============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz.0.1495/11903 is trying to acquire lock: ffff8880444c18f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_do_insn+0x2e/0x3e0 drivers/comedi/kcomedilib/kcomedilib_main.c:73 but task is already holding lock: ffff8880444c00f8 (&dev->mutex#4){+.+.}-{4:4}, at: compat_insnlist drivers/comedi/comedi_fops.c:3207 [inline] ffff8880444c00f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_compat_ioctl+0x7fe/0x990 drivers/comedi/comedi_fops.c:3273 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.0.1495/11903: #0: ffff8880444c00f8 (&dev->mutex#4){+.+.}-{4:4}, at: compat_insnlist drivers/comedi/comedi_fops.c:3207 [inline] #0: ffff8880444c00f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_compat_ioctl+0x7fe/0x990 drivers/comedi/comedi_fops.c:3273 stack backtrace: CPU: 0 UID: 0 PID: 11903 Comm: syz.0.1495 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_deadlock_bug+0x1e9/0x240 kernel/locking/lockdep.c:3041 check_deadlock kernel/locking/lockdep.c:3093 [inline] validate_chain kernel/locking/lockdep.c:3895 [inline] __lock_acquire+0x1106/0x1c90 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:598 [inline] __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760 comedi_do_insn+0x2e/0x3e0 drivers/comedi/kcomedilib/kcomedilib_main.c:73 comedi_dio_bitfield2+0x3c4/0x420 drivers/comedi/kcomedilib/kcomedilib_main.c:204 bonding_dio_insn_bits+0x2bd/0x570 drivers/comedi/drivers/comedi_bond.c:100 insn_rw_emulate_bits+0x29b/0x5f0 drivers/comedi/drivers.c:642 parse_insn+0xf4c/0x1970 drivers/comedi/comedi_fops.c:1454 do_insnlist_ioctl+0x272/0x700 drivers/comedi/comedi_fops.c:1594 compat_insnlist drivers/comedi/comedi_fops.c:3208 [inline] comedi_compat_ioctl+0x810/0x990 drivers/comedi/comedi_fops.c:3273 __do_compat_sys_ioctl fs/ioctl.c:695 [inline] __se_compat_sys_ioctl fs/ioctl.c:638 [inline] __ia32_compat_sys_ioctl+0x242/0x370 fs/ioctl.c:638 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0x7c/0x300 arch/x86/entry/syscall_32.c:306 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf7f31579 Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 RSP: 002b:00000000f540555c EFLAGS: 00000296 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 000000008008640b RDX: 0000000080000200 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 ---------------- Code disassembly (best guess), 2 bytes skipped: 0: 10 06 adc %al,(%rsi) 2: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi 6: 10 07 adc %al,(%rdi) 8: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi c: 10 08 adc %cl,(%rax) e: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi 1e: 00 51 52 add %dl,0x52(%rcx) 21: 55 push %rbp 22: 89 e5 mov %esp,%ebp 24: 0f 34 sysenter 26: cd 80 int $0x80 * 28: 5d pop %rbp <-- trapping instruction 29: 5a pop %rdx 2a: 59 pop %rcx 2b: c3 ret 2c: 90 nop 2d: 90 nop 2e: 90 nop 2f: 90 nop 30: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi 37: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi