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=-17.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,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 C64CCC433E0 for ; Fri, 12 Feb 2021 09:58:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8A40064E6C for ; Fri, 12 Feb 2021 09:58:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230268AbhBLJ6J (ORCPT ); Fri, 12 Feb 2021 04:58:09 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:46212 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229497AbhBLJ54 (ORCPT ); Fri, 12 Feb 2021 04:57:56 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1613123789; 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=7yGM74b6IVdGi3cBHRm26f8aU2+QxRSs1cbPQ3iAFeo=; b=NWeLFY7I6t3Cdi4jlo5diadft8G/HlChuSidaEb1FJLNkxm/AMPWiQIrxZGf4y4aHnc0Jt bs6M1B1rT2E5xi/tg96SghhtkOjYvMyXYBwbOe5LceX+Foa6sNettWxCnI3uaA9JyXDtky sUo++HMHu/6TnXy8Grdke3hcl+VZpwQ= 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-501-wpJ0hdjQNhmAQoQiGbTfcw-1; Fri, 12 Feb 2021 04:56:27 -0500 X-MC-Unique: wpJ0hdjQNhmAQoQiGbTfcw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B83CB192AB78; Fri, 12 Feb 2021 09:56:24 +0000 (UTC) Received: from [10.36.114.178] (ovpn-114-178.ams2.redhat.com [10.36.114.178]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6B09660BF1; Fri, 12 Feb 2021 09:56:20 +0000 (UTC) Subject: Re: [PATCH v5 1/1] mm: refactor initialization of struct page for holes in memory layout From: David Hildenbrand 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: <20210208110820.6269-1-rppt@kernel.org> <5dccbc93-f260-7f14-23bc-6dee2dff6c13@redhat.com> Organization: Red Hat GmbH Message-ID: Date: Fri, 12 Feb 2021 10:56:19 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: <5dccbc93-f260-7f14-23bc-6dee2dff6c13@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12.02.21 10:55, David Hildenbrand wrote: > On 08.02.21 12:08, 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. >> >> 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); >> >> because there are pages in both ZONE_DMA32 and ZONE_DMA (unset zone link >> in struct page) in the same pageblock. >> >> Moreover, it is possible that the lowest node and zone start is not aligned >> to the section boundarie, for example on x86: >> >> [ 0.078898] Zone ranges: >> [ 0.078899] DMA [mem 0x0000000000001000-0x0000000000ffffff] >> ... >> [ 0.078910] Early memory node ranges >> [ 0.078912] node 0: [mem 0x0000000000001000-0x000000000009cfff] >> [ 0.078913] node 0: [mem 0x0000000000100000-0x000000003fffffff] >> >> and thus with SPARSEMEM memory model the beginning of the memory map will >> have struct pages that are not spanned by any node and zone. >> >> Update detection of node boundaries in get_pfn_range_for_nid() so that the >> node range will be expanded to cover memory map section. Since zone spans >> are derived from the node span, there always will be a zone that covers the >> part of the memory map with unavailable pages. >> >> 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. >> >> Fixes: 73a6e474cb37 ("mm: memmap_init: iterate over memblock regions rather >> that check each PFN") >> Reported-by: Andrea Arcangeli >> Signed-off-by: Mike Rapoport >> Cc: Baoquan He >> Cc: David Hildenbrand >> Cc: Mel Gorman >> Cc: Michal Hocko >> Cc: Qian Cai >> Cc: Vlastimil Babka >> --- >> mm/page_alloc.c | 160 +++++++++++++++++++++++------------------------- >> 1 file changed, 75 insertions(+), 85 deletions(-) >> >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index 6446778cbc6b..1c3f7521028f 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -6257,22 +6257,84 @@ static void __meminit