INFO: task kworker/u4:10:7248 blocked for more than 140 seconds.
      Not tainted 4.9.135+ #59
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:10   D25208  7248      2 0x80000000
Workqueue: writeback wb_workfn (flush-8:0)
 ffff8801a2590000 0000000000000000 ffff8801cf264200 ffff8801d5cadf00
 ffff8801db621018 ffff8801d9def120 ffffffff827f3192 ffff8801d9def0f8
 ffffffff81206ab7 ffff8801d9def0b8 00ff8801d9def0b8 ffff8801db6218f0
Call Trace:
 [<ffffffff827f46bf>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff827fe47a>] __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:526 [inline]
 [<ffffffff827fe47a>] rwsem_down_write_failed+0x39a/0x730 kernel/locking/rwsem-xadd.c:555
 [<ffffffff81b69177>] call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 [<ffffffff827fd2ac>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
 [<ffffffff827fd2ac>] down_write+0x5c/0xa0 kernel/locking/rwsem.c:54
 [<ffffffff816c8d63>] ext4_map_blocks+0x6d3/0x16d0 fs/ext4/inode.c:605
 [<ffffffff816d5ee1>] mpage_map_one_extent fs/ext4/inode.c:2387 [inline]
 [<ffffffff816d5ee1>] mpage_map_and_submit_extent fs/ext4/inode.c:2443 [inline]
 [<ffffffff816d5ee1>] ext4_writepages+0x1551/0x2e00 fs/ext4/inode.c:2783
 [<ffffffff81433c8f>] do_writepages+0xef/0x1d0 mm/page-writeback.c:2331
 [<ffffffff8159eaa9>] __writeback_single_inode+0xd9/0x1020 fs/fs-writeback.c:1320
 [<ffffffff8159fe9c>] writeback_sb_inodes+0x4ac/0xe70 fs/fs-writeback.c:1584
 [<ffffffff815a095b>] __writeback_inodes_wb+0xfb/0x1e0 fs/fs-writeback.c:1653
 [<ffffffff815a0f52>] wb_writeback+0x512/0xbd0 fs/fs-writeback.c:1762
 [<ffffffff815a46cc>] wb_check_old_data_flush fs/fs-writeback.c:1877 [inline]
 [<ffffffff815a46cc>] wb_do_writeback fs/fs-writeback.c:1901 [inline]
 [<ffffffff815a46cc>] wb_workfn+0x8bc/0xe90 fs/fs-writeback.c:1930
 [<ffffffff81130d61>] process_one_work+0x831/0x1530 kernel/workqueue.c:2092
 [<ffffffff81131b36>] worker_thread+0xd6/0x1140 kernel/workqueue.c:2226
 [<ffffffff811428dd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff828035dc>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373

Showing all locks held in the system:
2 locks held by khungtaskd/24:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131bb4c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131bb4c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff813fe314>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/2025:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff828014e2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d2b032>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
5 locks held by kworker/u4:10/7248:
 #0:  ("writeback"){++++.+}, at: [<ffffffff81130c6c>] process_one_work+0x73c/0x1530 kernel/workqueue.c:2085
 #1:  ((&(&wb->dwork)->work)){+.+.+.}, at: [<ffffffff81130ca4>] process_one_work+0x774/0x1530 kernel/workqueue.c:2089
 #2:  (&type->s_umount_key#32){++++++}, at: [<ffffffff815149e0>] trylock_super+0x20/0xf0 fs/super.c:393
 #3:  (&sbi->s_journal_flag_rwsem){.+.+.+}, at: [<ffffffff81433c8f>] do_writepages+0xef/0x1d0 mm/page-writeback.c:2331
 #4:  (&ei->i_data_sem){++++..}, at: [<ffffffff816c8d63>] ext4_map_blocks+0x6d3/0x16d0 fs/ext4/inode.c:605

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

NMI backtrace for cpu 0
CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.135+ #59
 ffff8801d9907d08 ffffffff81b36bf9 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff81098330 ffff8801d9907d40
 ffffffff81b41d09 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81b36bf9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b36bf9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81b41d09>] nmi_cpu_backtrace.cold.0+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81b41c9c>] nmi_trigger_cpumask_backtrace+0x12c/0x151 lib/nmi_backtrace.c:60
 [<ffffffff81098434>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff8131c0dd>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff8131c0dd>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8131c0dd>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8131c0dd>] watchdog+0x6ad/0xa20 kernel/hung_task.c:239
 [<ffffffff811428dd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff828035dc>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 16743 Comm: syz-executor2 Not tainted 4.9.135+ #59
task: ffff88019ff98000 task.stack: ffff8801a2e30000
RIP: 0010:[<ffffffff8131b51b>] 
c [<ffffffff8131b51b>] __read_once_size include/linux/compiler.h:243 [inline]
RIP: 0010:[<ffffffff8131b51b>] 
c [<ffffffff8131b51b>] __sanitizer_cov_trace_pc+0x3b/0x50 kernel/kcov.c:105
RSP: 0018:ffff8801a2e37630  EFLAGS: 00000246
RAX: 0000000000040000 RBX: 0000000000000000 RCX: ffffc90000947000
RDX: 000000000003ffff RSI: ffffffff81773eb4 RDI: ffff88019c34b062
RBP: ffff8801a2e37630 R08: 000000000000000c R09: ffff8801a2e37390
R10: ffffed00345c6e65 R11: ffff8801a2e3732f R12: 0000000000000001
R13: ffff8801a2e378f8 R14: ffff88019c34b060 R15: ffff8801d1225080
FS:  00007fdecb490700(0000) GS:ffff8801db700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000001d6e308 CR3: 00000001d18c9000 CR4: 00000000001606b0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Stack:
 ffff8801a2e376a0
c ffffffff81773eb4
c 0000000000000010
c ffff8801a2e376f8
c
 ffff88019c34b250
c 5b9c051040000000
c ffff8801d1225080
c ffff8801d1225080
c
 ffff8801d1225090
c ffff8801d1225080
c 000000005b9c0510
c ffff8801a2e378f8
c
Call Trace:
 [<ffffffff81773eb4>] ext4_ext_binsearch fs/ext4/extents.c:819 [inline]
 [<ffffffff81773eb4>] ext4_find_extent+0x4a4/0x940 fs/ext4/extents.c:938
 [<ffffffff817b9cc6>] get_ext_path fs/ext4/move_extent.c:39 [inline]
 [<ffffffff817b9cc6>] mext_check_coverage.constprop.2+0x256/0x400 fs/ext4/move_extent.c:106
 [<ffffffff817bb6db>] move_extent_per_page fs/ext4/move_extent.c:333 [inline]
 [<ffffffff817bb6db>] ext4_move_extents+0x17bb/0x2a50 fs/ext4/move_extent.c:681
 [<ffffffff816ed76c>] ext4_ioctl+0x27fc/0x3620 fs/ext4/ioctl.c:594
 [<ffffffff81546ddc>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff81546ddc>] file_ioctl fs/ioctl.c:493 [inline]
 [<ffffffff81546ddc>] do_vfs_ioctl+0x1ac/0x11a0 fs/ioctl.c:677
 [<ffffffff81547e5f>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff81547e5f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff82803413>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
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c