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[2003:cb:c726:6100:20f2:6848:5b74:ca82]) by smtp.gmail.com with ESMTPSA id c7-20020a05600c0a4700b0041b434e5869sm5092683wmq.43.2024.04.26.01.49.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 26 Apr 2024 01:49:03 -0700 (PDT) Message-ID: Date: Fri, 26 Apr 2024 10:49:02 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: BUG_ON() in pfn_swap_entry_to_page() To: Felix Kuehling , Alistair Popple , Matthew Wilcox Cc: Sebastian Andrzej Siewior , linux-mm@kvack.org, Andrew Morton , Thomas Gleixner References: <871qyt4g4a.fsf@nvdebian.thelocal> <87fsn8hugi.fsf@nvdebian.thelocal> <25b39ce9-9631-45fd-a067-d806ff64e640@redhat.com> From: David Hildenbrand 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: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 2AC3620004 X-Stat-Signature: zj4yu3sxq6tiaba9wnbniinxbwai86t3 X-Rspam-User: X-HE-Tag: 1714121348-745590 X-HE-Meta: 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 ZJx19sG3 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 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: List-Subscribe: List-Unsubscribe: On 25.04.24 16:33, Felix Kuehling wrote: > > > On 2024-04-25 5:32, David Hildenbrand wrote: >> On 24.04.24 21:45, Felix Kuehling wrote: >>> Sorry for top-posting. I'm resurrecting an old thread here because I >>> think I ran into the same problem with this assertion failing on Linux >>> 6.7: >>> >>> static inline struct page *pfn_swap_entry_to_page(swp_entry_t entry) >>> { >>>          struct page *p = pfn_to_page(swp_offset_pfn(entry)); >>> >>>          /* >>>           * Any use of migration entries may only occur while the >>>           * corresponding page is locked >>>           */ >>> -->     BUG_ON(is_migration_entry(entry) && !PageLocked(p)); >>> >>>          return p; >>> } >>> >>> It looks like this thread just fizzled two years ago. Did anything >>> ever come of this? >>> >>> Maybe I should add that I saw this in a pre-silicon test environment. >>> I've never seen this on real hardware. Maybe something timing-sensitive. >> >> In the past, it indicated a swp pte corruption, that would e.g., mess up >> the stored PFN ot the swap entry type. >> >> On which call chain do you see that? >> > > This is the backtrace, it's coming from hmm_range_fault. Looks like the > swap entries are from migrated DEVICE_PRIVATE pages. Thanks, on which kernel version can you reproduce this? > > [Apr 3 20:11] ------------[ cut here ]------------ > [ +0.000041] kernel BUG at include/linux/swapops.h:466! > [ +0.000691] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI > [ +0.000342] CPU: 2 PID: 49 Comm: kworker/2:1 Not tainted > 6.7.0-kfd-compute-rocm-npi-186 #1 > [ +0.000556] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS > rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 > [ +0.000703] Workqueue: events amdgpu_irq_handle_ih_soft [amdgpu] > [ +0.000501] RIP: 0010:migration_entry_wait_on_locked+0x26b/0x2b0 > [ +0.000389] Code: fe ff ff 48 8d 7c 24 07 e8 02 7e f0 ff e9 58 fe ff > ff 48 8b 43 08 a8 01 75 3f 66 90 48 89 d8 48 8b 00 a8 01 0f 85 f1 fd ff > ff <0f> 0b 48 8d 58 ff e9 f7 fd ff ff 48 89 d8 f7 c3 ff 0f 00 00 75 df > [ +0.001161] RSP: 0018:ffffb211c01bb788 EFLAGS: 00010246 > [ +0.000339] RAX: 017fff8000080018 RBX: fffff682c40ce8c0 RCX: > 0000000000000001 > [ +0.000463] RDX: 0000000000000000 RSI: ffff977a45034840 RDI: > 000000000000001a > [ +0.000454] RBP: ffff977a45034840 R08: 68000000001033a3 R09: > 0000000000000030 > [ +0.000451] R10: ffffb211c01bb6a8 R11: 0000000000000001 R12: > ffff977a46bd1318 > [ +0.000461] R13: 0000000000000003 R14: 4000000000000000 R15: > ffffb211c01bb9b8 > [ +0.000454] FS: 0000000000000000(0000) GS:ffff977dafd00000(0000) > knlGS:0000000000000000 > [ +0.000518] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ +0.000372] CR2: 00007fa2d1cba000 CR3: 00000001030d2004 CR4: > 0000000000770ef0 > [ +0.000453] PKRU: 55555554 > [ +0.000182] Call Trace: > [ +0.000171] > [ +0.000147] ? die+0x37/0x90 > [ +0.000211] ? do_trap+0xe0/0x110 > [ +0.000221] ? migration_entry_wait_on_locked+0x26b/0x2b0 > [ +0.000351] ? do_error_trap+0x98/0x120 > [ +0.000252] ? migration_entry_wait_on_locked+0x26b/0x2b0 > [ +0.000346] ? migration_entry_wait_on_locked+0x26b/0x2b0 > [ +0.000355] ? exc_invalid_op+0x52/0x70 > [ +0.000254] ? migration_entry_wait_on_locked+0x26b/0x2b0 > [ +0.000345] ? asm_exc_invalid_op+0x1a/0x20 > [ +0.000274] ? migration_entry_wait_on_locked+0x26b/0x2b0 > [ +0.000361] ? migration_entry_wait+0x4e/0x160 > [ +0.000293] ? lock_release+0x119/0x260 > [ +0.000255] migration_entry_wait+0x105/0x160 > [ +0.000290] hmm_vma_walk_pmd+0x822/0x8a0 > [ +0.000263] walk_pgd_range+0x40b/0x900 > [ +0.000268] __walk_page_range+0x205/0x220 I wonder if that is coming from pmd_migration_entry_wait() or migration_entry_wait() -- the "?" above adds uncertainty :) Likely it's from migration_entry_wait(). I was first concerned about the lack of PTL in this function, but migration_entry_wait() will take the PTL and re-read the PTE. So when we call into migration_entry_wait_on_locked(), we are holding the PTL and we verified that we indeed have a migration entry. So if we fail in migration_entry_wait_on_locked()->pfn_swap_entry_folio(), we verified under PTL and still have a migration entry. The referenced folio is indeed not locked then. -- Cheers, David / dhildenb