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Wed, 15 Apr 2020 07:44:19 +0000 (UTC) Received: from [10.36.114.144] (ovpn-114-144.ams2.redhat.com [10.36.114.144]) by smtp.corp.redhat.com (Postfix) with ESMTP id A1C195C1B2; Wed, 15 Apr 2020 07:44:18 +0000 (UTC) Subject: Re: [PATCH v3] mm/memory_hotplug: refrain from adding memory into an impossible node From: David Hildenbrand To: Vishal Verma , linux-mm@kvack.org Cc: linux-nvdimm@lists.01.org, Dan Williams , Dave Hansen References: <20200414235812.6158-1-vishal.l.verma@intel.com> <8e1b55a3-0403-3fa5-ae5b-7c3b20f883dc@redhat.com> 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: <584d7831-ff99-a0e1-9c7c-f82486ced0a3@redhat.com> Date: Wed, 15 Apr 2020 09:44:17 +0200 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: <8e1b55a3-0403-3fa5-ae5b-7c3b20f883dc@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit 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 15.04.20 09:39, David Hildenbrand wrote: > On 15.04.20 01:58, Vishal Verma wrote: >> A misbehaving qemu created a situation where the ACPI SRAT table >> advertised one fewer proximity domains than intended. The NFIT table did >> describe all the expected proximity domains. This caused the device dax >> driver to assign an impossible target_node to the device, and when >> hotplugged as system memory, this would fail with the following >> signature: >> >> [ +0.001627] BUG: kernel NULL pointer dereference, address: 0000000000000088 >> [ +0.001331] #PF: supervisor read access in kernel mode >> [ +0.000975] #PF: error_code(0x0000) - not-present page >> [ +0.000976] PGD 80000001767d4067 P4D 80000001767d4067 PUD 10e0c4067 PMD 0 >> [ +0.001338] Oops: 0000 [#1] SMP PTI >> [ +0.000676] CPU: 4 PID: 22737 Comm: kswapd3 Tainted: G O 5.6.0-rc5 #9 >> [ +0.001457] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), >> BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 >> [ +0.001990] RIP: 0010:prepare_kswapd_sleep+0x7c/0xc0 >> [ +0.000780] Code: 89 df e8 87 fd ff ff 89 c2 31 c0 84 d2 74 e6 0f 1f 44 >> 00 00 48 8b 05 fb af 7a 01 48 63 93 88 1d 01 00 48 8b >> 84 d0 20 0f 00 00 <48> 3b 98 88 00 00 00 75 28 f0 80 a0 >> 80 00 00 00 fe f0 80 a3 38 20 >> [ +0.002877] RSP: 0018:ffffc900017a3e78 EFLAGS: 00010202 >> [ +0.000805] RAX: 0000000000000000 RBX: ffff8881209e0000 RCX: 0000000000000000 >> [ +0.001115] RDX: 0000000000000003 RSI: 0000000000000000 RDI: ffff8881209e0e80 >> [ +0.001098] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000008000 >> [ +0.001092] R10: 0000000000000000 R11: 0000000000000003 R12: 0000000000000003 >> [ +0.001092] R13: 0000000000000003 R14: 0000000000000000 R15: ffffc900017a3ec8 >> [ +0.001091] FS: 0000000000000000(0000) GS:ffff888318c00000(0000) knlGS:0000000000000000 >> [ +0.001275] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> [ +0.000882] CR2: 0000000000000088 CR3: 0000000120b50002 CR4: 00000000001606e0 >> [ +0.001095] Call Trace: >> [ +0.000388] kswapd+0x103/0x520 >> [ +0.000494] ? finish_wait+0x80/0x80 >> [ +0.000547] ? balance_pgdat+0x5a0/0x5a0 >> [ +0.000607] kthread+0x120/0x140 >> [ +0.000508] ? kthread_create_on_node+0x60/0x60 >> [ +0.000706] ret_from_fork+0x3a/0x50 >> >> Add a check in the add_memory path to ensure that the node to which we >> are adding memory is in the node_possible_map >> >> Cc: David Hildenbrand >> Cc: Dan Williams >> Cc: Dave Hansen >> Signed-off-by: Vishal Verma >> --- >> mm/memory_hotplug.c | 28 ++++++++++++++++++++++++++++ >> 1 file changed, 28 insertions(+) >> >> v2: >> - Centralize the check in the add_memory path (David) >> - Instead of failing, add the memory to a nearby node, while warning >> (and tainting) to call out attention to the firmware bug (Dan) >> >> v3: >> - Fix the CONFIG_NUMA=n case, and use node 0 as the final fallback (Dan) >> >> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >> index 0a54ffac8c68..536a809d6ebb 100644 >> --- a/mm/memory_hotplug.c >> +++ b/mm/memory_hotplug.c >> @@ -980,6 +980,30 @@ static int check_hotplug_memory_range(u64 start, u64 size) >> return 0; >> } >> >> +/* >> + * Check that the node provided for adding memory was valid. >> + * If not, find the nearest valid node and add the memory there while >> + * tainting the kernel and displaying a warning to bring attention to the >> + * underlying firmware problem. >> + * Return nid if valid, or an adjusted node number that can be used instead >> + * if the original nid was not valid >> + */ > > -ETOOMUCHDOCUMENTAION > > "If the given node cannot be used (!node_possible()), return the nearest > possible node and WARN_TAINT() about firmware issues." > >> +static int check_hotplug_node(int nid) >> +{ >> + int alt_nid; >> + >> + if (node_possible(nid)) >> + return nid; >> + >> + alt_nid = numa_map_to_online_node(nid); >> + if (alt_nid == NUMA_NO_NODE) >> + alt_nid = first_online_node; >> + WARN_TAINT(1, TAINT_FIRMWARE_WORKAROUND, >> + "node %d expected, but was absent from the node_possible_map, using %d instead\n", >> + nid, alt_nid); >> + return alt_nid; >> +} >> + >> static int online_memory_block(struct memory_block *mem, void *arg) >> { >> return device_online(&mem->dev); >> @@ -1005,6 +1029,10 @@ int __ref add_memory_resource(int nid, struct resource *res) >> if (ret) >> return ret; >> >> + nid = check_hotplug_node(nid); >> + if (nid < 0) >> + return -ENXIO; >> + >> mem_hotplug_begin(); >> >> /* >> > > You should do the same on the memory removal path. (I do wonder if the result could be different (numa_map_to_online_node()/first_online_node)) on the removal path, and if we should bail out when removing instead. Sounds better to me, adding memory is more important in this case. -- Thanks, David / dhildenb