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(p200300d82f0e2c00d6bb8859fbbcb8a9.dip0.t-ipconnect.de. [2003:d8:2f0e:2c00:d6bb:8859:fbbc:b8a9]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-458953eb7acsm194716745e9.28.2025.08.04.01.30.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 04 Aug 2025 01:30:46 -0700 (PDT) Message-ID: Date: Mon, 4 Aug 2025 10:30:45 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] mm: use per_vma lock for MADV_DONTNEED To: Qi Zheng , "Lai, Yi" , Barry Song <21cnbao@gmail.com> Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Barry Song , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Jann Horn , Suren Baghdasaryan , Lokesh Gidra , Tangquan Zheng , yi1.lai@intel.com References: <20250607220150.2980-1-21cnbao@gmail.com> <1d1d97f9-2a67-4920-850e-accf4c82440e@redhat.com> <4fa8f492-c7ef-451c-8dc7-38b031c8a092@bytedance.com> From: David Hildenbrand Content-Language: en-US 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/g1oFAmgsLPQFCRvGjuMACgkQTd4Q 9wD/g1o0bxAAqYC7gTyGj5rZwvy1VesF6YoQncH0yI79lvXUYOX+Nngko4v4dTlOQvrd/vhb 02e9FtpA1CxgwdgIPFKIuXvdSyXAp0xXuIuRPQYbgNriQFkaBlHe9mSf8O09J3SCVa/5ezKM OLW/OONSV/Fr2VI1wxAYj3/Rb+U6rpzqIQ3Uh/5Rjmla6pTl7Z9/o1zKlVOX1SxVGSrlXhqt kwdbjdj/csSzoAbUF/duDuhyEl11/xStm/lBMzVuf3ZhV5SSgLAflLBo4l6mR5RolpPv5wad GpYS/hm7HsmEA0PBAPNb5DvZQ7vNaX23FlgylSXyv72UVsObHsu6pT4sfoxvJ5nJxvzGi69U s1uryvlAfS6E+D5ULrV35taTwSpcBAh0/RqRbV0mTc57vvAoXofBDcs3Z30IReFS34QSpjvl Hxbe7itHGuuhEVM1qmq2U72ezOQ7MzADbwCtn+yGeISQqeFn9QMAZVAkXsc9Wp0SW/WQKb76 FkSRalBZcc2vXM0VqhFVzTb6iNqYXqVKyuPKwhBunhTt6XnIfhpRgqveCPNIasSX05VQR6/a OBHZX3seTikp7A1z9iZIsdtJxB88dGkpeMj6qJ5RLzUsPUVPodEcz1B5aTEbYK6428H8MeLq NFPwmknOlDzQNC6RND8Ez7YEhzqvw7263MojcmmPcLelYbfOwU0EVcufkQEQAOfX3n0g0fZz 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+DWgUCaCwtJQUJG8aPFAAKCRBN3hD3AP+DWlDnD/4k2TW+HyOOOePVm23F5HOhNNd7nNv3 Vq2cLcW1DteHUdxMO0X+zqrKDHI5hgnE/E2QH9jyV8mB8l/ndElobciaJcbl1cM43vVzPIWn 01vW62oxUNtEvzLLxGLPTrnMxWdZgxr7ACCWKUnMGE2E8eca0cT2pnIJoQRz242xqe/nYxBB /BAK+dsxHIfcQzl88G83oaO7vb7s/cWMYRKOg+WIgp0MJ8DO2IU5JmUtyJB+V3YzzM4cMic3 bNn8nHjTWw/9+QQ5vg3TXHZ5XMu9mtfw2La3bHJ6AybL0DvEkdGxk6YHqJVEukciLMWDWqQQ RtbBhqcprgUxipNvdn9KwNpGciM+hNtM9kf9gt0fjv79l/FiSw6KbCPX9b636GzgNy0Ev2UV m00EtcpRXXMlEpbP4V947ufWVK2Mz7RFUfU4+ETDd1scMQDHzrXItryHLZWhopPI4Z+ps0rB CQHfSpl+wG4XbJJu1D8/Ww3FsO42TMFrNr2/cmqwuUZ0a0uxrpkNYrsGjkEu7a+9MheyTzcm vyU2knz5/stkTN2LKz5REqOe24oRnypjpAfaoxRYXs+F8wml519InWlwCra49IUSxD1hXPxO WBe5lqcozu9LpNDH/brVSzHCSb7vjNGvvSVESDuoiHK8gNlf0v+epy5WYd7CGAgODPvDShGN g3eXuA== Organization: Red Hat In-Reply-To: <4fa8f492-c7ef-451c-8dc7-38b031c8a092@bytedance.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 04.08.25 10:26, Qi Zheng wrote: > > > On 8/4/25 3:57 PM, David Hildenbrand wrote: >> On 04.08.25 02:58, Lai, Yi wrote: >>> Hi Barry Song, >>> >>> Greetings! >>> >>> I used Syzkaller and found that there is general protection fault in >>> __pte_offset_map_lock in linux-next next-20250801. >>> >>> After bisection and the first bad commit is: >>> " >>> a6fde7add78d mm: use per_vma lock for MADV_DONTNEED >>> " >>> >>> All detailed into can be found at: >>> https://github.com/laifryiee/syzkaller_logs/tree/ >>> main/250803_193026___pte_offset_map_lock >>> Syzkaller repro code: >>> https://github.com/laifryiee/syzkaller_logs/tree/ >>> main/250803_193026___pte_offset_map_lock/repro.c >>> Syzkaller repro syscall steps: >>> https://github.com/laifryiee/syzkaller_logs/tree/ >>> main/250803_193026___pte_offset_map_lock/repro.prog >>> Syzkaller report: >>> https://github.com/laifryiee/syzkaller_logs/tree/ >>> main/250803_193026___pte_offset_map_lock/repro.report >>> Kconfig(make olddefconfig): >>> https://github.com/laifryiee/syzkaller_logs/tree/ >>> main/250803_193026___pte_offset_map_lock/kconfig_origin >>> Bisect info: >>> https://github.com/laifryiee/syzkaller_logs/tree/ >>> main/250803_193026___pte_offset_map_lock/bisect_info.log >>> bzImage: >>> https://github.com/laifryiee/syzkaller_logs/raw/refs/heads/ >>> main/250803_193026___pte_offset_map_lock/bzImage_next-20250801 >>> Issue dmesg: >>> https://github.com/laifryiee/syzkaller_logs/blob/ >>> main/250803_193026___pte_offset_map_lock/next-20250801_dmesg.log >> >> Skimming over the reproducer, we seem to have racing MADV_DONTNEED and >> MADV_COLLAPSE on the same anon area, but the problem only shows up once >> we tear down that MM. >> >> If I would have to guess, I'd assume it's related to PT_RECLAIM >> reclaiming empty page tables during MADV_DONTNEED -- but the kconfig >> does not indicate that CONFIG_PT_RECLAIM was set. > > On the x86_64, if PT_RECLAIM is not manually disabled, PT_RECLAIM should > be enabled That's what I thought: but I was not able to spot it in the provided config [1]. Or is that config *before* "make olfconfig"? confusing. I would want to see the actually used config. [1] https://github.com/laifryiee/syzkaller_logs/tree/main/250803_193026___pte_offset_map_lock/kconfig_origin -- Cheers, David / dhildenb