rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 1-...!: (10494 ticks this GP) idle=01b/1/0x4000000000000000 softirq=24170/24170 fqs=0
(t=10501 jiffies g=19777 q=3107)
rcu: rcu_preempt kthread starved for 10502 jiffies! g19777 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
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:27352 pid: 15 ppid: 2 flags:0x00004000
Call Trace:
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
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4943 Comm: kworker/0:22 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: events nsim_dev_trap_report_work
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:27 [inline]
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+0xc/0x80 kernel/kcov.c:300
Code: 44 02 08 05 00 00 00 4a 89 7c 02 10 4a 89 74 02 18 4a 89 44 02 20 48 ff c1 48 89 0a c3 90 48 8b 04 24 65 48 8b 0d c4 4a 89 7e <65> 8b 15 c5 4a 89 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75
RSP: 0018:ffffc90000007b48 EFLAGS: 00000293
RAX: ffffffff88153782 RBX: 00000010c6f7a0b5 RCX: ffff8880278b5940
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 00000010c6f7a0b5
RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000000f6c R12: 00000015798ee228
R13: 0019999999999998 R14: ffff888056e8ac10 R15: 0000000225c17d04
FS: 0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b30224000 CR3: 000000005b3c1000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
pie_calculate_probability+0x262/0x7e0 net/sched/sch_pie.c:348
fq_pie_timer+0x169/0x3a0 net/sched/sch_fq_pie.c:393
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+0x142/0x210 kernel/softirq.c:477
__local_bh_enable_ip+0x180/0x1c0 kernel/softirq.c:401
spin_unlock_bh include/linux/spinlock.h:409 [inline]
nsim_dev_trap_report drivers/net/netdevsim/dev.c:736 [inline]
nsim_dev_trap_report_work+0x7c0/0xb40 drivers/net/netdevsim/dev.c:762
process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
NMI backtrace for cpu 1
CPU: 1 PID: 16736 Comm: syz.2.5465 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
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_dump_cpu_stacks+0x22f/0x380 kernel/rcu/tree_stall.h:349
print_cpu_stall+0x31d/0x5f0 kernel/rcu/tree_stall.h:633
check_cpu_stall kernel/rcu/tree_stall.h:727 [inline]
rcu_pending kernel/rcu/tree.c:3936 [inline]
rcu_sched_clock_irq+0x6ea/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+0x4b4/0xb70 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+0x4d/0xc0 arch/x86/kernel/apic/apic.c:1108
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:pie_vars_init include/net/pie.h:103 [inline]
RIP: 0010:pie_calculate_probability+0x5d1/0x7e0 net/sched/sch_pie.c:415
Code: 0f 85 0c 02 00 00 8b 1b 31 ff 89 de e8 98 e9 63 f9 85 db 0f 84 c1 00 00 00 e8 2b e6 63 f9 eb 05 e8 24 e6 63 f9 48 8b 44 24 10 <48> 8d 78 10 48 89 f8 48 c1 e8 03 42 80 3c 20 00 74 05 e8 e8 f1 a8
RSP: 0018:ffffc90000dd0b50 EFLAGS: 00000246
RAX: ffff888068f6d9e0 RBX: 0000000000000000 RCX: ffff88805760d940
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff888068f6d9e8 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520001ba16c R12: dffffc0000000000
R13: ffff888077787b1a R14: 1ffff1100eef0f63 R15: 0000000000000000
fq_pie_timer+0x169/0x3a0 net/sched/sch_fq_pie.c:393
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+0x142/0x210 kernel/softirq.c:477
__local_bh_enable_ip+0x180/0x1c0 kernel/softirq.c:401
fpregs_unlock arch/x86/include/asm/fpu/api.h:78 [inline]
fpu_clone+0x239/0x630 arch/x86/kernel/fpu/core.c:264
dup_task_struct+0x289/0xb30 kernel/fork.c:908
copy_process+0x5f0/0x3e20 kernel/fork.c:2121
kernel_clone+0x23f/0x990 kernel/fork.c:2679
__do_sys_clone3 kernel/fork.c:2954 [inline]
__se_sys_clone3+0x312/0x3d0 kernel/fork.c:2938
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: 0033:0x7fd499c42d09
Code: 90 b8 01 00 00 00 b9 01 00 00 00 eb ec 0f 1f 40 00 b8 ea ff ff ff 48 85 ff 74 28 48 85 d2 74 23 49 89 c8 b8 b3 01 00 00 0f 05 <48> 85 c0 7c 14 74 01 c3 31 ed 4c 89 c7 ff d2 48 89 c7 b8 3c 00 00
RSP: 002b:00007ffe44a06378 EFLAGS: 00000202 ORIG_RAX: 00000000000001b3
RAX: ffffffffffffffda RBX: 00007fd499bfe320 RCX: 00007fd499c42d09
RDX: 00007fd499bfe320 RSI: 0000000000000058 RDI: 00007ffe44a063d0
RBP: 00007fd4992a56c0 R08: 00007fd4992a56c0 R09: 00007ffe44a064b7
R10: 0000000000000008 R11: 0000000000000202 R12: ffffffffffffffe8
R13: 000000000000000b R14: 00007ffe44a063d0 R15: 00007ffe44a064b8