rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=954c/1/0x4000000000000000 softirq=100957/100966 fqs=7 rcu: (detected by 0, t=10505 jiffies, g=81461, q=578 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 1204 Comm: kworker/1:2 Not tainted 6.15.0-rc4-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025 Workqueue: events_power_efficient wg_ratelimiter_gc_entries RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x70 kernel/kcov.c:210 Code: f6 5c 55 00 48 89 df 5b e9 2d b8 5a 00 be 03 00 00 00 5b e9 42 7f 15 03 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1e fa 48 8b 34 24 65 48 8b 15 08 8f e8 11 65 8b 05 19 8f e8 RSP: 0018:ffffc90000a08dd8 EFLAGS: 00000046 RAX: 0000000000000000 RBX: ffff88806c9df340 RCX: 1ffff110170a4f33 RDX: dffffc0000000000 RSI: ffffffff8b686e70 RDI: ffff88806c9df348 RBP: ffff8880b8527990 R08: 0000000000000006 R09: 0000000000000001 R10: ffff88806c9df340 R11: 0000000000000000 R12: ffff8880b8527998 R13: 0000000000000000 R14: ffff8880b8527840 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888124ae4000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f97a08e0300 CR3: 000000006f4ee000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000029 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: rb_erase_cached include/linux/rbtree.h:126 [inline] timerqueue_del+0x78/0x150 lib/timerqueue.c:57 __remove_hrtimer+0x99/0x290 kernel/time/hrtimer.c:1121 __run_hrtimer kernel/time/hrtimer.c:1741 [inline] __hrtimer_run_queues+0x4f9/0xad0 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline] __sysvec_apic_timer_interrupt+0x108/0x3f0 arch/x86/kernel/apic/apic.c:1055 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:in_lock_functions+0x0/0x20 kernel/locking/spinlock.c:408 Code: 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa c3 cc cc cc cc 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1e fa 31 c0 48 81 ff 30 d7 6e 8b 72 0c 31 c0 48 81 ff 75 1c RSP: 0018:ffffc900040efbe0 EFLAGS: 00000246 RAX: 0000000000000001 RBX: ffffffff8b6ed752 RCX: 1ffffffff35662bc RDX: 0000000000000000 RSI: ffffffff8670adfa RDI: ffffffff8b6ed752 RBP: 0000000000002000 R08: 0000000000000004 R09: 0000000000002000 R10: 00000000000006fe R11: 0000000000000000 R12: 0000000000000001 R13: ffffffff8f4bc820 R14: 000000e66a6a74e6 R15: 00000000000006fe get_lock_parent_ip include/linux/ftrace.h:1089 [inline] preempt_latency_start kernel/sched/core.c:5838 [inline] preempt_latency_start kernel/sched/core.c:5835 [inline] preempt_count_add+0x76/0x150 kernel/sched/core.c:5863 __raw_spin_lock include/linux/spinlock_api_smp.h:132 [inline] _raw_spin_lock+0x12/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] wg_ratelimiter_gc_entries+0xc6/0x520 drivers/net/wireguard/ratelimiter.c:63 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: rcu_preempt kthread starved for 10380 jiffies! g81461 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:27704 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x116f/0x5de0 kernel/sched/core.c:6767 __schedule_loop kernel/sched/core.c:6845 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6860 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2046 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2248 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 UID: 0 PID: 11733 Comm: kworker/u8:1 Not tainted 6.15.0-rc4-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025 Workqueue: events_unbound toggle_allocation_gate RIP: 0010:csd_lock_wait kernel/smp.c:340 [inline] RIP: 0010:smp_call_function_many_cond+0x4aa/0x1290 kernel/smp.c:885 Code: 0c 00 85 ed 74 48 48 8b 44 24 20 49 89 c4 83 e0 07 49 c1 ec 03 48 89 c5 4d 01 f4 83 c5 03 e8 5d 17 0c 00 f3 90 41 0f b6 04 24 <40> 38 c5 7c 08 84 c0 0f 85 de 0b 00 00 8b 43 08 31 ff 83 e0 01 41 RSP: 0018:ffffc90003097938 EFLAGS: 00000293 RAX: 0000000000000000 RBX: ffff8880b853f740 RCX: ffffffff81af19c9 RDX: ffff888026102440 RSI: ffffffff81af19a3 RDI: 0000000000000005 RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffffed10170a7ee9 R13: 0000000000000001 R14: dffffc0000000000 R15: ffff8880b843b040 FS: 0000000000000000(0000) GS:ffff8881249e4000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fa1c76e56c0 CR3: 000000000e180000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1052 on_each_cpu include/linux/smp.h:71 [inline] text_poke_sync arch/x86/kernel/alternative.c:2455 [inline] text_poke_bp_batch+0x220/0x760 arch/x86/kernel/alternative.c:2665 text_poke_flush arch/x86/kernel/alternative.c:2856 [inline] text_poke_flush arch/x86/kernel/alternative.c:2853 [inline] text_poke_finish+0x30/0x40 arch/x86/kernel/alternative.c:2863 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146 jump_label_update+0x376/0x550 kernel/jump_label.c:919 static_key_enable_cpuslocked+0x1b7/0x270 kernel/jump_label.c:210 static_key_enable+0x1a/0x20 kernel/jump_label.c:223 toggle_allocation_gate mm/kfence/core.c:850 [inline] toggle_allocation_gate+0xfa/0x280 mm/kfence/core.c:842 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245