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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato References: <20250617154345.2494405-1-david@redhat.com> <20250617154345.2494405-2-david@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-MFC-PROC-ID: NjeVbagD9DIyHA1H2fCXJoeNgTlVyWKf9YKFxm3yYBk_1750687445 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: rspam03 X-Stat-Signature: uciw6xcsmae38831p95n8jda7fmtu6dm X-Rspam-User: X-Rspamd-Queue-Id: 59311120005 X-HE-Tag: 1750687448-592364 X-HE-Meta: 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 jyy5PG9n LmQQM4EHIkngn07L1FiY6xflrVn2uRDv2i7umA4GL+yidFzK0ucG64+oE0gxpN6nwH+Pef6+t3UPzQvnjtmmclAiZ+760jgJs4Hh2s0OKwBmHjWpmRLVNFh+qvu00urkZa1owa6OipONs9ba4056OM8nbQ3S4DbdmKSVSYQAKuHbkZReBkOPNkXU96hQS4RFDGywthQKxZffH8H4VGnQbzprYuKZcVjRaaqnW6dunMGIuAjtUG+W/iVLSoYgYpUAjLiGJxclLjHRJOSzCdkG74CMgoDTyWt6mg09URRuqrU0mNIayozn7OHWS/aOjq7Yl0YIkuQIuQnk51KYp4mvevPHDJetObsag2KOSKEy8bdZA2grbtohhsQxvdDVvgVPApEMxQ5UqlGgxOVschL2ZAOV+1oSrgxNnXLWtahCW0BqsRN1ParmRE64sdJdMm19B+ivTqKR4UPk7J5c1X7eqhaFYQiUreo/CjRfN 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 20.06.25 14:50, Oscar Salvador wrote: > On Tue, Jun 17, 2025 at 05:43:32PM +0200, David Hildenbrand wrote: >> In 2009, we converted a VM_BUG_ON(!pfn_valid(pfn)) to the current >> highest_memmap_pfn sanity check in commit 22b31eec63e5 ("badpage: >> vm_normal_page use print_bad_pte"), because highest_memmap_pfn was >> readily available. >> >> Nowadays, this is the last remaining highest_memmap_pfn user, and this >> sanity check is not really triggering ... frequently. >> >> Let's convert it to VM_WARN_ON_ONCE(!pfn_valid(pfn)), so we can >> simplify and get rid of highest_memmap_pfn. Checking for >> pfn_to_online_page() might be even better, but it would not handle >> ZONE_DEVICE properly. >> >> Do the same in vm_normal_page_pmd(), where we don't even report a >> problem at all ... >> >> What might be better in the future is having a runtime option like >> page-table-check to enable such checks dynamically on-demand. Something >> for the future. >> >> Signed-off-by: David Hildenbrand > Hi Oscar, > I'm confused, I'm missing something here. > Before this change we would return NULL if e.g: pfn > highest_memmap_pfn, but > now we just print the warning and call pfn_to_page() anyway. > AFAIK, pfn_to_page() doesn't return NULL? You're missing that vm_normal_page_pmd() was created as a copy from vm_normal_page() [history of the sanity check above], but as we don't have (and shouldn't have ...) print_bad_pmd(), we made the code look like this would be something that can just happen. " Do the same in vm_normal_page_pmd(), where we don't even report a problem at all ... " So we made something that should never happen a runtime sanity check without ever reporting a problem ... -- Cheers, David / dhildenb