========================================================
WARNING: possible irq lock inversion dependency detected
6.12.0-rc1-syzkaller-00046-g7ec462100ef9 #0 Not tainted
--------------------------------------------------------
syz.1.709/8854 just changed the state of lock:
ffff88807b25c9e0 (&pch->downl){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff88807b25c9e0 (&pch->downl){+.+.}-{2:2}, at: ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline]
ffff88807b25c9e0 (&pch->downl){+.+.}-{2:2}, at: ppp_input+0x18b/0xa10 drivers/net/ppp/ppp_generic.c:2304
but this lock was taken by another, SOFTIRQ-safe lock in the past:
 (&ppp->rlock){+.-.}-{2:2}


and interrupts could create inverse lock ordering between them.


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

       CPU0                    CPU1
       ----                    ----
  lock(&pch->downl);
                               local_irq_disable();
                               lock(&ppp->rlock);
                               lock(&pch->downl);
  <Interrupt>
    lock(&ppp->rlock);

 *** DEADLOCK ***

2 locks held by syz.1.709/8854:
 #0: ffff88802f7c9258 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1609 [inline]
 #0: ffff88802f7c9258 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: pppoe_sendmsg+0x51/0x750 drivers/net/ppp/pppoe.c:849
 #1: ffffffff8e937de0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #1: ffffffff8e937de0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffffff8e937de0 (rcu_read_lock){....}-{1:2}, at: ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2267 [inline]
 #1: ffffffff8e937de0 (rcu_read_lock){....}-{1:2}, at: ppp_input+0x55/0xa10 drivers/net/ppp/ppp_generic.c:2304

