syzbot

================================
WARNING: inconsistent lock state
syzkaller #0 Not tainted
--------------------------------
inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
ksoftirqd/0/14 [HC0[0]:SC1[1]:HE1:SE0] takes:
ffff88807d8ea620 (slock-AF_PHONET/1){+.?.}-{2:2}, at: __sk_receive_skb+0x17b/0x980 net/core/sock.c:517
{SOFTIRQ-ON-W} state was registered at:
  lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
  _raw_spin_lock_nested+0x2e/0x40 kernel/locking/spinlock.c:368
  __sk_receive_skb+0x17b/0x980 net/core/sock.c:517
  sk_backlog_rcv include/net/sock.h:1080 [inline]
  __release_sock+0x1e1/0x450 net/core/sock.c:2731
  release_sock+0x5b/0x1b0 net/core/sock.c:3274
  pep_sock_accept+0xc73/0x1190 net/phonet/pep.c:878
  pn_socket_accept+0x126/0x360 net/phonet/socket.c:304
  do_accept+0x509/0x6f0 net/socket.c:1809
  __sys_accept4_file net/socket.c:1852 [inline]
  __sys_accept4+0x103/0x170 net/socket.c:1882
  __do_sys_accept4 net/socket.c:1894 [inline]
  __se_sys_accept4 net/socket.c:1891 [inline]
  __x64_sys_accept4+0x96/0xb0 net/socket.c:1891
  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
  do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
  entry_SYSCALL_64_after_hwframe+0x66/0xd0
irq event stamp: 193772
hardirqs last  enabled at (193772): [<ffffffff87e65964>] process_backlog+0x644/0x790 net/core/dev.c:6568
hardirqs last disabled at (193771): [<ffffffff87e657a6>] process_backlog+0x486/0x790 net/core/dev.c:6550
softirqs last  enabled at (193738): [<ffffffff814978f4>] run_ksoftirqd+0xa4/0x100 kernel/softirq.c:943
softirqs last disabled at (193743): [<ffffffff814978f4>] run_ksoftirqd+0xa4/0x100 kernel/softirq.c:943

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

       CPU0
       ----
  lock(slock-AF_PHONET/1);
  <Interrupt>
    lock(slock-AF_PHONET/1);

 *** DEADLOCK ***

3 locks held by ksoftirqd/0/14:
 #0: ffffffff8c31f320 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
 #1: ffff88807f244560 (slock-AF_PHONET){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
 #1: ffff88807f244560 (slock-AF_PHONET){+.-.}-{2:2}, at: __sk_receive_skb+0x18a/0x980 net/core/sock.c:519
 #2: ffff88807f2445e0 (sk_lock-AF_PHONET){+.+.}-{0:0}, at: sk_receive_skb include/net/sock.h:2001 [inline]
 #2: ffff88807f2445e0 (sk_lock-AF_PHONET){+.+.}-{0:0}, at: phonet_rcv+0x7e4/0xc70 net/phonet/af_phonet.c:405

stack backtrace:
CPU: 0 PID: 14 Comm: ksoftirqd/0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 valid_state+0x13b/0x1d0 kernel/locking/lockdep.c:3932
 mark_lock_irq+0xa9/0x900 kernel/locking/lockdep.c:4135
 mark_lock+0x208/0x320 kernel/locking/lockdep.c:4591
 mark_usage kernel/locking/lockdep.c:-1 [inline]
 __lock_acquire+0xc64/0x7d10 kernel/locking/lockdep.c:4966
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
 _raw_spin_lock_nested+0x2e/0x40 kernel/locking/spinlock.c:368
 __sk_receive_skb+0x17b/0x980 net/core/sock.c:517
 sk_backlog_rcv include/net/sock.h:1080 [inline]
 __sk_receive_skb+0x42c/0x980 net/core/sock.c:526
 sk_receive_skb include/net/sock.h:2001 [inline]
 phonet_rcv+0x7e4/0xc70 net/phonet/af_phonet.c:405
 __netif_receive_skb_one_core net/core/dev.c:5551 [inline]
 __netif_receive_skb+0xcc/0x290 net/core/dev.c:5665
 process_backlog+0x370/0x790 net/core/dev.c:6542
 __napi_poll+0xc0/0x430 net/core/dev.c:7101
 napi_poll net/core/dev.c:7168 [inline]
 net_rx_action+0x4d4/0xa10 net/core/dev.c:7258
 handle_softirqs+0x339/0x830 kernel/softirq.c:576
 run_ksoftirqd+0xa4/0x100 kernel/softirq.c:943
 smpboot_thread_fn+0x4f6/0x970 kernel/smpboot.c:164
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>