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Wed, 12 Feb 2020 08:21:59 +0000 (UTC) Received: from [10.36.117.92] (ovpn-117-92.ams2.redhat.com [10.36.117.92]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4FBD28ED1B; Wed, 12 Feb 2020 08:21:57 +0000 (UTC) Subject: Re: [Bug 206401] kernel panic on Hyper-V after 5 minutes due to memory hot-add To: Baoquan He , kkabe@vega.pgw.jp, bugzilla-daemon@bugzilla.kernel.org, Andrew Morton Cc: Wei Yang , Michal Hocko , Naoya Horiguchi , linux-mm@kvack.org, Dan Williams References: <20200209213217.73abdc867faec8c359e2ba08@linux-foundation.org> <20200210054027.GI26758@MiWiFi-R3L-srv> <20200209215644.f2dfd7b6cb13f374a0ef8f32@linux-foundation.org> <20200210060923.GC8965@MiWiFi-R3L-srv> <20200210061551.GD8965@MiWiFi-R3L-srv> <20200210230741.GB32495@richard> <20200211164131.a594d2efc45b4e8744c98421@linux-foundation.org> <20200212073123.GG8965@MiWiFi-R3L-srv> 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: <544bd3d0-c962-e97c-7c1c-5d4ffdd2046b@redhat.com> Date: Wed, 12 Feb 2020 09:21:56 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <20200212073123.GG8965@MiWiFi-R3L-srv> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-MC-Unique: f6bA9e6dMtKAAV4H1UohEQ-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 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 12.02.20 08:31, Baoquan He wrote: > On 02/11/20 at 04:41pm, Andrew Morton wrote: >> On Tue, 11 Feb 2020 07:07:41 +0800 Wei Yang wrote: >> >>> On Mon, Feb 10, 2020 at 02:15:51PM +0800, Baoquan He wrote: >>>> On 02/10/20 at 02:09pm, Baoquan He wrote: >>>>> On 02/09/20 at 09:56pm, Andrew Morton wrote: >>>>>> On Mon, 10 Feb 2020 13:40:27 +0800 Baoquan He wrote= : >>>>>> >>>>>>> Hi Andrew, >>>>>>> >>>>>>> On 02/09/20 at 09:32pm, Andrew Morton wrote: >>>>>>>> On Tue, 04 Feb 2020 11:25:48 +0000 bugzilla-daemon@bugzilla.kernel= .org wrote: >>>>>>>> >>>>>>>>> https://bugzilla.kernel.org/show_bug.cgi?id=3D206401 >>>>>>>>> >>>>>>>> >>>>>>>> An oops during mem hotadd. Could someone please take a look when >>>>>>>> convenient? >>>>>>> >>>>>>> This has been addressed by Wei Yang's patch, please check it here: >>>>>>> >>>>>>> http://lkml.kernel.org/r/20200209104826.3385-7-bhe@redhat.com >>>>>>> >>>>>> >>>>>> hm, OK, thanks. It's unfortunate that a 5.5 fix is buried in a >>>>>> six-patch series which is still in progress! Can we please merge th= at >>>>>> as a standalone fix with a cc:stable, Fixes:, etc? >>>> >>>> Maybe can add Fixes tag as follow when merge: >>>> >>>> Fixes: ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug") >>>> >> >> The reporter (cc'ed here) is still seeing issues: >> https://bugzilla.kernel.org/show_bug.cgi?id=3D206401 >> >> Could we please continue this investigation via emailed reply-to-all, >> rather than via the bugzilla interface? >=20 > Yes, people prefer mailing list to discuss issues. >=20 > Hi T.Kabe,=20 >=20 > Could you provide the call trace again after below patch is applied? > The comment #9 in bugzilla is not very clear to me. >=20 > mm/sparsemem: pfn_to_page is not valid yet on SPARSEMEM > http://lkml.kernel.org/r/20200209104826.3385-7-bhe@redhat.com >=20 > And, as you said, applying above patch, and do not call > __free_pages_core() in generic_online_page() will work. I doubt it, > because without __free_pages_core(), your added pages are not added > into buddy for managing.=20 Removing __free_pages_core() from generic_online_page() is just plain wrong and would break memory hotplug in general. So that is certainly not the right fix. HV supports memory sections that are fully added, but only parts of it are actually backed in the hypervisor, "online" and exposed to the buddy= . When onlining memory, it will online the backed parts via hv_online_page()->generic_online_page(). When requested to hot add more memory, the guest will online remaining parts that are now backed handle_pg_range()->hv_bring_pgs_online(). So if generic_online_page() fails it's either because 1. HV guest driver has a bug and tries to online something it shouldn't 2. HV hypervisor has a bug and does not back memory properly before hot/add= ing 3. Memory hotplug code has a bug and does not properly add the memory block= /sections Please note that to using generic_online_page() in=20 commit 30a9c246b9f6fe0591e8afb05758a3e3b096fabe Author: David Hildenbrand Date: Sat Nov 30 17:53:55 2019 -0800 hv_balloon: use generic_online_page() =20 Let's use the generic onlining function - which will now also take care of calling kernel_map_pages(). However, the old code ended up calling =09__free_pages_core() -> __free_pages() End the new one ends up calling =09__online_page_free() -> __free_reserved_page() -> __free_page() So I don't think it's related to that. Especially, looking at the kernel messages, I can see that the kernel crash= es when adding memory, not when onlining it? So I do think there is still something wrong in the SPARSE hot-add code if you keep seeing issues. --=20 Thanks, David / dhildenb