zone_init_free_lists(struct zone *zone) >> } >> } >> >> +#if !defined(CONFIG_FLAT_NODE_MEM_MAP) >> +/* >> + * Only struct pages that correspond to ranges defined by memblock.memory >> + * are zeroed and initialized by going through __init_single_page() during >> + * memmap_init_zone(). >> + * >> + * But, there could be struct pages that correspond to holes in >> + * memblock.memory. This can happen because of the following reasons: >> + * - phyiscal memory bank size is not necessarily the exact multiple of the >> + * arbitrary section size >> + * - early reserved memory may not be listed in memblock.memory >> + * - memory layouts defined with memmap= kernel parameter may not align >> + * nicely with memmap sections >> + * >> + * Explicitly initialize those struct pages so that: >> + * - PG_Reserved is set >> + * - zone and node links point to zone and node that span the page >> + */ >> +static u64 __meminit init_unavailable_range(unsigned long spfn, >> + unsigned long epfn, >> + int zone, int node) >> +{ >> + unsigned long pfn; >> + u64 pgcnt = 0; >> + >> + for (pfn = spfn; pfn < epfn; pfn++) { >> + if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages))) { >> + pfn = ALIGN_DOWN(pfn, pageblock_nr_pages) >> + + pageblock_nr_pages - 1; >> + continue; >> + } >> + __init_single_page(pfn_to_page(pfn), pfn, zone, node); >> + __SetPageReserved(pfn_to_page(pfn)); >> + pgcnt++; >> + } >> + >> + return pgcnt; >> +} >> +#else >> +static inline u64 init_unavailable_range(unsigned long spfn, unsigned long epfn, >> + int zone, int node) >> +{ >> + return 0; >> +} >> +#endif >> + >> void __meminit __weak memmap_init_zone(struct zone *zone) >> { >> unsigned long zone_start_pfn = zone->zone_start_pfn; >> unsigned long zone_end_pfn = zone_start_pfn + zone->spanned_pages; >> int i, nid = zone_to_nid(zone), zone_id = zone_idx(zone); >> unsigned long start_pfn, end_pfn; >> + unsigned long hole_pfn = 0; >> + u64 pgcnt = 0; >> >> for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) { >> start_pfn = clamp(start_pfn, zone_start_pfn, zone_end_pfn); >> end_pfn = clamp(end_pfn, zone_start_pfn, zone_end_pfn); >> + hole_pfn = clamp(hole_pfn, zone_start_pfn, zone_end_pfn); >> >> if (end_pfn > start_pfn) >> memmap_init_range(end_pfn - start_pfn, nid, >> zone_id, start_pfn, zone_end_pfn, >> MEMINIT_EARLY, NULL, MIGRATE_MOVABLE); >> + >> + if (hole_pfn < start_pfn) >> + pgcnt += init_unavailable_range(hole_pfn, start_pfn, >> + zone_id, nid); >> + hole_pfn = end_pfn; >> } >> + >> + if (hole_pfn < zone_end_pfn) >> + pgcnt += init_unavailable_range(hole_pfn, zone_end_pfn, >> + zone_id, nid); >> + >> + if (pgcnt) >> + pr_info(" %s zone: %lld pages in unavailable ranges\n", >> + zone->name, pgcnt); >> } >> >> static int zone_batchsize(struct zone *zone) >> @@ -6519,8 +6581,19 @@ void __init get_pfn_range_for_nid(unsigned int nid, >> *end_pfn = max(*end_pfn, this_end_pfn); >> } >> >> - if (*start_pfn == -1UL) >> + if (*start_pfn == -1UL) { >> *start_pfn = 0; >> + return; >> + } >> + >> +#ifdef CONFIG_SPARSEMEM >> + /* >> + * Sections in the memory map may not match actual populated >> + * memory, extend the node span to cover the entire section. >> + */ >> + *start_pfn = round_down(*start_pfn, PAGES_PER_SECTION); >> + *end_pfn = round_up(*end_pfn, PAGES_PER_SECTION); > > Does that mean that we might create overlapping zones when one node s/overlapping zones/overlapping nodes/ > starts in the middle of a section and the other one ends in the middle > of a section? > > Could it be a problem? (e.g., would we have to look at neighboring nodes > when making the decision to extend, and how far to extend?) > -- Thanks, David / dhildenb