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=-12.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 A44A7C433E6 for ; Fri, 26 Feb 2021 11:08:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 57FE264EF3 for ; Fri, 26 Feb 2021 11:08:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230474AbhBZLIr (ORCPT ); Fri, 26 Feb 2021 06:08:47 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:46645 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230164AbhBZLIo (ORCPT ); Fri, 26 Feb 2021 06:08:44 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1614337636; 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=Tk06oGoT/WyXBHM/QvyAXYl1KqMGMDdyTbImAeS6eqY=; b=Dc+xcAwHsUkj45s/gmduUpxL4+a46XsHmNlT8UyQA6GmLjVKJpo8cBjuAnSvvYJABsrCRY CRhaNTMg+pD7KOi1gHWStK9Fn5J4Oz2ZnvP68ub9xNXV3imq9Y9KUMYgQSZel+NTXwbWz9 f8wNgae5PY3lYtdcRbTLq5MLXdTHM/k= 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-175-bFck02I7PoyTOVy4T72SBw-1; Fri, 26 Feb 2021 06:07:12 -0500 X-MC-Unique: bFck02I7PoyTOVy4T72SBw-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8A38018BA28A; Fri, 26 Feb 2021 11:07:05 +0000 (UTC) Received: from [10.36.112.148] (ovpn-112-148.ams2.redhat.com [10.36.112.148]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1D60C7093A; Fri, 26 Feb 2021 11:07:00 +0000 (UTC) Subject: Re: [PATCH v8 1/1] mm/page_alloc.c: refactor initialization of struct page for holes in memory layout To: Mike Rapoport , Andrew Morton Cc: Andrea Arcangeli , Baoquan He , Borislav Petkov , Chris Wilson , "H. Peter Anvin" , Ingo Molnar , Linus Torvalds , =?UTF-8?Q?=c5=81ukasz_Majczak?= , Mel Gorman , Michal Hocko , Mike Rapoport , Qian Cai , "Sarvela, Tomi P" , Thomas Gleixner , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org, x86@kernel.org References: <20210225224351.7356-1-rppt@kernel.org> <20210225224351.7356-2-rppt@kernel.org> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: Date: Fri, 26 Feb 2021 12:07:00 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: <20210225224351.7356-2-rppt@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 25.02.21 23:43, Mike Rapoport wrote: > From: Mike Rapoport > > There could be struct pages that are not backed by actual physical memory. > This can happen when the actual memory bank is not a multiple of > SECTION_SIZE or when an architecture does not register memory holes > reserved by the firmware as memblock.memory. > > Such pages are currently initialized using init_unavailable_mem() function > that iterates through PFNs in holes in memblock.memory and if there is a > struct page corresponding to a PFN, the fields of this page are set to > default values and it is marked as Reserved. > > init_unavailable_mem() does not take into account zone and node the page > belongs to and sets both zone and node links in struct page to zero. > > Before commit 73a6e474cb37 ("mm: memmap_init: iterate over memblock regions > rather that check each PFN") the holes inside a zone were re-initialized > during memmap_init() and got their zone/node links right. However, after > that commit nothing updates the struct pages representing such holes. > > On a system that has firmware reserved holes in a zone above ZONE_DMA, for > instance in a configuration below: > > # grep -A1 E820 /proc/iomem > 7a17b000-7a216fff : Unknown E820 type > 7a217000-7bffffff : System RAM > > unset zone link in struct page will trigger > > VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page); > > in set_pfnblock_flags_mask() when called with a struct page from a range > other than E820_TYPE_RAM because there are pages in the range of ZONE_DMA32 > but the unset zone link in struct page makes them appear as a part of > ZONE_DMA. > > Interleave initialization of the unavailable pages with the normal > initialization of memory map, so that zone and node information will be > properly set on struct pages that are not backed by the actual memory. > > With this change the pages for holes inside a zone will get proper > zone/node links and the pages that are not spanned by any node will get > links to the adjacent zone/node. The holes between nodes will be prepended > to the zone/node above the hole and the trailing pages in the last section > that will be appended to the zone/node below. > > Fixes: 73a6e474cb37 ("mm: memmap_init: iterate over memblock regions rather that check each PFN") > Signed-off-by: Mike Rapoport > Reported-by: Qian Cai > Reported-by: Andrea Arcangeli > Reviewed-by: Baoquan He > Acked-by: Vlastimil Babka > --- Reviewed-by: David Hildenbrand Thanks Mike! -- Thanks, David / dhildenb