the shortest dependencies between 2nd lock and 1st lock:
 -> (&ppp->rlock){+.-.}-{2:2} {
    HARDIRQ-ON-W at:
                      lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
                      __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
                      _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178
                      spin_lock_bh include/linux/spinlock.h:356 [inline]
                      ppp_get_stats64+0x33/0x290 drivers/net/ppp/ppp_generic.c:1534
                      dev_get_stats+0xad/0xa00 net/core/dev.c:10937
                      rtnl_fill_stats+0x47/0x880 net/core/rtnetlink.c:1268
                      rtnl_fill_ifinfo+0x18da/0x2270 net/core/rtnetlink.c:1909
                      rtmsg_ifinfo_build_skb+0x18a/0x260 net/core/rtnetlink.c:4079
                      rtmsg_ifinfo_event net/core/rtnetlink.c:4112 [inline]
                      rtmsg_ifinfo+0x91/0x1b0 net/core/rtnetlink.c:4121
                      register_netdevice+0x1774/0x1b00 net/core/dev.c:10534
                      ppp_unit_register drivers/net/ppp/ppp_generic.c:1219 [inline]
                      ppp_dev_configure+0x883/0xb10 drivers/net/ppp/ppp_generic.c:1275
                      ppp_create_interface drivers/net/ppp/ppp_generic.c:3348 [inline]
                      ppp_unattached_ioctl drivers/net/ppp/ppp_generic.c:1060 [inline]
                      ppp_ioctl+0x797/0x1cd0 drivers/net/ppp/ppp_generic.c:733
                      vfs_ioctl fs/ioctl.c:51 [inline]
                      __do_sys_ioctl fs/ioctl.c:907 [inline]
                      __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:893
                      do_syscall_x64 arch/x86/entry/common.c:52 [inline]
                      do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
                      entry_SYSCALL_64_after_hwframe+0x77/0x7f
    IN-SOFTIRQ-W at:
                      lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
                      __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
                      _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178
                      spin_lock_bh include/linux/spinlock.h:356 [inline]
                      ppp_do_recv+0x38/0x26b0 drivers/net/ppp/ppp_generic.c:2210
                      ppp_input+0x5de/0xa10 drivers/net/ppp/ppp_generic.c:2327
                      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
                      __do_softirq kernel/softirq.c:588 [inline]
                      invoke_softirq kernel/softirq.c:428 [inline]
                      __irq_exit_rcu+0xf4/0x1c0 kernel/softirq.c:637
                      irq_exit_rcu+0x9/0x30 kernel/softirq.c:649
                      instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1037 [inline]
                      sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1037
                      asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
                      __tasklet_schedule_common+0x1fd/0x270 kernel/softirq.c:733
                      tasklet_schedule include/linux/interrupt.h:719 [inline]
                      ppp_asynctty_receive+0x1ea6/0x2000 drivers/net/ppp/ppp_async.c:345
                      tty_ldisc_receive_buf+0x11f/0x170 drivers/tty/tty_buffer.c:391
                      tty_port_default_receive_buf+0x6d/0xa0 drivers/tty/tty_port.c:37
                      receive_buf drivers/tty/tty_buffer.c:445 [inline]
                      flush_to_ldisc+0x328/0x860 drivers/tty/tty_buffer.c:495
                      process_one_work kernel/workqueue.c:3229 [inline]
                      process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310
                      worker_thread+0x870/0xd30 kernel/workqueue.c:3391
                      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
    INITIAL USE at:
                     lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
                     __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
                     _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178
                     spin_lock_bh include/linux/spinlock.h:356 [inline]
                     ppp_get_stats64+0x33/0x290 drivers/net/ppp/ppp_generic.c:1534
                     dev_get_stats+0xad/0xa00 net/core/dev.c:10937
                     rtnl_fill_stats+0x47/0x880 net/core/rtnetlink.c:1268
                     rtnl_fill_ifinfo+0x18da/0x2270 net/core/rtnetlink.c:1909
                     rtmsg_ifinfo_build_skb+0x18a/0x260 net/core/rtnetlink.c:4079
                     rtmsg_ifinfo_event net/core/rtnetlink.c:4112 [inline]
                     rtmsg_ifinfo+0x91/0x1b0 net/core/rtnetlink.c:4121
                     register_netdevice+0x1774/0x1b00 net/core/dev.c:10534
                     ppp_unit_register drivers/net/ppp/ppp_generic.c:1219 [inline]
                     ppp_dev_configure+0x883/0xb10 drivers/net/ppp/ppp_generic.c:1275
                     ppp_create_interface drivers/net/ppp/ppp_generic.c:3348 [inline]
                     ppp_unattached_ioctl drivers/net/ppp/ppp_generic.c:1060 [inline]
                     ppp_ioctl+0x797/0x1cd0 drivers/net/ppp/ppp_generic.c:733
                     vfs_ioctl fs/ioctl.c:51 [inline]
                     __do_sys_ioctl fs/ioctl.c:907 [inline]
                     __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:893
                     do_syscall_x64 arch/x86/entry/common.c:52 [inline]
                     do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
                     entry_SYSCALL_64_after_hwframe+0x77/0x7f
  }
  ... key      at: [<ffffffff9a7340a0>] ppp_dev_configure.__key+0x0/0x20
  ... acquired at:
   lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
   __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
   _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178
   spin_lock_bh include/linux/spinlock.h:356 [inline]
   ppp_connect_channel+0x194/0x650 drivers/net/ppp/ppp_generic.c:3485
   ppp_ioctl+0xdd4/0x1cd0 drivers/net/ppp/ppp_generic.c:761
   vfs_ioctl fs/ioctl.c:51 [inline]
   __do_sys_ioctl fs/ioctl.c:907 [inline]
   __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:893
   do_syscall_x64 arch/x86/entry/common.c:52 [inline]
   do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
   entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> (&pch->downl){+.+.}-{2:2} {
   HARDIRQ-ON-W at:
                    lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
                    __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
                    _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178
                    spin_lock_bh include/linux/spinlock.h:356 [inline]
                    ppp_unregister_channel+0x7c/0x300 drivers/net/ppp/ppp_generic.c:2992
                    pppox_unbind_sock+0x5c/0xb0 drivers/net/ppp/pppox.c:58
                    pppoe_release+0x16e/0x820 drivers/net/ppp/pppoe.c:584
                    __sock_release net/socket.c:658 [inline]
                    sock_close+0xbc/0x240 net/socket.c:1426
                    __fput+0x23f/0x880 fs/file_table.c:431
                    task_work_run+0x24f/0x310 kernel/task_work.c:228
                    exit_task_work include/linux/task_work.h:40 [inline]
                    do_exit+0xa2f/0x28e0 kernel/exit.c:939
                    do_group_exit+0x207/0x2c0 kernel/exit.c:1088
                    get_signal+0x16a3/0x1740 kernel/signal.c:2917
                    arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:337
                    exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
                    exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
                    __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
                    syscall_exit_to_user_mode+0xc9/0x370 kernel/entry/common.c:218
                    do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
                    entry_SYSCALL_64_after_hwframe+0x77/0x7f
   SOFTIRQ-ON-W at:
                    lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
                    __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:729 [inline]
                    __sock_sendmsg+0x221/0x270 net/socket.c:744
                    ____sys_sendmsg+0x52a/0x7e0 net/socket.c:2602
                    ___sys_sendmsg net/socket.c:2656 [inline]
                    __sys_sendmmsg+0x3ab/0x730 net/socket.c:2742
                    __do_sys_sendmmsg net/socket.c:2771 [inline]
                    __se_sys_sendmmsg net/socket.c:2768 [inline]
                    __x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2768
                    do_syscall_x64 arch/x86/entry/common.c:52 [inline]
                    do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
                    entry_SYSCALL_64_after_hwframe+0x77/0x7f
   INITIAL USE at:
                   lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
                   __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
                   _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178
                   spin_lock_bh include/linux/spinlock.h:356 [inline]
                   ppp_unregister_channel+0x7c/0x300 drivers/net/ppp/ppp_generic.c:2992
                   pppox_unbind_sock+0x5c/0xb0 drivers/net/ppp/pppox.c:58
                   pppoe_release+0x16e/0x820 drivers/net/ppp/pppoe.c:584
                   __sock_release net/socket.c:658 [inline]
                   sock_close+0xbc/0x240 net/socket.c:1426
                   __fput+0x23f/0x880 fs/file_table.c:431
                   task_work_run+0x24f/0x310 kernel/task_work.c:228
                   exit_task_work include/linux/task_work.h:40 [inline]
                   do_exit+0xa2f/0x28e0 kernel/exit.c:939
                   do_group_exit+0x207/0x2c0 kernel/exit.c:1088
                   get_signal+0x16a3/0x1740 kernel/signal.c:2917
                   arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:337
                   exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
                   exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
                   __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
                   syscall_exit_to_user_mode+0xc9/0x370 kernel/entry/common.c:218
                   do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
                   entry_SYSCALL_64_after_hwframe+0x77/0x7f
 }
 ... key      at: [<ffffffff9a733f80>] ppp_register_net_channel.__key.1+0x0/0x20
 ... acquired at:
   mark_lock+0x223/0x360 kernel/locking/lockdep.c:4725
   __lock_acquire+0x11b0/0x2050 kernel/locking/lockdep.c:5156
   lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
   __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:729 [inline]
   __sock_sendmsg+0x221/0x270 net/socket.c:744
   ____sys_sendmsg+0x52a/0x7e0 net/socket.c:2602
   ___sys_sendmsg net/socket.c:2656 [inline]
   __sys_sendmmsg+0x3ab/0x730 net/socket.c:2742
   __do_sys_sendmmsg net/socket.c:2771 [inline]
   __se_sys_sendmmsg net/socket.c:2768 [inline]
   __x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2768
   do_syscall_x64 arch/x86/entry/common.c:52 [inline]
   do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
   entry_SYSCALL_64_after_hwframe+0x77/0x7f


