Re: [PATCH] blk-mq: bitmap tag: fix potential unwakeable sleep in bt_get()

[Jens Axboe]

On 2014-07-21 10:10, Alexander Gordeev wrote:
> There is a race between __bt_get_word() and bt_clear_tag(). Since
> access to the tags bitmap is not serialized __bt_get_word() might
> miss a tag which is about to or being returned by bt_clear_tag().
> As result, the process requesting the tag might end up schedulled
> out forever.
>
> To avoid this corner case call io_schedule_timeout() instead of
> io_schedule(). The timeout should be long enough to not falsely
> wake up waiters often, so take the requests queue's "rq_timeout"
> for that.

What is this patch against?


--
Jens Axboe

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