rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (0 ticks this GP) idle=8a3/1/0x4000000000000002 softirq=71283/71283 fqs=162 
	(detected by 1, t=10506 jiffies, g=105253, q=824)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 14508 Comm: syz.0.3065 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:preempt_count_sub+0x3f/0x160 kernel/sched/core.c:5541
Code: e8 03 0f b6 04 18 84 c0 0f 85 bd 00 00 00 83 3d 26 cd ba 14 00 75 25 65 8b 05 65 fd b0 7e 89 c1 81 e1 ff ff ff 7f 39 cf 7f 25 <81> ff ff 00 00 00 0f 93 c1 84 c0 0f 95 c0 08 c8 74 53 65 8b 05 40
RSP: 0018:ffffc90000007f28 EFLAGS: 00000097
RAX: 0000000000010001 RBX: dffffc0000000000 RCX: 0000000000010001
RDX: 1ffffffff1dda400 RSI: ffffffff8a59a860 RDI: 0000000000010000
RBP: ffffc90000007fe0 R08: ffffffff8eed2008 R09: ffffffff8eed2018
R10: ffffffff8eed2010 R11: ffffffff8eed2003 R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 1ffff92000000fe8
FS:  00007f404dad56c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c326614 CR3: 000000005c0c2000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 __irq_exit_rcu+0x97/0x220 kernel/softirq.c:657
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 instr_sysvec_irq_work arch/x86/kernel/irq_work.c:17 [inline]
 sysvec_irq_work+0x9d/0xc0 arch/x86/kernel/irq_work.c:17
 </IRQ>
 <TASK>
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:do_raw_write_unlock+0x0/0x1a0 kernel/locking/spinlock_debug.c:230
Code: 96 db 5e 00 e9 2c ff ff ff e8 0c f7 4b 08 89 f9 80 e1 07 80 c1 03 38 c1 0f 8c 6f ff ff ff e8 e7 db 5e 00 e9 65 ff ff ff 66 90 <55> 41 57 41 56 41 55 41 54 53 48 89 fb 49 bc 00 00 00 00 00 fc ff
RSP: 0018:ffffc9000315f678 EFLAGS: 00000246
RAX: 9a8fa1d770753200 RBX: ffffffff8c246e00 RCX: 9a8fa1d770753200
RDX: 0000000000000001 RSI: ffffffff8a0b2b40 RDI: ffffffff8c246e00
RBP: ffff88805d7300c0 R08: dffffc0000000000 R09: fffffbfff1ad334e
R10: fffffbfff1ad334e R11: 1ffffffff1ad334d R12: ffff88805d7300d0
R13: dffffc0000000000 R14: ffff88805d730e58 R15: ffff888054c560c0
 __raw_write_unlock include/linux/rwlock_api_smp.h:219 [inline]
 _raw_write_unlock+0x1a/0x40 kernel/locking/spinlock.c:332
 proc_register+0x344/0x4e0 fs/proc/generic.c:382
 proc_create_net_data+0x13f/0x1a0 fs/proc/proc_net.c:117
 ipmr_net_init+0x2b8/0x3a0 net/ipv4/ipmr.c:3074
 ops_init+0x357/0x600 net/core/net_namespace.c:138
 setup_net+0x38d/0x9f0 net/core/net_namespace.c:333
 copy_net_ns+0x348/0x5b0 net/core/net_namespace.c:503
 create_new_namespaces+0x3d3/0x6f0 kernel/nsproxy.c:110
 copy_namespaces+0x37d/0x3e0 kernel/nsproxy.c:178
 copy_process+0x180f/0x3e00 kernel/fork.c:2293
 kernel_clone+0x219/0x930 kernel/fork.c:2679
 __do_sys_clone kernel/fork.c:2796 [inline]
 __se_sys_clone kernel/fork.c:2780 [inline]
 __x64_sys_clone+0x170/0x1c0 kernel/fork.c:2780
 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: 0033:0x7f404f86dfc9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f404dad4fe8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007f404fac4fa0 RCX: 00007f404f86dfc9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000061000600
RBP: 00007f404f8f0f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f404fac5038 R14: 00007f404fac4fa0 R15: 00007ffcd73b76b8
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 9694 jiffies! g105253 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=43721
rcu: rcu_preempt kthread starved for 9695 jiffies! g105253 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:26944 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x98/0x350 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: 6697 Comm: kworker/u4:7 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: netns cleanup_net
Call Trace:
 <IRQ>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x397/0x3d0 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+0x10c8/0x1220 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+0x831/0x1110 kernel/rcu/tree.c:2619
 update_process_times+0x193/0x200 kernel/time/timer.c:1818
 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+0x4fe/0xc40 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:queued_write_lock_slowpath+0x117/0x250 kernel/locking/qrwlock.c:78
Code: f0 41 81 0e 00 01 00 00 43 0f b6 04 27 84 c0 74 37 44 89 f1 80 e1 07 80 c1 03 38 c1 7c 2a 4c 89 f7 e8 6d d6 5e 00 eb 20 f3 90 <43> 0f b6 04 27 84 c0 74 15 44 89 f1 80 e1 07 80 c1 03 38 c1 7c 08
RSP: 0018:ffffc900033ff940 EFLAGS: 00000206
RAX: 00000000000001ff RBX: ffffc900033ff990 RCX: ffffffff815d5bbd
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff8c246e00
RBP: ffffc900033ff9f0 R08: dffffc0000000000 R09: fffffbfff1848dc1
R10: fffffbfff1848dc1 R11: 1ffffffff1848dc0 R12: dffffc0000000000
R13: 1ffff9200067ff2c R14: ffffffff8c246e00 R15: 1ffffffff1848dc0
 queued_write_lock include/asm-generic/qrwlock.h:97 [inline]
 do_raw_write_lock+0x1ea/0x250 kernel/locking/spinlock_debug.c:210
 remove_proc_entry+0x3d/0x4a0 fs/proc/generic.c:700
 vlan_proc_cleanup+0x8c/0x120 net/8021q/vlanproc.c:97
 ops_exit_list net/core/net_namespace.c:172 [inline]
 cleanup_net+0x6f0/0xb80 net/core/net_namespace.c:635
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>