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[91.12.107.89]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3825fad60f0sm1867734f8f.22.2024.11.22.01.32.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 22 Nov 2024 01:32:21 -0800 (PST) Message-ID: <608c7f17-037b-401b-9336-c26bd45d3147@redhat.com> Date: Fri, 22 Nov 2024 10:32:19 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1] mm/mempolicy: fix migrate_to_node() assuming there is at least one VMA in a MM To: Andrew Morton , "Liam R. Howlett" Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzbot+3511625422f7aa637f0d@syzkaller.appspotmail.com, stable@vger.kernel.org, Christoph Lameter References: <20241120201151.9518-1-david@redhat.com> <20241121221937.c41ee2b5e8534729e94fc104@linux-foundation.org> 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: <20241121221937.c41ee2b5e8534729e94fc104@linux-foundation.org> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: bOZsE27FV-EVPuYPQuxUu72AWx_dxHZynH1pnkx2OFk_1732267942 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 1558480005 X-Stat-Signature: p4k4nx9rmrdek4ye8j736tu7nhoordip X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1732267843-14840 X-HE-Meta: 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 RJOkzlc3 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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 22.11.24 07:19, Andrew Morton wrote: > On Wed, 20 Nov 2024 15:27:46 -0500 "Liam R. Howlett" wrote: > >> I hate the extra check because syzbot can cause this as this should >> basically never happen in real life, but it seems we have to add it. > > So.. > > --- a/mm/mempolicy.c~mm-mempolicy-fix-migrate_to_node-assuming-there-is-at-least-one-vma-in-a-mm-fix > +++ a/mm/mempolicy.c > @@ -1080,7 +1080,7 @@ static long migrate_to_node(struct mm_st > > mmap_read_lock(mm); > vma = find_vma(mm, 0); > - if (!vma) { > + if (unlikely(!vma)) { > mmap_read_unlock(mm); > return 0; > } > _ > > ? Why not, at least for documentation purposes. Because I don't think this is any fast-path we really care about, so expect the runtime effects to be mostly negligible. Thanks! -- Cheers, David / dhildenb