rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 GPs behind) idle=c0a/1/0x4000000000000000 softirq=45597/45598 fqs=1 
	(detected by 0, t=10502 jiffies, g=79773, q=123)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 421 Comm: kworker/u4:4 Not tainted 5.8.0-rc5-next-20200716-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
RIP: 0010:__sanitizer_cov_trace_pc+0x15/0x60 kernel/kcov.c:193
Code: 0f 1f 44 00 00 48 8b be b0 01 00 00 e8 b4 ff ff ff 31 c0 c3 90 65 48 8b 14 25 c0 fe 01 00 65 8b 05 90 ce 8d 7e a9 00 01 ff 00 <48> 8b 34 24 74 0f f6 c4 01 74 35 8b 82 0c 14 00 00 85 c0 74 2b 8b
RSP: 0018:ffffc90000da8de0 EFLAGS: 00000006
RAX: 0000000080010001 RBX: 1bc16d674ec8e6d2 RCX: ffffffff81647af1
RDX: ffff8880a8078400 RSI: ffff8880a8078400 RDI: 0000000000000006
RBP: 170427322e084e64 R08: 0000000000000000 R09: ffffffff8ab8ddcf
R10: 170427322e084e64 R11: 0000000000000000 R12: ffff8880ae727740
R13: ffff8880ae727840 R14: ffff888095babb40 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000743694 CR3: 0000000095aed000 CR4: 00000000001526e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 __run_hrtimer kernel/time/hrtimer.c:1486 [inline]
 __hrtimer_run_queues+0x37f/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:1079 [inline]
 __sysvec_apic_timer_interrupt+0x142/0x5e0 arch/x86/kernel/apic/apic.c:1096
 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:706
 </IRQ>
 __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]
 sysvec_apic_timer_interrupt+0xe0/0x120 arch/x86/kernel/apic/apic.c:1090
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:587
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:765 [inline]
RIP: 0010:lock_acquire+0x270/0xad0 kernel/locking/lockdep.c:4962
Code: 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 0f 85 f8 06 00 00 48 83 3d ed b1 5a 08 00 0f 84 a6 05 00 00 48 8b 7c 24 08 57 9d <0f> 1f 44 00 00 48 b8 00 00 00 00 00 fc ff df 48 03 44 24 10 48 c7
RSP: 0018:ffffc900016b7a38 EFLAGS: 00000286
RAX: 1ffffffff136a040 RBX: ffff8880a8078400 RCX: 0000000000000001
RDX: dffffc0000000000 RSI: ef13032bb8f3dcf1 RDI: 0000000000000286
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8c6549e7
R10: fffffbfff18ca93c R11: 0000000000000000 R12: 0000000000000002
R13: ffffffff89c53980 R14: 0000000000000000 R15: ffff8880a8078400
 rcu_lock_acquire include/linux/rcupdate.h:241 [inline]
 rcu_read_lock include/linux/rcupdate.h:634 [inline]
 inet_twsk_purge+0x112/0x7b0 net/ipv4/inet_timewait_sock.c:268
 ops_exit_list+0x10d/0x160 net/core/net_namespace.c:189
 cleanup_net+0x4ea/0xa00 net/core/net_namespace.c:603
 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
 kthread+0x3b5/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
rcu: rcu_preempt kthread starved for 10500 jiffies! g79773 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:
rcu_preempt     R  running task    29120    10      2 0x00004000
Call Trace:
 context_switch kernel/sched/core.c:3445 [inline]
 __schedule+0x8b4/0x1e80 kernel/sched/core.c:4169
 schedule+0xd0/0x2a0 kernel/sched/core.c:4244
 schedule_timeout+0x148/0x250 kernel/time/timer.c:1897
 rcu_gp_fqs_loop kernel/rcu/tree.c:1871 [inline]
 rcu_gp_kthread+0xae5/0x1b50 kernel/rcu/tree.c:2041
 kthread+0x3b5/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294