============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz.2.3503/16436 is trying to acquire lock: ffff88814c6870f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_do_insn+0x38/0x3d0 drivers/comedi/kcomedilib/kcomedilib_main.c:73 but task is already holding lock: ffff88814c7f20f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_unlocked_ioctl+0x13a/0x1020 drivers/comedi/comedi_fops.c:2166 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&dev->mutex#4); lock(&dev->mutex#4); *** DEADLOCK *** May be due to missing lock nesting notation 1 lock held by syz.2.3503/16436: #0: ffff88814c7f20f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_unlocked_ioctl+0x13a/0x1020 drivers/comedi/comedi_fops.c:2166 stack backtrace: CPU: 1 UID: 0 PID: 16436 Comm: syz.2.3503 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_deadlock_bug+0x28b/0x2a0 kernel/locking/lockdep.c:3041 check_deadlock kernel/locking/lockdep.c:3093 [inline] validate_chain+0x1a3f/0x2140 kernel/locking/lockdep.c:3895 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:598 [inline] __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760 comedi_do_insn+0x38/0x3d0 drivers/comedi/kcomedilib/kcomedilib_main.c:73 comedi_dio_bitfield2+0x2d7/0x3b0 drivers/comedi/kcomedilib/kcomedilib_main.c:204 bonding_dio_insn_bits+0x2a5/0x590 drivers/comedi/drivers/comedi_bond.c:100 insn_rw_emulate_bits+0x34d/0x5f0 drivers/comedi/drivers.c:642 parse_insn+0xa26/0x1910 drivers/comedi/comedi_fops.c:1454 do_insn_ioctl+0x174/0x5a0 drivers/comedi/comedi_fops.c:1679 comedi_unlocked_ioctl+0x8b0/0x1020 drivers/comedi/comedi_fops.c:2308 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ffbfa98f749 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffbf8bf6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007ffbfabe6090 RCX: 00007ffbfa98f749 RDX: 0000200000000080 RSI: 000000008028640c RDI: 0000000000000006 RBP: 00007ffbfaa13f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffbfabe6128 R14: 00007ffbfabe6090 R15: 00007ffe5c97a0a8