INFO: rcu detected stall in kcov

Kernel	Title	Rank 🛈	Count	Last	Reported	Patched	Status
linux-6.1	INFO: rcu detected stall in kcov_ioctl	1	2	643d	646d	0/3	auto-obsoleted due to no activity on 2024/10/16 15:00
upstream	INFO: rcu detected stall in kcov_ioctl (3) mm	1	30	8d11h	4d10h	0/29	upstream: reported on 2026/04/08 23:31
linux-6.1	INFO: rcu detected stall in kcov_ioctl (2)	1	4	168d	337d	0/3	auto-obsoleted due to no activity on 2026/02/03 14:39
upstream	INFO: rcu detected stall in kcov_ioctl (2) mm	1	78	462d	622d	0/29	auto-obsoleted due to no activity on 2025/03/17 09:34

rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-...!: (1 GPs behind) idle=56e/1/0x4000000000000002 softirq=10595/10596 fqs=38 (t=10500 jiffies g=5677 q=188) rcu: rcu_preempt kthread starved for 10423 jiffies! g5677 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29048 10 2 0x80004000 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x9a0/0xcc0 kernel/sched/core.c:4081 schedule+0x181/0x210 kernel/sched/core.c:4155 schedule_timeout+0x14f/0x240 kernel/time/timer.c:1895 rcu_gp_fqs_loop kernel/rcu/tree.c:1661 [inline] rcu_gp_kthread+0xed8/0x1770 kernel/rcu/tree.c:1821 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 NMI backtrace for cpu 0 CPU: 0 PID: 8045 Comm: syz-executor.0 Not tainted 5.4.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fb/0x318 lib/dump_stack.c:118 nmi_cpu_backtrace+0xaf/0x1a0 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x174/0x290 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x15a/0x220 kernel/rcu/tree_stall.h:254 print_cpu_stall kernel/rcu/tree_stall.h:455 [inline] check_cpu_stall kernel/rcu/tree_stall.h:529 [inline] rcu_pending kernel/rcu/tree.c:2827 [inline] rcu_sched_clock_irq+0xe25/0x1ad0 kernel/rcu/tree.c:2271 update_process_times+0x12d/0x180 kernel/time/timer.c:1726 tick_sched_handle kernel/time/tick-sched.c:167 [inline] tick_sched_timer+0x263/0x420 kernel/time/tick-sched.c:1310 __run_hrtimer kernel/time/hrtimer.c:1514 [inline] __hrtimer_run_queues+0x403/0x840 kernel/time/hrtimer.c:1576 hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1638 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline] smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1135 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 </IRQ> RIP: 0010:__read_once_size include/linux/compiler.h:199 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x2e/0x50 kernel/kcov.c:107 Code: 65 48 8b 0c 25 c0 1d 02 00 65 8b 15 b8 81 8b 7e f7 c2 00 01 1f 00 75 2c 8b 91 80 13 00 00 83 fa 02 75 21 48 8b 91 88 13 00 00 <48> 8b 32 48 8d 7e 01 8b 89 84 13 00 00 48 39 cf 73 08 48 89 44 f2 RSP: 0018:ffffc90002007bd0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: ffffffff81486ea4 RBX: ffffea00027c4300 RCX: ffff888090974040 RDX: ffffc90002029000 RSI: 000000000003ffff RDI: 0000000000040000 RBP: ffffc90002007c10 R08: 000000000003a768 R09: fffffbfff120248a R10: fffffbfff120248a R11: 0000000000000000 R12: ffff88808bd72ba0 R13: dffffc0000000000 R14: 1ffff110117ae574 R15: ffff88809c6e15a8 release_task_stack kernel/fork.c:440 [inline] put_task_stack+0xa3/0x130 kernel/fork.c:451 finish_task_switch+0x3f1/0x550 kernel/sched/core.c:3256 context_switch kernel/sched/core.c:3388 [inline] __schedule+0x9a8/0xcc0 kernel/sched/core.c:4081 preempt_schedule_common kernel/sched/core.c:4236 [inline] preempt_schedule+0xdb/0x120 kernel/sched/core.c:4261 ___preempt_schedule+0x16/0x18 arch/x86/entry/thunk_64.S:50 __raw_spin_unlock include/linux/spinlock_api_smp.h:152 [inline] _raw_spin_unlock+0x3a/0x40 kernel/locking/spinlock.c:183 spin_unlock include/linux/spinlock.h:378 [inline] kcov_ioctl+0x285/0x2c0 kernel/kcov.c:429 do_vfs_ioctl+0x744/0x1730 fs/ioctl.c:47 ksys_ioctl fs/ioctl.c:743 [inline] __do_sys_ioctl fs/ioctl.c:750 [inline] __se_sys_ioctl fs/ioctl.c:748 [inline] __x64_sys_ioctl+0xe3/0x120 fs/ioctl.c:748 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a4e7 Code: 48 83 c4 08 48 89 d8 5b 5d c3 66 0f 1f 84 00 00 00 00 00 48 89 e8 48 f7 d8 48 39 c3 0f 92 c0 eb 92 66 90 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 0d b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f88087a8ca8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000045a4e7 RDX: 0000000000000000 RSI: 0000000000006364 RDI: 00000000000000e8 RBP: 000000000075bfa8 R08: 00007f88087a9700 R09: 00007f88087a9700 R10: 00007f88087a99d0 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff681a414f R14: 00007f88087a99c0 R15: 000000000075bf2c