rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 ticks this GP) idle=8adc/1/0x4000000000000000 softirq=95679/95679 fqs=5 rcu: (detected by 0, t=10502 jiffies, g=107881, q=1569 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 11779 Comm: syz-executor Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 RIP: 0010:lock_acquire+0x101/0x350 kernel/locking/lockdep.c:5868 Code: 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 ff 74 24 30 da 02 00 00 48 83 c4 28 48 c7 c7 51 33 4b 8e e8 da fd 2e 0a b8 RSP: 0018:ffffc90000a08c38 EFLAGS: 00000046 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88807fe922c0 RBP: ffffffff89de4272 R08: 0000000000000001 R09: 0000000000000001 R10: dffffc0000000000 R11: ffffffff89de41b0 R12: 0000000000000000 R13: ffff88807fe922c0 R14: 0000000000000001 R15: 0000000000000046 FS: 000055555a36d500(0000) GS:ffff88812504d000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fbf5d9556c8 CR3: 0000000057f50000 CR4: 0000000000350ef0 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+0xc2/0xc80 net/sched/sch_taprio.c:930 __run_hrtimer kernel/time/hrtimer.c:2032 [inline] __hrtimer_run_queues+0x3bc/0xa10 kernel/time/hrtimer.c:2096 hrtimer_interrupt+0x448/0x910 kernel/time/hrtimer.c:2215 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline] __sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1068 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:__copy_present_ptes mm/memory.c:1111 [inline] RIP: 0010:copy_present_ptes mm/memory.c:1197 [inline] RIP: 0010:copy_pte_range mm/memory.c:1320 [inline] RIP: 0010:copy_pmd_range+0x1fda/0x5880 mm/memory.c:1408 Code: 00 e8 8a e7 aa ff eb 05 e8 83 e7 aa ff 48 b9 00 00 00 00 00 fc ff df 41 80 3c 0f 00 74 08 4c 89 ef e8 ca 7e 18 00 49 8b 75 00 <48> 83 e6 08 49 bf 9f ff ff ff ff ff ff fb 48 c7 c0 df ff ff ff 4c RSP: 0018:ffffc90004ce7320 EFLAGS: 00000246 RAX: ffffffff821c2ced RBX: 0000000000000028 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: 00000000180400fb RDI: 0000000000000020 RBP: ffffc90004ce75b0 R08: ffffea0000f6e707 R09: 1ffffd40001edce0 R10: dffffc0000000000 R11: fffff940001edce1 R12: ffff888078445150 R13: ffff88803374f660 R14: 800000003db9c007 R15: 1ffff110066e9ecc copy_pud_range mm/memory.c:1445 [inline] copy_p4d_range mm/memory.c:1469 [inline] copy_page_range+0xc26/0x1250 mm/memory.c:1555 dup_mmap+0xf21/0x1d90 mm/mmap.c:1840 dup_mm kernel/fork.c:1543 [inline] copy_mm+0x11a/0x480 kernel/fork.c:1595 copy_process+0x1e3e/0x4390 kernel/fork.c:2289 kernel_clone+0x2d7/0x940 kernel/fork.c:2748 __do_sys_clone kernel/fork.c:2889 [inline] __se_sys_clone kernel/fork.c:2873 [inline] __x64_sys_clone+0x1b6/0x230 kernel/fork.c:2873 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fbf5cbc6a92 Code: 89 e7 e8 71 8b f7 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 66 89 c5 85 c0 75 3b 64 48 8b 04 25 10 00 00 RSP: 002b:00007fff7f6ce190 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007fff7f6ce190 RCX: 00007fbf5cbc6a92 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 00007fff7f6ce31c R08: 0000000000000000 R09: 0000000000000001 R10: 000055555a36d7d0 R11: 0000000000000246 R12: 0000000000000001 R13: 00000000000927c0 R14: 00000000000f20b0 R15: 00007fff7f6ce370 rcu: rcu_preempt kthread starved for 10475 jiffies! g107881 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:27496 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234 __schedule_loop kernel/sched/core.c:7311 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7326 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2123 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2325 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: 7972 Comm: kworker/u8:21 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 Workqueue: events_unbound toggle_allocation_gate RIP: 0010:native_pause arch/x86/include/asm/vdso/processor.h:13 [inline] RIP: 0010:cpu_relax arch/x86/include/asm/vdso/processor.h:18 [inline] RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0x11e4/0x15f0 kernel/smp.c:912 Code: 1c 84 c0 75 7a 41 8b 1e 89 de 83 e6 01 31 ff e8 e2 22 0c 00 83 e3 01 48 bb 00 00 00 00 00 fc ff df 75 07 e8 8e 1e 0c 00 eb 37 90 41 0f b6 04 1c 84 c0 75 10 41 f7 06 01 00 00 00 74 1e e8 73 RSP: 0018:ffffc9000369f700 EFLAGS: 00000293 RAX: ffffffff81baf5fd RBX: dffffc0000000000 RCX: ffff888034859f00 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc9000369f860 R08: ffffffff90579937 R09: 1ffffffff20af326 R10: dffffc0000000000 R11: fffffbfff20af327 R12: 1ffff110170e81d1 R13: ffff8880b863c448 R14: ffff8880b8740e88 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff888124f4d000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000000240 CR3: 000000000e946000 CR4: 0000000000350ef0 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1077 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+0x5fd/0x1110 arch/x86/kernel/alternative.c:2983 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:911 process_one_work kernel/workqueue.c:3322 [inline] process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486 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