================================
WARNING: inconsistent lock state
6.11.0-syzkaller-10547-g684a64bf32b6 #0 Not tainted
--------------------------------
inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
ksoftirqd/1/24 [HC0[0]:SC1[1]:HE1:SE0] takes:
ffff88806eaaa9e0 (&pch->downl){+.?.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff88806eaaa9e0 (&pch->downl){+.?.}-{2:2}, at: ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline]
ffff88806eaaa9e0 (&pch->downl){+.?.}-{2:2}, at: ppp_input+0x18b/0xa10 drivers/net/ppp/ppp_generic.c:2304
{SOFTIRQ-ON-W} state was registered at:
  lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822
  __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
  _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
  spin_lock include/linux/spinlock.h:351 [inline]
  ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline]
  ppp_input+0x18b/0xa10 drivers/net/ppp/ppp_generic.c:2304
  pppoe_rcv_core+0x117/0x310 drivers/net/ppp/pppoe.c:379
  sk_backlog_rcv include/net/sock.h:1113 [inline]
  __release_sock+0x243/0x350 net/core/sock.c:3072
  release_sock+0x61/0x1f0 net/core/sock.c:3626
  pppoe_sendmsg+0xd5/0x750 drivers/net/ppp/pppoe.c:903
  sock_sendmsg_nosec net/socket.c:730 [inline]
  __sock_sendmsg+0x221/0x270 net/socket.c:745
  ____sys_sendmsg+0x52a/0x7e0 net/socket.c:2603
  ___sys_sendmsg net/socket.c:2657 [inline]
  __sys_sendmmsg+0x4a8/0x730 net/socket.c:2736
  __compat_sys_sendmmsg net/compat.c:360 [inline]
  __do_compat_sys_sendmmsg net/compat.c:367 [inline]
  __se_compat_sys_sendmmsg net/compat.c:364 [inline]
  __ia32_compat_sys_sendmmsg+0xa2/0xc0 net/compat.c:364
  do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
  __do_fast_syscall_32+0xb4/0x110 arch/x86/entry/common.c:386
  do_fast_syscall_32+0x34/0x80 arch/x86/entry/common.c:411
  entry_SYSENTER_compat_after_hwframe+0x84/0x8e
irq event stamp: 3386476
hardirqs last  enabled at (3386476): [<ffffffff81575518>] __local_bh_enable_ip+0x168/0x200 kernel/softirq.c:387
hardirqs last disabled at (3386475): [<ffffffff815754b6>] __local_bh_enable_ip+0x106/0x200 kernel/softirq.c:364
softirqs last  enabled at (3386464): [<ffffffff8157877a>] run_ksoftirqd+0xca/0x130 kernel/softirq.c:927
softirqs last disabled at (3386469): [<ffffffff8157877a>] run_ksoftirqd+0xca/0x130 kernel/softirq.c:927

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

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

 *** DEADLOCK ***

1 lock held by ksoftirqd/1/24:
 #0: ffffffff8e937ee0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #0: ffffffff8e937ee0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8e937ee0 (rcu_read_lock){....}-{1:2}, at: ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2267 [inline]
 #0: ffffffff8e937ee0 (rcu_read_lock){....}-{1:2}, at: ppp_input+0x55/0xa10 drivers/net/ppp/ppp_generic.c:2304

stack backtrace:
CPU: 1 UID: 0 PID: 24 Comm: ksoftirqd/1 Not tainted 6.11.0-syzkaller-10547-g684a64bf32b6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_usage_bug+0x62e/0x8b0 kernel/locking/lockdep.c:4035
 valid_state+0x13a/0x1c0 kernel/locking/lockdep.c:4049
 mark_lock_irq+0xbb/0xc20 kernel/locking/lockdep.c:4260
 mark_lock+0x223/0x360 kernel/locking/lockdep.c:4722
 __lock_acquire+0xbf9/0x2050 kernel/locking/lockdep.c:5153
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:351 [inline]
 ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline]
 ppp_input+0x18b/0xa10 drivers/net/ppp/ppp_generic.c:2304
 ppp_async_process+0x7f/0x150 drivers/net/ppp/ppp_async.c:495
 tasklet_action_common+0x321/0x4d0 kernel/softirq.c:784
 handle_softirqs+0x2c5/0x980 kernel/softirq.c:554
 run_ksoftirqd+0xca/0x130 kernel/softirq.c:927
 smpboot_thread_fn+0x544/0xa30 kernel/smpboot.c:164
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>