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=-5.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,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 02C1CCA9EB5 for ; Mon, 21 Oct 2019 08:28:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BDEB82064A for ; Mon, 21 Oct 2019 08:28:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571646527; bh=8iX6VZWt/0taI5lVXDxoZAEs8G7adOqXW+XiQUe06sM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=o3/OIE6+73p8BYrvu0E54mOL/+tM8XTe/t9FK/qeribglGOAFT0pw6NVmjMKW4ci/ dhUUkNrAHvH0uc1Uav5chPZAkCCrqL/+JHeBkU4oQdL6HpZWPfloyJMJdtaHJFn8Zs QEVHU6RZyOvDkpZxRAXl3p4b02ZD6I45+H06QndI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727796AbfJUI2q (ORCPT ); Mon, 21 Oct 2019 04:28:46 -0400 Received: from mx2.suse.de ([195.135.220.15]:34342 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727768AbfJUI2p (ORCPT ); Mon, 21 Oct 2019 04:28:45 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 685AFB077; Mon, 21 Oct 2019 08:28:42 +0000 (UTC) Date: Mon, 21 Oct 2019 10:28:41 +0200 From: Michal Hocko To: linux-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, alexander.h.duyck@linux.intel.com, aneesh.kumar@linux.ibm.com, anshuman.khandual@arm.com, benh@kernel.crashing.org, borntraeger@de.ibm.com, bp@alien8.de, cai@lca.pw, catalin.marinas@arm.com, christophe.leroy@c-s.fr, dalias@libc.org, damian.tometzki@gmail.com, dan.j.williams@intel.com, dave.hansen@linux.intel.com, david@redhat.com, fenghua.yu@intel.com, gerald.schaefer@de.ibm.com, glider@google.com, gor@linux.ibm.com, gregkh@linuxfoundation.org, heiko.carstens@de.ibm.com, hpa@zytor.com, ira.weiny@intel.com, jgg@ziepe.ca, linux-mm@kvack.org, logang@deltatee.com, luto@kernel.org, mark.rutland@arm.com, mgorman@techsingularity.net, mingo@redhat.com, mm-commits@vger.kernel.org, mpe@ellerman.id.au, osalvador@suse.de, pagupta@redhat.com, pasha.tatashin@soleen.com, pasic@linux.ibm.com, paulus@samba.org, pavel.tatashin@microsoft.com, peterz@infradead.org, richard.weiyang@gmail.com, richardw.yang@linux.intel.com, robin.murphy@arm.com, rppt@linux.ibm.com, stable@vger.kernel.org, steve.capper@arm.com, tglx@linutronix.de, thomas.lendacky@amd.com, tony.luck@intel.com, torvalds@linux-foundation.org, vbabka@suse.cz, will@kernel.org, willy@infradead.org, yamada.masahiro@socionext.com, yaojun8558363@gmail.com, ysato@users.sourceforge.jp, yuzhao@google.com Subject: Re: [patch 06/26] mm/memory_hotplug: don't access uninitialized memmaps in shrink_pgdat_span() Message-ID: <20191021082841.GD9379@dhcp22.suse.cz> References: <20191019031933.PakTLd2V_%akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191019031933.PakTLd2V_%akpm@linux-foundation.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Has this been reviewed properly? I do not see any Acks nor Reviewed-bys. Did Aneesh gave it some testing? On Fri 18-10-19 20:19:33, Andrew Morton wrote: > From: David Hildenbrand > Subject: mm/memory_hotplug: don't access uninitialized memmaps in shrink_pgdat_span() > > We might use the nid of memmaps that were never initialized. For example, > if the memmap was poisoned, we will crash the kernel in pfn_to_nid() right > now. Let's use the calculated boundaries of the separate zones instead. > This now also avoids having to iterate over a whole bunch of subsections > again, after shrinking one zone. > > Before commit d0dc12e86b31 ("mm/memory_hotplug: optimize memory hotplug"), > the memmap was initialized to 0 and the node was set to the right value. > After that commit, the node might be garbage. > > We'll have to fix shrink_zone_span() next. > > Link: http://lkml.kernel.org/r/20191006085646.5768-4-david@redhat.com > Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online") [d0dc12e86b319] > Signed-off-by: David Hildenbrand > Reported-by: Aneesh Kumar K.V > Cc: Oscar Salvador > Cc: David Hildenbrand > Cc: Michal Hocko > Cc: Pavel Tatashin > Cc: Dan Williams > Cc: Wei Yang > Cc: Alexander Duyck > Cc: Alexander Potapenko > Cc: Andy Lutomirski > Cc: Anshuman Khandual > Cc: Benjamin Herrenschmidt > Cc: Borislav Petkov > Cc: Catalin Marinas > Cc: Christian Borntraeger > Cc: Christophe Leroy > Cc: Damian Tometzki > Cc: Dave Hansen > Cc: Fenghua Yu > Cc: Gerald Schaefer > Cc: Greg Kroah-Hartman > Cc: Halil Pasic > Cc: Heiko Carstens > Cc: "H. Peter Anvin" > Cc: Ingo Molnar > Cc: Ira Weiny > Cc: Jason Gunthorpe > Cc: Jun Yao > Cc: Logan Gunthorpe > Cc: Mark Rutland > Cc: Masahiro Yamada > Cc: "Matthew Wilcox (Oracle)" > Cc: Mel Gorman > Cc: Michael Ellerman > Cc: Mike Rapoport > Cc: Pankaj Gupta > Cc: Paul Mackerras > Cc: Pavel Tatashin > Cc: Peter Zijlstra > Cc: Qian Cai > Cc: Rich Felker > Cc: Robin Murphy > Cc: Steve Capper > Cc: Thomas Gleixner > Cc: Tom Lendacky > Cc: Tony Luck > Cc: Vasily Gorbik > Cc: Vlastimil Babka > Cc: Wei Yang > Cc: Will Deacon > Cc: Yoshinori Sato > Cc: Yu Zhao > Cc: [4.13+] > Signed-off-by: Andrew Morton > --- > > mm/memory_hotplug.c | 74 +++++++++--------------------------------- > 1 file changed, 16 insertions(+), 58 deletions(-) > > --- a/mm/memory_hotplug.c~mm-memory_hotplug-dont-access-uninitialized-memmaps-in-shrink_pgdat_span > +++ a/mm/memory_hotplug.c > @@ -436,67 +436,25 @@ static void shrink_zone_span(struct zone > zone_span_writeunlock(zone); > } > > -static void shrink_pgdat_span(struct pglist_data *pgdat, > - unsigned long start_pfn, unsigned long end_pfn) > +static void update_pgdat_span(struct pglist_data *pgdat) > { > - unsigned long pgdat_start_pfn = pgdat->node_start_pfn; > - unsigned long p = pgdat_end_pfn(pgdat); /* pgdat_end_pfn namespace clash */ > - unsigned long pgdat_end_pfn = p; > - unsigned long pfn; > - int nid = pgdat->node_id; > - > - if (pgdat_start_pfn == start_pfn) { > - /* > - * If the section is smallest section in the pgdat, it need > - * shrink pgdat->node_start_pfn and pgdat->node_spanned_pages. > - * In this case, we find second smallest valid mem_section > - * for shrinking zone. > - */ > - pfn = find_smallest_section_pfn(nid, NULL, end_pfn, > - pgdat_end_pfn); > - if (pfn) { > - pgdat->node_start_pfn = pfn; > - pgdat->node_spanned_pages = pgdat_end_pfn - pfn; > - } > - } else if (pgdat_end_pfn == end_pfn) { > - /* > - * If the section is biggest section in the pgdat, it need > - * shrink pgdat->node_spanned_pages. > - * In this case, we find second biggest valid mem_section for > - * shrinking zone. > - */ > - pfn = find_biggest_section_pfn(nid, NULL, pgdat_start_pfn, > - start_pfn); > - if (pfn) > - pgdat->node_spanned_pages = pfn - pgdat_start_pfn + 1; > - } > - > - /* > - * If the section is not biggest or smallest mem_section in the pgdat, > - * it only creates a hole in the pgdat. So in this case, we need not > - * change the pgdat. > - * But perhaps, the pgdat has only hole data. Thus it check the pgdat > - * has only hole or not. > - */ > - pfn = pgdat_start_pfn; > - for (; pfn < pgdat_end_pfn; pfn += PAGES_PER_SUBSECTION) { > - if (unlikely(!pfn_valid(pfn))) > - continue; > - > - if (pfn_to_nid(pfn) != nid) > - continue; > - > - /* Skip range to be removed */ > - if (pfn >= start_pfn && pfn < end_pfn) > - continue; > + unsigned long node_start_pfn = 0, node_end_pfn = 0; > + struct zone *zone; > > - /* If we find valid section, we have nothing to do */ > - return; > + for (zone = pgdat->node_zones; > + zone < pgdat->node_zones + MAX_NR_ZONES; zone++) { > + unsigned long zone_end_pfn = zone->zone_start_pfn + > + zone->spanned_pages; > + > + /* No need to lock the zones, they can't change. */ > + if (zone_end_pfn > node_end_pfn) > + node_end_pfn = zone_end_pfn; > + if (zone->zone_start_pfn < node_start_pfn) > + node_start_pfn = zone->zone_start_pfn; > } > > - /* The pgdat has no valid section */ > - pgdat->node_start_pfn = 0; > - pgdat->node_spanned_pages = 0; > + pgdat->node_start_pfn = node_start_pfn; > + pgdat->node_spanned_pages = node_end_pfn - node_start_pfn; > } > > static void __remove_zone(struct zone *zone, unsigned long start_pfn, > @@ -507,7 +465,7 @@ static void __remove_zone(struct zone *z > > pgdat_resize_lock(zone->zone_pgdat, &flags); > shrink_zone_span(zone, start_pfn, start_pfn + nr_pages); > - shrink_pgdat_span(pgdat, start_pfn, start_pfn + nr_pages); > + update_pgdat_span(pgdat); > pgdat_resize_unlock(zone->zone_pgdat, &flags); > } > > _ -- Michal Hocko SUSE Labs