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[2003:cb:c70e:2600:cd60:7701:f644:b131]) by smtp.gmail.com with ESMTPSA id iv14-20020a05600c548e00b00412ee7d65a6sm400743wmb.6.2024.03.13.15.26.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 13 Mar 2024 15:26:23 -0700 (PDT) Message-ID: Date: Wed, 13 Mar 2024 23:26:22 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/memory: Fix missing pte marker for !page on pte zaps From: David Hildenbrand To: peterx@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Andrew Morton , Muhammad Usama Anjum References: <20240313213107.235067-1-peterx@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: X-Mimecast-Spam-Score: 0 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: 0025A40008 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: 7zip8zo9soft41ygh5tztugrn46ae8tc X-HE-Tag: 1710368786-599475 X-HE-Meta: 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 XWbEW5yx HEnnbX4psTrXFwX4FtIpalP4LVuaBGP50uk6Iy0SjB9gSDfhAWSQl3NyJntZQ72Oilc2DKkn/4EfcV8r2zUnOznQuAwWsplPx4JPkF5GZjjXbQO0CqJOCV0GL0sIQA2vpW5aU6iP6TH4PMVhlf9n2x+QurCIb29xNvZ+st09fpuBeIGrKBFm4OQdmUn8wRtbS6i44OIMRhrW3H/o2FeOA26T5mmAn/uHNADK88A1L6p/O+EyuhQtAUiIzyEkmfofOv4vXbzM4L7rUttzMwxUEGmU6qHtjeO7Xs1reiCb8pPFDVSxea+OQD+mdigAGlUOthu1YrvYB4wXo7I9MPnIJZ2+BaNCtd+vQMt8OYiNUVljVKohiqgYvsH6+twuuMwI/1CL9y+SF6ehj+VyCQ+kFBKcKFBgscg9rd5vQLjOXIx68zaY6+oxew8yFyGZturhWt3cuD382lse1fPItnoXH5ccrRlBjLNCY3awOcrhwbudAdnE= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000244, 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 13.03.24 23:03, David Hildenbrand wrote: > On 13.03.24 22:31, peterx@redhat.com wrote: >> From: Peter Xu >> >> Commit 0cf18e839f64 of large folio zap work broke uffd-wp. Now mm's uffd >> unit test "wp-unpopulated" will trigger this WARN_ON_ONCE(). > > Good that I added the WARN_ON_ONCE() :) > >> >> The WARN_ON_ONCE() asserts that an VMA cannot be registered with >> userfaultfd-wp if it contains a !normal page, but it's actually possible. >> One example is an anonymous vma, register with uffd-wp, read anything will >> install a zero page. Then when zap on it, this should trigger. > > Are you sure? zap_install_uffd_wp_if_needed() contains right at the start: > > /* Zap on anonymous always means dropping everything */ > if (vma_is_anonymous(vma)) > return; > > So if that's the case the unit test triggers, I'm confused. Ah, got it. It's not that we have to place a marker, just that it can happen. Of course it can. All makes sense. Thanks! -- Cheers, David / dhildenb