INFO: task syz-executor.1:9753 blocked for more than 140 seconds.
      Not tainted 4.9.141+ #23
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.1  D29608  9753   2099 0x20020000
 ffff8801d2c95f00 ffff8801d3239080 ffff8801d3986300 ffff8801a2122f80
 ffff8801db721018 ffff88019c3e7940 ffffffff828075c2 0000000000000286
 ffffffff83ce87e0 2948fd9158c5c1fc 0000000000004afb ffff8801db7218f0
Call Trace:
 [<ffffffff82808aef>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff828142d5>] schedule_timeout+0x735/0xe20 kernel/time/timer.c:1771
 [<ffffffff81d4312c>] down_read_failed drivers/tty/tty_ldsem.c:241 [inline]
 [<ffffffff81d4312c>] __ldsem_down_read_nested+0x33c/0x610 drivers/tty/tty_ldsem.c:332
 [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 [<ffffffff81d3ca85>] tty_ldisc_ref_wait+0x25/0x80 drivers/tty/tty_ldisc.c:275
 [<ffffffff81d221ca>] tty_read+0xfa/0x270 drivers/tty/tty_io.c:1084
 [<ffffffff81507b25>] __vfs_read+0x115/0x560 fs/read_write.c:449
 [<ffffffff8150a7a4>] vfs_read+0x124/0x390 fs/read_write.c:472
 [<ffffffff8150e809>] SYSC_read fs/read_write.c:588 [inline]
 [<ffffffff8150e809>] SyS_read+0xd9/0x1c0 fs/read_write.c:581
 [<ffffffff81006311>] do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline]
 [<ffffffff81006311>] do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390
 [<ffffffff82818de0>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137

Showing all locks held in the system:
2 locks held by khungtaskd/24:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131c0cc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131c0cc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff813fe63f>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/2024:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d37362>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor.1/9745:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d37362>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor.1/9753:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor.1/13740:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d37362>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor.2/24643:
 #0:  (&sb->s_type->i_mutex_key#8){+.+.+.}, at: [<ffffffff8229bd8b>] inode_lock include/linux/fs.h:766 [inline]
 #0:  (&sb->s_type->i_mutex_key#8){+.+.+.}, at: [<ffffffff8229bd8b>] __sock_release+0x8b/0x260 net/socket.c:604
1 lock held by syz-executor.2/24688:
 #0:  (&sb->s_type->i_mutex_key#8){+.+.+.}, at: [<ffffffff8229bd8b>] inode_lock include/linux/fs.h:766 [inline]
 #0:  (&sb->s_type->i_mutex_key#8){+.+.+.}, at: [<ffffffff8229bd8b>] __sock_release+0x8b/0x260 net/socket.c:604
1 lock held by syz-executor.0/24682:
 #0:  (&sb->s_type->i_mutex_key#8){+.+.+.}, at: [<ffffffff8229bd8b>] inode_lock include/linux/fs.h:766 [inline]
 #0:  (&sb->s_type->i_mutex_key#8){+.+.+.}, at: [<ffffffff8229bd8b>] __sock_release+0x8b/0x260 net/socket.c:604
1 lock held by syz-executor.4/24706:
 #0:  (&pipe->mutex/1){+.+.+.}, at: [<ffffffff81524a93>] pipe_lock_nested fs/pipe.c:66 [inline]
 #0:  (&pipe->mutex/1){+.+.+.}, at: [<ffffffff81524a93>] pipe_lock fs/pipe.c:74 [inline]
 #0:  (&pipe->mutex/1){+.+.+.}, at: [<ffffffff81524a93>] pipe_wait+0x1a3/0x1d0 fs/pipe.c:122

