syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-....: (5 ticks this GP) idle=671/1/0x4000000000000002 softirq=44783/44783 fqs=1063 
	(detected by 0, t=10505 jiffies, g=60401, q=444)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 16478 Comm: syz.1.3046 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:__sysvec_irq_work+0x0/0x240 arch/x86/kernel/irq_work.c:18
Code: 0a 48 83 c1 20 48 89 c8 48 c1 e8 03 42 80 3c 30 00 74 0e 48 89 cb 48 89 cf e8 5c 65 93 00 48 89 d9 5b 41 5e ff 21 0f 1f 40 00 <41> 56 53 49 be 00 00 00 00 00 fc ff df 48 c7 c0 e8 0b e3 8b 48 c1
RSP: 0018:ffffc90000dd0a38 EFLAGS: 00000006
RAX: 1ffff11017224ef1 RBX: ffffc90000dd0a58 RCX: 7cb657f03fdf7f00
RDX: 1ffffffff1e1d008 RSI: ffffffff8a79f7e0 RDI: ffffffff8a79f7a0
RBP: 0000000000000000 R08: ffffffff8f0e8048 R09: ffffffff8f0e8058
R10: ffffffff8f0e8050 R11: ffffffff8f0e8043 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  00007ff685ee66c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000030000 CR3: 0000000062672000 CR4: 00000000003506e0
DR0: 0000200000000300 DR1: 0000200000000300 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff1 DR7: 0000000000000600
Call Trace:
 <IRQ>
 instr_sysvec_irq_work arch/x86/kernel/irq_work.c:17 [inline]
 sysvec_irq_work+0x4a/0xc0 arch/x86/kernel/irq_work.c:17
 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 e2 f0 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:ffffc90000dd0b00 EFLAGS: 00000206
RAX: 7cb657f03fdf7f00 RBX: 1ffff920001ba164 RCX: 7cb657f03fdf7f00
RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f800
RBP: ffffc90000dd0be0 R08: ffffffff901d3157 R09: 1ffffffff203a62a
R10: dffffc0000000000 R11: fffffbfff203a62b R12: ffffffff8c322f00
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000002
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
 rcu_read_unlock include/linux/rcupdate.h:772 [inline]
 ieee80211_rx_napi+0x20f/0x390 net/mac80211/rx.c:5019
 ieee80211_rx include/net/mac80211.h:4573 [inline]
 ieee80211_handle_queued_frames+0x105/0x1b0 net/mac80211/main.c:237
 tasklet_action_common+0x2ad/0x410 kernel/softirq.c:806
 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:wake_q_add+0x2/0xd0 kernel/sched/core.c:908
Code: 89 fe e8 01 6b b1 02 e9 58 ff ff ff 89 f9 80 e1 07 80 c1 03 38 c1 7c 90 e8 2b b8 6b 00 eb 89 66 0f 1f 84 00 00 00 00 00 41 57 <41> 56 41 55 41 54 53 48 89 f3 49 89 fe 4c 8d be 50 0a 00 00 4c 89
RSP: 0018:ffffc900033efb30 EFLAGS: 00000202
RAX: ffffc900034dfbc0 RBX: dffffc0000000000 RCX: ffffffff962d9f03
RDX: 0000000000000001 RSI: ffff8880229ed940 RDI: ffffc900033efba0
RBP: ffffc900033efc30 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff5200067df58 R12: 1ffff9200067df6c
R13: ffff8880229ed940 R14: ffffffff8d43c7e0 R15: ffffc900033efba0
 __mutex_unlock_slowpath+0x3d7/0x6c0 kernel/locking/mutex.c:887
 __rtnl_unlock+0x28/0xa0 net/core/rtnetlink.c:98
 netdev_run_todo+0x2e6/0xa70 net/core/dev.c:10670
 __tun_chr_ioctl+0xb0b/0x1ec0 drivers/net/tun.c:3340
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 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: 0033:0x7ff687c8c799
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:00007ff685ee6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ff687f05fa0 RCX: 00007ff687c8c799
RDX: 0000200000000080 RSI: 00000000400454ca RDI: 000000000000000e
RBP: 00007ff687d22bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff687f06038 R14: 00007ff687f05fa0 R15: 00007ffd74d6cc78
 </TASK>
rcu: rcu_preempt kthread starved for 5185 jiffies! g60401 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:26576 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 0
CPU: 0 PID: 16260 Comm: kworker/0:58 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: events switchdev_deferred_process_work
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+0x4ad/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 a7 b4 4a 00 44 38 e3 75 10 66 90 0f 00 2d 99 e2 f3 08 fb f4 <e9> 16 ff ff ff fb e9 10 ff ff ff e8 47 8f 87 08 89 f9 80 e1 07 38
RSP: 0018:ffffc900037cf760 EFLAGS: 00000246
RAX: e866618595f4e900 RBX: 0000000000000003 RCX: e866618595f4e900
RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f800
RBP: ffffc900037cf810 R08: ffffffff901d3157 R09: 1ffffffff203a62a
R10: dffffc0000000000 R11: fffffbfff203a62b R12: 0000000000000003
R13: ffff8880b903b154 R14: dffffc0000000000 R15: 1ffff920006f9eec
 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
 __mutex_unlock_slowpath+0x36e/0x6c0 kernel/locking/mutex.c:876
 __rtnl_unlock+0x28/0xa0 net/core/rtnetlink.c:98
 netdev_run_todo+0x2e6/0xa70 net/core/dev.c:10670
 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>