syzbot

INFO: task loop2:20243 blocked for more than 140 seconds.
      Not tainted 4.14.139+ #34
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
loop2           D29040 20243      2 0x80000000
Call Trace:
 schedule+0x92/0x1c0 kernel/sched/core.c:3498
 schedule_timeout+0x752/0xe90 kernel/time/timer.c:1721
 io_schedule_timeout+0x26/0x80 kernel/sched/core.c:5091
 do_wait_for_common kernel/sched/completion.c:91 [inline]
 __wait_for_common kernel/sched/completion.c:112 [inline]
 wait_for_common_io.constprop.0+0x274/0x3b0 kernel/sched/completion.c:129
 submit_bio_wait+0x107/0x170 block/bio.c:1013
 blkdev_issue_flush+0x218/0x320 block/blk-flush.c:531
 blkdev_fsync+0x80/0xb0 fs/block_dev.c:659
 vfs_fsync_range+0x106/0x260 fs/sync.c:196
 lo_req_flush drivers/block/loop.c:444 [inline]
 do_req_filebacked drivers/block/loop.c:567 [inline]
 loop_handle_cmd drivers/block/loop.c:1768 [inline]
 loop_queue_work+0xbe5/0x1deb drivers/block/loop.c:1782
 kthread_worker_fn+0x28f/0x6d0 kernel/kthread.c:642
 kthread+0x31f/0x430 kernel/kthread.c:232
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:404
INFO: task syz-executor.5:26237 blocked for more than 140 seconds.
      Not tainted 4.14.139+ #34
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.5  D28912 26237   1842 0x00000004
Call Trace:
 schedule+0x92/0x1c0 kernel/sched/core.c:3498
 schedule_timeout+0x752/0xe90 kernel/time/timer.c:1721
 io_schedule_timeout+0x26/0x80 kernel/sched/core.c:5091
 do_wait_for_common kernel/sched/completion.c:91 [inline]
 __wait_for_common kernel/sched/completion.c:112 [inline]
 wait_for_common_io.constprop.0+0x274/0x3b0 kernel/sched/completion.c:129
 submit_bio_wait+0x107/0x170 block/bio.c:1013
 blkdev_issue_flush+0x218/0x320 block/blk-flush.c:531
 blkdev_fsync+0x80/0xb0 fs/block_dev.c:659
 vfs_fsync_range+0x106/0x260 fs/sync.c:196
 vfs_fsync fs/sync.c:210 [inline]
 do_fsync+0x3d/0xb0 fs/sync.c:220
 SYSC_fdatasync fs/sync.c:234 [inline]
 SyS_fdatasync+0x15/0x20 fs/sync.c:232
 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x459829
RSP: 002b:00007f1e32627c78 EFLAGS: 00000246 ORIG_RAX: 000000000000004b
RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000459829
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1e326286d4
R13: 00000000004c00c7 R14: 00000000004d2190 R15: 00000000ffffffff
INFO: task syz-executor.5:26310 blocked for more than 140 seconds.
      Not tainted 4.14.139+ #34
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.5  D29232 26310   1842 0x00000004
Call Trace:
 schedule+0x92/0x1c0 kernel/sched/core.c:3498
 schedule_timeout+0x752/0xe90 kernel/time/timer.c:1721
 io_schedule_timeout+0x26/0x80 kernel/sched/core.c:5091
 do_wait_for_common kernel/sched/completion.c:91 [inline]
 __wait_for_common kernel/sched/completion.c:112 [inline]
 wait_for_common_io.constprop.0+0x274/0x3b0 kernel/sched/completion.c:129
 submit_bio_wait+0x107/0x170 block/bio.c:1013
 blkdev_issue_flush+0x218/0x320 block/blk-flush.c:531
 blkdev_fsync+0x80/0xb0 fs/block_dev.c:659
 vfs_fsync_range+0x106/0x260 fs/sync.c:196
 vfs_fsync fs/sync.c:210 [inline]
 do_fsync+0x3d/0xb0 fs/sync.c:220
 SYSC_fdatasync fs/sync.c:234 [inline]
 SyS_fdatasync+0x15/0x20 fs/sync.c:232
 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x459829
RSP: 002b:00007f1e325e5c78 EFLAGS: 00000246 ORIG_RAX: 000000000000004b
RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000459829
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 000000000075c070 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1e325e66d4
R13: 00000000004c00c7 R14: 00000000004d2190 R15: 00000000ffffffff

Showing all locks held in the system:
1 lock held by khungtaskd/23:
 #0:  (tasklist_lock){.+.+}, at: [<000000002d150a49>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4541
2 locks held by getty/1754:
 #0:  (&tty->ldisc_sem){++++}, at: [<0000000035acf7d3>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<00000000658acbf2>] n_tty_read+0x1f7/0x1700 drivers/tty/n_tty.c:2156

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

NMI backtrace for cpu 0
CPU: 0 PID: 23 Comm: khungtaskd Not tainted 4.14.139+ #34
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xca/0x134 lib/dump_stack.c:53
 nmi_cpu_backtrace.cold+0x47/0x86 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x119/0x147 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
 watchdog+0x629/0xbe0 kernel/hung_task.c:274
 kthread+0x31f/0x430 kernel/kthread.c:232
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:404
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at pc 0xffffffffbc899443