# Re: \[PATCH\] raid1: include bio\_end\_io\_list in nr\_queued to prevent freeze\_array hang

- From: Shaohua Li \<shli@kernel.org\>
- Date: 2016-03-06 23:33:04 
- List: linux-raid
- Page: https://ratatoskr.run/linux-raid/2016/03/6631697
- Thread: https://ratatoskr.run/linux-raid/2016/02/6631655/t.md

```text
On Mon, Feb 29, 2016 at 10:43:58AM -0500, Nate Dailey wrote:
> If raid1d is handling a mix of read and write errors, handle_read_error's
> call to freeze_array can get stuck.
> 
> This can happen because, though the bio_end_io_list is initially drained,
> writes can be added to it via handle_write_finished as the retry_list
> is processed. These writes contribute to nr_pending but are not included
> in nr_queued.
> 
> If a later entry on the retry_list triggers a call to handle_read_error,
> freeze array hangs waiting for nr_pending == nr_queued+extra. The writes
> on the bio_end_io_list aren't included in nr_queued so the condition will
> never be satisfied.
> 
> To prevent the hang, include bio_end_io_list writes in nr_queued.
> 
> There's probably a better way to handle decrementing nr_queued, but this
> seemed like the safest way to avoid breaking surrounding code.
> 
> I'm happy to supply the script I used to repro this hang.

Looks good. Could you please also fix raid10?

Thanks,
Shaohua
```