syzbot

INFO: task syz-executor.3:15658 blocked for more than 140 seconds.
      Not tainted 4.14.164-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.3  D27200 15658  11502 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384
 schedule+0x92/0x1c0 kernel/sched/core.c:3428
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
 ext4_mb_group_or_file fs/ext4/mballoc.c:4245 [inline]
 ext4_mb_initialize_context+0x7ab/0xba0 fs/ext4/mballoc.c:4288
 ext4_mb_new_blocks+0x52f/0x3b30 fs/ext4/mballoc.c:4561
 ext4_alloc_branch fs/ext4/indirect.c:335 [inline]
 ext4_ind_map_blocks+0x1296/0x23a0 fs/ext4/indirect.c:619
 ext4_map_blocks+0xd61/0x17c0 fs/ext4/inode.c:646
 _ext4_get_block+0x1a0/0x590 fs/ext4/inode.c:797
 ext4_get_block_trans+0x145/0x230 fs/ext4/inode.c:858
 ext4_dio_get_block+0x6f/0xb0 fs/ext4/inode.c:875
 get_more_blocks fs/direct-io.c:718 [inline]
 do_direct_IO fs/direct-io.c:1003 [inline]
 do_blockdev_direct_IO+0x1f73/0x9130 fs/direct-io.c:1336
 __blockdev_direct_IO+0xa1/0xca fs/direct-io.c:1422
 ext4_direct_IO_write fs/ext4/inode.c:3712 [inline]
 ext4_direct_IO+0x7c1/0x18f0 fs/ext4/inode.c:3848
 generic_file_direct_write+0x1e7/0x430 mm/filemap.c:2950
 __generic_file_write_iter+0x2bc/0x5b0 mm/filemap.c:3129
 ext4_file_write_iter+0x2ac/0xe90 fs/ext4/file.c:268
 call_write_iter include/linux/fs.h:1777 [inline]
 new_sync_write fs/read_write.c:469 [inline]
 __vfs_write+0x4a7/0x6b0 fs/read_write.c:482
 vfs_write+0x198/0x500 fs/read_write.c:544
 SYSC_write fs/read_write.c:590 [inline]
 SyS_write+0xfd/0x230 fs/read_write.c:582
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45af49
RSP: 002b:00007fd8df293c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045af49
RDX: 000000010000000d RSI: 0000000020000000 RDI: 0000000000000009
RBP: 000000000075c118 R08: 0000000000000000 R09: 0000000000000000