watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [syz.1.1881:12690] Modules linked in: irq event stamp: 9851 hardirqs last enabled at (9850): [] irqentry_exit_to_kernel_mode_after_preempt include/linux/irq-entry-common.h:507 [inline] hardirqs last enabled at (9850): [] __arm64_exit_to_kernel_mode+0x64/0x78 arch/arm64/kernel/entry-common.c:60 hardirqs last disabled at (9851): [] __el1_irq arch/arm64/kernel/entry-common.c:527 [inline] hardirqs last disabled at (9851): [] el1_interrupt+0x28/0x60 arch/arm64/kernel/entry-common.c:543 softirqs last enabled at (2958): [] __alloc_skb+0x1c0/0x610 net/core/skbuff.c:698 softirqs last disabled at (2960): [] local_bh_disable include/linux/bottom_half.h:20 [inline] softirqs last disabled at (2960): [] rcu_read_lock_bh include/linux/rcupdate.h:902 [inline] softirqs last disabled at (2960): [] __dev_queue_xmit+0x1fc/0x2bc0 net/core/dev.c:4844 CPU: 0 UID: 0 PID: 12690 Comm: syz.1.1881 Tainted: G L syzkaller #0 PREEMPT Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026 pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) pc : __tcf_classify net/sched/cls_api.c:-1 [inline] pc : tcf_classify+0x490/0xdc0 net/sched/cls_api.c:1875 lr : __tcf_classify net/sched/cls_api.c:1792 [inline] lr : tcf_classify+0x490/0xdc0 net/sched/cls_api.c:1875 sp : ffff800095767010 x29: ffff800095767060 x28: ffff0000f54fcb40 x27: dfff800000000000 x26: 0000000000000000 x25: 0000000000000008 x24: ffff0000f566ae00 x23: 0000000000000000 x22: ffff0000f54fcbdc x21: 0000000000000000 x20: 1fffe0001ea9f97b x19: ffff80008a26b000 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 0000000020000780 x14: 00000000ffff8000 x13: 00000000fff10000 x12: ffff0000d2a84290 x11: 0000000000000000 x10: 0000000000080000 x9 : 0000000000000200 x8 : 0000000000000002 x7 : 00000000fff10000 x6 : ffff0000d2a84290 x5 : ffff800095767130 x4 : ffff0000f23ab658 x3 : ffff800084ec3ff8 x2 : 0000000000000000 x1 : ffff0000c8c0d880 x0 : 0000000000000000 Call trace: __tcf_classify net/sched/cls_api.c:1792 [inline] (P) tcf_classify+0x490/0xdc0 net/sched/cls_api.c:1875 (P) tcf_classify_qdisc include/net/pkt_cls.h:164 [inline] hfsc_classify net/sched/sch_hfsc.c:1146 [inline] hfsc_enqueue+0x2b4/0xd60 net/sched/sch_hfsc.c:1545 dev_qdisc_enqueue+0x60/0x450 net/core/dev.c:4227 __dev_xmit_skb net/core/dev.c:4342 [inline] __dev_queue_xmit+0x13f0/0x2bc0 net/core/dev.c:4884 dev_queue_xmit include/linux/netdevice.h:3461 [inline] packet_xmit+0x6c/0x314 net/packet/af_packet.c:277 packet_snd net/packet/af_packet.c:3110 [inline] packet_sendmsg+0x2f40/0x3e78 net/packet/af_packet.c:3142 sock_sendmsg_nosec net/socket.c:800 [inline] __sock_sendmsg+0xc8/0x17c net/socket.c:815 ____sys_sendmsg+0x3d0/0x6c8 net/socket.c:2713 ___sys_sendmsg+0x198/0x224 net/socket.c:2767 __sys_sendmsg+0x158/0x204 net/socket.c:2799 __do_sys_sendmsg net/socket.c:2804 [inline] __se_sys_sendmsg net/socket.c:2802 [inline] __arm64_sys_sendmsg+0x88/0x9c net/socket.c:2802 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:758 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:777 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:590 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G L syzkaller #0 PREEMPT Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026 pstate: 03400005 (nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) pc : queued_spin_lock_slowpath+0x138/0xd04 kernel/locking/qspinlock.c:219 lr : queued_spin_lock_slowpath+0x144/0xd04 kernel/locking/qspinlock.c:219 sp : ffff80008ec47200 x29: ffff80008ec472a0 x28: ffff0000c1aa8010 x27: 1fffe0001a55082c x26: 1fffe00018355002 x25: ffff0000c1aa8000 x24: dfff800000000000 x23: ffff700011d88e44 x22: ffff700011d88e64 x21: ffff0000d2a84160 x20: ffff0000d2a84168 x19: ffff0000d2a84158 x18: 1fffe00035ba3828 