rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (0 ticks this GP) idle=0bec/1/0x4000000000000000 softirq=24338/24338 fqs=0 rcu: (detected by 0, t=10505 jiffies, g=19101, q=390 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 6666 Comm: syz.2.18 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:debug_object_activate+0x2dd/0x420 lib/debugobjects.c:836 Code: 06 84 c0 74 2c ff 05 82 2d ea 0a eb 22 43 0f b6 04 37 84 c0 0f 85 28 01 00 00 c7 45 00 03 00 00 00 48 8b 7c 24 08 48 8b 34 24 5e 4c b6 06 31 ed 65 48 8b 05 d4 85 db 0d 48 3b 44 24 40 0f 85 RSP: 0018:ffffc90000a08c88 EFLAGS: 00000046 RAX: 0000000000000000 RBX: ffff888058854340 RCX: 0000000000000001 RDX: 0000000000000001 RSI: 0000000000000012 RDI: ffffffff99a88a30 RBP: ffff888031617780 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff5200014116c R12: ffff888031617788 R13: ffff888031617770 R14: dffffc0000000000 R15: 1ffff110062c2ef0 FS: 00007f84b2e586c0(0000) GS:ffff888126238000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f84b2e37d58 CR3: 0000000078f1b000 CR4: 0000000000350ef0 Call Trace: debug_hrtimer_activate kernel/time/hrtimer.c:438 [inline] debug_activate kernel/time/hrtimer.c:477 [inline] enqueue_hrtimer+0x30/0x3a0 kernel/time/hrtimer.c:1081 __run_hrtimer kernel/time/hrtimer.c:1794 [inline] __hrtimer_run_queues+0x656/0xc60 kernel/time/hrtimer.c:1841 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1903 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1041 [inline] __sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1058 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1052 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lockdep_unregister_key+0x2c5/0x310 kernel/locking/lockdep.c:6616 Code: 65 48 8b 05 2d 09 d1 10 48 3b 44 24 10 0f 84 26 fe ff ff e8 dd 39 a9 09 e8 08 3b a9 09 41 f7 c7 00 02 00 00 74 bd fb 40 84 ed <75> bc eb cd 90 0f 0b 90 e9 19 ff ff ff 90 0f 0b 90 e9 2a ff ff ff RSP: 0018:ffffc9000421f0a8 EFLAGS: 00000246 RAX: 36ab1e919ee50600 RBX: ffff88802f27b298 RCX: 36ab1e919ee50600 RDX: ffffffff93323358 RSI: ffffffff8d723880 RDI: ffffffff8bbf0960 RBP: ffff88802f27b200 R08: ffffffff8f7cf777 R09: 1ffffffff1ef9eee R10: dffffc0000000000 R11: fffffbfff1ef9eef R12: 0000000000000000 R13: 0000000000001000 R14: 0000000000000000 R15: 0000000000000216 __qdisc_destroy+0x166/0x420 net/sched/sch_generic.c:1086 taprio_attach+0x25a/0x380 net/sched/sch_taprio.c:2160 qdisc_graft+0x1175/0x1590 net/sched/sch_api.c:1162 __tc_modify_qdisc net/sched/sch_api.c:1761 [inline] tc_modify_qdisc+0x16d3/0x2020 net/sched/sch_api.c:1817 rtnetlink_rcv_msg+0x77c/0xb70 net/core/rtnetlink.c:6960 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2552 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg+0x21c/0x270 net/socket.c:742 ____sys_sendmsg+0x505/0x830 net/socket.c:2630 ___sys_sendmsg+0x21f/0x2a0 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] __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2719 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f84b1f8d169 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:00007f84b2e58038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f84b21a5fa0 RCX: 00007f84b1f8d169 RDX: 0000000000000000 RSI: 00002000000007c0 RDI: 0000000000000004 RBP: 00007f84b200e2a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f84b21a5fa0 R15: 00007ffe0d2c2438 rcu: rcu_preempt kthread timer wakeup didn't happen for 10504 jiffies! g19101 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=1 timer-softirq=8955 rcu: rcu_preempt kthread starved for 10505 jiffies! g19101 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1 rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior. rcu: RCU grace-period kthread stack dump: task:rcu_preempt state:I stack:27912 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5325 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929 __schedule_loop kernel/sched/core.c:7011 [inline] schedule+0x165/0x360 kernel/sched/core.c:7026 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245