INFO: task syz-executor.4:5956 blocked for more than 140 seconds.
      Not tainted 4.9.141+ #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4  D27096  5956   2116 0x00000000
 ffff8801c85a5f00 0000000000000000 ffff8801a70a6880 ffff8801a3ca2f80
 ffff8801db621018 ffff8801d7857b48 ffffffff828075c2 0000000000000286
 0000000000000002 0000000041b58ab3 00ffffff82e2b9d2 ffff8801db6218f0
Call Trace:
 [<ffffffff82808aef>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff815a17c9>] wb_wait_for_completion+0x149/0x1b0 fs/fs-writeback.c:221
 [<ffffffff815a1f6b>] sync_inodes_sb+0x1ab/0x9d0 fs/fs-writeback.c:2412
 [<ffffffff815b1653>] sync_inodes_one_sb+0x43/0x60 fs/sync.c:73
 [<ffffffff81515040>] iterate_supers+0x130/0x260 fs/super.c:593
 [<ffffffff815b1f62>] sys_sync+0xa2/0x170 fs/sync.c:112
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff82817893>] 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: [<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
1 lock held by rsyslogd/1908:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff8156cc7c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/2035:
 #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
4 locks held by kworker/u4:11/3774:
 #0:  ("writeback"){++++.+}, at: [<ffffffff81130f0c>] process_one_work+0x73c/0x15f0 kernel/workqueue.c:2085
 #1:  ((&(&wb->dwork)->work)){+.+.+.}, at: [<ffffffff81130f44>] process_one_work+0x774/0x15f0 kernel/workqueue.c:2089
 #2:  (&type->s_umount_key#32){++++.+}, at: [<ffffffff815149f0>] trylock_super+0x20/0xf0 fs/super.c:393
 #3:  (&sbi->s_journal_flag_rwsem){.+.+.+}, at: [<ffffffff81433d3f>] do_writepages+0xef/0x1d0 mm/page-writeback.c:2331
1 lock held by syz-executor.4/5956:
 #0:  (&type->s_umount_key#32){++++.+}, at: [<ffffffff81514ff1>] iterate_supers+0xe1/0x260 fs/super.c:591
1 lock held by syz-executor.3/11539:
 #0:  (&sbi->s_journal_flag_rwsem){.+.+.+}, at: [<ffffffff81433d3f>] do_writepages+0xef/0x1d0 mm/page-writeback.c:2331

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

NMI backtrace for cpu 1
CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.141+ #1
 ffff8801d9907d08 ffffffff81b42e79 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810983b0 ffff8801d9907d40
 ffffffff81b4df89 0000000000000001 0000000000000000 0000000000000002
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: 9794 Comm: syz-executor.5 Not tainted 4.9.141+ #1
task: ffff8801c6c9df00 task.stack: ffff8801d3bc8000
RIP: 0010:[<ffffffff812e6a20>] 
c [<ffffffff812e6a20>] make_kuid+0x0/0x180 kernel/user_namespace.c:286
RSP: 0018:ffff8801d3bcfcd0  EFLAGS: 00000246
RAX: 0000000000000007 RBX: ffff8801085d2448 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8309a140
RBP: ffff8801d3bcfd00 R08: 000000000000000c R09: ffff8801d3bcfa58
R10: ffffffff81560ae7 R11: ffff8801d3bcf9f7 R12: ffff8801d9659100
R13: ffff8801085d2640 R14: ffff8801085d2470 R15: ffffffff8309a140
FS:  00007f5ad60e9700(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000007fa000 CR3: 00000001d4bf9000 CR4: 00000000001606b0
Stack:
 ffffffff8155f594
c ffff8801d9659100
c ffff8801085d2448
c 00000000ffffffe9
c
 ffff8801d3bcfe98
c 0000000000000000
c ffff8801d3bcfd20
c ffffffff81560ac0
c
 ffff8801d9659100
c dffffc0000000000
c ffff8801d3bcfd40
c ffffffff81566557
c
Call Trace:
 [<ffffffff81560ac0>] alloc_inode+0x80/0x180 fs/inode.c:214
 [<ffffffff81566557>] new_inode_pseudo+0x17/0xe0 fs/inode.c:890
 [<ffffffff8152752c>] get_pipe_inode fs/pipe.c:703 [inline]
 [<ffffffff8152752c>] create_pipe_files+0x9c/0x880 fs/pipe.c:744
 [<ffffffff81527d45>] __do_pipe_flags+0x35/0x210 fs/pipe.c:802
 [<ffffffff81528111>] SYSC_pipe2 fs/pipe.c:850 [inline]
 [<ffffffff81528111>] SyS_pipe2+0x91/0x190 fs/pipe.c:844
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff82817893>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
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c