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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,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 6DB26C2D0ED for ; Fri, 27 Mar 2020 16:50:17 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id F13C9206E6 for ; Fri, 27 Mar 2020 16:50:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="U6Ik5QyH" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F13C9206E6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 903A66B000E; Fri, 27 Mar 2020 12:50:15 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8B3C86B0010; Fri, 27 Mar 2020 12:50:15 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 77C396B0032; Fri, 27 Mar 2020 12:50:15 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0238.hostedemail.com [216.40.44.238]) by kanga.kvack.org (Postfix) with ESMTP id 5B4CF6B000E for ; Fri, 27 Mar 2020 12:50:15 -0400 (EDT) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 0EA244427 for ; Fri, 27 Mar 2020 16:50:15 +0000 (UTC) X-FDA: 76641729948.28.pin04_768a07079a843 X-HE-Tag: pin04_768a07079a843 X-Filterd-Recvd-Size: 10069 Received: from us-smtp-delivery-74.mimecast.com (us-smtp-delivery-74.mimecast.com [216.205.24.74]) by imf02.hostedemail.com (Postfix) with ESMTP for ; Fri, 27 Mar 2020 16:50:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585327813; 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:autocrypt:autocrypt; bh=nnzkbZqVUgnra7CNXUXdYdVrlOR8vlayJA0nBvj6W5k=; b=U6Ik5QyHVZTEzEG+Ll2iaWJJUo0fNzKUgHi3qBpHjGn/QIPOBE8x72lIu9YRS5MzQpZsRv uACwWC23oHBFvkmsB/KO/WuO1SlqVuBVrEu9E3pep5VW0cSLpGo0VmGhQgQtKwji1G6FnH vddolMi6kSTo5JBG6Tl5sEB8LC+YvbE= 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-331-ge5IGVbXOoCPcwX97k4oOQ-1; Fri, 27 Mar 2020 12:50:09 -0400 X-MC-Unique: ge5IGVbXOoCPcwX97k4oOQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D6A0C80269A; Fri, 27 Mar 2020 16:50:06 +0000 (UTC) Received: from [10.36.112.108] (ovpn-112-108.ams2.redhat.com [10.36.112.108]) by smtp.corp.redhat.com (Postfix) with ESMTP id BD1FA100EBA7; Fri, 27 Mar 2020 16:50:02 +0000 (UTC) Subject: Re: [PATCH v1] drivers/base/memory.c: indicate all memory blocks as removable To: Dan Williams Cc: Michal Hocko , Linux Kernel Mailing List , Linux MM , Greg Kroah-Hartman , "Rafael J. Wysocki" , Andrew Morton , powerpc-utils-devel@googlegroups.com, util-linux@vger.kernel.org, Badari Pulavarty , Nathan Fontenot , Robert Jennings , Heiko Carstens , Karel Zak , "Scargall, Steve" References: <20200128093542.6908-1-david@redhat.com> <20200327074718.GT27965@dhcp22.suse.cz> <8c74afdc-98cb-dd48-c516-ff6e8b59d598@redhat.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= mQINBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABtCREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT6JAlgEEwEIAEICGwMFCQlmAYAGCwkIBwMCBhUI AgkKCwQWAgMBAh4BAheAFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl3pImkCGQEACgkQTd4Q 9wD/g1o+VA//SFvIHUAvul05u6wKv/pIR6aICPdpF9EIgEU448g+7FfDgQwcEny1pbEzAmiw zAXIQ9H0NZh96lcq+yDLtONnXk/bEYWHHUA014A1wqcYNRY8RvY1+eVHb0uu0KYQoXkzvu+s Dncuguk470XPnscL27hs8PgOP6QjG4jt75K2LfZ0eAqTOUCZTJxA8A7E9+XTYuU0hs7QVrWJ jQdFxQbRMrYz7uP8KmTK9/Cnvqehgl4EzyRaZppshruKMeyheBgvgJd5On1wWq4ZUV5PFM4x II3QbD3EJfWbaJMR55jI9dMFa+vK7MFz3rhWOkEx/QR959lfdRSTXdxs8V3zDvChcmRVGN8U Vo93d1YNtWnA9w6oCW1dnDZ4kgQZZSBIjp6iHcA08apzh7DPi08jL7M9UQByeYGr8KuR4i6e RZI6xhlZerUScVzn35ONwOC91VdYiQgjemiVLq1WDDZ3B7DIzUZ4RQTOaIWdtXBWb8zWakt/ ztGhsx0e39Gvt3391O1PgcA7ilhvqrBPemJrlb9xSPPRbaNAW39P8ws/UJnzSJqnHMVxbRZC Am4add/SM+OCP0w3xYss1jy9T+XdZa0lhUvJfLy7tNcjVG/sxkBXOaSC24MFPuwnoC9WvCVQ ZBxouph3kqc4Dt5X1EeXVLeba+466P1fe1rC8MbcwDkoUo65Ag0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAGJAiUEGAECAA8FAlXLn5ECGwwFCQlmAYAACgkQTd4Q 9wD/g1qA6w/+M+ggFv+JdVsz5+ZIc6MSyGUozASX+bmIuPeIecc9UsFRatc91LuJCKMkD9Uv GOcWSeFpLrSGRQ1Z7EMzFVU//qVs6uzhsNk0RYMyS0B6oloW3FpyQ+zOVylFWQCzoyyf227y GW8HnXunJSC+4PtlL2AY4yZjAVAPLK2l6mhgClVXTQ/S7cBoTQKP+jvVJOoYkpnFxWE9pn4t H5QIFk7Ip8TKr5k3fXVWk4lnUi9MTF/5L/mWqdyIO1s7cjharQCstfWCzWrVeVctpVoDfJWp 4LwTuQ5yEM2KcPeElLg5fR7WB2zH97oI6/Ko2DlovmfQqXh9xWozQt0iGy5tWzh6I0JrlcxJ ileZWLccC4XKD1037Hy2FLAjzfoWgwBLA6ULu0exOOdIa58H4PsXtkFPrUF980EEibUp0zFz