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=-15.8 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 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 D0874C433DB for ; Fri, 26 Feb 2021 06:43:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7D99964EE3 for ; Fri, 26 Feb 2021 06:43:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229989AbhBZGnY (ORCPT ); Fri, 26 Feb 2021 01:43:24 -0500 Received: from mail.kernel.org ([198.145.29.99]:44980 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229727AbhBZGnT (ORCPT ); Fri, 26 Feb 2021 01:43:19 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 132F160238; Fri, 26 Feb 2021 06:42:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614321758; bh=hX4Qhz8Qgp1SzWBjSDDYOU56u7r54bsxVnDXREAgGN8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=R25R6XdINokIbzL59wiY4Rkm7fp/nYt523xLNqSO0+TQ5gWmHqqUDlZEpbY5jiNIP YfzetFUC3HabYiPDRO+DwX3HrzfMbqYEB8cqbIelYbyk2KvtGQtLlyY1oZaJjr/cVI KxfBlbqWJS863wM/eXzhvONJqNtWukSRuusF3u8A= Date: Fri, 26 Feb 2021 07:42:36 +0100 From: Greg KH To: Mike Rapoport Cc: Andrew Morton , Andrea Arcangeli , Baoquan He , 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 v8 1/1] mm/page_alloc.c: refactor initialization of struct page for holes in memory layout Message-ID: References: <20210225224351.7356-1-rppt@kernel.org> <20210225224351.7356-2-rppt@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210225224351.7356-2-rppt@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 26, 2021 at 12:43:51AM +0200, 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 > --- > mm/page_alloc.c | 158 +++++++++++++++++++++++------------------------- > 1 file changed, 75 insertions(+), 83 deletions(-) This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly.