rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (3 ticks this GP) idle=c95/1/0x4000000000000002 softirq=6357/6357 fqs=772 
	(detected by 1, t=10502 jiffies, g=7085, q=595)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4314 Comm: syz.2.19 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:__lock_acquire+0xee/0x7d10 kernel/locking/lockdep.c:4882
Code: c0 c4 23 8a 8d 48 c1 e8 03 42 0f b6 04 00 84 c0 0f 85 cb 65 00 00 83 3d f3 0c 2d 0c 00 0f 84 a8 27 00 00 83 3d 82 c6 c1 0a 00 <74> 29 48 89 d8 48 c1 e8 03 42 80 3c 00 00 74 12 48 89 df e8 6a 3c
RSP: 0018:ffffc90000006dc0 EFLAGS: 00000002
RAX: 0000000000000000 RBX: ffffffff8c31eb20 RCX: 1ffff92000000ddc
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8c31eb20
RBP: ffffc90000007010 R08: dffffc0000000000 R09: 0000000000000001
R10: dffffc0000000000 R11: fffffbfff1b13e06 R12: 0000000000000000
R13: ffff88807db10000 R14: 0000000000000000 R15: 0000000000000001
FS:  00007f1c513bd6c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000004600000000 CR3: 0000000028266000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000200000000300 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
 rcu_read_lock include/linux/rcupdate.h:740 [inline]
 __perf_event_output kernel/events/core.c:7800 [inline]
 perf_event_output_forward+0xbc/0x2e0 kernel/events/core.c:7822
 __perf_event_overflow+0x364/0x530 kernel/events/core.c:9515
 perf_tp_event+0x383/0xbf0 kernel/events/core.c:10047
 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10021
 perf_trace_preemptirq_template+0x2aa/0x360 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:rcu_read_unlock_special+0x7f/0x4a0 kernel/rcu/tree_plugin.h:674
Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 32 e1 9c 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc900000077c0 EFLAGS: 00000206
RAX: b86f49d17ac54000 RBX: 1ffff92000000efc RCX: b86f49d17ac54000
RDX: dffffc0000000000 RSI: ffffffff8a2b2800 RDI: ffffffff8a79fe00
RBP: ffffc900000078a0 R08: ffffffff901d51c7 R09: 1ffffffff203aa38
R10: dffffc0000000000 R11: fffffbfff203aa39 R12: ffffffff8c323000
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
 rcu_read_unlock include/linux/rcupdate.h:772 [inline]
 ndisc_send_skb+0xde0/0x1500 net/ipv6/ndisc.c:521
 addrconf_rs_timer+0x2d1/0x630 net/ipv6/addrconf.c:3956
 call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648
 expire_timers kernel/time/timer.c:1699 [inline]
 __run_timers+0x53e/0x800 kernel/time/timer.c:1970
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983
 handle_softirqs+0x339/0x830 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:node_tag_clear+0x255/0x300 lib/radix-tree.c:1011
Code: 24 e8 ef 0e 73 fd 41 f7 d4 48 b8 00 00 00 00 00 fc ff df 41 0f b6 04 07 84 c0 0f 85 8a 00 00 00 45 21 26 eb 05 e8 cb 0e 73 fd <48> 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f 5d c3 44 89 f1 80 e1 07 80
RSP: 0018:ffffc90002d8f4a0 EFLAGS: 00000287
RAX: ffffffff8406254a RBX: dffffc0000000000 RCX: 0000000000080000
RDX: ffffc9000c701000 RSI: 000000000000a48a RDI: 000000000000a48b
RBP: 0000000000000000 R08: ffff8880606a156f R09: 1ffff1100c0d42ad
R10: dffffc0000000000 R11: ffffed100c0d42ae R12: ffffffffffffff00
R13: ffff8880606a1568 R14: ffff8880606a1340 R15: 0000000000000000
 idr_alloc_u32 lib/idr.c:55 [inline]
 idr_alloc_cyclic+0x2fd/0x5c0 lib/idr.c:127
 __kernfs_new_node+0x12d/0x6c0 fs/kernfs/dir.c:599
 kernfs_new_node+0x148/0x250 fs/kernfs/dir.c:669
 __kernfs_create_file+0x47/0x2e0 fs/kernfs/file.c:985
 cgroup_add_file kernel/cgroup/cgroup.c:4091 [inline]
 cgroup_addrm_files+0xac5/0x1020 kernel/cgroup/cgroup.c:4153
 css_populate_dir+0x12d/0x2f0 kernel/cgroup/cgroup.c:1744
 cgroup_apply_control_enable+0x636/0xb00 kernel/cgroup/cgroup.c:3221
 cgroup_mkdir+0xcc0/0xec0 kernel/cgroup/cgroup.c:5609
