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b=oWYj+DK9G7R7SbizbH3STLSaU8Lo6I4REPxazn98tRvg8owFxze7IZD0Fgc8ONMao 3iQ/lzXs009ZGq92BwM6afz6LtquWd5BXicLzg6k0Cp0qr1bkgsBG1odk/EyExAqqo ArRnWP7cDxcy0erdcHEX2ZEn+RPjVxLKpxAxGXukSTuMGIzMjCGUwJNDC6Ip8SH50/ MYBGLV+9X+w0/g5AMlJDGCSqYKCNzpGzR52mzkVZOCM6k8F+k+DRf/CjRLGDowEsrp q+RNgtkqGfvwwEdSPAwgfjoNhm3LSQraEc/DG8VFjUrBXGE/rAUY3/3SlVOYdwqCaN Y8Hq6uOXTl3dg== Message-ID: <24cbde8e-53b1-48bb-b44d-2b4bdc674d55@kernel.org> Date: Wed, 25 Feb 2026 14:50:16 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: VM_BUG_ON_VMA in split_huge_pmd_locked: huge PMD doesn't cover full VMA range To: Sasha Levin , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Lorenzo Stoakes , Andrew Morton , Hugh Dickins , Zi Yan , Gavin Guo References: From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 7573B80011 X-Stat-Signature: s73a8m5yu96wjfurbbnhq4jn6j7a4quo X-HE-Tag: 1772027421-88102 X-HE-Meta: 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 5aX9TlWg EI2+Dt1uRWaYTKdagl/ysMcCowXd1WFkdYjJUpbKkMnKNepzmgW4/KXFNkXieppm15DZMLno+Z+PuFVnKryV3apKzo6ftUZ0pNyAoYRzNsr8IbS3X21/J1Z/51IvSG1BXZ/r83k3wS6LlAqAw/HL/0UGRMJ691CPkH3SptvKGMvGQeWNQHj9wvnj0ukM8nSBFk6cMu18XMT5e64AaVOxxroGdRrc2K5jyy2fOLWQ3+TSDMn3saKL727mI0fD8MoiQgzaYtB5ciD0JcUOtxpiyLFKpRtPm2yIta7V8F51YXU1Fn1huDz18gmZOr4rQlVdKifC4cYKihxQ/h10= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2/25/26 14:43, Sasha Levin wrote: > Hi, > > I've been playing around with improvements to syzkaller locally, and hit > the > following crash on v7.0-rc1: > >   vma ffff888109f988c0 start 0000555580cc0000 end 0000555580ce2000 mm > ffff8881048e1780 >   prot 8000000000000025 anon_vma ffff88810b20f100 vm_ops 0000000000000000 >   pgoff 555580cc0 file 0000000000000000 private_data 0000000000000000 >   refcnt 1 >   flags: 0x100073(read|write|mayread|maywrite|mayexec|account) >   ------------[ cut here ]------------ >   kernel BUG at mm/huge_memory.c:2999! >   Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI >   CPU: 3 UID: 0 PID: 15162 Comm: syz.7.3120 Tainted: G                 > N  7.0.0-rc1-00001-gc5447a46efed #51 PREEMPT(full) >   Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0- > debian-1.17.0-1 04/01/2014 >   RIP: 0010:split_huge_pmd_locked+0x11a0/0x2f80 >   RSP: 0018:ffff888053cc7338 EFLAGS: 00010282 >   RAX: 0000000000000126 RBX: ffff888109f988d0 RCX: 0000000000000000 >   RDX: 0000000000000126 RSI: 0000000000000000 RDI: ffffed100a798e43 >   RBP: 0000555580cc0000 R08: ffffffffa3e62775 R09: 0000000000000001 >   R10: 0000000000000005 R11: 0000000000000000 R12: 0000000000000080 >   R13: 0000000000000000 R14: 0000555580c00000 R15: ffff888109f988c0 >   FS:  0000000000000000(0000) GS:ffff88816f701000(0000) > knlGS:0000000000000000 >   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >   CR2: 00007fe2ac1907a0 CR3: 0000000021c91000 CR4: 0000000000750ef0 >   PKRU: 80000000 >   Call Trace: >    >    __split_huge_pmd+0x201/0x350 >    unmap_page_range+0xa6a/0x3db0 >    unmap_single_vma+0x14b/0x230 >    unmap_vmas+0x28f/0x580 >    exit_mmap+0x203/0xa80 >    __mmput+0x11b/0x540 >    mmput+0x81/0xa0 >    do_exit+0x7b9/0x2c60 >    do_group_exit+0xd5/0x2a0 >    get_signal+0x1fdc/0x2340 >    arch_do_signal_or_restart+0x93/0x790 >    exit_to_user_mode_loop+0x84/0x480 >    do_syscall_64+0x4df/0x700 >    entry_SYSCALL_64_after_hwframe+0x77/0x7f >    >   Kernel panic - not syncing: Fatal exception > > The assertion VM_BUG_ON_VMA(vma->vm_start > haddr, vma) fires at > mm/huge_memory.c:2999 because a huge PMD exists at PMD-aligned address > 0x555580c00000 but the VMA only covers [0x555580cc0000, 0x555580ce2000): > a 136KB region starting 816KB past the PMD base. Do you have a reproducer and would this trigger before v7.0-rc1? Lorenzo did some changes around anon_vma locking recently, maybe related to that. -- Cheers, David