rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=8f34/1/0x4000000000000000 softirq=23313/23314 fqs=5 rcu: (detected by 0, t=10502 jiffies, g=20757, q=1410 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 6667 Comm: modprobe Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 RIP: 0010:lock_acquire+0xfd/0x350 kernel/locking/lockdep.c:5868 Code: 11 45 31 c9 4c 89 7c 24 08 41 f7 c7 00 02 00 00 41 0f 94 c1 4c 89 ef 89 de 8b 54 24 04 44 89 e1 45 89 f0 6a 00 6a 00 6a 00 55 74 24 30 e8 da 02 00 00 48 83 c4 28 48 c7 c7 19 a1 22 8e e8 da RSP: 0000:ffffc90000a08c38 EFLAGS: 00000046 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88807d9532c0 RBP: ffffffff89b9d7f4 R08: 0000000000000001 R09: 0000000000000001 R10: dffffc0000000000 R11: ffffffff89b9d730 R12: 0000000000000000 R13: ffff88807d9532c0 R14: 0000000000000001 R15: 0000000000000046 FS: 00007efc9b783c80(0000) GS:ffff888125345000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007efc9b923850 CR3: 0000000072e44000 CR4: 00000000003526f0 Call Trace: __raw_spin_lock include/linux/spinlock_api_smp.h:158 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:158 spin_lock include/linux/spinlock.h:342 [inline] advance_sched+0xc4/0xc90 net/sched/sch_taprio.c:930 __run_hrtimer kernel/time/hrtimer.c:1930 [inline] __hrtimer_run_queues+0x3c0/0xa20 kernel/time/hrtimer.c:1994 hrtimer_interrupt+0x44b/0x950 kernel/time/hrtimer.c:2113 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] __sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1067 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1061 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_acquire+0x221/0x350 kernel/locking/lockdep.c:5872 Code: ff ff ff e8 b1 9d 11 0a f7 44 24 08 00 02 00 00 0f 84 3a ff ff ff 65 48 8b 05 8b 38 9c 11 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 48 8d 3d 98 f2 93 RSP: 0000:ffffc900039577e0 EFLAGS: 00000282 RAX: cf237606f36f5900 RBX: 0000000000000000 RCX: 0000000080000002 RDX: 0000000093416993 RSI: ffffffff8e22a119 RDI: ffffffff8c27f000 RBP: ffffffff823d794a R08: ffffffff823d794a R09: ffffffff8e95d0e0 R10: dffffc0000000000 R11: fffff9400005dda9 R12: 0000000000000002 R13: ffffffff8e95d0e0 R14: 0000000000000000 R15: 0000000000000246 rcu_lock_acquire include/linux/rcupdate.h:300 [inline] rcu_read_lock_sched include/linux/rcupdate.h:936 [inline] pfn_valid+0xd6/0x480 include/linux/mmzone.h:2197 page_table_check_set+0x25/0x610 mm/page_table_check.c:105 page_table_check_ptes_set include/linux/page_table_check.h:83 [inline] set_ptes include/linux/pgtable.h:413 [inline] set_pte_range+0x84b/0x8a0 mm/memory.c:5527 filemap_map_order0_folio mm/filemap.c:3861 [inline] filemap_map_pages+0xfe0/0x2100 mm/filemap.c:3931 do_fault_around mm/memory.c:5757 [inline] do_read_fault mm/memory.c:5790 [inline] do_fault mm/memory.c:5933 [inline] do_pte_missing+0x211a/0x3490 mm/memory.c:4477 handle_pte_fault mm/memory.c:6317 [inline] __handle_mm_fault mm/memory.c:6455 [inline] handle_mm_fault+0x1bec/0x3310 mm/memory.c:6624 do_user_addr_fault+0xa73/0x1340 arch/x86/mm/fault.c:1334 handle_page_fault arch/x86/mm/fault.c:1474 [inline] exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 RIP: 0033:0x7efc9b923850 Code: Unable to access opcode bytes at 0x7efc9b923826. RSP: 002b:00007fff56352858 EFLAGS: 00010246 RAX: 0000000000000004 RBX: 00007fff56352910 RCX: 00007fff56352860 RDX: 00007fff563528b0 RSI: 00007fff563531d8 RDI: 0000000000000004 RBP: 00007fff56352e70 R08: 0000000000000000 R09: 0000000000000001 R10: 000000000000006c R11: 00007fff56352a0c R12: 0000000000000000 R13: 00007efc9bae5c3f R14: 00007fff56352e80 R15: 0000000000000000 rcu: rcu_preempt kthread starved for 10492 jiffies! g20757 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:27544 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x17b4/0x5680 kernel/sched/core.c:7183 __schedule_loop kernel/sched/core.c:7262 [inline] schedule+0x164/0x360 kernel/sched/core.c:7277 schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x312/0x11d0 kernel/rcu/tree.c:2095 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 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: 57 Comm: kworker/u8:4 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Workqueue: events_unbound toggle_allocation_gate RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0xe32/0x1210 kernel/smp.c:892 Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 77 e7 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 22 e3 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 06 e3 RSP: 0018:ffffc900015e7700 EFLAGS: 00000293 RAX: ffffffff81b97aea RBX: 1ffff110170e8165 RCX: ffff888022ee3d80 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc900015e7840 R08: ffffffff903215b7 R09: 1ffffffff20642b6 R10: dffffc0000000000 R11: fffffbfff20642b7 R12: ffff8880b8740b28 R13: dffffc0000000000 R14: ffff8880b863c148 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff888125245000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00005624f0b96950 CR3: 000000000e74a000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1057 on_each_cpu include/linux/smp.h:72 [inline] smp_text_poke_sync_each_cpu arch/x86/kernel/alternative.c:2761 [inline] smp_text_poke_batch_finish+0x5f5/0x1160 arch/x86/kernel/alternative.c:2971 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146 static_key_enable_cpuslocked+0x128/0x240 kernel/jump_label.c:210 static_key_enable+0x1a/0x20 kernel/jump_label.c:223 toggle_allocation_gate+0xab/0x290 mm/kfence/core.c:900 process_one_work kernel/workqueue.c:3288 [inline] process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3371 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3452 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245