============================================ WARNING: possible recursive locking detected syzkaller #0 Tainted: G L -------------------------------------------- syz.4.1256/10376 is trying to acquire lock: ffff88814d2d70f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_do_insn+0x38/0x3d0 drivers/comedi/kcomedilib/kcomedilib_main.c:183 but task is already holding lock: ffff88814d2d58f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_unlocked_ioctl+0x146/0x1020 drivers/comedi/comedi_fops.c:2228 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.4.1256/10376: #0: ffff88814d2d58f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_unlocked_ioctl+0x146/0x1020 drivers/comedi/comedi_fops.c:2228 stack backtrace: CPU: 0 UID: 0 PID: 10376 Comm: syz.4.1256 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP 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+0x279/0x290 kernel/locking/lockdep.c:3041 check_deadlock kernel/locking/lockdep.c:3093 [inline] validate_chain kernel/locking/lockdep.c:3895 [inline] __lock_acquire+0x2540/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x117/0x340 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:776 comedi_do_insn+0x38/0x3d0 drivers/comedi/kcomedilib/kcomedilib_main.c:183 comedi_dio_bitfield2+0x2d7/0x3b0 drivers/comedi/kcomedilib/kcomedilib_main.c:314 bonding_dio_insn_bits+0x2a5/0x590 drivers/comedi/drivers/comedi_bond.c:100 insn_rw_emulate_bits+0x34d/0x5f0 drivers/comedi/drivers.c:703 parse_insn+0xa26/0x1b30 drivers/comedi/comedi_fops.c:1510 do_insn_ioctl+0x174/0x5a0 drivers/comedi/comedi_fops.c:1735 comedi_unlocked_ioctl+0x907/0x1020 drivers/comedi/comedi_fops.c:2365 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/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f271598f749 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:00007f27168c4038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f2715be5fa0 RCX: 00007f271598f749 RDX: 0000200000000000 RSI: 000000008028640c RDI: 0000000000000003 RBP: 00007f2715a13f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f2715be6038 R14: 00007f2715be5fa0 R15: 00007ffce9ddec58