From patchwork Fri Nov 22 01:53:56 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 11257139 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9A79F14C0 for ; Fri, 22 Nov 2019 01:54:02 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4DC85206F4 for ; Fri, 22 Nov 2019 01:54:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="2rAKCHA3" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4DC85206F4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 52C2F6B0498; Thu, 21 Nov 2019 20:54:01 -0500 (EST) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 4DC926B0499; Thu, 21 Nov 2019 20:54:01 -0500 (EST) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 41AB96B049A; Thu, 21 Nov 2019 20:54:01 -0500 (EST) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0211.hostedemail.com [216.40.44.211]) by kanga.kvack.org (Postfix) with ESMTP id 2C43C6B0498 for ; Thu, 21 Nov 2019 20:54:01 -0500 (EST) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id EFC6F583E for ; Fri, 22 Nov 2019 01:54:00 +0000 (UTC) X-FDA: 76182242640.27.love56_5d34a614c7e14 X-Spam-Summary: 50, X-HE-Tag: love56_5d34a614c7e14 X-Filterd-Recvd-Size: 11591 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf31.hostedemail.com (Postfix) with ESMTP for ; Fri, 22 Nov 2019 01:54:00 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5D2C5206CB; Fri, 22 Nov 2019 01:53:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574387639; bh=yHVJsaehfNsBrMdK3lMb7ajJ1qLyQpOg5+UQ+MYBYoI=; h=Date:From:To:Subject:From; b=2rAKCHA3kDsuhlBvQxM+3fLAi9z/pdWbJxYemgWj7BLRqgDHyLZQoJyb9TNDoLZnJ a7eMCms8jNt4/dEjavivnk/PaK+INJs9gzixlUSEGoJRsBTrIjhRM1xVG+vJ4DVDGK 4eQ0MmopmcFzBSlK5tMTsO0SA5FVI3dfvE0kr6Kc= Date: Thu, 21 Nov 2019 17:53:56 -0800 From: akpm@linux-foundation.org To: 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, mhocko@suse.com, 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, t-fukasawa@vx.jp.nec.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: [patch 3/4] mm/memory_hotplug: don't access uninitialized memmaps in shrink_zone_span() Message-ID: <20191122015356.2g-fSbCJ0%akpm@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: David Hildenbrand Subject: mm/memory_hotplug: don't access uninitialized memmaps in shrink_zone_span() Let's limit shrinking to !ZONE_DEVICE so we can fix the current code. We should never try to touch the memmap of offline sections where we could have uninitialized memmaps and could trigger BUGs when calling page_to_nid() on poisoned pages. There is no reliable way to distinguish an uninitialized memmap from an initialized memmap that belongs to ZONE_DEVICE, as we don't have anything like SECTION_IS_ONLINE we can use similar to pfn_to_online_section() for !ZONE_DEVICE memory. E.g., set_zone_contiguous() similarly relies on pfn_to_online_section() and will therefore never set a ZONE_DEVICE zone consecutive. Stopping to shrink the ZONE_DEVICE therefore results in no observable changes, besides /proc/zoneinfo indicating different boundaries - something we can totally live with. Before commit d0dc12e86b31 ("mm/memory_hotplug: optimize memory hotplug"), the memmap was initialized with 0 and the node with the right value. So the zone might be wrong but not garbage. After that commit, both the zone and the node will be garbage when touching uninitialized memmaps. Toshiki reported a BUG (race between delayed initialization of ZONE_DEVICE memmaps without holding the memory hotplug lock and concurrent zone shrinking). https://lkml.org/lkml/2019/11/14/1040 "Iteration of create and destroy namespace causes the panic as below: [ 41.207694] kernel BUG at mm/page_alloc.c:535! [ 41.208109] invalid opcode: 0000 [#1] SMP PTI [ 41.208508] CPU: 7 PID: 2766 Comm: ndctl Not tainted 5.4.0-rc4 #6 [ 41.209064] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.0-0-g63451fca13-prebuilt.qemu-project.org 04/01/2014 [ 41.210175] RIP: 0010:set_pfnblock_flags_mask+0x95/0xf0 [ 41.210643] Code: 04 41 83 e2 3c 48 8d 04 a8 48 c1 e0 07 48 03 04 dd e0 59 55 bb 48 8b 58 68 48 39 da 73 0e 48 c7 c6 70 ac 11 bb e8 1b b2 fd ff <0f> 0b 48 03 58 78 48 39 da 73 e9 49 01 ca b9 3f 00 00 00 4f 8d 0c [ 41.212354] RSP: 0018:ffffac0d41557c80 EFLAGS: 00010246 [ 41.212821] RAX: 000000000000004a RBX: 0000000000244a00 RCX: 0000000000000000 [ 41.213459] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffffbb1197dc [ 41.214100] RBP: 