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(p200300d82f1bb8006fdb1af24fbd1fdf.dip0.t-ipconnect.de. [2003:d8:2f1b:b800:6fdb:1af2:4fbd:1fdf]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a4f0097210sm22068168f8f.73.2025.06.04.09.01.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 04 Jun 2025 09:01:19 -0700 (PDT) Message-ID: Date: Wed, 4 Jun 2025 18:01:18 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1] mm/gup: remove (VM_)BUG_ONs To: Jason Gunthorpe Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , John Hubbard , Peter Xu References: <20250604140544.688711-1-david@redhat.com> <20250604151432.GC17991@ziepe.ca> 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: <20250604151432.GC17991@ziepe.ca> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: LK0qqABh5H1OhBXXZyB-yud1RIJF0mP47Xx72dKseaM_1749052881 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: CBF5EA0009 X-Stat-Signature: fkoyr1ym47wtpfa8intsftae4f644w31 X-Rspam-User: X-HE-Tag: 1749052883-372093 X-HE-Meta: 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 V24+wBtA xWVarfK8l0YLsMVtslXpougVR2x8CYD7Mr5TGfE8qyIxUhgsCq/q92u16/1qRxWqhi76Ou96CNOU7rThl/HPu2hGL3sn3iN3OJJ3p5AU8KG1IqFL4J+GrPsoIaZk5DwiKaGgx 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 04.06.25 17:14, Jason Gunthorpe wrote: > On Wed, Jun 04, 2025 at 04:05:44PM +0200, David Hildenbrand wrote: >> Especially once we hit one of the assertions in >> sanity_check_pinned_pages(), observing follow-up assertions failing >> in other code can give good clues about what went wrong, so use >> VM_WARN_ON_ONCE instead. >> >> While at it, let's just convert all VM_BUG_ON to VM_WARN_ON_ONCE as >> well. Add one comment for the pfn_valid() check. >> >> We have to introduce VM_WARN_ON_ONCE_VMA() to make that fly. > > I'm fine with this, but IMHO, using ON_ONCE is wasteful here. > > They have been BUG_ONs for ages, they really do never happen. If there > was ever a case to justify not using ON_ONCE this is it.. Well, history told us that if one of them happens, we get a whole flood. ... which is usually not particularly helpful when trying to extract information from a syslog :) DEBUG_VM is already "wasteful" ... ;) -- Cheers, David / dhildenb