GotRVekFAceUaRvAj7dh76cToeZkfsjAvBVb4COXuhgX6N4pofgNkW2AtgYu1nUsPAo+NftU CxrhjHtLn4QEBpkbErnXQyMjHpIatlYGutVMS91XTQXYydCh5crMPs7hYVsvnmGHIaB9ZMfB njnuI31KBiLUks+paRkHQlFcgS2N3gkRBzH7xSZ+t7Re3jvXdXEzKBbQ+dC3lpJB0wPnyMcX FOTT3aZT7IgePkt5iC/BKBk3hqKteTnJFeVIT7EC+a6YUFg= Organization: Red Hat GmbH Message-ID: <1bf9777b-90a1-35be-b909-facf1812f91e@redhat.com> Date: Fri, 27 Mar 2020 17:50:01 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Content-Transfer-Encoding: quoted-printable 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: On 27.03.20 17:28, Dan Williams wrote: > On Fri, Mar 27, 2020 at 2:00 AM David Hildenbrand wr= ote: >> >> On 27.03.20 08:47, Michal Hocko wrote: >>> On Thu 26-03-20 23:24:08, Dan Williams wrote: >>> [...] >>>> David, Andrew, >>>> >>>> I'd like to recommend this patch for -stable as it likely (test >>>> underway) solves this crash report from Steve: >>>> >>>> [ 148.796036] page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) >>>> [ 148.796074] ------------[ cut here ]------------ >>>> [ 148.796098] kernel BUG at include/linux/mm.h:1087! >>>> [ 148.796126] invalid opcode: 0000 [#1] SMP NOPTI >>>> [ 148.796146] CPU: 63 PID: 5471 Comm: lsmem Not tainted 5.5.10-200.= fc31.x8=3D >>>> 6_64+debug #1 >>>> [ 148.796173] Hardware name: Intel Corporation S2600WFD/S2600WFD, B= IOS SE5=3D >>>> C620.86B.02.01.0010.010620200716 01/06/2020 >>>> [ 148.796212] RIP: 0010:is_mem_section_removable+0x1a4/0x1b0 >>>> [ 148.796561] Call Trace: >>>> [ 148.796591] removable_show+0x6e/0xa0 >>>> [ 148.796608] dev_attr_show+0x19/0x40 >>>> [ 148.796625] sysfs_kf_seq_show+0xa9/0x100 >>>> [ 148.796640] seq_read+0xd5/0x450 >>>> [ 148.796657] vfs_read+0xc5/0x180 >>>> [ 148.796672] ksys_read+0x68/0xe0 >>>> [ 148.796688] do_syscall_64+0x5c/0xa0 >>>> [ 148.796704] entry_SYSCALL_64_after_hwframe+0x49/0xbe >>>> [ 148.796721] RIP: 0033:0x7f3ab1646412 >>>> >>>> ...on a non-debug kernel it just crashes. >>>> >>>> In this case lsmem is failing when reading memory96: >>>> >>>> openat(3, "memory96/removable", O_RDONLY|O_CLOEXEC) =3D 4 >>>> fcntl(4, F_GETFL) =3D 0x8000 (flags O_RDONLY|O= _LARGEFILE) >>>> fstat(4, {st_mode=3DS_IFREG|0444, st_size=3D4096, ...}) =3D 0 >>>> read(4, ) =3D ? >>>> +++ killed by SIGSEGV +++ >>>> Segmentation fault (core dumped) >>>> >>>> ...which is phys_index 0x60 =3D> memory address 0x3000000000 >>>> >>>> On this platform that lands us here: >>>> >>>> 100000000-303fffffff : System RAM >>>> 291f000000-291fe00f70 : Kernel code >>>> 2920000000-292051efff : Kernel rodata >>>> 2920600000-292093b0bf : Kernel data >>>> 29214f3000-2922dfffff : Kernel bss >>>> 3040000000-305fffffff : Reserved >>>> 3060000000-1aa5fffffff : Persistent Memory >>> >>> OK, 2GB memblocks and that would mean [0x3000000000, 0x3080000000] >>> >>>> ...where the last memory block of System RAM is shared with persiste= nt >>>> memory. I.e. the block is only partially online which means that >>>> page_to_nid() in is_mem_section_removable() will assert or crash for >>>> some of the offline pages in that block. >>> >>> Yes, this patch is a simple workaround. Normal memory hotplug will no= t >>> blow up because it should be able to find out that test_pages_in_a_zo= ne >>> is false. Who knows how other potential pfn walkers handle that. >> >> All other pfn walkers now correctly use pfn_to_online_page() - which >> will also result in false positives in this scenario and is still to b= e >> fixed by Dan IIRC. [1] >=20 > Sorry, it's been too long and this fell out of my cache. I also turned > away once the major fire in KVM was put out with special consideration > for for devmem pages. What's left these days? ...besides > removable_show()? Essentially any pfn_to_online_page() is a candidate. E.g., mm/memory-failure.c:memory_failure() is obviously broken (could be worked around) Also mm/memory-failure.c:soft_offline_page() is obviously broken. Also set_zone_contiguous()->__pageblock_pfn_to_page() is broken, when it checks for "page_zone(start_page) !=3D zone" if the memmap contains garba= ge. And I only checked a handful of examples. --=20 Thanks, David / dhildenb