================================
WARNING: inconsistent lock state
5.15.167-syzkaller #0 Not tainted
--------------------------------
inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
ksoftirqd/0/14 [HC0[0]:SC1[1]:HE1:SE0] takes:
ffff888023f141e0 (&pch->downl){+.?.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
ffff888023f141e0 (&pch->downl){+.?.}-{2:2}, at: ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2271 [inline]
ffff888023f141e0 (&pch->downl){+.?.}-{2:2}, at: ppp_input+0x160/0x980 drivers/net/ppp/ppp_generic.c:2303
{SOFTIRQ-ON-W} state was registered at:
  lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
  __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
  _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
  spin_lock include/linux/spinlock.h:363 [inline]
  ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2271 [inline]
  ppp_input+0x160/0x980 drivers/net/ppp/ppp_generic.c:2303
  pppoe_rcv_core+0x109/0x2f0 drivers/net/ppp/pppoe.c:379
  sk_backlog_rcv include/net/sock.h:1059 [inline]
  __release_sock+0x198/0x4b0 net/core/sock.c:2724
  release_sock+0x5d/0x1c0 net/core/sock.c:3265
  pppoe_sendmsg+0xd1/0x740 drivers/net/ppp/pppoe.c:903
  sock_sendmsg_nosec net/socket.c:704 [inline]
  __sock_sendmsg net/socket.c:716 [inline]
  ____sys_sendmsg+0x59e/0x8f0 net/socket.c:2431
  ___sys_sendmsg+0x252/0x2e0 net/socket.c:2485
  __sys_sendmmsg+0x2bf/0x560 net/socket.c:2571
  __do_sys_sendmmsg net/socket.c:2600 [inline]
  __se_sys_sendmmsg net/socket.c:2597 [inline]
  __x64_sys_sendmmsg+0x9c/0xb0 net/socket.c:2597
  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
  do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
  entry_SYSCALL_64_after_hwframe+0x66/0xd0
irq event stamp: 344786
hardirqs last  enabled at (344786): [<ffffffff814d7f84>] __local_bh_enable_ip+0x164/0x1f0 kernel/softirq.c:388
hardirqs last disabled at (344785): [<ffffffff814d7f22>] __local_bh_enable_ip+0x102/0x1f0 kernel/softirq.c:365
softirqs last  enabled at (344760): [<ffffffff814dac96>] run_ksoftirqd+0xc6/0x120 kernel/softirq.c:925
softirqs last disabled at (344765): [<ffffffff814dac96>] run_ksoftirqd+0xc6/0x120 kernel/softirq.c:925

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

       CPU0
       ----
  lock(&pch->downl);
  <Interrupt>
    lock(&pch->downl);

 *** DEADLOCK ***

4 locks held by ksoftirqd/0/14:
 #0: ffffffff8c91fc60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
 #1: ffff8880745bb0a0 (slock-AF_PPPOX){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
 #1: ffff8880745bb0a0 (slock-AF_PPPOX){+.-.}-{2:2}, at: __sk_receive_skb+0x17c/0x9c0 net/core/sock.c:521
 #2: ffff8880745bb120 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: __netif_receive_skb_one_core net/core/dev.c:5485 [inline]
 #2: ffff8880745bb120 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: __netif_receive_skb+0x1c6/0x530 net/core/dev.c:5599
 #3: ffffffff8c91fc60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311

stack backtrace:
CPU: 0 PID: 14 Comm: ksoftirqd/0 Not tainted 5.15.167-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 valid_state+0x134/0x1c0 kernel/locking/lockdep.c:3932
 mark_lock_irq+0xa8/0xba0 kernel/locking/lockdep.c:4135
 mark_lock+0x21a/0x340 kernel/locking/lockdep.c:4591
 __lock_acquire+0xb9d/0x1ff0 kernel/locking/lockdep.c:4966
 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:363 [inline]
 ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2271 [inline]
 ppp_input+0x160/0x980 drivers/net/ppp/ppp_generic.c:2303
 pppoe_rcv_core+0x109/0x2f0 drivers/net/ppp/pppoe.c:379
 sk_backlog_rcv include/net/sock.h:1059 [inline]
 __sk_receive_skb+0x416/0x9c0 net/core/sock.c:528
 __netif_receive_skb_one_core net/core/dev.c:5485 [inline]
 __netif_receive_skb+0x1c6/0x530 net/core/dev.c:5599
 process_backlog+0x363/0x7f0 net/core/dev.c:6476
 __napi_poll+0xc7/0x440 net/core/dev.c:7035
 napi_poll net/core/dev.c:7102 [inline]
 net_rx_action+0x617/0xda0 net/core/dev.c:7192
 handle_softirqs+0x3a7/0x930 kernel/softirq.c:558
 run_ksoftirqd+0xc6/0x120 kernel/softirq.c:925
 smpboot_thread_fn+0x51b/0x9d0 kernel/smpboot.c:164
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>