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=-17.2 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,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 378ADC433E0 for ; Tue, 23 Feb 2021 01:18:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DD10A64E32 for ; Tue, 23 Feb 2021 01:18:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230516AbhBWBRj (ORCPT ); Mon, 22 Feb 2021 20:17:39 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:32069 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230422AbhBWBRf (ORCPT ); Mon, 22 Feb 2021 20:17:35 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1614042967; 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=Z06oP2BonMtvWqkjwE3/34hVf9FcpnpURlORAYi8j3g=; b=Y0FvxUpStx1Wmvy32yiHIWUfOZaN7BVAYEAGHHwEY3O2qeP6Ze99rTLxPWsa6e8voijeyk jjNe0ReMJtHpktc2oX0/ryTkKqhIXUT9xQuZBrzahoE0OBxXPQmfK+OTgW62S88043BDjT wCx2MxXxceK2WHwOgYLa2wsnVOtIxBQ= 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-402-jP6MU6_jNrOzD0wXp7FWHA-1; Mon, 22 Feb 2021 20:16:03 -0500 X-MC-Unique: jP6MU6_jNrOzD0wXp7FWHA-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 A5F12107ACF6; Tue, 23 Feb 2021 01:16:00 +0000 (UTC) Received: from localhost (ovpn-12-41.pek2.redhat.com [10.72.12.41]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 72A306091A; Tue, 23 Feb 2021 01:15:56 +0000 (UTC) Date: Tue, 23 Feb 2021 09:15:54 +0800 From: Baoquan He To: Mike Rapoport Cc: Andrew Morton , Andrea Arcangeli , Borislav Petkov , Chris Wilson , David Hildenbrand , "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 Subject: Re: [PATCH v6 1/1] mm/page_alloc.c: refactor initialization of struct page for holes in memory layout Message-ID: <20210223011554.GP2871@MiWiFi-R3L-srv> References: <20210222105728.28636-1-rppt@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210222105728.28636-1-rppt@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/22/21 at 12:57pm, 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 Yeah, and the old code re-initialized the unavailable memory in a implicit and confusing way. This patch does it explicitly in the similar way to make it basically consistent with the old code. This looks great to me. > 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); > > because there are pages in both ZONE_DMA32 and ZONE_DMA (unset zone link > in struct page) in the same pageblock. > > 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. Thanks for spending so much effort with patience to fix this. Reviewed-by: Baoquan He > > 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 > Cc: Baoquan He > Cc: David Hildenbrand > Cc: Mel Gorman > Cc: Michal Hocko > Cc: Qian Cai > Cc: Vlastimil Babka > --- > mm/page_alloc.c | 144 ++++++++++++++++++++---------------------------- > 1 file changed, 61 insertions(+), 83 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 3e93f8b29bae..1f1db70b7789 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -6280,12 +6280,60 @@ 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); > + static unsigned long hole_pfn = 0; > unsigned long start_pfn, end_pfn; > + 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); > @@ -6295,7 +6343,20 @@ void __meminit __weak memmap_init_zone(struct zone *zone) > 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) > @@ -7092,88 +7153,6 @@ void __init free_area_init_memoryless_node(int nid) > free_area_init_node(nid); > } > > -#if !defined(CONFIG_FLAT_NODE_MEM_MAP) > -/* > - * Initialize all valid struct pages in the range [spfn, epfn) and mark them > - * PageReserved(). Return the number of struct pages that were initialized. > - */ > -static u64 __init init_unavailable_range(unsigned long spfn, unsigned long epfn) > -{ > - 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; > - } > - /* > - * Use a fake node/zone (0) for now. Some of these pages > - * (in memblock.reserved but not in memblock.memory) will > - * get re-initialized via reserve_bootmem_region() later. > - */ > - __init_single_page(pfn_to_page(pfn), pfn, 0, 0); > - __SetPageReserved(pfn_to_page(pfn)); > - pgcnt++; > - } > - > - return pgcnt; > -} > - > -/* > - * Only struct pages that are backed by physical memory are zeroed and > - * initialized by going through __init_single_page(). But, there are some > - * struct pages which are reserved in memblock allocator and their fields > - * may be accessed (for example page_to_pfn() on some configuration accesses > - * flags). We must explicitly initialize those struct pages. > - * > - * This function also addresses a similar issue where struct pages are left > - * uninitialized because the physical address range is not covered by > - * memblock.memory or memblock.reserved. That could happen when memblock > - * layout is manually configured via memmap=, or when the highest physical > - * address (max_pfn) does not end on a section boundary. > - */ > -static void __init init_unavailable_mem(void) > -{ > - phys_addr_t start, end; > - u64 i, pgcnt; > - phys_addr_t next = 0; > - > - /* > - * Loop through unavailable ranges not covered by memblock.memory. > - */ > - pgcnt = 0; > - for_each_mem_range(i, &start, &end) { > - if (next < start) > - pgcnt += init_unavailable_range(PFN_DOWN(next), > - PFN_UP(start)); > - next = end; > - } > - > - /* > - * Early sections always have a fully populated memmap for the whole > - * section - see pfn_valid(). If the last section has holes at the > - * end and that section is marked "online", the memmap will be > - * considered initialized. Make sure that memmap has a well defined > - * state. > - */ > - pgcnt += init_unavailable_range(PFN_DOWN(next), > - round_up(max_pfn, PAGES_PER_SECTION)); > - > - /* > - * Struct pages that do not have backing memory. This could be because > - * firmware is using some of this memory, or for some other reasons. > - */ > - if (pgcnt) > - pr_info("Zeroed struct page in unavailable ranges: %lld pages", pgcnt); > -} > -#else > -static inline void __init init_unavailable_mem(void) > -{ > -} > -#endif /* !CONFIG_FLAT_NODE_MEM_MAP */ > - > #if MAX_NUMNODES > 1 > /* > * Figure out the number of possible node ids. > @@ -7597,7 +7576,6 @@ void __init free_area_init(unsigned long *max_zone_pfn) > /* Initialise every node */ > mminit_verify_pageflags_layout(); > setup_nr_node_ids(); > - init_unavailable_mem(); > for_each_online_node(nid) { > pg_data_t *pgdat = NODE_DATA(nid); > free_area_init_node(nid); > -- > 2.28.0 >