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[2003:cb:c708:1500:d584:7ad8:d3f7:5539]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-381eda03e8asm18765330f8f.90.2024.11.13.08.25.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 13 Nov 2024 08:25:30 -0800 (PST) Message-ID: <5929cbc4-d8c5-4b1b-b7ca-b4daf47b13d0@redhat.com> Date: Wed, 13 Nov 2024 17:25:29 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC for stable 5.15 and 5.10] mm/memory: only copy anonymous pages during fork() To: Vlastimil Babka , linux-mm@kvack.org Cc: Peter Xu References: <20241113160103.48943-2-vbabka@suse.cz> <5c881108-41d8-4e8c-a1ec-9c04bc68a008@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: 6J_4APkAMJrv8EY1kbNy3AGXoiDylcp3gei-ThHrTyE_1731515131 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: rspam04 X-Rspamd-Queue-Id: 30DF3A0005 X-Stat-Signature: oej4g8s4cckw75jyywe6xhqth6udozua X-Rspam-User: X-HE-Tag: 1731515089-951442 X-HE-Meta: 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 FIrvkken SBdIMvKjTEZSk9JmH4+oU6xdGpFFDkExBD336k1NlJ7/4pRfl3ojUJK+jQS3hn1YUuM9NeAKuLO++jlQOSoRcgnw59TwxDrt+DAuaeTR2hODBrerTPtzTZt3QwK4TlqD+qRieBUtMMmPHo3GgIWnlmRPBZmVxiPUVKAK5AXGhpOVfn/j5bULqwV+MKT8J5aHOIbDjM0CN+RXkzzkwCOAaD/V/8V3PpBx15QoqoMUwarrlj3ox4+HvSHGuZ1qCB3FVOU2FQCGEQRWtVqWHqlNxVXlNXAmjZfs06P4HweZG6C5hH2If1oxeUupbgGreq6KW364TyBa7YMSKp3V9UOVqLF6lHpE/QGnHnHuZyJlovm+DJKeiY6QfftyBe1glKMBK92w5poXMPShfX7FCuuZ3Fk/5quusckBrEjJEx4zQg705SGqLCiQzvgVsUB0Fj4avCt2F 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 13.11.24 17:18, Vlastimil Babka wrote: > On 11/13/24 17:09, David Hildenbrand wrote: >>> --- >>> Hi, we've seen this in our 5.14 based kernel and it involved the out of >>> tree gpfs module, but I believe the same thing can happen in LTS's 5.10 >>> and 5.15 without out of tree modules as well. So I'd like your opinion >>> on this fix before I propose it to stable as a non-standard >>> version-specific fix (I don't think we'd want to backport fb3d824d1a46 >>> with prerequisities). Thanks. >> >> I recall seeing+discussing this exact patch already a couple years ago :D >> >> Ah, here is the 5.15 version >> >> https://lkml.kernel.org/r/20221028075244.3112566-1-songyuanzheng@huawei.com >> >> And the 5.10 version >> >> https://lore.kernel.org/lkml/20221024094911.3054769-1-songyuanzheng@huawei.com/ >> >> >> ... I could have sworn they got applied. >> >> ... and in linux-5.10.y I see >> >> commit 935a8b6202101d7f58fe9cd11287f9cec0d8dd32 >> Author: Yuanzheng Song >> Date: Fri Oct 28 03:07:05 2022 +0000 >> >> mm/memory: add non-anonymous page check in the copy_present_page() >> >> The vma->anon_vma of the child process may be NULL because >> the entire vma does not contain anonymous pages. In this >> case, a BUG will occur when the copy_present_page() passes >> a copy of a non-anonymous page of that vma to the >> page_add_new_anon_rmap() to set up new anonymous rmap. >> >> >> >> Maybe you missed that the PageAnon() check is simply a couple of lines >> further down in there? > > No I was only looking at the 5.15 branch so far, and seems it was never > applied there, unlike 5.10. Weird. But thanks for the heads up. Indeed, looks like it never got applied to 5.15 ... -- Cheers, David / dhildenb