sched: RT throttling activated for rt_rq ffff8801db721198 (cpu 1)
potential CPU hogs:
	syz-executor5 (7749)
BUG: workqueue lockup - pool[  285.905869] INFO: task kworker/0:2:351 blocked for more than 140 seconds.
      Not tainted 4.9.125+ #37
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/0:2     D
26904   351      2 0x00000000
Workqueue: events linkwatch_event
 ffff8801d52d4740
 0000000000000000 ffff8801d3460000 ffff8801d9e18000 ffff8801db621018
 ffff8801d3f5fae8 ffffffff8277d092 0000000000000002 ffff8801d52d4ff0
 ffff8801d9edb778 00ff8801d52d4740 ffff8801db6218f0Call Trace:
 [<ffffffff8277e5bf>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff8277ef43>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3586
 [<ffffffff82780bc6>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff82780bc6>] mutex_lock_nested+0x326/0x870 kernel/locking/mutex.c:621
 [<ffffffff822c12d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
 [<ffffffff822d7c4e>] linkwatch_event+0xe/0x60 net/core/link_watch.c:236
 [<ffffffff8112c511>] process_one_work+0x791/0x1470 kernel/workqueue.c:2092
 [<ffffffff8112d2c6>] worker_thread+0xd6/0x10a0 kernel/workqueue.c:2226
 [<ffffffff8113d9ad>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff8278c35c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373

Showing all locks held in the system:
2 locks held by khungtaskd/24:
 #0: 
 (rcu_read_lock){......}, at: [<ffffffff81309abc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 (rcu_read_lock){......}, at: [<ffffffff81309abc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 (tasklist_lock){.+.+..}, at: [<ffffffff813e68fc>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
 #0: 
 ("events"){.+.+.+}, at: [<ffffffff8112c420>] process_one_work+0x6a0/0x1470 kernel/workqueue.c:2085
 ((linkwatch_work).work){+.+...}, at: [<ffffffff8112c458>] process_one_work+0x6d8/0x1470 kernel/workqueue.c:2089
 (rtnl_mutex){+.+.+.}, at: [<ffffffff822c12d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
 #0: 
 (&f->f_pos_lock){+.+.+.}, at: [<ffffffff8154c11c>] __fdget_pos+0xac/0xd0 fs/file.c:781
 #0: 
 (&tty->ldisc_sem){++++++}, at: [<ffffffff8278a262>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81cdd442>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
 #0: 
 ("%s"("ipv6_addrconf")){.+.+..}, at: [<ffffffff8112c420>] process_one_work+0x6a0/0x1470 kernel/workqueue.c:2085
 ((&(&ifa->dad_work)->work)){+.+...}, at: [<ffffffff8112c458>] process_one_work+0x6d8/0x1470 kernel/workqueue.c:2089
 (rtnl_mutex){+.+.+.}, at: [<ffffffff822c12d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
 #0: 
 (rtnl_mutex){+.+.+.}, at: [<ffffffff822c12d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
 (cpu_hotplug.dep_map){++++++}, at: [<ffffffff810dee12>] get_online_cpus+0x32/0x90 kernel/cpu.c:253
 #0: 
 (rtnl_mutex){+.+.+.}, at: [<ffffffff822c12d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
 #0: 
 (rtnl_mutex){+.+.+.}, at: [<ffffffff822c12d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
 #0: 
 (rtnl_mutex){+.+.+.}, at: [<ffffffff822c12d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.125+ #37
 ffff8801d94a7d08
 ffffffff81af0ae9 0000000000000000 0000000000000001 0000000000000001
 0000000000000001 ffffffff810967d0 ffff8801d94a7d40 ffffffff81afb849
 0000000000000001 0000000000000000 0000000000000003Call Trace:
 [<ffffffff81af0ae9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81af0ae9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81afb849>] nmi_cpu_backtrace.cold.0+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81afb7dc>] nmi_trigger_cpumask_backtrace+0x12c/0x151 lib/nmi_backtrace.c:60
