rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-....: (1 GPs behind) idle=30e/1/0x4000000000000000 softirq=238439/238440 fqs=5233 (t=10502 jiffies g=472637 q=1986) NMI backtrace for cpu 0 CPU: 0 PID: 20710 Comm: syz-executor.5 Not tainted 5.8.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x18f/0x20d lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1b3/0x223 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x194/0x1cf kernel/rcu/tree_stall.h:320 print_cpu_stall kernel/rcu/tree_stall.h:553 [inline] check_cpu_stall kernel/rcu/tree_stall.h:627 [inline] rcu_pending kernel/rcu/tree.c:3489 [inline] rcu_sched_clock_irq.cold+0x5b3/0xccc kernel/rcu/tree.c:2504 update_process_times+0x25/0x60 kernel/time/timer.c:1737 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:176 tick_sched_timer+0x108/0x290 kernel/time/tick-sched.c:1320 __run_hrtimer kernel/time/hrtimer.c:1520 [inline] __hrtimer_run_queues+0x1d5/0xfc0 kernel/time/hrtimer.c:1584 hrtimer_interrupt+0x32a/0x930 kernel/time/hrtimer.c:1646 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1080 [inline] __sysvec_apic_timer_interrupt+0x142/0x5e0 arch/x86/kernel/apic/apic.c:1097 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:50 [inline] sysvec_apic_timer_interrupt+0x4f/0x120 arch/x86/kernel/apic/apic.c:1091 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:585 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:770 [inline] RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0x8c/0xe0 kernel/locking/spinlock.c:191 Code: 48 c7 c0 88 e0 b4 89 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 75 37 48 83 3d e3 52 cc 01 00 74 22 48 89 df 57 9d <0f> 1f 44 00 00 bf 01 00 00 00 e8 35 e5 66 f9 65 8b 05 fe 70 19 78 RSP: 0018:ffffc90000007cb8 EFLAGS: 00000282 RAX: 1ffffffff1369c11 RBX: 0000000000000282 RCX: 0000000000000002 RDX: dffffc0000000000 RSI: 0000000000000000 RDI: 0000000000000282 RBP: ffff888210f960b8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000 R13: ffff888210f960b8 R14: 1ffff92000000fa9 R15: dffffc0000000000 spin_unlock_irqrestore include/linux/spinlock.h:408 [inline] skb_dequeue+0x125/0x180 net/core/skbuff.c:3040 garp_queue_xmit net/802/garp.c:258 [inline] garp_join_timer+0xc6/0xf0 net/802/garp.c:410 call_timer_fn+0x1ac/0x760 kernel/time/timer.c:1415 expire_timers kernel/time/timer.c:1460 [inline] __run_timers.part.0+0x54c/0xa20 kernel/time/timer.c:1784 __run_timers kernel/time/timer.c:1756 [inline] run_timer_softirq+0xae/0x1a0 kernel/time/timer.c:1797 __do_softirq+0x34c/0xa60 kernel/softirq.c:292 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:711 __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline] run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline] do_softirq_own_stack+0x111/0x170 arch/x86/kernel/irq_64.c:77 invoke_softirq kernel/softirq.c:387 [inline] __irq_exit_rcu kernel/softirq.c:417 [inline] irq_exit_rcu+0x229/0x270 kernel/softirq.c:429 sysvec_apic_timer_interrupt+0x54/0x120 arch/x86/kernel/apic/apic.c:1091 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:585 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:770 [inline] RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0x8c/0xe0 kernel/locking/spinlock.c:191 Code: 48 c7 c0 88 e0 b4 89 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 75 37 48 83 3d e3 52 cc 01 00 74 22 48 89 df 57 9d <0f> 1f 44 00 00 bf 01 00 00 00 e8 35 e5 66 f9 65 8b 05 fe 70 19 78 RSP: 0018:ffffc90018147910 EFLAGS: 00000282 RAX: 1ffffffff1369c11 RBX: 0000000000000282 RCX: 0000000000000007 RDX: dffffc0000000000 RSI: 0000000000000000 RDI: 0000000000000282 RBP: ffffffff89cd1140 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 000000000fffffff R13: 0000000000000000 R14: 000000000000027d R15: 000000000000027d spin_unlock_irqrestore include/linux/spinlock.h:408 [inline] ida_alloc_range+0x3c3/0x820 lib/idr.c:452 proc_alloc_inum fs/proc/generic.c:211 [inline] proc_register+0x34/0x700 fs/proc/generic.c:365 proc_create_net_single+0x108/0x170 fs/proc/proc_net.c:225 fib_proc_init+0xa1/0x1c0 net/ipv4/fib_trie.c:2991 fib_net_init net/ipv4/fib_frontend.c:1586 [inline] fib_net_init+0x21a/0x360 net/ipv4/fib_frontend.c:1573 ops_init+0xaf/0x470 net/core/net_namespace.c:151 setup_net+0x2d8/0x850 net/core/net_namespace.c:341 copy_net_ns+0x2cf/0x5e0 net/core/net_namespace.c:482 create_new_namespaces+0x3f6/0xb10 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0xbd/0x1f0 kernel/nsproxy.c:231 ksys_unshare+0x36c/0x9a0 kernel/fork.c:2983 __do_sys_unshare kernel/fork.c:3051 [inline] __se_sys_unshare kernel/fork.c:3049 [inline] __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3049 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45c369 Code: 8d b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 5b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f841c4b5c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000110 RAX: ffffffffffffffda RBX: 0000000000034c00 RCX: 000000000045c369 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000000 RBP: 000000000078bf30 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bf0c R13: 00007fff6655490f R14: 00007f841c4b69c0 R15: 000000000078bf0c