andrew Morton , linux-mm@kvack.org, Qian Cai , Michal Hocko , linux-kernel@vger.kernel.org, Mike Rapoport , Baoquan He Subject: Re: [PATCH 1/1] mm: compaction: avoid fast_isolate_around() to set pageblock_skip on reserved pages Message-ID: References: <35F8AADA-6CAA-4BD6-A4CF-6F29B3F402A4@redhat.com> <20201125103933.GM3306@suse.de> <5f01bde6-fe31-9b0e-f288-06b82598a8b3@redhat.com> <33612969-92a1-6c49-a2e0-3a95715b1e7f@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <33612969-92a1-6c49-a2e0-3a95715b1e7f@redhat.com> User-Agent: Mutt/2.0.2 (2020-11-20) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 25, 2020 at 12:41:55PM +0100, David Hildenbrand wrote: > On 25.11.20 12:04, David Hildenbrand wrote: > > On 25.11.20 11:39, Mel Gorman wrote: > >> On Wed, Nov 25, 2020 at 07:45:30AM +0100, David Hildenbrand wrote: > >>>> Something must have changed more recently than v5.1 that caused the > >>>> zoneid of reserved pages to be wrong, a possible candidate for the > >>>> real would be this change below: > >>>> > >>>> + __init_single_page(pfn_to_page(pfn), pfn, 0, 0); > >>>> > >>> > >>> Before that change, the memmap of memory holes were only zeroed out. So the zones/nid was 0, however, pages were not reserved and had a refcount of zero - resulting in other issues. > >>> > >>> Most pfn walkers shouldn???t mess with reserved pages and simply skip them. That would be the right fix here. > >>> > >> > >> Ordinarily yes, pfn walkers should not care about reserved pages but it's > >> still surprising that the node/zone linkages would be wrong for memory > >> holes. If they are in the middle of a zone, it means that a hole with > >> valid struct pages could be mistaken for overlapping nodes (if the hole > >> was in node 1 for example) or overlapping zones which is just broken. > > > > I agree within zones - but AFAIU, the issue is reserved memory between > > zones, right? > > Double checking, I was confused. This applies also to memory holes > within zones in x86. Yes this is a memory hole within the DMA32 zone. Still why there should be any difference? As long as a page struct exists it's in a well defined mem_map array which comes for one and only one zoneid/nid combination. So what would be the benefit of treating memory holes within zones or in between zones differently and leave one or the other with a zoneid/nid uninitialized?