 [<ffffffff810968d4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff8130a04d>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff8130a04d>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8130a04d>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8130a04d>] watchdog+0x6ad/0xa20 kernel/hung_task.c:239
 [<ffffffff8113d9ad>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff8278c35c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 7756 Comm: syz-executor5 Not tainted 4.9.125+ #37
task: ffff8801b9254740 task.stack: ffff8801a1f60000
RIP: 0010:[<ffffffff81d07e0b>] 
c [<ffffffff81d07e0b>] inb arch/x86/include/asm/io.h:316 [inline]
RIP: 0010:[<ffffffff81d07e0b>] 
c [<ffffffff81d07e0b>] io_serial_in+0x6b/0x90 drivers/tty/serial/8250/8250_port.c:413
RSP: 0000:ffff8801db607790  EFLAGS: 00000002
RAX: dffffc0000000020 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: ffffffff81d07db1 RDI: ffffffff84959a18
RBP: ffff8801db6077a0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff849599e0
R13: 0000000000000020 R14: fffffbfff092b383 R15: fffffbfff092b345
FS:  00007f65bde97700(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f65bde75db8 CR3: 00000001d1600000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff849599e0
c 0000000000002706
c ffff8801db6077f0
c ffffffff81d0a024
c
 1ffff1003b6c0ef9
c ffffffff84959a28
c ffffffff84959c1a
c ffffffff849599e0
c
 0000000000000030
c ffffffff81d0a170
c dffffc0000000000
c 0000000000000030
c
Call Trace:
 <IRQ> 
d [<ffffffff81d0a024>] serial_in drivers/tty/serial/8250/8250.h:111 [inline]
 <IRQ> 
d [<ffffffff81d0a024>] wait_for_xmitr+0x94/0x1e0 drivers/tty/serial/8250/8250_port.c:1997
 [<ffffffff81d0a18f>] serial8250_console_putchar+0x1f/0x60 drivers/tty/serial/8250/8250_port.c:3103
 [<ffffffff81cf2b69>] uart_console_write+0x59/0xf0 drivers/tty/serial/serial_core.c:1859
 [<ffffffff81d153a8>] serial8250_console_write+0x528/0x820 drivers/tty/serial/8250/8250_port.c:3169
 [<ffffffff81d0301f>] univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:594
 [<ffffffff8121ae5d>] call_console_drivers.isra.0.constprop.15+0x1ad/0x360 kernel/printk/printk.c:1589
 [<ffffffff8121d88e>] console_cont_flush kernel/printk/printk.c:2316 [inline]
 [<ffffffff8121d88e>] console_unlock+0x17e/0xb50 kernel/printk/printk.c:2382
 [<ffffffff8121e6a8>] vprintk_emit+0x448/0x790 kernel/printk/printk.c:1903
 [<ffffffff8121ea18>] vprintk+0x28/0x30 kernel/printk/printk.c:1913
 [<ffffffff8121ea3d>] vprintk_default+0x1d/0x30 kernel/printk/printk.c:1914
 [<ffffffff813eb48a>] vprintk_func kernel/printk/internal.h:36 [inline]
 [<ffffffff813eb48a>] printk+0xaf/0xd7 kernel/printk/printk.c:1975
 [<ffffffff813e1b37>] wq_watchdog_timer_fn.cold.24+0x11/0x65 kernel/workqueue.c:5393
 [<ffffffff81259703>] call_timer_fn+0x163/0x6e0 kernel/time/timer.c:1319
 [<ffffffff81259eb4>] expire_timers+0x234/0x580 kernel/time/timer.c:1359
 [<ffffffff8125a5d3>] __run_timers kernel/time/timer.c:1658 [inline]
 [<ffffffff8125a5d3>] run_timer_softirq+0x3d3/0x5b0 kernel/time/timer.c:1686
 [<ffffffff82791480>] __do_softirq+0x210/0x940 kernel/softirq.c:288
 [<ffffffff810ecb14>] invoke_softirq kernel/softirq.c:368 [inline]
 [<ffffffff810ecb14>] irq_exit+0x114/0x150 kernel/softirq.c:409
 [<ffffffff82790061>] exiting_irq arch/x86/include/asm/apic.h:669 [inline]
 [<ffffffff82790061>] smp_apic_timer_interrupt+0x81/0xa0 arch/x86/kernel/apic/apic.c:962
 [<ffffffff8278d92d>] apic_timer_interrupt+0x9d/0xb0 arch/x86/entry/entry_64.S:648
 <EOI> 
dCode: 
c24 
cc9 
c00 
c00 
c00 
c49 
c8d 
c7c 
c24 
c38 
c48 
cb8 
c00 
c00 
c00 
c00 
c00 
cfc 
cff 
cdf 
c48 
c89 
cfa 
c48 
cc1 
cea 
c03 
cd3 
ce3 
c80 
c3c 
c02 
c00 
c75 
c17 
c41 
c03 
c5c 
c24 
c38 
c89 
cda 
cec 
c<5b> 
c0f 
cb6 
cc0 
c41 
c5c 
c5d 
cc3 
ce8 
cd8 
cb7 
c7c 
cff 
ceb 
cc2 
ce8 
c31 
cb8 
c7c 
cff 
ceb 
c