From: Jens Axboe <axboe@kernel.dk>
To: Alexander Gordeev <agordeev@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] blk-mq: bitmap tag: fix potential unwakeable sleep in bt_get()
Date: Mon, 21 Jul 2014 10:16:54 +0200 [thread overview]
Message-ID: <53CCCC76.7060506@kernel.dk> (raw)
In-Reply-To: <1405930246-2051-1-git-send-email-agordeev@redhat.com>
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
next prev parent reply other threads:[~2014-07-21 8:16 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-21 8:10 [PATCH] blk-mq: bitmap tag: fix potential unwakeable sleep in bt_get() Alexander Gordeev
2014-07-21 8:16 ` Jens Axboe [this message]
2014-07-21 8:32 ` Alexander Gordeev
2014-07-21 8:34 ` Jens Axboe
2014-07-21 9:11 ` Alexander Gordeev
2014-07-22 8:27 ` Alexander Gordeev
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