watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [syz.5.285:8372] Modules linked in: irq event stamp: 5187 hardirqs last enabled at (5186): [] irqentry_exit+0xd8/0x108 kernel/entry/common.c:214 hardirqs last disabled at (5187): [] __enter_from_kernel_mode arch/arm64/kernel/entry-common.c:43 [inline] hardirqs last disabled at (5187): [] enter_from_kernel_mode+0x14/0x34 arch/arm64/kernel/entry-common.c:50 softirqs last enabled at (472): [] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32 softirqs last disabled at (486): [] spin_lock_bh include/linux/spinlock.h:356 [inline] softirqs last disabled at (486): [] sch_tree_lock+0x120/0x1d4 include/net/sch_generic.h:-1 CPU: 0 UID: 0 PID: 8372 Comm: syz.5.285 Not tainted syzkaller #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025 pstate: 63400005 (nZCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) pc : preempt_count+0x38/0x68 arch/arm64/include/asm/preempt.h:12 lr : preempt_count+0x14/0x68 arch/arm64/include/asm/preempt.h:11 sp : ffff8000a11b6c00 x29: ffff8000a11b6c10 x28: 1ffff00011b352a4 x27: dfff800000000000 x26: 0000000000000000 x25: ffff0000d1761040 x24: ffff0000ce6ca000 x23: ffff0000d3309ec0 x22: ffff80008b3fac80 x21: ffff80008b3facc0 x20: b0c780008adf4880 x19: 0000000000000000 x18: 0000000000000001 x17: ffff800093303000 x16: ffff800082debf80 x15: ffff700014236d8c x14: 0000000000000002 x13: 00000000ffffffff x12: 0000000000ff0100 x11: 0000000000080000 x10: 0000000000000003 x9 : 0000000000000000 x8 : ffff0000d3309ec8 x7 : ffff80008928f608 x6 : 0000000000000000 x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000002 x2 : 0000000000000008 x1 : ffff80008b3facc0 x0 : ffff80008b3fac80 Call trace: preempt_count+0x38/0x68 arch/arm64/include/asm/preempt.h:12 (P) check_preemption_disabled+0x30/0xe4 lib/smp_processor_id.c:16 debug_smp_processor_id+0x20/0x2c lib/smp_processor_id.c:58 rcu_lockdep_current_cpu_online+0x7c/0x1dc kernel/rcu/tree.c:4032 rcu_read_lock_held_common kernel/rcu/update.c:113 [inline] rcu_read_lock_held+0x20/0x50 kernel/rcu/update.c:349 dev_ingress_queue_rcu include/linux/rtnetlink.h:168 [inline] qdisc_lookup_rcu+0x2d8/0x668 net/sched/sch_api.c:331 qdisc_tree_reduce_backlog+0x188/0x410 net/sched/sch_api.c:795 fq_change+0x11e4/0x1d00 net/sched/sch_fq.c:1149 fq_init+0x5fc/0xdec net/sched/sch_fq.c:1203 qdisc_create+0x6a4/0xce4 net/sched/sch_api.c:1319 __tc_modify_qdisc net/sched/sch_api.c:1748 [inline] tc_modify_qdisc+0x11f4/0x1cd4 net/sched/sch_api.c:1812 rtnetlink_rcv_msg+0x624/0x97c net/core/rtnetlink.c:6960 netlink_rcv_skb+0x220/0x3fc net/netlink/af_netlink.c:2552 rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6978 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x694/0x8c4 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x648/0x930 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0x490/0x7b8 net/socket.c:2630 ___sys_sendmsg+0x204/0x278 net/socket.c:2684 __sys_sendmsg net/socket.c:2716 [inline] __do_sys_sendmsg net/socket.c:2721 [inline] __se_sys_sendmsg net/socket.c:2719 [inline] __arm64_sys_sendmsg+0x184/0x238 net/socket.c:2719 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 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+0x5c/0x254 arch/arm64/kernel/entry-common.c:746 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:765 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025 pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) pc : arch_local_irq_enable+0x8/0xc arch/arm64/include/asm/irqflags.h:50 lr : default_idle_call+0xd0/0xfc kernel/sched/idle.c:129 sp : ffff800097ad7d60 x29: ffff800097ad7d60 x28: 0000000000000002 x27: dfff800000000000 x26: 1ffff00012f5afb4 x25: 0000000000000000 x24: 0000000000000000 x23: 1fffe00018343b88 x22: ffff80008f57e768 x21: 1ffff00011eafced x20: 0000000000000000 x19: ffff8000804cbc00 x18: 1fffe000337dfe90 x17: ffff80008f57e000 x16: ffff8000804cb524 x15: 0000000000000001 x14: 1fffe000337e1b40 x13: 0000000000000000 x12: 0000000000000000 x11: ffff6000337e1b41 x10: 0000000000000003 x9 : 0000000000000000 x8 : 000000000006a9e9 x7 : ffff800080663398 x6 : 0000000000000000 x5 : 0000000000000001 x4 : 0000000000000001 x3 : ffff80008adf42c4 x2 : 0000000000000000 x1 : ffff80008eb98661 x0 : ffff80010ca32000 Call trace: __daif_local_irq_enable arch/arm64/include/asm/irqflags.h:26 [inline] (P) arch_local_irq_enable+0x8/0xc arch/arm64/include/asm/irqflags.h:48 (P) cpuidle_idle_call kernel/sched/idle.c:190 [inline] do_idle+0x1d8/0x454 kernel/sched/idle.c:330 cpu_startup_entry+0x5c/0x74 kernel/sched/idle.c:428 secondary_start_kernel+0x1bc/0x1e4 arch/arm64/kernel/smp.c:271 __secondary_switched+0xc0/0xc4 arch/arm64/kernel/head.S:401