INFO: task syz-executor0:6895 blocked for more than 140 seconds.
      Not tainted 4.9.112-g9e79039 #7
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D28440  6895   3867 0x00000004
 ffff8801d8e31800 ffff8801d85b8540 ffff8801b583f480 ffff8801c97d4800
 ffff8801db321c18 ffff88019aba7898 ffffffff839e907d ffffffff81235667
 0000000000000000 ffff8801d8e320c0 0000000600000007 ffff8801db3224e8
Call Trace:
 [<ffffffff839ea67f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839f5cb8>] __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:526 [inline]
 [<ffffffff839f5cb8>] rwsem_down_write_failed+0x598/0x990 kernel/locking/rwsem-xadd.c:555
 [<ffffffff81ee7527>] call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 [<ffffffff8122c290>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
 [<ffffffff8122c290>] down_write_nested+0x60/0xa0 kernel/locking/rwsem.c:174
 [<ffffffff815cc288>] inode_lock_nested include/linux/fs.h:801 [inline]
 [<ffffffff815cc288>] lock_two_nondirectories+0xb8/0xf0 fs/inode.c:983
 [<ffffffff81596b3a>] vfs_rename2+0x42a/0x18f0 fs/namei.c:4473
 [<ffffffff815af282>] SYSC_renameat2 fs/namei.c:4657 [inline]
 [<ffffffff815af282>] SyS_renameat2 fs/namei.c:4546 [inline]
 [<ffffffff815af282>] SYSC_rename fs/namei.c:4697 [inline]
 [<ffffffff815af282>] SyS_rename+0x612/0x800 fs/namei.c:4695
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f9f53>] 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: [<ffffffff8136675c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136675c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81425de7>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3777:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f8122>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211edc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
3 locks held by syz-executor0/6895:
 #0:  (sb_writers#10){.+.+.+}, at: [<ffffffff815e0a2f>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#10){.+.+.+}, at: [<ffffffff815e0a2f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#14/1){+.+.+.}, at: [<ffffffff815940f6>] inode_lock_nested include/linux/fs.h:801 [inline]
 #1:  (&sb->s_type->i_mutex_key#14/1){+.+.+.}, at: [<ffffffff815940f6>] lock_rename+0x236/0x290 fs/namei.c:2857
 #2:  (&sb->s_type->i_mutex_key#14/4){+.+...}, at: [<ffffffff815cc288>] inode_lock_nested include/linux/fs.h:801 [inline]
 #2:  (&sb->s_type->i_mutex_key#14/4){+.+...}, at: [<ffffffff815cc288>] lock_two_nondirectories+0xb8/0xf0 fs/inode.c:983
2 locks held by syz-executor0/6905:
 #0:  (sb_writers#10){.+.+.+}, at: [<ffffffff815e0a2f>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#10){.+.+.+}, at: [<ffffffff815e0a2f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#14){++++++}, at: [<ffffffff815a4df5>] inode_lock include/linux/fs.h:766 [inline]
 #1:  (&sb->s_type->i_mutex_key#14){++++++}, at: [<ffffffff815a4df5>] do_last fs/namei.c:3312 [inline]
 #1:  (&sb->s_type->i_mutex_key#14){++++++}, at: [<ffffffff815a4df5>] path_openat+0xed5/0x3590 fs/namei.c:3534
1 lock held by syz-executor0/6946:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d818c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by syz-executor0/6967:
 #0:  (sb_writers#10){.+.+.+}, at: [<ffffffff815e0a2f>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#10){.+.+.+}, at: [<ffffffff815e0a2f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#14/1){+.+.+.}, at: [<ffffffff815940f6>] inode_lock_nested include/linux/fs.h:801 [inline]
 #1:  (&sb->s_type->i_mutex_key#14/1){+.+.+.}, at: [<ffffffff815940f6>] lock_rename+0x236/0x290 fs/namei.c:2857

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

NMI backtrace for cpu 1
CPU: 1 PID: 519 Comm: khungtaskd Not tainted 4.9.112-g9e79039 #7
