syzbot

INFO: task kworker/u8:14:3572 blocked for more than 143 seconds.
Workqueue: writeback wb_workfn (flush-7:1)
 writeback_sb_inodes+0x73c/0x16b4 fs/fs-writeback.c:2030
 __writeback_inodes_wb+0xec/0x228 fs/fs-writeback.c:2107
 wb_writeback+0x3c8/0xd70 fs/fs-writeback.c:2218
 wb_check_old_data_flush fs/fs-writeback.c:2322 [inline]
 wb_do_writeback fs/fs-writeback.c:2375 [inline]
 wb_workfn+0xa08/0xdc0 fs/fs-writeback.c:2403
 process_one_work+0x7c0/0x1558 kernel/workqueue.c:3257
      Not tainted syzkaller #0
Call trace:
 __down_write_common kernel/locking/rwsem.c:1317 [inline]
 __down_write kernel/locking/rwsem.c:1326 [inline]
 down_write+0xb4/0xc0 kernel/locking/rwsem.c:1591
 process_one_work+0x7c0/0x1558 kernel/workqueue.c:3257
 process_scheduled_works kernel/workqueue.c:3340 [inline]
 worker_thread+0x958/0xed8 kernel/workqueue.c:3421
 kthread+0x5fc/0x75c kernel/kthread.c:463
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844
1 lock held by khungtaskd/32:
4 locks held by kworker/u8:2/41:
4 locks held by kworker/u8:3/42:
2 locks held by pr/ttyAMA-1/43:
 #2: ffff0000d49500e0 (&type->s_umount_key#54){.+.+}-{4:4}, at: super_trylock_shared+0x24/0xdc fs/super.c:563
 #2: ffff0000cb9880e0 (&type->s_umount_key#54){.+.+}-{4:4}, at: super_trylock_shared+0x24/0xdc fs/super.c:563
4 locks held by kworker/u8:20/6003:
 #3: ffff0000e0531510 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_down_write fs/f2fs/f2fs.h:2313 [inline]
 #3: ffff0000e0531510 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_balance_fs+0x4c0/0x6d8 fs/f2fs/segment.c:464
 #0: ffff0000d535d0a0 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x4c drivers/tty/tty_ldsem.c:340
 #0: ffff0000c1ff2948 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x63c/0x1558 kernel/workqueue.c:3231
 #1: ffff80009ee57be0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x6d0/0x1558 kernel/workqueue.c:3231