INFO: task syz-executor6:4166 blocked for more than 120 seconds.
      Not tainted 4.4.107-g610c835 #4
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor6   D ffff8800b9cdf748 27192  4166   3569 0x20020004
 ffff8800b9cdf748 dffffc0000000000 ffff8801d8270870 ffff8800b9cdf728
 ffffffff8123364f ffff8801d8270800 ffff8801db21f878 ffff8801db21f8a0
 ffff8801db21ef98 ffff8801d83dc740 ffff8801d8270000 ffff8800b9cd8000
Call Trace:
 [<ffffffff83765d3a>] schedule+0x9a/0x1c0 kernel/sched/core.c:3351
 [<ffffffff8376ffef>] rwsem_down_read_failed+0x1bf/0x300 kernel/locking/rwsem-xadd.c:250
 [<ffffffff81d34e44>] call_rwsem_down_read_failed+0x14/0x30 arch/x86/lib/rwsem.S:90
 [<ffffffff81f58d33>] n_tty_read+0x233/0x1cd0 drivers/tty/n_tty.c:2184
 [<ffffffff81f46b98>] tty_read+0x158/0x240 drivers/tty/tty_io.c:1071
 [<ffffffff8151b341>] do_loop_readv_writev+0x141/0x1e0 fs/read_write.c:680
 [<ffffffff8151dedf>] compat_do_readv_writev+0x5df/0x6e0 fs/read_write.c:984
 [<ffffffff8151e0b9>] compat_readv+0xd9/0x140 fs/read_write.c:1013
 [<ffffffff81520448>] C_SYSC_readv fs/read_write.c:1033 [inline]
 [<ffffffff81520448>] compat_SyS_readv+0xd8/0x1b0 fs/read_write.c:1022
 [<ffffffff81006d84>] do_syscall_32_irqs_on arch/x86/entry/common.c:390 [inline]
 [<ffffffff81006d84>] do_fast_syscall_32+0x314/0x890 arch/x86/entry/common.c:457
 [<ffffffff837754d7>] sysenter_flags_fixed+0xd/0x17
3 locks held by syz-executor6/4166:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff81f5e9ab>] tty_ldisc_ref_wait+0x2b/0xc0 drivers/tty/tty_ldisc.c:264
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff81f58d10>] n_tty_read+0x210/0x1cd0 drivers/tty/n_tty.c:2180
 #2:  (&o_tty->termios_rwsem/1){++++.+}, at: [<ffffffff81f58d33>] n_tty_read+0x233/0x1cd0 drivers/tty/n_tty.c:2184
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 485 Comm: khungtaskd Not tainted 4.4.107-g610c835 #4
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800bac95f00 task.stack: ffff8800bac20000
RIP: 0010:[<ffffffff810c32e7>]  [<ffffffff810c32e7>] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline]
RIP: 0010:[<ffffffff810c32e7>]  [<ffffffff810c32e7>] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline]
RIP: 0010:[<ffffffff810c32e7>]  [<ffffffff810c32e7>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline]
RIP: 0010:[<ffffffff810c32e7>]  [<ffffffff810c32e7>] flat_send_IPI_mask+0xf7/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8800bac27cb8  EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8800bac27ce0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000000000003 R14: ffffffff8426abe0 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fef1fabd9b8 CR3: 00000000b7754000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8426abe0 ffffffff847e8600 00000000000194a0 0000000000000040
 dffffc0000000000 ffff8800bac27d00 ffffffff810b8e1b ffffffff839f53e0
 0000000000000003 ffff8800bac27d60 ffffffff81d0f4d7 ffffffff81417c73
Call Trace:
 [<ffffffff810b8e1b>] nmi_raise_cpu_backtrace+0x5b/0x70 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81d0f4d7>] nmi_trigger_all_cpu_backtrace+0x4a7/0x550 lib/nmi_backtrace.c:85
 [<ffffffff810b8eb4>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 [<ffffffff81365a7a>] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline]
 [<ffffffff81365a7a>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81365a7a>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81365a7a>] watchdog+0x6fa/0xae0 kernel/hung_task.c:238
 [<ffffffff8118dea8>] kthread+0x268/0x300 kernel/kthread.c:211
 [<ffffffff837740ef>] ret_from_fork+0x3f/0x70 arch/x86/entry/entry_64.S:468
Code: b3 5f ff f6 c4 10 75 e1 44 89 e8 c1 e0 18 89 04 25 10 b3 5f ff 44 89 fa 09 da 80 cf 04 41 83 ff 02 0f 44 d3 89 14 25 00 b3 5f ff <41> f7 c4 00 02 00 00 74 1a e8 3b 09 17 00 4c 89 e7 57 9d 0f 1f 
NMI backtrace for cpu 1
CPU: 1 PID: 3163 Comm: rsyslogd Not tainted 4.4.107-g610c835 #4
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d3f95f00 task.stack: ffff8801d35f8000
RIP: 0010:[<ffffffff81189291>]  [<ffffffff81189291>] __kernel_text_address+0x91/0xa0 kernel/extable.c:118
RSP: 0018:ffff8801d35ff7c8  EFLAGS: 00000287
RAX: ffff8801d35ffff8 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000002 RSI: ffffffff81003044 RDI: ffffffff83773d36
RBP: ffff8801d35ff818 R08: ffff8801d35ff8c8 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801d35fff48
R13: ffffffffffff8000 R14: ffff8801d35fff50 R15: ffffffff83773d36
FS:  00007f84834fc700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff512f3fbbd CR3: 00000000b7754000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff81017a08 ffff8801d35f8000 ffff8801d35fff48 ffff8801d35ff8c8
 ffffffff83810a40 0000000000000000 ffffffff83810a40 ffff8801d35ff8c8
 0000000000013ea0 ffff8801d35ff868 ffff8801d35ff8a0 ffffffff81016be2
Call Trace:
 [<ffffffff81016be2>] dump_trace+0x142/0x350 arch/x86/kernel/dumpstack_64.c:243
 [<ffffffff81035c86>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814fab93>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814fae5d>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814fae5d>] kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:616
 [<ffffffff814f6dd0>] kmem_cache_alloc_trace+0x100/0x2b0 mm/slub.c:2642
 [<ffffffff81265ccf>] kmalloc include/linux/slab.h:476 [inline]
 [<ffffffff81265ccf>] syslog_print kernel/printk/printk.c:1148 [inline]
 [<ffffffff81265ccf>] do_syslog+0x60f/0xae0 kernel/printk/printk.c:1331
 [<ffffffff8168e3d4>] kmsg_read+0x74/0xa0 fs/proc/kmsg.c:39
 [<ffffffff816651ff>] proc_reg_read+0xef/0x170 fs/proc/inode.c:202
 [<ffffffff8151aa73>] __vfs_read+0x103/0x440 fs/read_write.c:432
 [<ffffffff8151c913>] vfs_read+0x123/0x3a0 fs/read_write.c:454
 [<ffffffff8151f259>] SYSC_read fs/read_write.c:569 [inline]
 [<ffffffff8151f259>] SyS_read+0xd9/0x1b0 fs/read_write.c:562
 [<ffffffff83773d36>] entry_SYSCALL_64_fastpath+0x16/0x76
Code: e8 e5 c7 16 00 84 c0 75 1a 31 c0 48 81 fb 00 90 81 84 72 14 31 c0 48 81 fb 4f ea 8f 84 5b 0f 92 c0 5d c3 b8 01 00 00 00 5b 5d c3 <b8> 01 00 00 00 c3 e8 c4 2e 37 00 eb a9 66 90 48 81 ff b8 02 00