rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=d114/1/0x4000000000000000 softirq=9372/9373 fqs=1 (detected by 1, t=10502 jiffies, g=8341, q=67 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 4397 Comm: syz.4.13 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 RIP: 0010:rcu_dynticks_curr_cpu_in_eqs include/linux/context_tracking.h:122 [inline] RIP: 0010:rcu_is_watching+0xc/0xa0 kernel/rcu/tree.c:721 Code: 49 b3 8c 4c 89 f6 e8 43 ca cc 02 e9 44 ff ff ff 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 41 57 41 56 53 65 ff 05 1c fc 95 7e cf f7 c2 08 89 c3 83 f8 08 73 60 49 bf 00 00 00 00 00 fc ff df RSP: 0018:ffffc90000007c90 EFLAGS: 00000086 RAX: ffffffff88648ae7 RBX: ffffffff88648ab7 RCX: 0000000000010000 RDX: ffff888030699e00 RSI: 0000000000000001 RDI: 0000000000000000 RBP: 0000000000000001 R08: dffffc0000000000 R09: 1ffffffff215fe48 R10: dffffc0000000000 R11: fffffbfff215fe49 R12: 18b936cfc7581cf8 R13: dffffc0000000000 R14: ffff88802f46ea80 R15: ffff888053e05000 FS: 00007f9f7d8cb6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00002000000012c0 CR3: 00000000247d0000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_read_lock include/linux/rcupdate.h:792 [inline] advance_sched+0x6f0/0x950 net/sched/sch_taprio.c:759 __run_hrtimer kernel/time/hrtimer.c:1751 [inline] __hrtimer_run_queues+0x54a/0xd50 kernel/time/hrtimer.c:1815 hrtimer_interrupt+0x3c5/0x9c0 kernel/time/hrtimer.c:1877 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline] __sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline] sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1118 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691 RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194 Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 af 7f 1f f7 65 8b 05 80 ff c8 75 85 c0 74 3c 48 c7 04 24 0e 36 RSP: 0018:ffffc9000484ed00 EFLAGS: 00000206 RAX: dffffc0000000004 RBX: 0000000000000a06 RCX: e01e808f1f1c2400 RDX: dffffc0000000000 RSI: ffffffff8a8c1aa0 RDI: 0000000000000001 RBP: ffffc9000484ed90 R08: ffffffff90aff357 R09: 1ffffffff215fe6a R10: dffffc0000000000 R11: fffffbfff215fe6b R12: dffffc0000000000 R13: 0000000000000a06 R14: ffff888053e052e8 R15: 1ffff92000909da0 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline] taprio_change+0x4474/0x5490 net/sched/sch_taprio.c:1695 qdisc_create+0x7eb/0x10b0 net/sched/sch_api.c:1305 tc_modify_qdisc+0xb5f/0x1d10 net/sched/sch_api.c:-1 rtnetlink_rcv_msg+0x87c/0xfc0 net/core/rtnetlink.c:6158 netlink_rcv_skb+0x1fb/0x450 net/netlink/af_netlink.c:2511 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x74d/0x8d0 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8ad/0xbd0 net/netlink/af_netlink.c:1872 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg net/socket.c:730 [inline] ____sys_sendmsg+0x5be/0x970 net/socket.c:2518 ___sys_sendmsg+0x2a2/0x360 net/socket.c:2572 __sys_sendmsg net/socket.c:2601 [inline] __do_sys_sendmsg net/socket.c:2610 [inline] __se_sys_sendmsg+0x1bb/0x2a0 net/socket.c:2608 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f9f7c99ce59 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f9f7d8cb028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f9f7cc15fa0 RCX: 00007f9f7c99ce59 RDX: 0000000000000010 RSI: 00002000000012c0 RDI: 0000000000000005 RBP: 00007f9f7ca32d6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f9f7cc16038 R14: 00007f9f7cc15fa0 R15: 00007ffd2105c7a8 rcu: rcu_preempt kthread starved for 10500 jiffies! g8341 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R running task stack:28016 pid:16 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5245 [inline] __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562 schedule+0xb9/0x180 kernel/sched/core.c:6638 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168 rcu_gp_fqs_loop+0x303/0x1340 kernel/rcu/tree.c:1706 rcu_gp_kthread+0x99/0x3b0 kernel/rcu/tree.c:1905 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: Stack dump where RCU GP kthread last ran: CPU: 1 PID: 9 Comm: kworker/u4:0 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Workqueue: events_unbound toggle_allocation_gate RIP: 0010:csd_lock_wait kernel/smp.c:424 [inline] RIP: 0010:smp_call_function_many_cond+0xea7/0x1290 kernel/smp.c:998 Code: 1f 89 de 83 e6 01 31 ff e8 f6 f6 0a 00 83 e3 01 48 bb 00 00 00 00 00 fc ff df 75 07 e8 82 f3 0a 00 eb 37 f3 90 41 0f b6 04 1c <84> c0 75 10 41 f7 07 01 00 00 00 74 1e e8 67 f3 0a 00 eb e5 44 89 RSP: 0018:ffffc900000e7800 EFLAGS: 00000293 RAX: 0000000000000000 RBX: dffffc0000000000 RCX: ffff88813fe90000 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc900000e7960 R08: ffffffff90aff247 R09: 1ffffffff215fe48 R10: dffffc0000000000 R11: fffffbfff215fe49 R12: 1ffff110171c8601 R13: ffff8880b8f3bbc0 R14: 0000000000000000 R15: ffff8880b8e43008 FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe17d14da08 CR3: 000000000c88e000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: on_each_cpu_cond_mask+0x3b/0x80 kernel/smp.c:1165 on_each_cpu include/linux/smp.h:71 [inline] text_poke_sync arch/x86/kernel/alternative.c:1574 [inline] text_poke_bp_batch+0x2b7/0x850 arch/x86/kernel/alternative.c:1774 text_poke_flush arch/x86/kernel/alternative.c:1965 [inline] text_poke_finish+0x16/0x30 arch/x86/kernel/alternative.c:1972 arch_jump_label_transform_apply+0x13/0x20 arch/x86/kernel/jump_label.c:146 static_key_enable_cpuslocked+0x11f/0x240 kernel/jump_label.c:207 static_key_enable+0x16/0x20 kernel/jump_label.c:220 toggle_allocation_gate+0xba/0x470 mm/kfence/core.c:821 process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292 worker_thread+0xaa2/0x1270 kernel/workqueue.c:2439 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295