 kernfs_iop_mkdir+0x24c/0x3d0 fs/kernfs/dir.c:1175
 vfs_mkdir+0x387/0x570 fs/namei.c:4073
 do_mkdirat+0x1df/0x5b0 fs/namei.c:4098
 __do_sys_mkdirat fs/namei.c:4113 [inline]
 __se_sys_mkdirat fs/namei.c:4111 [inline]
 __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4111
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f1c53163dd9
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:00007f1c513bd028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f1c533dcfa0 RCX: 00007f1c53163dd9
RDX: 00000000000001ff RSI: 0000200000000000 RDI: ffffffffffffff9c
RBP: 00007f1c531f9d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1c533dd038 R14: 00007f1c533dcfa0 R15: 00007ffeeb614718
 </TASK>
rcu: rcu_preempt kthread starved for 8958 jiffies! g7085 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:28016 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117
 rcu_gp_fqs_loop+0x2be/0x11d0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x9b/0x370 kernel/rcu/tree.c:2145
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 1
CPU: 1 PID: 1698 Comm: kworker/1:2 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: events request_firmware_work_func
Call Trace:
 <IRQ>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487
 print_other_cpu_stall+0x1110/0x1270 kernel/rcu/tree_stall.h:592
 check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
 rcu_pending kernel/rcu/tree.c:3936 [inline]
 rcu_sched_clock_irq+0x843/0x1120 kernel/rcu/tree.c:2619
 update_process_times+0x193/0x200 kernel/time/timer.c:2021
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x4b4/0xb70 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1811
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
RIP: 0010:arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
RIP: 0010:kvm_wait+0x159/0x1b0 arch/x86/kernel/kvm.c:918
Code: 89 df 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 75 4b 0f b6 1f e8 f7 b6 4a 00 44 38 e3 75 10 66 90 0f 00 2d 59 d3 f3 08 fb f4 <e9> 16 ff ff ff fb e9 10 ff ff ff e8 27 20 88 08 89 f9 80 e1 07 38
RSP: 0018:ffffc9000570f660 EFLAGS: 00000246
RAX: fa10f0efd8a0cb00 RBX: 0000000000000003 RCX: fa10f0efd8a0cb00
RDX: dffffc0000000000 RSI: ffffffff8a2b2800 RDI: ffffffff8a79fe00
RBP: ffffc9000570f710 R08: ffffffff901d50cf R09: 1ffffffff203aa19
R10: dffffc0000000000 R11: fffffbfff203aa1a R12: 0000000000000003
R13: ffff8880b913b154 R14: dffffc0000000000 R15: 1ffff92000ae1ecc
 pv_wait arch/x86/include/asm/paravirt.h:597 [inline]
 pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline]
 __pv_queued_spin_lock_slowpath+0x60f/0x9c0 kernel/locking/qspinlock.c:508
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:585 [inline]
 queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51
 queued_spin_lock include/asm-generic/qspinlock.h:85 [inline]
 do_raw_spin_lock+0x265/0x2f0 kernel/locking/spinlock_debug.c:115
 spin_lock include/linux/spinlock.h:364 [inline]
 kernfs_put+0x2bd/0x490 fs/kernfs/dir.c:544
 kernfs_remove_by_name_ns+0x99/0x100 fs/kernfs/dir.c:1567
 kernfs_remove_by_name include/linux/kernfs.h:598 [inline]
 sysfs_unmerge_group+0xd0/0x130 fs/sysfs/group.c:369
 rpm_sysfs_remove drivers/base/power/sysfs.c:826 [inline]
 dpm_sysfs_remove+0x72/0xc0 drivers/base/power/sysfs.c:835
 device_del+0x2cb/0xaf0 drivers/base/core.c:3577
 fw_load_sysfs_fallback drivers/base/firmware_loader/fallback.c:545 [inline]
 fw_load_from_user_helper drivers/base/firmware_loader/fallback.c:583 [inline]
 firmware_fallback_sysfs+0x8d1/0xbc0 drivers/base/firmware_loader/fallback.c:659
 _request_firmware+0xc86/0x12b0 drivers/base/firmware_loader/main.c:876
 request_firmware_work_func+0xac/0x1b0 drivers/base/firmware_loader/main.c:1127
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>