stack backtrace:
CPU: 0 UID: 0 PID: 8854 Comm: syz.1.709 Not tainted 6.12.0-rc1-syzkaller-00046-g7ec462100ef9 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_irq_inversion_bug+0x33d/0x390 kernel/locking/lockdep.c:4121
 mark_lock_irq+0x867/0xc20 kernel/locking/lockdep.c:4283
 mark_lock+0x223/0x360 kernel/locking/lockdep.c:4725
 __lock_acquire+0x11b0/0x2050 kernel/locking/lockdep.c:5156
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
 __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:729 [inline]
 __sock_sendmsg+0x221/0x270 net/socket.c:744
 ____sys_sendmsg+0x52a/0x7e0 net/socket.c:2602
 ___sys_sendmsg net/socket.c:2656 [inline]
 __sys_sendmmsg+0x3ab/0x730 net/socket.c:2742
 __do_sys_sendmmsg net/socket.c:2771 [inline]
 __se_sys_sendmmsg net/socket.c:2768 [inline]
 __x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2768
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f28e017dff9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f28e0f4f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f28e0335f80 RCX: 00007f28e017dff9
RDX: 0400000000000026 RSI: 0000000020001cc0 RDI: 0000000000000005
RBP: 00007f28e01f0296 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f28e0335f80 R15: 00007f28e045fa28
 </TASK>