rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (30 ticks this GP) idle=4ad/1/0x4000000000000002 softirq=9041/9041 fqs=12 
	(detected by 1, t=10502 jiffies, g=11613, q=83)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 5362 Comm: syz.0.265 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:check_kcov_mode kernel/kcov.c:172 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:227 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp8+0x2a/0x80 kernel/kcov.c:300
Code: 48 8b 04 24 65 48 8b 0d 94 49 89 7e 65 8b 15 95 49 89 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 57 83 b9 34 16 00 00 00 <74> 4e 8b 91 10 16 00 00 83 fa 03 75 43 48 8b 91 18 16 00 00 44 8b
RSP: 0018:ffffc90000006e10 EFLAGS: 00000046
RAX: ffffffff810110df RBX: ffff8880b90351c8 RCX: ffff88805dc93b80
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffc90000006fb7 R09: ffffc90000006f80
R10: dffffc0000000000 R11: fffff52000000df7 R12: dffffc0000000000
R13: ffffc90000006fe6 R14: 0000000000000000 R15: dffffc0000000000
FS:  00007f9ad773a6c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000100000000 CR3: 00000000754b6000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000200000000300 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 user_mode arch/x86/include/asm/ptrace.h:136 [inline]
 perf_misc_flags+0x13f/0x1b0 arch/x86/events/core.c:2970
 perf_prepare_sample+0x132/0x1cd0 kernel/events/core.c:7622
 __perf_event_output kernel/events/core.c:7802 [inline]
 perf_event_output_forward+0x185/0x2e0 kernel/events/core.c:7822
 __perf_event_overflow+0x364/0x530 kernel/events/core.c:9515
 perf_tp_event+0x383/0xbf0 kernel/events/core.c:10047
 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10021
 perf_trace_preemptirq_template+0x2aa/0x360 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:rcu_read_unlock_special+0x7f/0x4a0 kernel/rcu/tree_plugin.h:674
Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 e2 f0 9c 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc90000007580 EFLAGS: 00000206
RAX: 067e600c39ac9c00 RBX: 1ffff92000000eb4 RCX: 067e600c39ac9c00
RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f740
RBP: ffffc90000007648 R08: ffffffff901d218f R09: 1ffffffff203a431
R10: dffffc0000000000 R11: fffffbfff203a432 R12: ffffffff8c322f00
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
 rcu_read_unlock include/linux/rcupdate.h:772 [inline]
 dev_queue_xmit_nit+0x9ca/0xb00 net/core/dev.c:2390
 xmit_one net/core/dev.c:3657 [inline]
 dev_hard_start_xmit+0x13e/0x7e0 net/core/dev.c:3678
 sch_direct_xmit+0x25a/0x4b0 net/sched/sch_generic.c:345
 __dev_xmit_skb net/core/dev.c:3897 [inline]
 __dev_queue_xmit+0x179f/0x2fd0 net/core/dev.c:4266
 lapb_data_transmit+0x86/0xa0 net/lapb/lapb_iface.c:447
 lapb_transmit_buffer+0x15f/0x1f0 net/lapb/lapb_out.c:149
 lapb_t1timer_expiry+0x652/0xa70 net/lapb/lapb_timer.c:-1
 call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648
 expire_timers kernel/time/timer.c:1699 [inline]
 __run_timers+0x53e/0x800 kernel/time/timer.c:1970
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983
 handle_softirqs+0x339/0x830 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:INIT_LIST_HEAD include/linux/list.h:36 [inline]
RIP: 0010:list_del_init include/linux/list.h:205 [inline]
RIP: 0010:plist_del+0x382/0x3f0 lib/plist.c:130
Code: e8 d3 7c b8 fd 49 89 2c 24 eb 05 e8 68 70 73 fd 4c 89 f8 48 c1 e8 03 42 80 3c 28 00 74 08 4c 89 ff e8 b2 7c b8 fd 4d 89 7e 18 <49> 83 c6 20 4c 89 f0 48 c1 e8 03 42 80 3c 28 00 74 08 4c 89 f7 e8
RSP: 0018:ffffc900038afab0 EFLAGS: 00000246
RAX: 1ffff92000729f75 RBX: ffffc90000e08548 RCX: dffffc0000000000
RDX: ffffc90004064000 RSI: 00000000000016ae RDI: 00000000000016af
RBP: ffffc90000e08548 R08: ffff88807eaa9deb R09: 1ffff1100fd553bd
R10: dffffc0000000000 R11: ffffed100fd553be R12: ffffc90000e08548
R13: dffffc0000000000 R14: ffffc9000394fb90 R15: ffffc9000394fba8
 __unqueue_futex+0xec/0x160 kernel/futex/core.c:1525
 mark_wake_futex+0xe8/0x150 kernel/futex/core.c:1543
 futex_wake+0x3c2/0x540 kernel/futex/core.c:1695
 do_futex+0xd73/0x12b0 kernel/futex/core.c:3987
 __do_sys_futex kernel/futex/core.c:4059 [inline]
 __se_sys_futex+0x389/0x420 kernel/futex/core.c:4040
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f9ad94dff79
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:00007f9ad773a0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 00007f9ad9759fa8 RCX: 00007f9ad94dff79
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f9ad9759fac
RBP: 00007f9ad9759fa0 R08: 0007f4efdc81fa66 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9ad975a038 R14: 00007ffe34a62f90 R15: 00007ffe34a63078
 </TASK>
rcu: rcu_preempt kthread starved for 10472 jiffies! g11613 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:27992 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117
 rcu_gp_fqs_loop+0x2be/0x11d0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x9b/0x370 kernel/rcu/tree.c:2145
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 1
CPU: 1 PID: 5361 Comm: syz.0.265 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <IRQ>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487
 print_other_cpu_stall+0x1110/0x1270 kernel/rcu/tree_stall.h:592
 check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
 rcu_pending kernel/rcu/tree.c:3936 [inline]
 rcu_sched_clock_irq+0x843/0x1120 kernel/rcu/tree.c:2619
 update_process_times+0x193/0x200 kernel/time/timer.c:2021
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x4ad/0xb70 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1811
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
RIP: 0010:arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
RIP: 0010:kvm_wait+0x159/0x1b0 arch/x86/kernel/kvm.c:918
Code: 89 df 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 75 4b 0f b6 1f e8 a7 b4 4a 00 44 38 e3 75 10 66 90 0f 00 2d 99 e2 f3 08 fb f4 <e9> 16 ff ff ff fb e9 10 ff ff ff e8 47 7f 87 08 89 f9 80 e1 07 38
RSP: 0018:ffffc9000394f800 EFLAGS: 00000246
RAX: 379d93caa6576c00 RBX: 0000000000000003 RCX: 379d93caa6576c00
RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f740
RBP: ffffc9000394f8b0 R08: ffffffff901d21af R09: 1ffffffff203a435
R10: dffffc0000000000 R11: fffffbfff203a436 R12: 0000000000000003
R13: ffff8880b913b154 R14: dffffc0000000000 R15: 1ffff92000729f00
 pv_wait arch/x86/include/asm/paravirt.h:597 [inline]
 pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline]
 __pv_queued_spin_lock_slowpath+0x60f/0x9c0 kernel/locking/qspinlock.c:508
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:585 [inline]
 queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51
 queued_spin_lock include/asm-generic/qspinlock.h:85 [inline]
 do_raw_spin_lock+0x265/0x2f0 kernel/locking/spinlock_debug.c:115
 spin_lock include/linux/spinlock.h:364 [inline]
 unqueue_me kernel/futex/core.c:2548 [inline]
 futex_wait+0x26f/0x680 kernel/futex/core.c:2968
 do_futex+0xdb2/0x12b0 kernel/futex/core.c:3982
 __do_sys_futex kernel/futex/core.c:4059 [inline]
 __se_sys_futex+0x389/0x420 kernel/futex/core.c:4040
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f9ad94dff79
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:00007ffe34a631d8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 000000000001a673 RCX: 00007f9ad94dff79
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f9ad9759fac
RBP: 0000000000000032 R08: 0007f4efdc81fa66 R09: 0000000000000000
R10: 00007ffe34a632e0 R11: 0000000000000246 R12: 00007ffe34a63300
R13: 00007f9ad9759fac R14: 000000000001a6a5 R15: 00007ffe34a632e0
 </TASK>