Re: Re: [PATCH 2/3] bcache: Avoid hung task happen.

[majianpeng <majianpeng@gmail.com>]

>On Wed, Jan 08, 2014 at 07:39:26PM +0800, majianpeng wrote:
>> Because after kthread_create, the state of kthread is TASK_UNINTERRUPTIBLE.
>> If we don't wake up dc->writeback_thread, the thread will be hung-task.
>> For those reasons, we don't wake up writeback_thread:
>> A:only create backed device
>> B:create backed device and cache device, but don't write at once
>> C:write without writeback poliy
>> 
>> So like the way of create gc_thread, after creating writeback_thread, i
>> set the state is TASK_INTERRUPTIBLE.
>
>I've seen this issue, but this isn't even where the sleep happens,
>there's no way this could be fixing it..
Yes.But now, the default cache mode is writethrough.So kernel also printk hung-task messages.
If you don't like this way, you can use kthread_run instead kthread_create.
Because you test dc->has_dirty in bch_writeback_thread,so using kthread_run is safe.

Thanks!
Jianpeng Ma