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Tue, 20 Oct 2026 08:32:09 -0700 (PDT) Date: Tue, 20 Oct 2026 08:32:08 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6ad78978.b5bd089a.6b57.008d.GAE@google.com> Subject: [syzbot] [block?] possible deadlock in blkdev_buffered_write From: syzbot To: axboe@kernel.dk, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 2efb7a11f1aa Add linux-next specific files for 20261016 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=15344895580000 kernel config: https://syzkaller.appspot.com/x/.config?x=129fca4e65ab9877 dashboard link: https://syzkaller.appspot.com/bug?extid=bd975ef54294bec73f0e compiler: Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=110b0f01580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17b99031580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/cd996cff1b76/disk-2efb7a11.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/59577d58bd5a/vmlinux-2efb7a11.xz kernel image: https://storage.googleapis.com/syzbot-assets/a3dfa3b04143/bzImage-2efb7a11.xz mounted in repro: https://storage.googleapis.com/syzbot-assets/2b9971624b86/mount_0.gz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+bd975ef54294bec73f0e@syzkaller.appspotmail.com ============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz.0.40/6005 is trying to acquire lock: ffff888024956f68 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:1039 [inline] ffff888024956f68 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: blkdev_buffered_write+0xd7/0x160 block/fops.c:738 but task is already holding lock: ffff888024956f68 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:1039 [inline] ffff888024956f68 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: blkdev_write_iter+0x6c5/0x810 block/fops.c:815 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&sb->s_type->i_mutex_key#10); lock(&sb->s_type->i_mutex_key#10); *** DEADLOCK *** May be due to missing lock nesting notation locks held by syz.0.40/6005: 1, last CPU#1: #0: ffff888024956f68 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:1039 [inline] #0: ffff888024956f68 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: blkdev_write_iter+0x6c5/0x810 block/fops.c:815 stack backtrace: CPU: 1 UID: 0 PID: 6005 Comm: syz.0.40 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_deadlock_bug+0x27a/0x290 kernel/locking/lockdep.c:3085 check_deadlock kernel/locking/lockdep.c:3137 [inline] validate_chain kernel/locking/lockdep.c:3939 [inline] __lock_acquire+0x25db/0x2de0 kernel/locking/lockdep.c:5288 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942 down_read+0x45/0x320 kernel/locking/rwsem.c:1574 inode_lock_shared include/linux/fs.h:1039 [inline] blkdev_buffered_write+0xd7/0x160 block/fops.c:738 blkdev_write_iter+0x6d5/0x810 block/fops.c:816 do_iter_readv_writev+0x612/0x8c0 fs/read_write.c:-1 vfs_writev+0x343/0x990 fs/read_write.c:1768 do_pwritev fs/read_write.c:1864 [inline] __do_sys_pwritev2 fs/read_write.c:1922 [inline] __se_sys_pwritev2+0x177/0x2a0 fs/read_write.c:1913 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff2f2b9e559 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fff19d23ca8 EFLAGS: 00000246 ORIG_RAX: 0000000000000148 RAX: ffffffffffffffda RBX: 00007ff2f2e25fa0 RCX: 00007ff2f2b9e559 RDX: 0000000000000001 RSI: 0000200000000240 RDI: 0000000000000004 RBP: 00007ff2f2c35ab8 R08: 0000000000000000 R09: 0000000000000003 R10: 0000000000007a00 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ff2f2e25fac R14: 00007ff2f2e25fa0 R15: 00007ff2f2e25fa0 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing. If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup