random: crng init done
INFO: task syz-executor116:4100 blocked for more than 120 seconds.
      Not tainted 4.9.103-g0cecdf8 #35
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor116 D29128  4100   3816 0x00000004
 ffff8801d7663000 0000000000000000 ffff8801d7446f40 ffff8801cff98000
 ffff8801db221c18 ffff8801d734f8b8 ffffffff839e711d ffff8801d76638c8
 ffffed003aecc718 ffff8801d7663000 00fffc0000000000 ffff8801db2224e8
Call Trace:
 [<ffffffff839e871f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839e90a3>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3590
 [<ffffffff839ed526>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff839ed526>] mutex_lock_nested+0x326/0x870 kernel/locking/mutex.c:621
 [<ffffffff82124a7d>] flush_echoes drivers/tty/n_tty.c:799 [inline]
 [<ffffffff82124a7d>] __receive_buf drivers/tty/n_tty.c:1617 [inline]
 [<ffffffff82124a7d>] n_tty_receive_buf_common+0xcfd/0x2300 drivers/tty/n_tty.c:1711
 [<ffffffff821260f0>] n_tty_receive_buf+0x30/0x40 drivers/tty/n_tty.c:1740
 [<ffffffff8211650f>] tiocsti drivers/tty/tty_io.c:2314 [inline]
 [<ffffffff8211650f>] tty_ioctl+0xc8f/0x2270 drivers/tty/tty_io.c:2905
 [<ffffffff815b27cc>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff815b27cc>] file_ioctl fs/ioctl.c:493 [inline]
 [<ffffffff815b27cc>] do_vfs_ioctl+0x1ac/0x11a0 fs/ioctl.c:677
 [<ffffffff815b384f>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff815b384f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f8013>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/519:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136688c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136688c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81425e10>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3686:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f61c2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211f1d2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
3 locks held by syz-executor116/4100:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f61c2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&o_tty->termios_rwsem/1){++++..}, at: [<ffffffff82123e0b>] n_tty_receive_buf_common+0x8b/0x2300 drivers/tty/n_tty.c:1674
 #2:  (&ldata->output_lock){+.+...}, at: [<ffffffff82124a7d>] flush_echoes drivers/tty/n_tty.c:799 [inline]
 #2:  (&ldata->output_lock){+.+...}, at: [<ffffffff82124a7d>] __receive_buf drivers/tty/n_tty.c:1617 [inline]
 #2:  (&ldata->output_lock){+.+...}, at: [<ffffffff82124a7d>] n_tty_receive_buf_common+0xcfd/0x2300 drivers/tty/n_tty.c:1711

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 519 Comm: khungtaskd Not tainted 4.9.103-g0cecdf8 #35
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8677d08 ffffffff81eb34a9 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b9590 ffff8801d8677d40
 ffffffff81ebe7a7 0000000000000001 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb34a9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb34a9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebe7a7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebe73a>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b9694>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366e24>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366e24>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366e24>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366e24>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119cead>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f81dc>] 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: 104 Comm: kworker/u4:2 Not tainted 4.9.103-g0cecdf8 #35
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound flush_to_ldisc
c
task: ffff8801d96f1800 task.stack: ffff8801d9790000
RIP: 0010:[<ffffffff8211b0c1>] 
c [<ffffffff8211b0c1>] echo_buf drivers/tty/n_tty.c:146 [inline]
RIP: 0010:[<ffffffff8211b0c1>] 
c [<ffffffff8211b0c1>] __process_echoes+0x611/0x780 drivers/tty/n_tty.c:735
RSP: 0018:ffff8801d97979d8  EFLAGS: 00000293
RAX: ffff8801d96f1800 RBX: ffffc90000be1000 RCX: 0000000000000006
RDX: 0000000000000000 RSI: ffffffff8211b0c1 RDI: ffffc90000be308e
RBP: ffff8801d9797a40 R08: ffff8801d96f21b0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000a6e938e2e
R13: 0000000000003214 R14: dffffc0000000000 R15: 0000000a6e938e2f
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000001dd3b10 CR3: 00000001d8a1c000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801d9797a18
c 0000000000000000
c ffffc90000be3278
c ffffed00396dd7e5
c
 ffff8801cb6ebf2c
c ffffc90000be1020
c 0000000100000cff
c ffff8801cb6ebb80
c
 ffffc90000be3300
c ffffc90000be1000
c dffffc0000000000
c ffffc90000be1020
c
Call Trace:
 [<ffffffff82124ab4>] flush_echoes drivers/tty/n_tty.c:801 [inline]
 [<ffffffff82124ab4>] __receive_buf drivers/tty/n_tty.c:1617 [inline]
 [<ffffffff82124ab4>] n_tty_receive_buf_common+0xd34/0x2300 drivers/tty/n_tty.c:1711
 [<ffffffff821260b3>] n_tty_receive_buf2+0x33/0x40 drivers/tty/n_tty.c:1746
 [<ffffffff8212bbaf>] tty_ldisc_receive_buf+0xaf/0x190 drivers/tty/tty_buffer.c:455
 [<ffffffff8212cbb3>] receive_buf drivers/tty/tty_buffer.c:474 [inline]
 [<ffffffff8212cbb3>] flush_to_ldisc+0x253/0x370 drivers/tty/tty_buffer.c:533
 [<ffffffff8118cf81>] process_one_work+0x7e1/0x1500 kernel/workqueue.c:2092
 [<ffffffff8118dd76>] worker_thread+0xd6/0x10a0 kernel/workqueue.c:2226
 [<ffffffff8119cead>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f81dc>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Code: 
cc1 
cea 
c03 
c83 
ce1 
c07 
c42 
c0f 
cb6 
c14 
c32 
c38 
cca 
c7f 
c08 
c84 
cd2 
c0f 
c85 
cb0 
c00 
c00 
c00 
c80 
cbc 
c03 
c60 
c12 
c00 
c00 
cff 
c4d 
c8d 
c7c 
c24 
c01 
c75 
ca4 
ce8 
cdf 
c3a 
c24 
cff 
c<41> 
c81 
ce7 
cff 
c0f 
c00 
c00 
c4a 
c8d 
cbc 
c3b 
c60 
c12 
c00 
c00 
c48 
c89 
cf8 
c48 
c89 
cfa 
c