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[2003:cb:c708:9d00:edd9:835b:4bfb:2ce3]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38a1c847d7fsm3499780f8f.60.2024.12.20.00.50.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 20 Dec 2024 00:50:25 -0800 (PST) Message-ID: Date: Fri, 20 Dec 2024 09:50:23 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm/memory-failure: fix VM_BUG_ON_PAGE(PagePoisoned(page)) when unpoison memory To: Miaohe Lin , akpm@linux-foundation.org, Dan Williams Cc: nao.horiguchi@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20241219115209.574065-1-linmiaohe@huawei.com> <06a45f8a-0981-40a2-a12a-5964fcdace13@redhat.com> From: David Hildenbrand Content-Language: en-US Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz 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+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 20.12.24 03:35, Miaohe Lin wrote: > On 2024/12/19 20:18, David Hildenbrand wrote: >> On 19.12.24 12:52, Miaohe Lin wrote: >>> When I did memory failure tests recently, below panic occurs: >>> >>> page dumped because: VM_BUG_ON_PAGE(PagePoisoned(page)) >>> kernel BUG at include/linux/page-flags.h:616! >>> Oops: invalid opcode: 0000 [#1] PREEMPT SMP NOPTI >>> CPU: 3 PID: 720 Comm: bash Not tainted 6.10.0-rc1-00195-g148743902568 #40 >>> RIP: 0010:unpoison_memory+0x2f3/0x590 >>> RSP: 0018:ffffa57fc8787d60 EFLAGS: 00000246 >>> RAX: 0000000000000037 RBX: 0000000000000009 RCX: ffff9be25fcdc9c8 >>> RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff9be25fcdc9c0 >>> RBP: 0000000000300000 R08: ffffffffb4956f88 R09: 0000000000009ffb >>> R10: 0000000000000284 R11: ffffffffb4926fa0 R12: ffffe6b00c000000 >>> R13: ffff9bdb453dfd00 R14: 0000000000000000 R15: fffffffffffffffe >>> FS:  00007f08f04e4740(0000) GS:ffff9be25fcc0000(0000) knlGS:0000000000000000 >>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>> CR2: 0000564787a30410 CR3: 000000010d4e2000 CR4: 00000000000006f0 >>> Call Trace: >>>   >>>   unpoison_memory+0x2f3/0x590 >>>   simple_attr_write_xsigned.constprop.0.isra.0+0xb3/0x110 >>>   debugfs_attr_write+0x42/0x60 >>>   full_proxy_write+0x5b/0x80 >>>   vfs_write+0xd5/0x540 >>>   ksys_write+0x64/0xe0 >>>   do_syscall_64+0xb9/0x1d0 >>>   entry_SYSCALL_64_after_hwframe+0x77/0x7f >>> RIP: 0033:0x7f08f0314887 >>> RSP: 002b:00007ffece710078 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 >>> RAX: ffffffffffffffda RBX: 0000000000000009 RCX: 00007f08f0314887 >>> RDX: 0000000000000009 RSI: 0000564787a30410 RDI: 0000000000000001 >>> RBP: 0000564787a30410 R08: 000000000000fefe R09: 000000007fffffff >>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000009 >>> R13: 00007f08f041b780 R14: 00007f08f0417600 R15: 00007f08f0416a00 >>>   >>> Modules linked in: hwpoison_inject >>> ---[ end trace 0000000000000000 ]--- >>> RIP: 0010:unpoison_memory+0x2f3/0x590 >>> RSP: 0018:ffffa57fc8787d60 EFLAGS: 00000246 >>> RAX: 0000000000000037 RBX: 0000000000000009 RCX: ffff9be25fcdc9c8 >>> RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff9be25fcdc9c0 >>> RBP: 0000000000300000 R08: ffffffffb4956f88 R09: 0000000000009ffb >>> R10: 0000000000000284 R11: ffffffffb4926fa0 R12: ffffe6b00c000000 >>> R13: ffff9bdb453dfd00 R14: 0000000000000000 R15: fffffffffffffffe >>> FS:  00007f08f04e4740(0000) GS:ffff9be25fcc0000(0000) knlGS:0000000000000000 >>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>> CR2: 0000564787a30410 CR3: 000000010d4e2000 CR4: 00000000000006f0 >>> Kernel panic - not syncing: Fatal exception >>> Kernel Offset: 0x31c00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) >>> ---[ end Kernel panic - not syncing: Fatal exception ]--- >>> >>> The root cause is that unpoison_memory() tries to check the PG_HWPoison >>> flags of an uninitialized page. So VM_BUG_ON_PAGE(PagePoisoned(page)) is >>> triggered. This can be reproduced by below steps: >>> 1.Offline memory block: >>>   echo offline > /sys/devices/system/memory/memory12/state >>> 2.Get offlined memory pfn: >>>   page-types -b n -rlN >>> 3.Write pfn to unpoison-pfn >>>   echo > /sys/kernel/debug/hwpoison/unpoison-pfn >>> >>> Signed-off-by: Miaohe Lin >>> --- >>> v2: Use pfn_to_online_page per David. Thanks. >>> --- >>>   mm/memory-failure.c | 14 +++++++++++--- >>>   1 file changed, 11 insertions(+), 3 deletions(-) >>> >>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c >>> index a7b8ccd29b6f..02be0596ce67 100644 >>> --- a/mm/memory-failure.c >>> +++ b/mm/memory-failure.c >>> @@ -2556,10 +2556,18 @@ int unpoison_memory(unsigned long pfn) >>>       static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL, >>>                       DEFAULT_RATELIMIT_BURST); >>>   -    if (!pfn_valid(pfn)) >>> -        return -ENXIO; >>> +    p = pfn_to_online_page(pfn); >>> +    if (!p) { >>> +        struct dev_pagemap *pgmap; >>>   -    p = pfn_to_page(pfn); >>> +        if (!pfn_valid(pfn)) >>> +            return -ENXIO; >>> +        pgmap = get_dev_pagemap(pfn, NULL); >>> +        if (!pgmap) >>> +            return -ENXIO; >>> +        put_dev_pagemap(pgmap); >>> +        p = pfn_to_page(pfn); >>> +    } >> >> Hm, I wonder if we can do anything reasonable with ZONE_DEVICE pages here? > > All I can see in unpoison_memory() is folio_test_clear_hwpoison() for ZONE_DEVICE pages. IIRC, it can only be triggered via debugfs in special kernel configs. So chances are this was never ever actually run against a ZONE_DEVICE page. > >> >> CCing Dan, maybe he knows if this interface used to do something reasonable with ZONE_DEVICE pages. >> >> Also, I'm not sure about using the page after doing the put_dev_pagemap(). Likely we would have to do that at the before exiting from this function. > > IMHO, the page can be used after doing put_dev_pagemap(). The page should still be > available while it has HWPoison set. 1) Why do you think it can be used afterwards? :) 2) At that point in time you don't even know yet if the page is HWPoisoned! That check is performed later 3) From GUP code, I recall that we must keep the pagemap referenced until we grabbed a page/folio reference. Or are you worrying about memory offline? That > might not be the scope of this problem. But I might be miss something. I suspect unpoison_memory() doesn't do with ZONE_DEVICE pages what it should be doing. Maybe I'm wrong, it would be great to get feedback from Dan. -- Cheers, David / dhildenb