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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 3EF32C432C0 for ; Tue, 19 Nov 2019 14:19:42 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 884D220885 for ; Tue, 19 Nov 2019 14:19:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="R/1Pi1Ki" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 884D220885 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 47HSd70mTTzDqfb for ; Wed, 20 Nov 2019 01:19:39 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=redhat.com (client-ip=205.139.110.61; helo=us-smtp-delivery-1.mimecast.com; envelope-from=david@redhat.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.b="R/1Pi1Ki"; dkim-atps=neutral Received: from us-smtp-delivery-1.mimecast.com (us-smtp-2.mimecast.com [205.139.110.61]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 47HSYc3wgSzDqK5 for ; Wed, 20 Nov 2019 01:16:35 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1574172992; 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=VC3V3Jxjtko1SYQH3MBBOMxUY3xpVbVtJKD+tE80Bi8=; b=R/1Pi1KiUOvQqx/1+G/iAMHYZvPE8TdGYz58x8AmfUnVzq/+Y3dBBw6EXY8r5sTZlh4qKU lOGlYrQ7sI8lqt1x5CmEiPGd8m0grUEfhtOaTJxhaUizf69h1ikLi618MSr6FZI9ryA9dY kkDpLjFeG9wSWhYavDS3j3ABORf0Z/s= 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-106-9OzMB_CeNSaU2ssn_ay_0g-1; Tue, 19 Nov 2019 09:16:29 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 017E99A697; Tue, 19 Nov 2019 14:16:27 +0000 (UTC) Received: from [10.36.117.126] (ovpn-117-126.ams2.redhat.com [10.36.117.126]) by smtp.corp.redhat.com (Postfix) with ESMTP id B33435E7A6; Tue, 19 Nov 2019 14:16:23 +0000 (UTC) Subject: Re: [PATCH v6 04/10] mm/memory_hotplug: Don't access uninitialized memmaps in shrink_zone_span() To: Andrew Morton References: <20191006085646.5768-1-david@redhat.com> <20191006085646.5768-5-david@redhat.com> <5a4573de-bd8a-6cd3-55d0-86d503a236fd@redhat.com> <20191014121719.cb9b9efe51a7e9e985b38075@linux-foundation.org> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <8bbbd4f1-e2c9-b654-ab73-aa4314135f21@redhat.com> Date: Tue, 19 Nov 2019 15:16:22 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 MIME-Version: 1.0 In-Reply-To: <20191014121719.cb9b9efe51a7e9e985b38075@linux-foundation.org> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-MC-Unique: 9OzMB_CeNSaU2ssn_ay_0g-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-s390@vger.kernel.org, Michal Hocko , linux-ia64@vger.kernel.org, Pavel Tatashin , linux-sh@vger.kernel.org, "Aneesh Kumar K . V" , x86@kernel.org, linux-kernel@vger.kernel.org, Alexander Duyck , linux-mm@kvack.org, Dan Williams , linuxppc-dev@lists.ozlabs.org, Toshiki Fukasawa , linux-arm-kernel@lists.infradead.org, Oscar Salvador Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 14.10.19 21:17, Andrew Morton wrote: > On Mon, 14 Oct 2019 11:32:13 +0200 David Hildenbrand w= rote: >=20 >>> Fixes: d0dc12e86b31 ("mm/memory_hotplug: optimize memory hotplug") >> >> @Andrew, can you convert that to >> >> Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded >> memory to zones until online") # visible after d0dc12e86b319 >> >> and add >> >> Cc: stable@vger.kernel.org # v4.13+ >=20 > Done, thanks. >=20 Just a note that 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: 00000000000= 00000 [ 41.213459] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffffbb1= 197dc [ 41.214100] RBP: 000000000000000c R08: 0000000000000439 R09: 00000000000= 00059 [ 41.214736] R10: 0000000000000000 R11: ffffac0d41557b08 R12: ffff8be475e= a72b0 [ 41.215376] R13: 000000000000fa00 R14: 0000000000250000 R15: 00000000fff= c0bb5 [ 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: 00000000000= 006e0 [ 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: 000000= 0000000001 [ 41.226608] RAX: ffffffffffffffda RBX: 000055e824d07f40 RCX: 00007f30865= d0ed8 [ 41.227242] RDX: 0000000000000007 RSI: 000055e824d07f40 RDI: 00000000000= 00004 [ 41.227870] RBP: 0000000000000007 R08: 0000000000000007 R09: 00000000000= 00006 [ 41.228753] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000= 00004 [ 41.229419] R13: 00007f30862ab528 R14: 0000000000000001 R15: 000055e824d= 07f40 While creating a namespace and initializing memmap, if you destroy the name= space 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. --=20 Thanks, David / dhildenb