000000000000000c R08: 0000000000000439 R09: 0000000000000059 [ 41.214736] R10: 0000000000000000 R11: ffffac0d41557b08 R12: ffff8be475ea72b0 [ 41.215376] R13: 000000000000fa00 R14: 0000000000250000 R15: 00000000fffc0bb5 [ 41.216008] FS: 00007f30862ab600(0000) GS:ffff8be57bc40000(0000) knlGS:0000000000000000 [ 41.216771] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 41.217299] CR2: 000055e824d0d508 CR3: 0000000231dac000 CR4: 00000000000006e0 [ 41.217934] Call Trace: [ 41.218225] memmap_init_zone_device+0x165/0x17c [ 41.218642] memremap_pages+0x4c1/0x540 [ 41.218989] devm_memremap_pages+0x1d/0x60 [ 41.219367] pmem_attach_disk+0x16b/0x600 [nd_pmem] [ 41.219804] ? devm_nsio_enable+0xb8/0xe0 [ 41.220172] nvdimm_bus_probe+0x69/0x1c0 [ 41.220526] really_probe+0x1c2/0x3e0 [ 41.220856] driver_probe_device+0xb4/0x100 [ 41.221238] device_driver_attach+0x4f/0x60 [ 41.221611] bind_store+0xc9/0x110 [ 41.221919] kernfs_fop_write+0x116/0x190 [ 41.222326] vfs_write+0xa5/0x1a0 [ 41.222626] ksys_write+0x59/0xd0 [ 41.222927] do_syscall_64+0x5b/0x180 [ 41.223264] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 41.223714] RIP: 0033:0x7f30865d0ed8 [ 41.224037] Code: 89 02 48 c7 c0 ff ff ff ff eb b3 0f 1f 80 00 00 00 00 f3 0f 1e fa 48 8d 05 45 78 0d 00 8b 00 85 c0 75 17 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 58 c3 0f 1f 80 00 00 00 00 41 54 49 89 d4 55 [ 41.225920] RSP: 002b:00007fffe5d30a78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 [ 41.226608] RAX: ffffffffffffffda RBX: 000055e824d07f40 RCX: 00007f30865d0ed8 [ 41.227242] RDX: 0000000000000007 RSI: 000055e824d07f40 RDI: 0000000000000004 [ 41.227870] RBP: 0000000000000007 R08: 0000000000000007 R09: 0000000000000006 [ 41.228753] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000004 [ 41.229419] R13: 00007f30862ab528 R14: 0000000000000001 R15: 000055e824d07f40 While creating a namespace and initializing memmap, if you destroy the namespace and shrink the zone, it will initialize the memmap outside the zone and trigger VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page) in set_pfnblock_flags_mask()." This BUG is also mitigated by this commit, where we for now stop to shrink the ZONE_DEVICE zone until we can do it in a safe and clean way. Link: http://lkml.kernel.org/r/20191006085646.5768-5-david@redhat.com Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online") [visible after d0dc12e86b319] Signed-off-by: David Hildenbrand Reported-by: Aneesh Kumar K.V Reported-by: Toshiki Fukasawa Cc: Oscar Salvador Cc: David Hildenbrand Cc: Michal Hocko Cc: Pavel Tatashin Cc: Dan Williams 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: Wei Yang Cc: Will Deacon Cc: Yoshinori Sato Cc: Yu Zhao Cc: [4.13+] Signed-off-by: Andrew Morton --- mm/memory_hotplug.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) --- a/mm/memory_hotplug.c~mm-memory_hotplug-dont-access-uninitialized-memmaps-in-shrink_zone_span +++ a/mm/memory_hotplug.c @@ -331,7 +331,7 @@ static unsigned long find_smallest_secti unsigned long end_pfn) { for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SUBSECTION) { - if (unlikely(!pfn_valid(start_pfn))) + if (unlikely(!pfn_to_online_page(start_pfn))) continue; if (unlikely(pfn_to_nid(start_pfn) != nid)) @@ -356,7 +356,7 @@ static unsigned long find_biggest_sectio /* pfn is the end pfn of a memory section. */ pfn = end_pfn - 1; for (; pfn >= start_pfn; pfn -= PAGES_PER_SUBSECTION) { - if (unlikely(!pfn_valid(pfn))) + if (unlikely(!pfn_to_online_page(pfn))) continue; if (unlikely(pfn_to_nid(pfn) != nid)) @@ -415,7 +415,7 @@ static void shrink_zone_span(struct zone */ pfn = zone_start_pfn; for (; pfn < zone_end_pfn; pfn += PAGES_PER_SUBSECTION) { - if (unlikely(!pfn_valid(pfn))) + if (unlikely(!pfn_to_online_page(pfn))) continue; if (page_zone(pfn_to_page(pfn)) != zone) @@ -471,6 +471,16 @@ static void __remove_zone(struct zone *z struct pglist_data *pgdat = zone->zone_pgdat; unsigned long flags; +#ifdef CONFIG_ZONE_DEVICE + /* + * Zone shrinking code cannot properly deal with ZONE_DEVICE. So + * we will not try to shrink the zones - which is okay as + * set_zone_contiguous() cannot deal with ZONE_DEVICE either way. + */ + if (zone_idx(zone) == ZONE_DEVICE) + return; +#endif + pgdat_resize_lock(zone->zone_pgdat, &flags); shrink_zone_span(zone, start_pfn, start_pfn + nr_pages); update_pgdat_span(pgdat);