x17: 0000000000000000 x16: 0000000000000000 x15: ffff0000c6218010 x14: 00000000ffff8000 x13: 0000000000000001 x12: 0000000000000000 x11: 0000000000000000 x10: ffff60001a55082c x9 : 0000000000000000 x8 : 0000000000000001 x7 : ffff800084ce0284 x6 : 0000000000000000 x5 : 0000000000000000 x4 : 0000000000000001 x3 : ffff8000869aa754 x2 : 0000000000000000 x1 : 0000000000000001 x0 : 0000000000000001 Call trace: __cmpwait_case_8 arch/arm64/include/asm/cmpxchg.h:231 [inline] (P) __cmpwait arch/arm64/include/asm/cmpxchg.h:259 [inline] (P) queued_spin_lock_slowpath+0x138/0xd04 kernel/locking/qspinlock.c:219 (P) queued_spin_lock include/asm-generic/qspinlock.h:115 [inline] do_raw_spin_lock+0x21c/0x2d0 kernel/locking/spinlock_debug.c:116 __raw_spin_lock include/linux/spinlock_api_smp.h:191 [inline] _raw_spin_lock+0x50/0x60 kernel/locking/spinlock.c:173 spin_lock include/linux/spinlock.h:347 [inline] __dev_xmit_skb net/core/dev.c:4300 [inline] __dev_queue_xmit+0xa74/0x2bc0 net/core/dev.c:4884 dev_queue_xmit include/linux/netdevice.h:3461 [inline] neigh_connected_output+0x378/0x40c net/core/neighbour.c:1645 neigh_output include/net/neighbour.h:560 [inline] ip6_finish_output2+0xd5c/0x1b68 net/ipv6/ip6_output.c:138 __ip6_finish_output net/ipv6/ip6_output.c:-1 [inline] ip6_finish_output+0x230/0x618 net/ipv6/ip6_output.c:221 NF_HOOK_COND include/linux/netfilter.h:314 [inline] ip6_output+0x2d0/0x644 net/ipv6/ip6_output.c:248 dst_output include/net/dst.h:470 [inline] NF_HOOK include/linux/netfilter.h:325 [inline] ndisc_send_skb+0xc18/0x162c net/ipv6/ndisc.c:513 ndisc_send_rs+0x378/0x504 net/ipv6/ndisc.c:724 addrconf_rs_timer+0x230/0x574 net/ipv6/addrconf.c:4073 call_timer_fn+0x194/0xa4c kernel/time/timer.c:1748 expire_timers kernel/time/timer.c:1799 [inline] __run_timers kernel/time/timer.c:2374 [inline] __run_timer_base+0x530/0x744 kernel/time/timer.c:2386 run_timer_base+0x84/0x1b8 kernel/time/timer.c:2395 run_timer_softirq+0x20/0x48 kernel/time/timer.c:2405 handle_softirqs+0x2ec/0xd98 kernel/softirq.c:645 __do_softirq+0x14/0x20 kernel/softirq.c:679 ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:78 call_on_irq_stack+0x30/0x48 arch/arm64/kernel/entry.S:885 do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:83 invoke_softirq kernel/softirq.c:526 [inline] __irq_exit_rcu+0x1c0/0x458 kernel/softirq.c:767 irq_exit_rcu+0x14/0x84 kernel/softirq.c:784 __el1_irq arch/arm64/kernel/entry-common.c:531 [inline] el1_interrupt+0x40/0x60 arch/arm64/kernel/entry-common.c:543 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:548 el1h_64_irq+0x6c/0x70 arch/arm64/kernel/entry.S:586 __daif_local_irq_enable arch/arm64/include/asm/irqflags.h:26 [inline] (P) arch_local_irq_enable arch/arm64/include/asm/irqflags.h:48 [inline] (P) default_idle_call+0xd0/0xfc kernel/sched/idle.c:129 (P) cpuidle_idle_call kernel/sched/idle.c:199 [inline] do_idle+0x1ec/0x450 kernel/sched/idle.c:355 cpu_startup_entry+0x5c/0x74 kernel/sched/idle.c:454 secondary_start_kernel+0x1bc/0x1e0 arch/arm64/kernel/smp.c:273 __secondary_switched+0xc0/0xc4 arch/arm64/kernel/head.S:401 watchdog: BUG: soft lockup - CPU#1 stuck for 23s! [swapper/1:0] Modules linked in: irq event stamp: 2702609 hardirqs last enabled at (2702608): [] arm64_exit_to_kernel_mode_preempt+0x28/0x38 arch/arm64/kernel/entry-common.c:70 hardirqs last disabled at (2702609): [] __el1_irq arch/arm64/kernel/entry-common.c:527 [inline] hardirqs last disabled at (2702609): [] el1_interrupt+0x28/0x60 arch/arm64/kernel/entry-common.c:543 softirqs last enabled at (2698222): [] softirq_handle_end kernel/softirq.c:491 [inline] softirqs last enabled at (2698222): [] handle_softirqs+0xc28/0xd98 kernel/softirq.c:673 softirqs last disabled at (2698275): [] __do_softirq+0x14/0x20 kernel/softirq.c:679