rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=21e4/1/0x4000000000000000 softirq=84185/84185 fqs=0 rcu: (detected by 0, t=10502 jiffies, g=95869, q=296 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 15863 Comm: syz.5.2419 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 RIP: 0010:task_wait_context kernel/locking/lockdep.c:4786 [inline] RIP: 0010:task_wait_context kernel/locking/lockdep.c:4776 [inline] RIP: 0010:check_wait_context kernel/locking/lockdep.c:4875 [inline] RIP: 0010:__lock_acquire+0x2af/0x2630 kernel/locking/lockdep.c:5187 Code: ee 28 83 f8 ff 0f 84 0f 05 00 00 0f b6 7e 21 44 31 cf 83 e7 60 74 e4 44 8d 48 01 65 8b 05 01 ad 25 12 85 c0 0f 84 d5 04 00 00 <8b> 85 60 0b 00 00 85 c0 75 10 44 8b bd 78 0b 00 00 45 85 ff 0f 84 RSP: 0018:ffffc90000a08c40 EFLAGS: 00000002 RAX: 0000000000000001 RBX: ffff8880359d8be0 RCX: 0000000000000002 RDX: 0000000000000002 RSI: ffff8880359d8b90 RDI: 0000000000000040 RBP: ffff8880359d8000 R08: 0000000000000001 R09: 0000000000000001 R10: 0000000000000002 R11: 0000000000000001 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f4c0eeb46c0(0000) GS:ffff888124483000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f4c0e04f156 CR3: 0000000034c9c000 CR4: 00000000003526f0 Call Trace: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b1/0x370 kernel/locking/lockdep.c:5825 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline] _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:166 debug_object_deactivate+0x135/0x3b0 lib/debugobjects.c:900 debug_hrtimer_deactivate kernel/time/hrtimer.c:490 [inline] __run_hrtimer kernel/time/hrtimer.c:1898 [inline] __hrtimer_run_queues+0x2f0/0xa00 kernel/time/hrtimer.c:1994 hrtimer_interrupt+0x3e5/0x940 kernel/time/hrtimer.c:2113 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] __sysvec_apic_timer_interrupt+0x10b/0x460 arch/x86/kernel/apic/apic.c:1067 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline] sysvec_apic_timer_interrupt+0x9e/0xc0 arch/x86/kernel/apic/apic.c:1061 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:arch_static_branch arch/x86/include/asm/jump_label.h:37 [inline] RIP: 0010:native_write_msr arch/x86/include/asm/msr.h:139 [inline] RIP: 0010:wrmsrq arch/x86/include/asm/msr.h:199 [inline] RIP: 0010:native_x2apic_icr_write arch/x86/include/asm/apic.h:229 [inline] RIP: 0010:__x2apic_send_IPI_dest arch/x86/kernel/apic/local.h:49 [inline] RIP: 0010:x2apic_send_IPI+0x9a/0xe0 arch/x86/kernel/apic/x2apic_phys.c:50 Code: 8b 13 0f ae f0 0f ae e8 b9 00 04 00 00 41 83 fc 02 44 89 e0 48 0f 44 c1 48 c1 e2 20 b9 30 08 00 00 48 09 d0 48 c1 ea 20 0f 30 <66> 90 5b 5d 41 5c c3 cc cc cc cc 5b 31 d2 5d 48 89 c6 bf 30 08 00 RSP: 0018:ffffc9000608fb20 EFLAGS: 00000246 RAX: 00000000000000fb RBX: ffff8880b84201b4 RCX: 0000000000000830 RDX: 0000000000000000 RSI: 00000000000000fb RDI: ffffffff8e1c1920 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 00000000000000fb R13: ffff8880b843c5c0 R14: ffff8880b843c501 R15: 0000000000000000 arch_send_call_function_single_ipi arch/x86/include/asm/smp.h:95 [inline] send_call_function_single_ipi kernel/smp.c:120 [inline] smp_call_function_many_cond+0x139e/0x1700 kernel/smp.c:872 clock_was_set+0x62b/0x870 kernel/time/hrtimer.c:999 do_settimeofday64+0x330/0x4d0 kernel/time/timekeeping.c:1603 do_sys_settimeofday64+0x1dc/0x260 kernel/time/time.c:195 __do_sys_clock_settime kernel/time/posix-timers.c:1124 [inline] __se_sys_clock_settime kernel/time/posix-timers.c:1108 [inline] __x64_sys_clock_settime+0x1c1/0x2a0 kernel/time/posix-timers.c:1108 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f4c0df9ce59 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:00007f4c0eeb4028 EFLAGS: 00000246 ORIG_RAX: 00000000000000e3 RAX: ffffffffffffffda RBX: 00007f4c0e215fa0 RCX: 00007f4c0df9ce59 RDX: 0000000000000000 RSI: 0000200000000240 RDI: 0000000000000000 RBP: 00007f4c0e032d6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f4c0e216038 R14: 00007f4c0e215fa0 R15: 00007ffcef3b79b8 rcu: rcu_preempt kthread starved for 10502 jiffies! g95869 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:26728 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5388 [inline] __schedule+0x1295/0x67a0 kernel/sched/core.c:7189 __schedule_loop kernel/sched/core.c:7268 [inline] schedule+0xdd/0x390 kernel/sched/core.c:7283 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2095 rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2297 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 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: 14499 Comm: kworker/u8:67 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Workqueue: events_unbound toggle_allocation_gate RIP: 0010:write_comp_data+0x40/0x90 kernel/kcov.c:246 Code: 01 12 a9 00 01 ff 00 74 1b f6 c4 01 74 07 a9 00 00 ff 00 74 05 c3 cc cc cc cc 8b 87 ec 16 00 00 85 c0 74 f1 8b 87 c8 16 00 00 <83> f8 03 75 e6 48 8b 87 d0 16 00 00 8b bf cc 16 00 00 48 8b 30 48 RSP: 0018:ffffc90003647868 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff81fc2c4d RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff888053c4ca80 RBP: ffff8880b8540f80 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000003 R13: ffffed10170a81f1 R14: 0000000000000001 R15: ffff8880b843c600 FS: 0000000000000000(0000) GS:ffff888124383000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f4c0e217dac CR3: 000000000e596000 CR4: 00000000003526f0 Call Trace: csd_lock_wait kernel/smp.c:342 [inline] smp_call_function_many_cond+0x5ad/0x1700 kernel/smp.c:892 on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1057 on_each_cpu include/linux/smp.h:72 [inline] smp_text_poke_sync_each_cpu arch/x86/kernel/alternative.c:2773 [inline] smp_text_poke_batch_finish+0x337/0xc60 arch/x86/kernel/alternative.c:2983 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146 jump_label_update+0x37a/0x550 kernel/jump_label.c:910 static_key_enable_cpuslocked+0x1bc/0x270 kernel/jump_label.c:210 static_key_enable+0x1a/0x20 kernel/jump_label.c:223 toggle_allocation_gate mm/kfence/core.c:906 [inline] toggle_allocation_gate+0xfe/0x2d0 mm/kfence/core.c:898 process_one_work+0xa0e/0x1980 kernel/workqueue.c:3314 process_scheduled_works kernel/workqueue.c:3397 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3478 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245