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Mon, 17 Feb 2020 10:24:20 +0000 (UTC) Received: from [10.36.117.64] (ovpn-117-64.ams2.redhat.com [10.36.117.64]) by smtp.corp.redhat.com (Postfix) with ESMTP id 052778DC1E; Mon, 17 Feb 2020 10:24:14 +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, Oscar Salvador Cc: bugzilla-daemon@bugzilla.kernel.org, akpm@linux-foundation.org, richardw.yang@linux.intel.com, mhocko@kernel.org, n-horiguchi@ah.jp.nec.com, linux-mm@kvack.org References: <20200212073123.GG8965@MiWiFi-R3L-srv> <200217144627.M0113305@vega.pgw.jp> <20200217093447.GA1139@linux> <20200217101318.GL26758@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: <383e5dbf-b402-575d-8dae-5e92b51e9834@redhat.com> Date: Mon, 17 Feb 2020 11:24:13 +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: <20200217101318.GL26758@MiWiFi-R3L-srv> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-MC-Unique: bCjiF_zkNDa0sdvtoGGBLQ-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 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 17.02.20 11:13, Baoquan He wrote: > On 02/17/20 at 10:34am, Oscar Salvador wrote: >> On Mon, Feb 17, 2020 at 02:46:27PM +0900, kkabe@vega.pgw.jp wrote: >>> =========================================== >>> struct page * __meminit populate_section_memmap(unsigned long pfn, >>> unsigned long nr_pages, int nid, struct vmem_altmap *altmap) >>> { >>> struct page *page, *ret; >>> unsigned long memmap_size = sizeof(struct page) * PAGES_PER_SECTION; >>> >>> page = alloc_pages(GFP_KERNEL|__GFP_NOWARN, get_order(memmap_size)); >>> if (page) { >>> goto got_map_page; >>> } >>> pr_info("%s: alloc_pages() returned 0x%p (should be 0), reverting to vmalloc(memmap_size=%lu)\n", __func__, page, memmap_size); >>> BUG_ON(page != 0); >>> >>> ret = vmalloc(memmap_size); >>> pr_info("%s: vmalloc(%lu) returned 0x%p\n", __func__, memmap_size, ret); >>> if (ret) { >>> goto got_map_ptr; >>> } >>> >>> return NULL; >>> got_map_page: >>> ret = (struct page *)pfn_to_kaddr(page_to_pfn(page)); >>> pr_info("%s: allocated struct page *page=0x%p\n", __func__, page); >>> got_map_ptr: >>> >>> pr_info("%s: returning struct page * =0x%p\n", __func__, ret); >>> return ret; >>> } >> >> Could you please replace %p with %px. Wih the first, pointers are hashed so it is trickier >> to get an overview of the meaning. >> >> David could be right about ZONE_NORMAL vs ZONE_HIGHMEM. >> IIUC, default_kernel_zone_for_pfn and default_zone_for_pfn seem to only deal with >> (ZONE_DMA,ZONE_NORMAL] or ZONE_MOVABLE. > > Ah, I think you both have spotted the problem. > > In i386, if w/o momory hot add, normal memory will only include those > below 896M and they are added into normal zone. The left are added into > highmem zone. > > How this influence the page allocation? > > Very huge. As we know, in i386, normal memory can be accessed with > virt_to_phys, namely PAGE_OFFSET + phys. But highmem has to be accessed > with kmap. However, the later hot added memory are all put into normal > memmory, accessing into them will stump into vmalloc area, I would say. > > So, i386 doesn't support memory hot add well. Not sure if below change > can make it work normally. > > We can just adjus the hot adding code as we have done for boot memmory. > Iterate zone from highmem if allowed when hot add memory. > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 475d0d68a32c..1380392d9ef5 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -716,7 +716,10 @@ static struct zone *default_kernel_zone_for_pfn(int nid, unsigned long start_pfn > struct pglist_data *pgdat = NODE_DATA(nid); > int zid; > > - for (zid = 0; zid <= ZONE_NORMAL; zid++) { > + for (zid = 0; zid < MAX_NR_ZONES; zid++) { ZONE_DEVICE? :/ > + if (zid == ZONE_MOVABLE) > + continue; > + > struct zone *zone = &pgdat->node_zones[zid]; > > if (zone_intersects(zone, start_pfn, nr_pages)) > > What if somebody onlines memory from user space explicitly to the normal zone? We can trigger crashes? This doesn't look like it ever worked reliably, can we just disable memory hotplug in case we have PAE? (especially, as continued i386 support is questionable) -- Thanks, David / dhildenb