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([2a09:80c0:192:0:5dac:bf3d:c41:c3e7]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38a8e37d11csm11752748f8f.16.2025.01.13.01.30.55 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 13 Jan 2025 01:30:56 -0800 (PST) Message-ID: Date: Mon, 13 Jan 2025 10:30:55 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/3] selftests/mm: virtual_address_range: Avoid reading VVAR mappings To: =?UTF-8?Q?Thomas_Wei=C3=9Fschuh?= Cc: Andrew Morton , Shuah Khan , Dev Jain , Thomas Gleixner , linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, kernel test robot References: <20250110-virtual_address_range-tests-v2-0-262a2bf3c3d0@linutronix.de> <20250110-virtual_address_range-tests-v2-3-262a2bf3c3d0@linutronix.de> <9243dd8e-3f03-4ed5-bdcf-95c947c57849@redhat.com> <20250113095211-bde77070-8be1-4393-898e-22eff532189b@linutronix.de> 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: <20250113095211-bde77070-8be1-4393-898e-22eff532189b@linutronix.de> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: wONNeBkgKElBX3pDHacvPTt-4UFj--joWL_iKUI2uZc_1736760657 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: B3A52100016 X-Rspamd-Server: rspam12 X-Stat-Signature: 9uiqh4hp4ced8xwn5dwopkbw3fs7yx1m X-Rspam-User: X-HE-Tag: 1736760662-142014 X-HE-Meta: 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 YhrbMTAo 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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 13.01.25 10:09, Thomas Weißschuh wrote: > On Fri, Jan 10, 2025 at 04:41:03PM +0100, David Hildenbrand wrote: >> On 10.01.25 14:05, Thomas Weißschuh wrote: >>> The virtual_address_range selftest reads from the start of each mapping >>> listed in /proc/self/maps. >>> However not all mappings are valid to be arbitrarily accessed. >>> For example the vvar data used for virtual clocks on x86 [vvar_vclock] >>> can only be accessed if 1) the kernel configuration enables virtual >>> clocks and 2) the hypervisor provided the data for it. >>> Only the VDSO itself has the necessary information to know this. >>> Since commit e93d2521b27f ("x86/vdso: Split virtual clock pages into dedicated mapping") >>> the virtual clock data was split out into its own mapping, leading >>> to EFAULT from read() during the validation. >>> >>> Skip the various vvar mappings in virtual_address_range to avoid the issue. >>> >>> Fixes: e93d2521b27f ("x86/vdso: Split virtual clock pages into dedicated mapping") >>> Fixes: 010409649885 ("selftests/mm: confirm VA exhaustion without reliance on correctness of mmap()") >>> Reported-by: kernel test robot >>> Closes: https://lore.kernel.org/oe-lkp/202412271148.2656e485-lkp@intel.com >>> Signed-off-by: Thomas Weißschuh >>> --- >>> tools/testing/selftests/mm/virtual_address_range.c | 4 ++++ >>> 1 file changed, 4 insertions(+) >>> >>> diff --git a/tools/testing/selftests/mm/virtual_address_range.c b/tools/testing/selftests/mm/virtual_address_range.c >>> index 4fc1c21a5e218eaec4d059b75c31a21dd4e8a215..993990aba56fc986c42084ffa91973558aa07e87 100644 >>> --- a/tools/testing/selftests/mm/virtual_address_range.c >>> +++ b/tools/testing/selftests/mm/virtual_address_range.c >>> @@ -152,6 +152,10 @@ static int validate_complete_va_space(void) >>> if (prot[0] != 'r') >>> continue; >>> + /* Only the VDSO can know if a VVAR mapping is really readable */ >>> + if (vma_name && !strncmp(vma_name, "[vvar", 5)) >>> + continue; >> >> I'm wondering if there is a more generic way ... but likely not when staring >> at /proc/self/maps. >> >> /proc/self/smaps would indicate this as >> >> VM_IO: "io" >> VM_DONTDUMP: "dd" >> VM_PFNMAP: "pf" >> >> Especially checking for VM_IO sounds reasonable ... > > Agreed. > > Can we instead rely on madvise(MADV_DOFORK) returning EINVAL iff VM_IO? That might be one option indeed, although it feels like this is something that might change in the future ... not sure. MADV_POPULATE_READ fails with -EFAULT on VM_IO, but also on VM_PFNMAP and some other conditions, and might not be completely what we want. We do have some initial smaps parsing in vm_util.c:__check_huge(), maybe that could be factored out / reused, not sure how hard that would be to extend to return the flags. -- Cheers, David / dhildenb