================================ WARNING: inconsistent lock state 6.12.0-rc1-syzkaller-g2d8bce6e34be #0 Not tainted -------------------------------- inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. syz.3.555/8958 [HC0[0]:SC1[1]:HE1:SE0] takes: ffff0000dbb401e0 (&pch->downl){+.?.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff0000dbb401e0 (&pch->downl){+.?.}-{2:2}, at: ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline] ffff0000dbb401e0 (&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: 3378 hardirqs last enabled at (3378): [] __local_bh_enable_ip+0x224/0x44c kernel/softirq.c:387 hardirqs last disabled at (3377): [] __local_bh_enable_ip+0x194/0x44c kernel/softirq.c:364 softirqs last enabled at (3302): [] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32 softirqs last disabled at (3351): [] __do_softirq+0x14/0x20 kernel/softirq.c:588 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.3.555/8958: #0: ffff80008f9cf760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:336 #1: ffff0000e52021d8 (slock-AF_PPPOX){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #1: ffff0000e52021d8 (slock-AF_PPPOX){+.-.}-{2:2}, at: __sk_receive_skb+0x164/0x8c0 net/core/sock.c:563 #2: ffff0000e5202258 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: sk_receive_skb include/net/sock.h:1898 [inline] #2: ffff0000e5202258 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: pppoe_rcv+0x314/0x5b0 drivers/net/ppp/pppoe.c:451 #3: ffff80008f9cf760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:336 stack backtrace: CPU: 1 UID: 0 PID: 8958 Comm: syz.3.555 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 pppoe_rcv_core+0xfc/0x314 drivers/net/ppp/pppoe.c:379 sk_backlog_rcv include/net/sock.h:1113 [inline] __sk_receive_skb+0x3e8/0x8c0 net/core/sock.c:570 sk_receive_skb include/net/sock.h:1898 [inline] pppoe_rcv+0x314/0x5b0 drivers/net/ppp/pppoe.c:451 __netif_receive_skb_one_core net/core/dev.c:5662 [inline] __netif_receive_skb+0x18c/0x3c8 net/core/dev.c:5775 process_backlog+0x640/0x123c net/core/dev.c:6107 __napi_poll+0xb4/0x3fc net/core/dev.c:6771 napi_poll net/core/dev.c:6840 [inline] net_rx_action+0x6a8/0xf4c net/core/dev.c:6962 handle_softirqs+0x2e0/0xbf8 kernel/softirq.c:554 __do_softirq+0x14/0x20 kernel/softirq.c:588 ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:81 call_on_irq_stack+0x24/0x4c arch/arm64/kernel/entry.S:889 do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:86 invoke_softirq kernel/softirq.c:435 [inline] __irq_exit_rcu+0x1d8/0x434 kernel/softirq.c:637 irq_exit_rcu+0x14/0x84 kernel/softirq.c:649 el0_interrupt+0x6c/0x248 arch/arm64/kernel/entry-common.c:818 __el0_irq_handler_common+0x18/0x24 arch/arm64/kernel/entry-common.c:825 el0t_64_irq_handler+0x10/0x1c arch/arm64/kernel/entry-common.c:830 el0t_64_irq+0x190/0x194 arch/arm64/kernel/entry.S:599