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

NMI backtrace for cpu 1
CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.141+ #23
 ffff8801d9907d08 ffffffff81b42e79 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810983b0 ffff8801d9907d40
 ffffffff81b4df89 0000000000000001 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81b42e79>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b42e79>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81b4df89>] nmi_cpu_backtrace.cold.0+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81b4df1c>] nmi_trigger_cpumask_backtrace+0x12c/0x151 lib/nmi_backtrace.c:60
 [<ffffffff810984b4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff8131c65d>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff8131c65d>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8131c65d>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8131c65d>] watchdog+0x6ad/0xa20 kernel/hung_task.c:239
 [<ffffffff81142c3d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff82817a5c>] 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: 24714 Comm: syz-executor.4 Not tainted 4.9.141+ #23
task: ffff880179362f80 task.stack: ffff880170028000
RIP: 0010:[<ffffffff81202cff>] 
c [<ffffffff81202cff>] arch_local_irq_restore arch/x86/include/asm/paravirt.h:768 [inline]
RIP: 0010:[<ffffffff81202cff>] 
c [<ffffffff81202cff>] lock_is_held+0xff/0x140 kernel/locking/lockdep.c:3796
RSP: 0018:ffff88017002f468  EFLAGS: 00000246
RAX: 0000000000000007 RBX: 0000000000000246 RCX: 1ffff1002f26c705
RDX: 0000000000000000 RSI: ffffffff81ba7d7b RDI: 0000000000000246
RBP: ffff88017002f480 R08: ffff880179363850 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000001 R12: ffff880179362f80
R13: 0000000000000000 R14: ffff88016c5463c0 R15: ffff88017002f570
FS:  0000000000000000(0000) GS:ffff8801db600000(0063) knlGS:00000000f5597b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f54e9ecc CR3: 000000018093f000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 0000000000000003
c ffff880175b49100
c ffff8801cfc005d8
c ffff88017002f498
c
 ffffffff81243e83
c ffff88016c5463c0
c ffff88017002f4c8
c ffffffff822bb05e
c
 ffff8801cfc00000
c ffff880175b49100
c ffff8801cfc005d8
c ffff88016c5463c0
c
Call Trace:
 [<ffffffff81243e83>] rcu_read_lock_sched_held+0x103/0x120 kernel/rcu/update.c:112
 [<ffffffff822bb05e>] trace_consume_skb include/trace/events/skb.h:36 [inline]
 [<ffffffff822bb05e>] consume_skb+0x27e/0x340 net/core/skbuff.c:756
 [<ffffffff823d4480>] netlink_unicast_kernel net/netlink/af_netlink.c:1286 [inline]
 [<ffffffff823d4480>] netlink_unicast+0x4e0/0x6d0 net/netlink/af_netlink.c:1311
 [<ffffffff823d4e44>] netlink_sendmsg+0x694/0xc30 net/netlink/af_netlink.c:1859
 [<ffffffff822a063b>] sock_sendmsg_nosec net/socket.c:648 [inline]
 [<ffffffff822a063b>] sock_sendmsg+0xbb/0x110 net/socket.c:658
 [<ffffffff822a0a83>] kernel_sendmsg+0x43/0x50 net/socket.c:666
 [<ffffffff822ab2c2>] sock_no_sendpage+0x112/0x150 net/core/sock.c:2334
 [<ffffffff822a0313>] kernel_sendpage+0x93/0xf0 net/socket.c:3334
 [<ffffffff822a03fc>] sock_sendpage+0x8c/0xc0 net/socket.c:802
 [<ffffffff815a98c6>] pipe_to_sendpage+0x266/0x330 fs/splice.c:470
 [<ffffffff815ad926>] splice_from_pipe_feed fs/splice.c:521 [inline]
 [<ffffffff815ad926>] __splice_from_pipe+0x316/0x710 fs/splice.c:645
 [<ffffffff815af439>] splice_from_pipe+0xf9/0x170 fs/splice.c:680
 [<ffffffff815af4ec>] generic_splice_sendpage+0x3c/0x50 fs/splice.c:851
 [<ffffffff815a9ab8>] do_splice_from fs/splice.c:870 [inline]
 [<ffffffff815a9ab8>] direct_splice_actor+0x128/0x190 fs/splice.c:1037
 [<ffffffff815ab6c1>] splice_direct_to_actor+0x2c1/0x7e0 fs/splice.c:992
 [<ffffffff815abd83>] do_splice_direct+0x1a3/0x270 fs/splice.c:1080
 [<ffffffff8150d780>] do_sendfile+0x4f0/0xc30 fs/read_write.c:1393
 [<ffffffff8150f9c3>] C_SYSC_sendfile fs/read_write.c:1475 [inline]
 [<ffffffff8150f9c3>] compat_SyS_sendfile+0x143/0x160 fs/read_write.c:1458
 [<ffffffff81006311>] do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline]
 [<ffffffff81006311>] do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390
 [<ffffffff82818de0>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137
Code: 
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c