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[2003:cb:c747:ff00:9d85:4afb:a7df:6c45]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-390cd8667d5sm6039474f8f.20.2025.02.26.07.53.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 26 Feb 2025 07:53:07 -0800 (PST) Message-ID: <8dd155b4-cdf5-42b9-9865-862184339fc2@redhat.com> Date: Wed, 26 Feb 2025 16:53:06 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm: make page_mapped_in_vma() hugetlb walk aware From: David Hildenbrand To: Jane Chu , willy@infradead.org, peterx@redhat.com, akpm@linux-foundation.org, linmiaohe@huawei.com, kirill.shutemov@linux.intel.com, hughd@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20250224211445.2663312-1-jane.chu@oracle.com> <0e825585-3421-4fa9-8912-41b936f29fae@redhat.com> 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: <0e825585-3421-4fa9-8912-41b936f29fae@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: GqBQ60jMMoujRQhwzEd5q-W_ijDZfZsKhWuRfStq57Y_1740585188 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 9D73140012 X-Stat-Signature: ubk5indpiyem79readnh11shmqg11sjx X-Rspamd-Server: rspam03 X-HE-Tag: 1740585191-468531 X-HE-Meta: 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 CyMmNV3M 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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 26.02.25 16:49, David Hildenbrand wrote: > On 24.02.25 22:14, Jane Chu wrote: >> When a process consumes a UE in a page, the memory failure handler >> attempts to collect information for a potential SIGBUS. >> If the page is an anonymous page, page_mapped_in_vma(page, vma) is >> invoked in order to >> 1. retrieve the vaddr from the process' address space, >> 2. verify that the vaddr is indeed mapped to the poisoned page, >> where 'page' is the precise small page with UE. >> >> It's been observed that when injecting poison to a non-head subpage >> of an anonymous hugetlb page, no SIGBUS show up; while injecting to >> the head page produces a SIGBUS. The casue is that, though hugetlb_walk() >> returns a valid pmd entry (on x86), but check_pte() detects mismatch >> between the head page per the pmd and the input subpage. Thus the vaddr >> is considered not mapped to the subpage and the process is not collected >> for SIGBUS purpose. This is the calling stack >> collect_procs_anon >> page_mapped_in_vma >> page_vma_mapped_walk >> hugetlb_walk >> huge_pte_lock >> check_pte >> > > Why can't we require callers to never pass in subpages of hugetlb pages, > and sanity check that this is the case? To be precise: in collect_procs_anon() pass the head page of the hugetlb page, or in page_mapped_in_vma(), use the head page of the folio for hugetlb folios. hugetlb folios are always entirely mapped, adding logic to detect if sub-pages are mapped doesn't make too much sense. -- Cheers, David / dhildenb