netlink: 20 bytes leftover after parsing attributes in process `syz.4.2315'. loop4: detected capacity change from 0 to 1024 ============================================ WARNING: possible recursive locking detected syzkaller #0 Tainted: G L -------------------------------------------- syz.4.2315/15896 is trying to acquire lock: ffff8880307aa0f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_do_insn+0x38/0x3d0 drivers/comedi/kcomedilib/kcomedilib_main.c:183 but task is already holding lock: ffff8880307ab0f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_unlocked_ioctl+0x210/0x1af0 drivers/comedi/comedi_fops.c:2288 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.4.2315/15896: #0: ffff8880307ab0f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_unlocked_ioctl+0x210/0x1af0 drivers/comedi/comedi_fops.c:2288 stack backtrace: CPU: 0 UID: 0 PID: 15896 Comm: syz.4.2315 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Call Trace: dump_stack_lvl+0xe8/0x150 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+0x253f/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776 comedi_do_insn+0x38/0x3d0 drivers/comedi/kcomedilib/kcomedilib_main.c:183 comedi_dio_bitfield2+0x301/0x3e0 drivers/comedi/kcomedilib/kcomedilib_main.c:314 bonding_dio_insn_bits+0x2cc/0x5e0 drivers/comedi/drivers/comedi_bond.c:100 insn_rw_emulate_bits+0x363/0x620 drivers/comedi/drivers.c:703 parse_insn+0xa3e/0x1b20 drivers/comedi/comedi_fops.c:1563 do_insn_ioctl+0x174/0x5a0 drivers/comedi/comedi_fops.c:1788 comedi_unlocked_ioctl+0xe06/0x1af0 drivers/comedi/comedi_fops.c:2420 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+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fc54939c629 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:00007fc54a1b3028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fc549615fa0 RCX: 00007fc54939c629 RDX: 0000200000000000 RSI: 000000008028640c RDI: 0000000000000007 RBP: 00007fc549432b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc549616038 R14: 00007fc549615fa0 R15: 00007fffd01d5318