rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (2 ticks this GP) idle=ebcc/1/0x4000000000000000 softirq=18122/18122 fqs=4 rcu: (detected by 1, t=10506 jiffies, g=10733, q=2039 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 6027 Comm: napi/wg1-0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:check_preemption_disabled+0x6/0x120 lib/smp_processor_id.c:13 Code: c7 c6 60 38 e3 8b eb 1c 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 41 57 41 56 53 <48> 83 ec 10 65 48 8b 05 be 2e 26 07 48 89 44 24 08 65 8b 05 c6 2e RSP: 0018:ffffc90000007b18 EFLAGS: 00000007 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff8be33860 RDI: ffffffff8be33820 RBP: ffffffff84d059aa R08: 0000000000000001 R09: 0000000000000000 R10: ffffc90000007cb0 R11: fffff52000000f98 R12: 0000000000000000 R13: ffffffff99cf9ee0 R14: 0000000000000000 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff888125c14000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c001c8cea0 CR3: 00000000327de000 CR4: 00000000003526f0 Call Trace: rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline] rcu_is_watching+0x15/0xb0 kernel/rcu/tree.c:751 trace_lock_acquire include/trace/events/lock.h:24 [inline] lock_acquire+0x5f/0x360 kernel/locking/lockdep.c:5831 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162 debug_object_deactivate+0x9a/0x250 lib/debugobjects.c:873 debug_hrtimer_deactivate kernel/time/hrtimer.c:450 [inline] debug_deactivate+0x1d/0x200 kernel/time/hrtimer.c:490 __run_hrtimer kernel/time/hrtimer.c:1729 [inline] __hrtimer_run_queues+0x2b0/0xc60 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline] __sysvec_apic_timer_interrupt+0x108/0x410 arch/x86/kernel/apic/apic.c:1056 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1050 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:lock_acquire+0x70/0x360 kernel/locking/lockdep.c:5833 Code: f8 08 0f 83 b8 01 00 00 89 c0 48 0f a3 05 a8 34 06 0e 73 16 e8 61 02 09 00 84 c0 75 0d f6 05 a2 1b f0 0d 01 0f 84 d7 01 00 00 <83> 3d b9 65 06 0e 00 0f 84 f0 00 00 00 48 8b b4 24 90 00 00 00 4c RSP: 0018:ffffc900030f7860 EFLAGS: 00000202 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 101bc0945caca000 RDX: 0000000000000000 RSI: ffffffff8be33860 RDI: ffffffff8be33820 RBP: ffffffff866f217d R08: 0000000000000000 R09: 0000000000000000 R10: 000000000000000a R11: 0000000000000000 R12: 0000000000000002 R13: ffffffff8e139f80 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:331 [inline] rcu_read_lock_bh include/linux/rcupdate.h:894 [inline] keep_key_fresh drivers/net/wireguard/receive.c:228 [inline] wg_packet_consume_data_done drivers/net/wireguard/receive.c:351 [inline] wg_packet_rx_poll+0xbf7/0x24a0 drivers/net/wireguard/receive.c:474 __napi_poll+0xc7/0x360 net/core/dev.c:7555 napi_threaded_poll_loop+0x2e3/0x6c0 net/core/dev.c:7674 napi_threaded_poll+0x1be/0x2b0 net/core/dev.c:7701 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: rcu_preempt kthread starved for 7655 jiffies! g10733 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:27160 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961 __schedule_loop kernel/sched/core.c:7043 [inline] schedule+0x165/0x360 kernel/sched/core.c:7058 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: Stack dump where RCU GP kthread last ran: CPU: 1 UID: 0 PID: 5528 Comm: dhcpcd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0xd33/0x12d0 kernel/smp.c:877 Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 06 63 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 b1 5e 0b 00 eb 38 f3 90 <42> 0f b6 04 2b 84 c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 95 5e RSP: 0018:ffffc90003a1f540 EFLAGS: 00000293 RAX: ffffffff81b44fbb RBX: 1ffff110170c8341 RCX: ffff88802e660000 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc90003a1f6c0 R08: ffffffff8fa39237 R09: 1ffffffff1f47246 R10: dffffc0000000000 R11: fffffbfff1f47247 R12: ffff8880b8641a08 R13: dffffc0000000000 R14: ffff8880b873b1c0 R15: 0000000000000000 FS: 00007f591e6aa740(0000) GS:ffff888125d14000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f2df5fc2008 CR3: 000000002f366000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1044 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline] flush_tlb_mm_range+0x6b1/0x12d0 arch/x86/mm/tlb.c:1451 dup_mmap+0x15a0/0x1ac0 mm/mmap.c:1873 dup_mm kernel/fork.c:1485 [inline] copy_mm+0x13c/0x4b0 kernel/fork.c:1537 copy_process+0x1706/0x3c00 kernel/fork.c:2175 kernel_clone+0x21e/0x840 kernel/fork.c:2605 __do_sys_clone kernel/fork.c:2748 [inline] __se_sys_clone kernel/fork.c:2732 [inline] __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2732 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f591e77e636 Code: 89 df e8 6d e8 f6 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 52 89 c5 85 c0 75 31 64 48 8b 04 25 10 00 00 RSP: 002b:00007ffd8bc5d0b0 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007ffd8bc5d0b8 RCX: 00007f591e77e636 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 00007ffd8bc7d600 R08: 0000000000000000 R09: 0000000000000001 R10: 00007f591e6aaa10 R11: 0000000000000246 R12: 00007ffd8bc5d1f0 R13: 0000000000000000 R14: 0000000000000000 R15: 0000559539888ac0