rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P14014/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=657397, q=1655 ncpus=2)
task:syz.6.19868     state:R  running task     stack:26360 pid:14014 tgid:14013 ppid:12912  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17d9/0x56c0
 preempt_schedule_irq+0x4d/0xa0
 irqentry_exit+0x14f/0x8f0
 asm_sysvec_reschedule_ipi+0x1a/0x20
RIP: 0010:lock_release+0x3c/0x3c0
Code: 49 89 f5 49 89 fe 65 48 8b 05 80 ec 9c 11 48 89 44 24 28 0f 1f 44 00 00 65 8b 05 83 ec 9c 11 83 f8 08 0f 83 56 02 00 00 89 c0 <48> 0f a3 05 2c 7a 90 0e 73 0d e8 25 f9 08 00 84 c0 0f 84 94 02 00
RSP: 0018:ffffc9000a87f818 EFLAGS: 00000297
RAX: 0000000000000001 RBX: ffffffff8273d15c RCX: ffff888168ab0000
RDX: 0000000000000000 RSI: ffffffff8273d15c RDI: ffffffff8e959c20
RBP: 0000000000000001 R08: ffffffff8273d15c R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff8e959c20 R12: dffffc0000000000
R13: ffffffff8273d15c R14: ffffffff8e959c20 R15: ffff8881bc660780
 kernfs_root+0x1e5/0x230
 kernfs_next_descendant_post+0x4e/0x310
 __kernfs_remove+0x277/0x8e0
 kernfs_remove_by_name_ns+0xc0/0x140
 sysfs_remove_group+0x101/0x2e0
 sysfs_remove_groups+0x54/0xb0
 ib_free_port_attrs+0xc4/0x3a0
 rdma_dev_exit_net+0x1d8/0x340
 ops_undo_list+0x43d/0x8d0
 setup_net+0x2f6/0x350
 copy_net_ns+0x4f9/0x720
 create_new_namespaces+0x3f0/0x6b0
 unshare_nsproxy_namespaces+0x149/0x190
 ksys_unshare+0x57d/0xa00
 __x64_sys_unshare+0x38/0x50
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5ca1f9ce59
RSP: 002b:00007f5ca01ee028 EFLAGS: 00000246 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 00007f5ca2215fa0 RCX: 00007f5ca1f9ce59
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000006e000000
RBP: 00007f5ca2032e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5ca2216038 R14: 00007f5ca2215fa0 R15: 00007ffcd44cd1a8
 </TASK>
rcu: rcu_preempt kthread starved for 7785 jiffies! g657397 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:27496 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 __schedule+0x17d9/0x56c0
 schedule+0x164/0x2b0
 schedule_timeout+0x152/0x2c0
 rcu_gp_fqs_loop+0x30c/0x11f0
 rcu_gp_kthread+0x9e/0x2b0
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31146 Comm: kworker/1:2 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: events_power_efficient neigh_managed_work
RIP: 0010:asm_sysvec_apic_timer_interrupt+0x0/0x20
Code: b6 89 b3 0a e9 81 06 00 00 90 f3 0f 1e fa 0f 1f 00 fc 6a ff e8 31 05 00 00 48 89 c4 48 89 e7 e8 c6 88 b3 0a e9 61 06 00 00 90 <f3> 0f 1e fa 0f 1f 00 fc 6a ff e8 11 05 00 00 48 89 c4 48 89 e7 e8
RSP: 0018:ffffc90000a07e38 EFLAGS: 00000002
RAX: 00000000f229e701 RBX: ffffc90000a07f20 RCX: 0000000080000101
RDX: 0000000000000002 RSI: ffffffff8e25a0a1 RDI: ffff88816e28d940
RBP: ffffc90000a07ef0 R08: ffffc90000a08cf0 R09: 0000000000000000
R10: ffffc90000a07eb8 R11: fffff52000140fd9 R12: ffff88816e28d940
R13: 00000000ffffffff R14: ffffffff81b168f0 R15: ffffc90000a07e68
FS:  0000000000000000(0000) GS:ffff8882a922c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe28f13fe4 CR3: 0000000115784000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
RIP: 0010:arch_stack_walk+0x122/0x150
Code: 6d 09 00 48 85 c0 74 24 48 89 df 48 89 c6 4d 89 f3 2e e8 f1 17 49 0a 84 c0 74 11 4c 89 ff e8 d5 6e 09 00 83 bd 78 ff ff ff 00 <75> cf 65 48 8b 05 54 bd d1 11 48 3b 45 d8 75 12 48 83 c4 68 5b 41
RSP: 0018:ffffc90000a07e68 EFLAGS: 00000202
 stack_trace_save+0xa9/0x100
 kasan_save_track+0x3e/0x80
 __kasan_slab_alloc+0x6c/0x80
 kmem_cache_alloc_node_noprof+0x355/0x610
 __alloc_skb+0x276/0x7a0
 synproxy_send_client_synack+0x175/0xde0
 nft_synproxy_eval_v4+0x362/0x4e0
 nft_synproxy_do_eval+0x335/0x550
 nft_do_chain+0x48d/0x1b10
 nft_do_chain_inet+0x360/0x4b0
 nf_hook_slow+0xc5/0x220
 NF_HOOK+0x21f/0x3c0
 NF_HOOK+0x336/0x3c0
 process_backlog+0xa34/0x1860
 __napi_poll+0xaa/0x330
 net_rx_action+0x61d/0xf50
 handle_softirqs+0x225/0x840
 __irq_exit_rcu+0xca/0x220
 irq_exit_rcu+0x9/0x30
 sysvec_apic_timer_interrupt+0xa6/0xc0
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:_raw_spin_unlock_irq+0x29/0x50
Code: 90 f3 0f 1e fa 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 4a f6 eb f5 48 89 df e8 a2 6b ec f5 e8 6d 50 18 f6 fb bf 01 00 00 00 <e8> 02 82 dd f5 65 8b 05 db e2 88 07 85 c0 74 07 5b e9 01 48 00 00
RSP: 0018:ffffc900041dfaf0 EFLAGS: 00000202
RAX: 000000000038abb9 RBX: ffff88823c63a880 RCX: 0000000080000001
RDX: 0000000000000000 RSI: ffffffff8dfdfe36 RDI: 0000000000000001
RBP: ffffc900041dfce8 R08: ffffffff9032cdf7 R09: 1ffffffff20659be
R10: dffffc0000000000 R11: fffffbfff20659bf R12: 0000000001800000
R13: dffffc0000000000 R14: 0000000000000000 R15: ffffffff8fecd508
 process_scheduled_works+0x90f/0x14e0
 worker_thread+0xa47/0xfb0
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
