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[2003:d8:2f14:2400:afc:9797:137c:a25b]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-46e2a996d7dsm29743925e9.4.2025.09.24.04.32.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 24 Sep 2025 04:32:50 -0700 (PDT) Message-ID: Date: Wed, 24 Sep 2025 13:32:48 +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: [syzbot] [mm?] WARNING in memory_failure To: syzbot , akpm@linux-foundation.org, linmiaohe@huawei.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, nao.horiguchi@gmail.com, syzkaller-bugs@googlegroups.com, Zi Yan References: <68d2c943.a70a0220.1b52b.02b3.GAE@google.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 ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZoEEwEIAEQCGwMCF4ACGQEFCwkIBwICIgIG FQoJCAsCBBYCAwECHgcWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaJzangUJJlgIpAAKCRBN 3hD3AP+DWhAxD/9wcL0A+2rtaAmutaKTfxhTP0b4AAp1r/eLxjrbfbCCmh4pqzBhmSX/4z11 opn2KqcOsueRF1t2ENLOWzQu3Roiny2HOU7DajqB4dm1BVMaXQya5ae2ghzlJN9SIoopTWlR 0Af3hPj5E2PYvQhlcqeoehKlBo9rROJv/rjmr2x0yOM8qeTroH/ZzNlCtJ56AsE6Tvl+r7cW 3x7/Jq5WvWeudKrhFh7/yQ7eRvHCjd9bBrZTlgAfiHmX9AnCCPRPpNGNedV9Yty2Jnxhfmbv Pw37LA/jef8zlCDyUh2KCU1xVEOWqg15o1RtTyGV1nXV2O/mfuQJud5vIgzBvHhypc3p6VZJ lEf8YmT+Ol5P7SfCs5/uGdWUYQEMqOlg6w9R4Pe8d+mk8KGvfE9/zTwGg0nRgKqlQXrWRERv cuEwQbridlPAoQHrFWtwpgYMXx2TaZ3sihcIPo9uU5eBs0rf4mOERY75SK+Ekayv2ucTfjxr Kf014py2aoRJHuvy85ee/zIyLmve5hngZTTe3Wg3TInT9UTFzTPhItam6dZ1xqdTGHZYGU0O otRHcwLGt470grdiob6PfVTXoHlBvkWRadMhSuG4RORCDpq89vu5QralFNIf3EysNohoFy2A LYg2/D53xbU/aa4DDzBb5b1Rkg/udO1gZocVQWrDh6I2K3+cCs7BTQRVy5+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: <68d2c943.a70a0220.1b52b.02b3.GAE@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 23.09.25 18:22, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: b5db4add5e77 Merge branch 'for-next/core' into for-kernelci > git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci > console output: https://syzkaller.appspot.com/x/log.txt?x=10edb8e2580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=d2ae34a0711ff2f1 > dashboard link: https://syzkaller.appspot.com/bug?extid=e6367ea2fdab6ed46056 > compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8 > userspace arch: arm64 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14160f12580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1361627c580000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/6eee2232d5c1/disk-b5db4add.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/a8b00f2f1234/vmlinux-b5db4add.xz > kernel image: https://storage.googleapis.com/syzbot-assets/fc0d466f156c/Image-b5db4add.gz.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+e6367ea2fdab6ed46056@syzkaller.appspotmail.com > > Injecting memory failure for pfn 0x104000 at process virtual address 0x20000000 > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 6700 at mm/memory-failure.c:2391 memory_failure+0x18ec/0x1db4 mm/memory-failure.c:2391 > Modules linked in: > CPU: 1 UID: 0 PID: 6700 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025 > pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) > pc : memory_failure+0x18ec/0x1db4 mm/memory-failure.c:2391 > lr : memory_failure+0x18ec/0x1db4 mm/memory-failure.c:2391 > sp : ffff8000a41478c0 > x29: ffff8000a41479a0 x28: 05ffc00000200868 x27: ffff700014828f20 > x26: 1fffffbff8620001 x25: 05ffc0000020086d x24: 1fffffbff8620000 > x23: fffffdffc3100008 x22: fffffdffc3100000 x21: fffffdffc3100000 > x20: 0000000000000023 x19: dfff800000000000 x18: 1fffe00033793888 > x17: ffff80008f7ee000 x16: ffff80008052aa64 x15: 0000000000000001 > x14: 1fffffbff8620000 x13: 0000000000000000 x12: 0000000000000000 > x11: ffff7fbff8620001 x10: 0000000000ff0100 x9 : 0000000000000000 > x8 : ffff0000d7eedb80 x7 : ffff800080428910 x6 : 0000000000000000 > x5 : 0000000000000001 x4 : 0000000000000001 x3 : ffff800080cf5438 > x2 : 0000000000000001 x1 : 0000000000000040 x0 : 0000000000000000 > Call trace: > memory_failure+0x18ec/0x1db4 mm/memory-failure.c:2391 (P) > madvise_inject_error mm/madvise.c:1475 [inline] > madvise_do_behavior+0x2c8/0x7c4 mm/madvise.c:1875 > do_madvise+0x190/0x248 mm/madvise.c:1978 > __do_sys_madvise mm/madvise.c:1987 [inline] > __se_sys_madvise mm/madvise.c:1985 [inline] > __arm64_sys_madvise+0xa4/0xc0 mm/madvise.c:1985 > __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] > invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 > el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 > do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 > el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:744 > el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:763 > el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 We're running into the WARN_ON(folio_test_large(folio)); in memory_failure(). Which is weird because we have the if (folio_test_large(folio)) { /* * The flag must be set after the refcount is bumped * otherwise it may race with THP split. * And the flag can't be set in get_hwpoison_page() since * it is called by soft offline too and it is just called * for !MF_COUNT_INCREASED. So here seems to be the best * place. * * Don't need care about the above error handling paths for * get_hwpoison_page() since they handle either free page * or unhandlable page. The refcount is bumped iff the * page is a valid handlable page. */ folio_set_has_hwpoisoned(folio); if (try_to_split_thp_page(p, false) < 0) { res = -EHWPOISON; kill_procs_now(p, pfn, flags, folio); put_page(p); action_result(pfn, MF_MSG_UNSPLIT_THP, MF_FAILED); goto unlock_mutex; } VM_BUG_ON_PAGE(!page_count(p), p); folio = page_folio(p); } before it. But likely that's what I raised to Zi Yan recently: if try_to_split_thp_page()->split_huge_page() silently decided to split to something that is not a small folio (the min_order_for_split() bit), this changed the semantics of the function. Likely split_huge_page() should have failed if the min_order makes us not split to order-0, or there would have to be some "parameter" that tells split_huge_page() what expectation (order) the callers has. We can check folio_test_large() after the split, but really, we should just not be splitting at all if it doesn't serve our purpose. -- Cheers David / dhildenb