================================ WARNING: inconsistent lock state 6.1.112-syzkaller #0 Not tainted -------------------------------- inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. syz.0.26/4607 [HC0[0]:SC1[1]:HE1:SE0] takes: ffff0000f0a1d1e0 (&pch->downl){+.?.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff0000f0a1d1e0 (&pch->downl){+.?.}-{2:2}, at: ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline] ffff0000f0a1d1e0 (&pch->downl){+.?.}-{2:2}, at: ppp_input+0x168/0x840 drivers/net/ppp/ppp_generic.c:2304 {SOFTIRQ-ON-W} state was registered at: lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5662 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x54/0x6c 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+0x168/0x840 drivers/net/ppp/ppp_generic.c:2304 pppoe_rcv_core+0xfc/0x310 drivers/net/ppp/pppoe.c:379 sk_backlog_rcv include/net/sock.h:1117 [inline] __release_sock+0x1a8/0x408 net/core/sock.c:2936 release_sock+0x68/0x1cc net/core/sock.c:3500 pppoe_sendmsg+0xc8/0x5d4 drivers/net/ppp/pppoe.c:903 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg net/socket.c:730 [inline] ____sys_sendmsg+0x55c/0x848 net/socket.c:2514 ___sys_sendmsg net/socket.c:2568 [inline] __sys_sendmmsg+0x318/0x7d8 net/socket.c:2654 __do_sys_sendmmsg net/socket.c:2683 [inline] __se_sys_sendmmsg net/socket.c:2680 [inline] __arm64_sys_sendmmsg+0xa0/0xbc net/socket.c:2680 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 irq event stamp: 2710 hardirqs last enabled at (2710): [] __local_bh_enable_ip+0x230/0x470 kernel/softirq.c:401 hardirqs last disabled at (2709): [] __local_bh_enable_ip+0x1a0/0x470 kernel/softirq.c:378 softirqs last enabled at (2676): [] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32 softirqs last disabled at (2683): [] __do_softirq+0x14/0x20 kernel/softirq.c:605 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&pch->downl); lock(&pch->downl); *** DEADLOCK *** 4 locks held by syz.0.26/4607: #0: ffff800015ba4f20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:349 #1: ffff0000d57f90b0 (slock-AF_PPPOX){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #1: ffff0000d57f90b0 (slock-AF_PPPOX){+.-.}-{2:2}, at: __sk_receive_skb+0x164/0x900 net/core/sock.c:562 #2: ffff0000d57f9130 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: sk_receive_skb include/net/sock.h:2040 [inline] #2: ffff0000d57f9130 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: pppoe_rcv+0x310/0x5b4 drivers/net/ppp/pppoe.c:451 #3: ffff800015ba4f20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 stack backtrace: CPU: 1 PID: 4607 Comm: syz.0.26 Not tainted 6.1.112-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024 Call trace: dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106 dump_stack+0x1c/0x58 lib/dump_stack.c:113 print_usage_bug+0x654/0x9b0 kernel/locking/lockdep.c:3957 mark_lock_irq+0x980/0xd2c mark_lock+0x258/0x360 kernel/locking/lockdep.c:4628 __lock_acquire+0xb80/0x7680 kernel/locking/lockdep.c:5003 lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5662 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x54/0x6c 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+0x168/0x840 drivers/net/ppp/ppp_generic.c:2304 pppoe_rcv_core+0xfc/0x310 drivers/net/ppp/pppoe.c:379 sk_backlog_rcv include/net/sock.h:1117 [inline] __sk_receive_skb+0x3f8/0x900 net/core/sock.c:569 sk_receive_skb include/net/sock.h:2040 [inline] pppoe_rcv+0x310/0x5b4 drivers/net/ppp/pppoe.c:451 __netif_receive_skb_one_core net/core/dev.c:5528 [inline] __netif_receive_skb+0x18c/0x400 net/core/dev.c:5642 process_backlog+0x410/0x784 net/core/dev.c:5970 __napi_poll+0xb4/0x3f0 net/core/dev.c:6537 napi_poll net/core/dev.c:6604 [inline] net_rx_action+0x5cc/0xd3c net/core/dev.c:6718 handle_softirqs+0x318/0xd58 kernel/softirq.c:571 __do_softirq+0x14/0x20 kernel/softirq.c:605 ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:80 call_on_irq_stack+0x24/0x4c arch/arm64/kernel/entry.S:893 do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:85 invoke_softirq kernel/softirq.c:452 [inline] __irq_exit_rcu+0x264/0x4d4 kernel/softirq.c:654 irq_exit_rcu+0x14/0x84 kernel/softirq.c:666 __el1_irq arch/arm64/kernel/entry-common.c:472 [inline] el1_interrupt+0x38/0x68 arch/arm64/kernel/entry-common.c:486 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:491 el1h_64_irq+0x64/0x68 arch/arm64/kernel/entry.S:581 local_daif_restore arch/arm64/include/asm/daifflags.h:117 [inline] el0_svc_common+0xa8/0x258 arch/arm64/kernel/syscall.c:105 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585