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From: Bart Van Assche <bvanassche@acm.org>
To: Jens Axboe <axboe@kernel.dk>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>
Cc: Omar Sandoval <osandov@fb.com>
Subject: Re: [PATCH] blk-mq: fix sbitmap ws_active for shared tags
Date: Mon, 25 Mar 2019 09:39:47 -0700	[thread overview]
Message-ID: <1553531987.118779.9.camel@acm.org> (raw)
In-Reply-To: <c0d3f0c8-a5d7-19dd-7b7f-1d4f860c425b@kernel.dk>

On Mon, 2019-03-25 at 10:22 -0600, Jens Axboe wrote:
> We now wrap sbitmap waitqueues in an active counter, so we can avoid
> iterating wakeups unless we have waiters there. This works as long as
> everyone that's manipulating the waitqueues use the proper helpers. For
> the tag wait case for shared tags, however, we add ourselves to the
> waitqueue without incrementing/decrementing the ->ws_active count. This
> means that wakeups can take a long time to happen.
> 
> Fix this by manually doing the inc/dec as needed for the wait queue
> handling.
> 
> Fixes: 5d2ee7122c73 ("sbitmap: optimize wakeup check")
> Signed-off-by: Jens Axboe <axboe@kernel.dk>

Hi Jens,

Since commit 5d2ee7122c73 went upstream in kernel v5.0, does this patch need
a "Cc: stable" tag?

Thanks,

Bart.

  reply	other threads:[~2019-03-25 16:39 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-25 16:22 [PATCH] blk-mq: fix sbitmap ws_active for shared tags Jens Axboe
2019-03-25 16:39 ` Bart Van Assche [this message]
2019-03-25 16:42   ` Jens Axboe
2019-03-25 18:56 ` Omar Sandoval
2019-03-25 18:58   ` Jens Axboe
2019-03-25 19:04     ` Omar Sandoval
2019-03-25 19:05       ` Jens Axboe

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