BUG: workqueue lockup - pool[ 1149.648313] INFO: task syz-executor2:22700 blocked for more than 140 seconds.
      Not tainted 4.9.144+ #79
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor2   D
30264 22700   2142 0x10000000
 ffff8801ce44ac00 ffff8801a0655d80 ffff8801c965df00 ffff8801db621018
 ffff8801a985fad8 ffffffff82808a22 ffff8801a985fb58 ffff880178900000
 ffffffff810efb6a 00fffc0000000000 ffff8801db6218f0Call Trace:
 [<ffffffff82809f4f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff822ae45c>] __lock_sock+0x13c/0x250 net/core/sock.c:2035
 [<ffffffff822ae666>] lock_sock_nested+0xf6/0x120 net/core/sock.c:2505
 [<ffffffff827d339f>] lock_sock include/net/sock.h:1404 [inline]
 [<ffffffff827d339f>] packet_setsockopt+0x50f/0x2630 net/packet/af_packet.c:3668
 [<ffffffff822a61d6>] SYSC_setsockopt net/socket.c:1785 [inline]
 [<ffffffff822a61d6>] SyS_setsockopt+0x166/0x260 net/socket.c:1764
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff82818cd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/24:
 #0: 
 (rcu_read_lock){......}, at: [<ffffffff8131c22c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 (rcu_read_lock){......}, at: [<ffffffff8131c22c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 (tasklist_lock){.+.?..}, at: [<ffffffff813fea8f>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
 #0: 
 (&tty->ldisc_sem){++++++}, at: [<ffffffff82816db2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d38122>] n_tty_read+0x202/0x1830 drivers/tty/n_tty.c:2156
 #0: 
 (&sig->cred_guard_mutex){+.+.+.}, at: [<ffffffff81520ff3>] prepare_bprm_creds+0x53/0x110 fs/exec.c:1369
 #0: 
 (&sig->cred_guard_mutex){+.+.+.}, at: [<ffffffff81520ff3>] prepare_bprm_creds+0x53/0x110 fs/exec.c:1369
=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.144+ #79
 ffff8801d9907d08
 ffffffff81b43b89 0000000000000000 0000000000000001 0000000000000001
 0000000000000001 ffffffff81098440 ffff8801d9907d40 ffffffff81b4ec99
 0000000000000001 0000000000000000 0000000000000003Call Trace:
 [<ffffffff81b43b89>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b43b89>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81b4ec99>] nmi_cpu_backtrace.cold.0+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81b4ec2c>] nmi_trigger_cpumask_backtrace+0x12c/0x151 lib/nmi_backtrace.c:60
 [<ffffffff81098544>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff8131c7bd>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff8131c7bd>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8131c7bd>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8131c7bd>] watchdog+0x6ad/0xa20 kernel/hung_task.c:239
 [<ffffffff81142ccd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff82818e9c>] 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: 22713 Comm: syz-executor5 Not tainted 4.9.144+ #79
task: ffff8801a19d8000 task.stack: ffff88014e340000
RIP: 0010:[<ffffffff81d6349b>] 
c [<ffffffff81d6349b>] inb arch/x86/include/asm/io.h:316 [inline]
RIP: 0010:[<ffffffff81d6349b>] 
c [<ffffffff81d6349b>] io_serial_in+0x6b/0x90 drivers/tty/serial/8250/8250_port.c:413
RSP: 0000:ffff8801db607788  EFLAGS: 00000002
RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: ffffffff81d63441 RDI: ffffffff84b5db98
RBP: ffff8801db607798 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff84b5db60
R13: 0000000000000020 R14: fffffbfff096bbb3 R15: fffffbfff096bb75
FS:  00007fe6d0b58700(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2f521000 CR3: 0000000180fb4000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0001000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 ffffffff84b5db60
c 0000000000002709
c ffff8801db6077e8
c ffffffff81d656b4
c
 1ffff1003b6c0ef8
c ffffffff84b5dba8
c ffffffff84b5dd9a
c ffffffff84b5db60
c
 0000000000000039
c ffffffff81d65800
c dffffc0000000000
c 0000000000000039
c
Call Trace:
 <IRQ> 
d [<ffffffff81d656b4>] serial_in drivers/tty/serial/8250/8250.h:111 [inline]
 <IRQ> 
d [<ffffffff81d656b4>] wait_for_xmitr+0x94/0x1e0 drivers/tty/serial/8250/8250_port.c:1997
 [<ffffffff81d6581f>] serial8250_console_putchar+0x1f/0x60 drivers/tty/serial/8250/8250_port.c:3103
 [<ffffffff81d4dc39>] uart_console_write+0x59/0xf0 drivers/tty/serial/serial_core.c:1866
 [<ffffffff81d70a38>] serial8250_console_write+0x528/0x820 drivers/tty/serial/8250/8250_port.c:3169
 [<ffffffff81d5e44f>] univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:594
 [<ffffffff812239dd>] call_console_drivers.isra.0.constprop.15+0x1ad/0x360 kernel/printk/printk.c:1594
 [<ffffffff8122640e>] console_cont_flush kernel/printk/printk.c:2321 [inline]
 [<ffffffff8122640e>] console_unlock+0x17e/0xb50 kernel/printk/printk.c:2387
 [<ffffffff81227228>] vprintk_emit+0x448/0x790 kernel/printk/printk.c:1908
 [<ffffffff81227598>] vprintk+0x28/0x30 kernel/printk/printk.c:1918
 [<ffffffff812275bd>] vprintk_default+0x1d/0x30 kernel/printk/printk.c:1919
 [<ffffffff814033ef>] vprintk_func kernel/printk/internal.h:36 [inline]
 [<ffffffff814033ef>] printk+0xaf/0xd7 kernel/printk/printk.c:1980
 [<ffffffff813f9d9e>] wq_watchdog_timer_fn.cold.23+0x11/0x65 kernel/workqueue.c:5393
 [<ffffffff81262ba3>] call_timer_fn+0x163/0x6e0 kernel/time/timer.c:1319
 [<ffffffff81263354>] expire_timers+0x234/0x580 kernel/time/timer.c:1359
 [<ffffffff81263aa5>] __run_timers kernel/time/timer.c:1674 [inline]
 [<ffffffff81263aa5>] run_timer_softirq+0x405/0x5e0 kernel/time/timer.c:1689
 [<ffffffff8281dfde>] __do_softirq+0x20e/0x964 kernel/softirq.c:288
 [<ffffffff810efe4c>] invoke_softirq kernel/softirq.c:368 [inline]
 [<ffffffff810efe4c>] irq_exit+0x11c/0x150 kernel/softirq.c:409
 [<ffffffff8281cbb1>] exiting_irq arch/x86/include/asm/apic.h:669 [inline]
 [<ffffffff8281cbb1>] smp_apic_timer_interrupt+0x81/0xb0 arch/x86/kernel/apic/apic.c:962
 [<ffffffff8281a46d>] 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 
cfd 
c78 
cff 
ceb 
cc2 
ce8 
c31 
cfe 
c78 
cff 
ceb 
c