================================
WARNING: inconsistent lock state
6.12.0-rc1-syzkaller-g2d8bce6e34be #0 Not tainted
--------------------------------
inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
ksoftirqd/0/16 [HC0[0]:SC1[1]:HE1:SE0] takes:
ffff0000c4e9a9e0 (&pch->downl){+.?.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff0000c4e9a9e0 (&pch->downl){+.?.}-{2:2}, at: ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline]
ffff0000c4e9a9e0 (&pch->downl){+.?.}-{2:2}, at: ppp_input+0x16c/0x854 drivers/net/ppp/ppp_generic.c:2304
{SOFTIRQ-ON-W} state was registered at:
  lock_acquire+0x240/0x728 kernel/locking/lockdep.c:5825
  __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
  _raw_spin_lock+0x48/0x60 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+0x16c/0x854 drivers/net/ppp/ppp_generic.c:2304
  pppoe_rcv_core+0xfc/0x314 drivers/net/ppp/pppoe.c:379
  sk_backlog_rcv include/net/sock.h:1113 [inline]
  __release_sock+0x1a8/0x3d8 net/core/sock.c:3072
  release_sock+0x68/0x1b8 net/core/sock.c:3626
  pppoe_sendmsg+0xc8/0x5d8 drivers/net/ppp/pppoe.c:903
  sock_sendmsg_nosec net/socket.c:729 [inline]
  __sock_sendmsg net/socket.c:744 [inline]
  ____sys_sendmsg+0x56c/0x840 net/socket.c:2602
  ___sys_sendmsg net/socket.c:2656 [inline]
  __sys_sendmmsg+0x318/0x7e0 net/socket.c:2742
  __do_sys_sendmmsg net/socket.c:2771 [inline]
  __se_sys_sendmmsg net/socket.c:2768 [inline]
  __arm64_sys_sendmmsg+0xa0/0xbc net/socket.c:2768
  __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
  invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
  el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
  do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
  el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:732
  el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:750
  el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598
irq event stamp: 826242
hardirqs last  enabled at (826242): [<ffff80008b5770b8>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline]
hardirqs last  enabled at (826242): [<ffff80008b5770b8>] _raw_spin_unlock_irqrestore+0x38/0x98 kernel/locking/spinlock.c:194
hardirqs last disabled at (826241): [<ffff80008b576ee8>] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:108 [inline]
hardirqs last disabled at (826241): [<ffff80008b576ee8>] _raw_spin_lock_irqsave+0x2c/0x7c kernel/locking/spinlock.c:162
softirqs last  enabled at (826232): [<ffff800080206648>] softirq_handle_end kernel/softirq.c:400 [inline]
softirqs last  enabled at (826232): [<ffff800080206648>] handle_softirqs+0xa38/0xbf8 kernel/softirq.c:582
softirqs last disabled at (826237): [<ffff8000802095b8>] run_ksoftirqd+0x70/0x158 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/0/16:
 #0: ffff80008f9cf760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:336

stack backtrace:
CPU: 0 UID: 0 PID: 16 Comm: ksoftirqd/0 Not tainted 6.12.0-rc1-syzkaller-g2d8bce6e34be #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call trace:
 dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:319
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:326
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:120
 dump_stack+0x1c/0x28 lib/dump_stack.c:129
 print_usage_bug+0x6a4/0x9c0 kernel/locking/lockdep.c:4038
 mark_lock_irq+0x980/0xd2c
 mark_lock+0x258/0x368 kernel/locking/lockdep.c:4725
 __lock_acquire+0xf48/0x77c8 kernel/locking/lockdep.c:5156
 lock_acquire+0x240/0x728 kernel/locking/lockdep.c:5825
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x48/0x60 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+0x16c/0x854 drivers/net/ppp/ppp_generic.c:2304
 ppp_sync_process+0x88/0x164 drivers/net/ppp/ppp_synctty.c:490
 tasklet_action_common+0x318/0x3f4 kernel/softirq.c:784
 tasklet_action+0x68/0x8c kernel/softirq.c:810
 handle_softirqs+0x2e0/0xbf8 kernel/softirq.c:554
 run_ksoftirqd+0x70/0x158 kernel/softirq.c:927
 smpboot_thread_fn+0x4b0/0x90c kernel/smpboot.c:164
 kthread+0x288/0x310 kernel/kthread.c:389
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860