rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (1 ticks this GP) idle=a89/1/0x4000000000000002 softirq=63331/63331 fqs=2 
	(detected by 1, t=10503 jiffies, g=91529, q=20)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 22189 Comm: syz.3.3890 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:29 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:106 [inline]
RIP: 0010:lock_is_held_type+0x61/0x190 kernel/locking/lockdep.c:5662
Code: 0f 85 f4 00 00 00 65 48 8b 1d 6b 93 45 76 83 bb ec 0a 00 00 00 0f 85 df 00 00 00 41 89 f7 49 89 fe 48 c7 04 24 00 00 00 00 9c <8f> 04 24 4c 8b 2c 24 fa 48 c7 c7 00 36 2b 8a e8 4b 0e 00 00 65 ff
RSP: 0018:ffffc90000006ff0 EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffff888021ad8000 RCX: 73a97edab9e5c700
RDX: 0000000000000100 RSI: 00000000ffffffff RDI: ffffffff8c31eb20
RBP: 00000000ffffffff R08: ffffc900000070f7 R09: ffffc900000070e0
R10: dffffc0000000000 R11: fffff52000000e1f R12: 1ffff92000000e18
R13: ffffc900000071c0 R14: ffffffff8c31eb20 R15: 00000000ffffffff
FS:  00007f6174ee56c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6174ea3d58 CR3: 000000007f1f5000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 __perf_output_begin kernel/events/ring_buffer.c:170 [inline]
 perf_output_begin_forward+0x1af/0xa40 kernel/events/ring_buffer.c:271
 __perf_event_output kernel/events/core.c:7804 [inline]
 perf_event_output_forward+0x19b/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:__kasan_slab_alloc+0xb8/0xd0 mm/kasan/common.c:470
Code: 89 ff be 40 00 00 00 31 d2 e8 34 77 a9 ff 4c 89 ff 89 c6 e8 aa 83 a9 ff 4c 89 ff 89 c6 44 89 f2 e8 0d 96 45 02 41 89 44 24 04 <48> 89 d8 48 8d 65 e0 5b 41 5c 41 5e 41 5f 5d c3 0f 1f 84 00 00 00
RSP: 0018:ffffc900000077b0 EFLAGS: 00000286
RAX: 00000000dee001a5 RBX: ffff88805db238c0 RCX: 73a97edab9e5c700
RDX: 0000000000000a20 RSI: 000000000000000e RDI: ffffc900000077b0
RBP: ffffc900000079d0 R08: ffffffff89e00d06 R09: 0000000000000001
R10: 00000000f3f24e9c R11: 00000000716bdb5a R12: ffff88805db239a8
R13: ffff88801bbe4140 R14: 0000000000000a20 R15: ffffc900000077b0
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3225 [inline]
 kmem_cache_alloc_node+0x12d/0x2d0 mm/slub.c:3261
 __alloc_skb+0xf4/0x750 net/core/skbuff.c:415
 alloc_skb include/linux/skbuff.h:1162 [inline]
 lapb_send_control+0x34/0x3e0 net/lapb/lapb_subr.c:227
 lapb_t1timer_expiry+0x652/0xa70 net/lapb/lapb_timer.c:-1
 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:list_empty include/linux/list.h:290 [inline]
RIP: 0010:plist_head_empty include/linux/plist.h:212 [inline]
RIP: 0010:plist_add+0xe0/0x480 lib/plist.c:82
Code: 39 e0 0f 85 5a 03 00 00 e8 fd 3d 73 fd 4c 89 64 24 10 4c 89 74 24 20 42 80 7c 2d 00 00 74 08 48 89 df e8 b3 5c b8 fd 4c 8b 23 <49> 39 dc 4c 89 7c 24 18 0f 84 94 00 00 00 48 89 6c 24 08 49 83 c4
RSP: 0018:ffffc90003a3f9d0 EFLAGS: 00000246
RAX: ffffffff8405f693 RBX: ffffc90000e05fc8 RCX: 0000000000080000
RDX: ffffc9001548e000 RSI: 0000000000007cb0 RDI: 0000000000007cb1
RBP: 1ffff920001c0bf9 R08: ffff888021ad801b R09: 1ffff1100435b003
R10: dffffc0000000000 R11: ffffed100435b004 R12: ffffc90000e05fc8
R13: dffffc0000000000 R14: ffffc90003a3fba8 R15: ffffc90003a3fb90
 __queue_me kernel/futex/core.c:2500 [inline]
 queue_me kernel/futex/core.c:2519 [inline]
 futex_wait_queue_me+0x14a/0x440 kernel/futex/core.c:2846
 futex_wait+0x256/0x680 kernel/futex/core.c:2964
 do_futex+0xdb2/0x12b0 kernel/futex/core.c:3983
 __do_sys_futex kernel/futex/core.c:4060 [inline]
 __se_sys_futex+0x389/0x420 kernel/futex/core.c:4041
 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: 0033:0x7f6176c8b819
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:00007f6174ee50e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 00007f6176f04fa8 RCX: 00007f6176c8b819
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f6176f04fa8
RBP: 00007f6176f04fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6176f05038 R14: 00007fffdee71f00 R15: 00007fffdee71fe8
 </TASK>
rcu: rcu_preempt kthread starved for 10495 jiffies! g91529 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:27088 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: 22187 Comm: syz.3.3890 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
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 30 88 08 89 f9 80 e1 07 38
RSP: 0018:ffffc900034378e0 EFLAGS: 00000246
RAX: 2fdf165e36f89100 RBX: 0000000000000003 RCX: 2fdf165e36f89100
RDX: dffffc0000000000 RSI: ffffffff8a2b2800 RDI: ffffffff8a79fe40
RBP: ffffc90003437990 R08: ffffffff901d51af R09: 1ffffffff203aa35
R10: dffffc0000000000 R11: fffffbfff203aa36 R12: 0000000000000003
R13: ffff8880b913b154 R14: dffffc0000000000 R15: 1ffff92000686f1c
 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]
 futex_wake+0x219/0x540 kernel/futex/core.c:1682
 do_futex+0xd73/0x12b0 kernel/futex/core.c:3988
 __do_sys_futex kernel/futex/core.c:4060 [inline]
 __se_sys_futex+0x389/0x420 kernel/futex/core.c:4041
 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: 0033:0x7f6176c8b819
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:00007fffdee72148 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f6176c8b819
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f6176f04fa8
RBP: 0000000000001ab6 R08: 0000000000000000 R09: 0000000000000000
R10: 00007f6176f04fa0 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6176f04fac R14: 00007f6176f04fa8 R15: 00007f6176f04fa0
 </TASK>