syzbot

================================
WARNING: inconsistent lock state
syzkaller #0 Not tainted
--------------------------------
inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
syz.0.25/4445 [HC0[0]:SC1[1]:HE1:SE0] takes:
ffff88807d89d1f0 (slock-AF_PHONET/1){+.?.}-{2:2}, at: __sk_receive_skb+0x17c/0x980 net/core/sock.c:560
{SOFTIRQ-ON-W} state was registered at:
  lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
  _raw_spin_lock_nested+0x2e/0x40 kernel/locking/spinlock.c:378
  __sk_receive_skb+0x17c/0x980 net/core/sock.c:560
  sk_backlog_rcv include/net/sock.h:1138 [inline]
  __release_sock+0x1e1/0x450 net/core/sock.c:2945
  release_sock+0x5b/0x1b0 net/core/sock.c:3511
  pep_sock_accept+0xcb1/0x1200 net/phonet/pep.c:879
  pn_socket_accept+0x126/0x360 net/phonet/socket.c:304
  do_accept+0x509/0x6f0 net/socket.c:1890
  __sys_accept4_file net/socket.c:1931 [inline]
  __sys_accept4+0x97/0x100 net/socket.c:1961
  __do_sys_accept4 net/socket.c:1972 [inline]
  __se_sys_accept4 net/socket.c:1969 [inline]
  __x64_sys_accept4+0x96/0xb0 net/socket.c:1969
  do_syscall_x64 arch/x86/entry/common.c:46 [inline]
  do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
  entry_SYSCALL_64_after_hwframe+0x68/0xd2
irq event stamp: 124
hardirqs last  enabled at (124): [<ffffffff8a380f3f>] __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:159 [inline]
hardirqs last  enabled at (124): [<ffffffff8a380f3f>] _raw_spin_unlock_irq+0x1f/0x40 kernel/locking/spinlock.c:202
hardirqs last disabled at (123): [<ffffffff8a380d06>] __raw_spin_lock_irq include/linux/spinlock_api_smp.h:117 [inline]
hardirqs last disabled at (123): [<ffffffff8a380d06>] _raw_spin_lock_irq+0x86/0xf0 kernel/locking/spinlock.c:170
softirqs last  enabled at (102): [<ffffffff88319355>] local_bh_enable include/linux/bottom_half.h:33 [inline]
softirqs last  enabled at (102): [<ffffffff88319355>] netif_rx+0x75/0x90 net/core/dev.c:5140
softirqs last disabled at (103): [<ffffffff814f6852>] do_softirq+0x142/0x210 kernel/softirq.c:497

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 ***

4 locks held by syz.0.25/4445:
 #0: ffff88807d89cc30 (sk_lock-AF_PHONET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1805 [inline]
 #0: ffff88807d89cc30 (sk_lock-AF_PHONET){+.+.}-{0:0}, at: pep_sendmsg+0x795/0xad0 net/phonet/pep.c:1199
 #1: ffffffff8cb2d5e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #1: ffffffff8cb2d5e0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #1: ffffffff8cb2d5e0 (rcu_read_lock){....}-{1:2}, at: process_backlog+0x2cb/0x6f0 net/core/dev.c:6060
 #2: ffff88807d89c570 (slock-AF_PHONET){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
 #2: ffff88807d89c570 (slock-AF_PHONET){+.-.}-{2:2}, at: __sk_receive_skb+0x18b/0x980 net/core/sock.c:562
 #3: ffff88807d89c5f0 (sk_lock-AF_PHONET){+.+.}-{0:0}, at: sk_receive_skb include/net/sock.h:2097 [inline]
 #3: ffff88807d89c5f0 (sk_lock-AF_PHONET){+.+.}-{0:0}, at: phonet_rcv+0x7c5/0xca0 net/phonet/af_phonet.c:405

stack backtrace:
CPU: 0 PID: 4445 Comm: syz.0.25 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <IRQ>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 valid_state+0x13b/0x1d0 kernel/locking/lockdep.c:3969
 mark_lock_irq+0xa9/0x900 kernel/locking/lockdep.c:4172
 mark_lock+0x208/0x320 kernel/locking/lockdep.c:4628
 mark_usage kernel/locking/lockdep.c:-1 [inline]
 __lock_acquire+0xc78/0x7d10 kernel/locking/lockdep.c:5003
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
 _raw_spin_lock_nested+0x2e/0x40 kernel/locking/spinlock.c:378
 __sk_receive_skb+0x17c/0x980 net/core/sock.c:560
 sk_backlog_rcv include/net/sock.h:1138 [inline]
 __sk_receive_skb+0x432/0x980 net/core/sock.c:569
 sk_receive_skb include/net/sock.h:2097 [inline]
 phonet_rcv+0x7c5/0xca0 net/phonet/af_phonet.c:405
 __netif_receive_skb_one_core net/core/dev.c:5619 [inline]
 __netif_receive_skb+0xcc/0x290 net/core/dev.c:5733
 process_backlog+0x38d/0x6f0 net/core/dev.c:6061
 __napi_poll+0xc0/0x460 net/core/dev.c:6628
 napi_poll net/core/dev.c:6695 [inline]
 net_rx_action+0x5dd/0xb20 net/core/dev.c:6809
 handle_softirqs+0x2a1/0x930 kernel/softirq.c:596
 do_softirq+0x142/0x210 kernel/softirq.c:497
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x180/0x1c0 kernel/softirq.c:421
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 netif_rx+0x7f/0x90 net/core/dev.c:5140
 pn_send+0x553/0x7f0 net/phonet/af_phonet.c:185
 pn_skb_send+0x214/0x510 net/phonet/af_phonet.c:272
 pipe_skb_send+0x2d7/0x500 net/phonet/pep.c:1130
 pep_sendmsg+0x9a6/0xad0 net/phonet/pep.c:1206
 pn_socket_sendmsg+0x1cd/0x230 net/phonet/socket.c:425
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 sock_write_iter+0x2d9/0x3e0 net/socket.c:1143
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x4b1/0xa30 fs/read_write.c:584
 ksys_write+0x14c/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f8b0b79c819
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:00007f8b0c697028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f8b0ba16090 RCX: 00007f8b0b79c819
RDX: 00000000000003db RSI: 0000200000000480 RDI: 0000000000000006
RBP: 00007f8b0b832c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8b0ba16128 R14: 00007f8b0ba16090 R15: 00007ffc46153de8
 </TASK>