rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=04fc/1/0x4000000000000000 softirq=21354/21377 fqs=2 rcu: (detected by 1, t=10504 jiffies, g=16281, q=875 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 6520 Comm: sed Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 RIP: 0010:lockdep_recursion_finish kernel/locking/lockdep.c:470 [inline] RIP: 0010:lock_acquire+0x130/0x360 kernel/locking/lockdep.c:5870 Code: 8b 54 24 04 44 89 e1 45 89 f0 6a 00 6a 00 6a 00 55 ff 74 24 30 e8 e0 02 00 00 48 83 c4 28 48 c7 c7 e2 3e 8f 8d e8 40 09 a9 09 ff ff ff ff 65 0f c1 05 43 0d d1 10 83 f8 01 0f 85 c9 00 00 00 RSP: 0000:ffffc90000007bc0 EFLAGS: 00000082 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 89de0cbb5a62ef00 RDX: 0000000000000000 RSI: ffffffff8d8f3ee2 RDI: ffffffff8bbf05e0 RBP: ffffffff895fe1e4 R08: 0000000000000000 R09: ffffffff895fe1e4 R10: dffffc0000000000 R11: ffffffff895fe120 R12: 0000000000000000 R13: ffff88801a7e1300 R14: 0000000000000001 R15: 0000000000000046 FS: 0000000000000000(0000) GS:ffff88812613e000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f2a011ba010 CR3: 00000000774ee000 CR4: 00000000003526f0 Call Trace: __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] advance_sched+0xc4/0xc90 net/sched/sch_taprio.c:929 __run_hrtimer kernel/time/hrtimer.c:1777 [inline] __hrtimer_run_queues+0x52c/0xc60 kernel/time/hrtimer.c:1841 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1903 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1041 [inline] __sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1058 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1052 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_acquire+0x175/0x360 kernel/locking/lockdep.c:5872 Code: 00 00 00 00 9c 8f 44 24 30 f7 44 24 30 00 02 00 00 0f 85 cd 00 00 00 f7 44 24 08 00 02 00 00 74 01 fb 65 48 8b 05 bb cc d0 10 <48> 3b 44 24 58 0f 85 f2 00 00 00 48 83 c4 60 5b 41 5c 41 5d 41 5e RSP: 0000:ffffc90003177ac8 EFLAGS: 00000206 RAX: 89de0cbb5a62ef00 RBX: 0000000000000000 RCX: 89de0cbb5a62ef00 RDX: 0000000000000000 RSI: ffffffff8d8f3ee2 RDI: ffffffff8bbf05e0 RBP: ffffffff8211da09 R08: 0000000000000000 R09: ffffffff8211da09 R10: ffffc90003177cec R11: fffff5200062efa6 R12: 0000000000000002 R13: ffffffff8df3d2e0 R14: 0000000000000000 R15: 0000000000000246 rcu_lock_acquire include/linux/rcupdate.h:331 [inline] rcu_read_lock include/linux/rcupdate.h:867 [inline] ___pte_offset_map+0x45/0x250 mm/pgtable-generic.c:286 __pte_offset_map include/linux/mm.h:3118 [inline] pte_offset_map_rw_nolock+0x3b/0x160 mm/pgtable-generic.c:326 handle_pte_fault mm/memory.c:6162 [inline] __handle_mm_fault+0xb3a/0x5400 mm/memory.c:6318 handle_mm_fault+0x40a/0x8e0 mm/memory.c:6487 do_user_addr_fault+0xa7c/0x1380 arch/x86/mm/fault.c:1336 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x82/0x100 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 RIP: 0033:0x7f2a014ef070 Code: 30 c3 0f 1f 84 00 00 00 00 00 66 48 0f 7e c6 83 fa 08 7d 16 83 fa 04 7d 1a 83 fa 01 7f 1c 7c 03 40 88 37 c3 66 0f 1f 44 00 00 <48> 89 37 48 89 74 17 f8 c3 89 37 89 74 17 fc c3 66 89 37 40 88 74 RSP: 002b:00007ffc4a27d818 EFLAGS: 00010246 RAX: 00007f2a011ba010 RBX: 0000000000000004 RCX: 00007f2a011ba018 RDX: 0000000000000008 RSI: 0000000000000000 RDI: 00007f2a011ba010 RBP: 00007ffc4a27dba0 R08: 00007f2a011ba010 R09: 0000000000000003 R10: 0000000000000812 R11: 00007ffc4a27dc88 R12: 00007ffc4a27d8c8 R13: 00007f2a011c56b0 R14: 00007ffc4a27dc40 R15: 00007f2a011ba018 rcu: rcu_preempt kthread starved for 10495 jiffies! g16281 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:27224 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5325 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929 __schedule_loop kernel/sched/core.c:7011 [inline] schedule+0x165/0x360 kernel/sched/core.c:7026 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+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x4bc/0x870 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: 1 UID: 0 PID: 12 Comm: kworker/u8:0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Workqueue: events_unbound toggle_allocation_gate 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 b6 73 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 61 6f 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 45 6f RSP: 0018:ffffc90000117640 EFLAGS: 00000293 RAX: ffffffff81b4952b RBX: 1ffff11017108441 RCX: ffff88801ca85ac0 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc900001177c0 R08: ffffffff8f7cdb77 R09: 1ffffffff1ef9b6e R10: dffffc0000000000 R11: fffffbfff1ef9b6f R12: ffff8880b8842208 R13: dffffc0000000000 R14: ffff8880b893b240 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff88812623e000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc39adc97e8 CR3: 000000000dd38000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1043 on_each_cpu include/linux/smp.h:71 [inline] smp_text_poke_sync_each_cpu arch/x86/kernel/alternative.c:2713 [inline] smp_text_poke_batch_finish+0x5f9/0x1130 arch/x86/kernel/alternative.c:2923 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146 static_key_enable_cpuslocked+0x128/0x250 kernel/jump_label.c:210 static_key_enable+0x1a/0x20 kernel/jump_label.c:223 toggle_allocation_gate+0xad/0x240 mm/kfence/core.c:852 process_one_work kernel/workqueue.c:3263 [inline] process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245