rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-....: (1 GPs behind) idle=ee0c/1/0x4000000000000000 softirq=18419/18422 fqs=5248
rcu: 	         hardirqs   softirqs   csw/system
rcu: 	 number:  1074277          0            0
rcu: 	cputime:    25327      27171           86   ==> 52510(ms)
rcu: 	(t=10502 jiffies g=12081 q=2781 ncpus=2)
CPU: 1 UID: 0 PID: 6792 Comm: syz.0.398 Not tainted 6.16.0-rc6-syzkaller-00411-g95993dc3039e #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:rcu_read_unlock_special+0x87/0x4c0
Code: f1 f1 f1 00 f2 f2 f2 4a 89 04 2b 66 42 c7 44 2b 09 f3 f3 42 c6 44 2b 0b f3 65 44 8b 35 62 2c f8 10 41 f7 c6 00 00 f0 00 74 49 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 66 42 c7 44 2b
RSP: 0018:ffffc900001dffc0 EFLAGS: 00000206
RAX: c36cebbb2fce9d00 RBX: 1ffff9200003c000 RCX: c36cebbb2fce9d00
RDX: 0000000000000002 RSI: ffffffff8d998836 RDI: ffffffff8be29f40
RBP: ffffc900001e00b8 R08: ffffffff8fa1e8f7 R09: 1ffffffff1f43d1e
R10: dffffc0000000000 R11: fffffbfff1f43d1f R12: ffffffff8e144400
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000002
FS:  00007fac07b456c0(0000) GS:ffff8881a3c1f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9e314e56c0 CR3: 0000000037c10000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 __rcu_read_unlock+0x84/0xe0
 unwind_next_frame+0x19ae/0x2390
 arch_stack_walk+0x11c/0x150
 stack_trace_save+0x9c/0xe0
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x62/0x70
 kmem_cache_free+0x18f/0x400
 ifb_xmit+0x1e2/0x5c0
 dev_hard_start_xmit+0x2d7/0x830
 sch_direct_xmit+0x241/0x4b0
 __dev_queue_xmit+0x17b6/0x3a70
 lapb_data_transmit+0x90/0xb0
 lapb_transmit_buffer+0x163/0x200
 lapb_t1timer_expiry+0x699/0xab0
 call_timer_fn+0x17e/0x5f0
 __run_timer_base+0x61a/0x860
 run_timer_softirq+0xb7/0x180
 handle_softirqs+0x286/0x870
 __irq_exit_rcu+0xca/0x1f0
 irq_exit_rcu+0x9/0x30
 sysvec_apic_timer_interrupt+0xa6/0xc0
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:format_decode+0x203/0xe30
Code: 8b 4c 24 08 80 e1 07 38 c1 7c 8b 48 8b 7c 24 08 e8 82 93 b8 f6 e9 7c ff ff ff e8 c8 70 55 f6 eb 05 e8 c1 70 55 f6 49 8d 75 04 <49> 8d 5d 07 49 89 f5 49 c1 ed 03 48 ba 00 00 00 00 00 fc ff df 41
RSP: 0018:ffffc9000327f7f0 EFLAGS: 00000293
RAX: ffffffff8b6ab828 RBX: 0000000000000053 RCX: ffff888026b71cc0
RDX: 0000000000000000 RSI: ffffc9000327f89c RDI: 0000000000000011
RBP: ffffffff8cb9ae08 R08: ffff888026b71cc0 R09: 0000000000000002
R10: 0000000000000025 R11: 0000000000000000 R12: 1ffffffff19735c1
R13: ffffc9000327f898 R14: 1ffff9200064ff13 R15: ffffffff8cb9ae08
 vsnprintf+0x102/0xf00
 add_uevent_var+0x1cc/0x450
 kobject_uevent_env+0x2ba/0x8c0
 net_rx_queue_update_kobjects+0x3ba/0x720
 netdev_register_kobject+0x1fd/0x2f0
 register_netdevice+0x126c/0x1ae0
 tun_set_iff+0x844/0xef0
 __tun_chr_ioctl+0x788/0x1df0
 __se_sys_ioctl+0xfc/0x170
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fac06d8e9a9
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:00007fac07b45038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fac06fb6080 RCX: 00007fac06d8e9a9
RDX: 0000200000000040 RSI: 00000000400454ca RDI: 0000000000000009
RBP: 00007fac06e10d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fac06fb6080 R15: 00007ffc8808ab38
 </TASK>
sched: DL replenish lagged too much