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8607d08 ffffffff81eb3249 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b9bd0 ffff8801d8607d40
 ffffffff81ebe547 0000000000000001 0000000000000000 0000000000000002
Call Trace:
 [<ffffffff81eb3249>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb3249>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebe547>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebe4da>] 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
 [<ffffffff81366cf4>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366cf4>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366cf4>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366cf4>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d0bd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839fa11c>] 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: 1702 Comm: kworker/u4:3 Not tainted 4.9.112-g9e79039 #7
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: writeback wb_workfn
c (flush-7:0)
c
task: ffff8801cf5d3000 task.stack: ffff8801cf788000
RIP: 0010:[<ffffffff81f1ac82>] 
c [<ffffffff81f1ac82>] check_preemption_disabled+0x12/0x170 lib/smp_processor_id.c:12
RSP: 0018:ffff8801cf78f548  EFLAGS: 00000093
RAX: ffff8801cf5d3000 RBX: ffffffff83cce7a0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff83cce7a0 RDI: ffffffff83e2de20
RBP: ffff8801cf78f568 R08: ffff8801cf5d3960 R09: 0000000000000001
R10: 0000000000000000 R11: 1ffff10039eba727 R12: ffffffff83e2de20
R13: ffffffff83cce7a0 R14: ffff8801b67859d8 R15: 0000000000000004
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f70a0735518 CR3: 00000001cb4ee000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801b67859d8
c dffffc0000000000
c ffff8801b67859d8
c 0000000000000004
c
 ffff8801cf78f580
c ffffffff81f1ae1c
c 0000000000000004
c ffff8801cf78f5d0
c
 ffffffff81624365
c 0000020007001e00
c 0000000000000041
c ffff8801d61c8b80
c
Call Trace:
 [<ffffffff81f1ae1c>] __this_cpu_preempt_check+0x1c/0x20 lib/smp_processor_id.c:62
 [<ffffffff81624365>] lookup_bh_lru fs/buffer.c:1327 [inline]
 [<ffffffff81624365>] __find_get_block+0x75/0x4c0 fs/buffer.c:1356
 [<ffffffff81625339>] __getblk_slow fs/buffer.c:1101 [inline]
 [<ffffffff81625339>] __getblk_gfp+0x189/0x710 fs/buffer.c:1386
 [<ffffffff81628cdd>] __bread_gfp+0x2d/0x270 fs/buffer.c:1420
 [<ffffffff818cc5db>] sb_bread include/linux/buffer_head.h:300 [inline]
 [<ffffffff818cc5db>] __fat_write_inode+0x2ab/0x980 fs/fat/inode.c:844
 [<ffffffff818d07e9>] fat_write_inode+0x79/0x170 fs/fat/inode.c:893
 [<ffffffff8160232d>] write_inode fs/fs-writeback.c:1180 [inline]
 [<ffffffff8160232d>] __writeback_single_inode+0x86d/0x1020 fs/fs-writeback.c:1379
 [<ffffffff8160362c>] writeback_sb_inodes+0x4ac/0xe70 fs/fs-writeback.c:1584
 [<ffffffff816040eb>] __writeback_inodes_wb+0xfb/0x1e0 fs/fs-writeback.c:1653
 [<ffffffff81604872>] wb_writeback+0x512/0xbd0 fs/fs-writeback.c:1762
 [<ffffffff8160e073>] wb_check_background_flush fs/fs-writeback.c:1843 [inline]
 [<ffffffff8160e073>] wb_do_writeback fs/fs-writeback.c:1902 [inline]
 [<ffffffff8160e073>] wb_workfn+0x723/0xdb0 fs/fs-writeback.c:1930
 [<ffffffff8118d191>] process_one_work+0x7e1/0x1500 kernel/workqueue.c:2092
 [<ffffffff8118df86>] worker_thread+0xd6/0x10a0 kernel/workqueue.c:2226
 [<ffffffff8119d0bd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839fa11c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Code: 
cff 
cff 
c48 
c8b 
c85 
ce0 
cfe 
cff 
cff 
ce9 
ce0 
cf3 
cff 
cff 
c66 
c2e 
c0f 
c1f 
c84 
c00 
c00 
c00 
c00 
c00 
c90 
c55 
c48 
c89 
ce5 
c41 
c57 
c41 
c56 
c41 
c55 
c49 
c89 
cf5 
c41 
c54 
c49 
c89 
cfc 
c<53> 
c48 
c83 
cec 
c08 
ce8 
ce4 
c3d 
c44 
cff 
c65 
c8b 
c1d 
c95 
cb4 
c0f 
c7e 
c65 
c8b 
c05 
cb6 
c