INFO: task syz-executor1:22547 blocked for more than 140 seconds.
      Not tainted 4.9.117-g8b21e85 #19
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor1   D28136 22547   3872 0x00000004
 ffff8801d088c800 0000000000000000 ffff8801bbc12f40 ffff8801d9a6b000
 ffff8801db321c18 ffff8801cb697ae8 ffffffff839ebd0d ffffffff81235687
 0000000000000000 ffff8801d088d0c0 0000000600000007 ffff8801db3224e8
Call Trace:
 [<ffffffff839ed30f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff839f8948>] __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:526 [inline]
 [<ffffffff839f8948>] rwsem_down_write_failed+0x598/0x990 kernel/locking/rwsem-xadd.c:555
 [<ffffffff81ee8ec7>] call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 [<ffffffff839f671c>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
 [<ffffffff839f671c>] down_write+0x5c/0xa0 kernel/locking/rwsem.c:54
 [<ffffffff815691d1>] inode_lock include/linux/fs.h:766 [inline]
 [<ffffffff815691d1>] chmod_common+0x171/0x450 fs/open.c:543
 [<ffffffff8156ce73>] SYSC_fchmod fs/open.c:568 [inline]
 [<ffffffff8156ce73>] SyS_fchmod+0xb3/0x110 fs/open.c:561
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839fcc13>] 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: [<ffffffff813667fc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813667fc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81426017>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3753:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839fadb2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff821207f2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor1/22494:
 #0:  (sb_writers#20){.+.+.+}, at: [<ffffffff815e0e3f>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#20){.+.+.+}, at: [<ffffffff815e0e3f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#27){++++++}, at: [<ffffffff815691d1>] inode_lock include/linux/fs.h:766 [inline]
 #1:  (&sb->s_type->i_mutex_key#27){++++++}, at: [<ffffffff815691d1>] chmod_common+0x171/0x450 fs/open.c:543
2 locks held by syz-executor1/22547:
 #0:  (sb_writers#20){.+.+.+}, at: [<ffffffff815e0e3f>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#20){.+.+.+}, at: [<ffffffff815e0e3f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#27){++++++}, at: [<ffffffff815691d1>] inode_lock include/linux/fs.h:766 [inline]
 #1:  (&sb->s_type->i_mutex_key#27){++++++}, at: [<ffffffff815691d1>] chmod_common+0x171/0x450 fs/open.c:543
1 lock held by syz-executor1/22549:
 #0:  (sb_writers#20){.+.+.+}, at: [<ffffffff815e0e3f>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#20){.+.+.+}, at: [<ffffffff815e0e3f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
2 locks held by syz-executor1/22550:
 #0:  (sb_writers#20){.+.+.+}, at: [<ffffffff815e0fc8>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#20){.+.+.+}, at: [<ffffffff815e0fc8>] mnt_want_write_file+0x68/0x110 fs/namespace.c:449
 #1:  (&sb->s_type->i_mutex_key#27){++++++}, at: [<ffffffff815f0069>] inode_lock include/linux/fs.h:766 [inline]
 #1:  (&sb->s_type->i_mutex_key#27){++++++}, at: [<ffffffff815f0069>] vfs_removexattr+0x79/0x1a0 fs/xattr.c:392

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

NMI backtrace for cpu 1
CPU: 1 PID: 519 Comm: khungtaskd Not tainted 4.9.117-g8b21e85 #19
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d84dfd08 ffffffff81eb4be9 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b9bd0 ffff8801d84dfd40
 ffffffff81ebfee7 0000000000000001 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb4be9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb4be9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebfee7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebfe7a>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b9cd4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366d94>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366d94>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366d94>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366d94>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d0ed>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839fcddc>] 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 skipped: idling at pc 0xffffffff839fb816