================================
WARNING: inconsistent lock state
syzkaller #0 Not tainted
--------------------------------
inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
ksoftirqd/1/23 [HC0[0]:SC1[1]:HE1:SE0] takes:
ffff8881136ec260 (sk_lock-AF_X25){+.?.}-{0:0}, at: x25_kill_by_neigh+0x10d/0x250
{SOFTIRQ-ON-W} state was registered at:
  lock_acquire+0x106/0x350
  lock_sock_nested+0x41/0x100
  x25_ioctl+0x66f/0xff0
  sock_do_ioctl+0x101/0x320
  sock_ioctl+0x57a/0x7e0
  __se_sys_ioctl+0xfc/0x170
  do_syscall_64+0x174/0x580
  entry_SYSCALL_64_after_hwframe+0x77/0x7f
irq event stamp: 1183262
hardirqs last  enabled at (1183262): [<ffffffff81888fb0>] __local_bh_enable_ip+0xd0/0x130
hardirqs last disabled at (1183261): [<ffffffff81888f51>] __local_bh_enable_ip+0x71/0x130
softirqs last  enabled at (1183206): [<ffffffff8188bc56>] run_ksoftirqd+0x36/0x60
softirqs last disabled at (1183211): [<ffffffff8188bc56>] run_ksoftirqd+0x36/0x60

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(sk_lock-AF_X25);
  <Interrupt>
    lock(sk_lock-AF_X25);

 *** DEADLOCK ***

1 lock held by ksoftirqd/1/23:
 #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: netif_receive_skb_core+0x33/0x2b0

stack backtrace:
CPU: 1 UID: 0 PID: 23 Comm: ksoftirqd/1 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 print_usage_bug+0x28b/0x2e0
 mark_lock_irq+0x410/0x420
 mark_lock+0x115/0x190
 __lock_acquire+0x65c/0x2cf0
 lock_acquire+0x106/0x350
 lock_sock_nested+0x41/0x100
 x25_kill_by_neigh+0x10d/0x250
 x25_lapb_receive_frame+0x1b0/0xfb0
 netif_receive_skb_core+0x2a6/0x2b0
 lapbeth_napi_poll+0x42/0x90
 __napi_poll+0xaa/0x330
 net_rx_action+0x61d/0xf50
 handle_softirqs+0x225/0x840
 run_ksoftirqd+0x36/0x60
 smpboot_thread_fn+0x57c/0xa80
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
BUG: sleeping function called from invalid context at net/core/sock.c:3830
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 23, name: ksoftirqd/1
preempt_count: 100, expected: 0
RCU nest depth: 1, expected: 0
INFO: lockdep is turned off.
Preemption disabled at:
[<ffffffff818891ab>] handle_softirqs+0xab/0x840
CPU: 1 UID: 0 PID: 23 Comm: ksoftirqd/1 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 __might_resched+0x378/0x4d0
 lock_sock_nested+0x56/0x100
 x25_kill_by_neigh+0x10d/0x250
 x25_lapb_receive_frame+0x1b0/0xfb0
 netif_receive_skb_core+0x2a6/0x2b0
 lapbeth_napi_poll+0x42/0x90
 __napi_poll+0xaa/0x330
 net_rx_action+0x61d/0xf50
 handle_softirqs+0x225/0x840
 run_ksoftirqd+0x36/0x60
 smpboot_thread_fn+0x57c/0xa80
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
