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From: Aaron Carroll <aaronc@gelato.unsw.edu.au>
To: "Alan D. Brunelle" <Alan.Brunelle@hp.com>
Cc: linux-kernel@vger.kernel.org, Jens Axboe <jens.axboe@oracle.com>
Subject: Re: [RFC][PATCH 3/3] Do not use rqhash when merges disabled
Date: Thu, 24 Apr 2008 10:37:28 +1000	[thread overview]
Message-ID: <480FD648.70404@gelato.unsw.edu.au> (raw)
In-Reply-To: <480F8AB9.2050805@hp.com>

Hi Alan,

Alan D. Brunelle wrote:
> --- a/block/elevator.c
> +++ b/block/elevator.c
> @@ -313,7 +313,7 @@ static inline void __elv_rqhash_del(struct request *rq)
>  
>  static void elv_rqhash_del(struct request_queue *q, struct request *rq)
>  {
> -	if (ELV_ON_HASH(rq))
> +	if (!blk_queue_nomerges(q) && ELV_ON_HASH(rq))
>  		__elv_rqhash_del(rq);
>  }

If you switch the nomerges tunable while requests are in flight, it is possible that
a request is put into the rqhash table but not removed here, leading to the BUG_ON
in elv_dequeue_request() triggering.  ELV_ON_HASH needs to be checked regardless of
the nomerges state.


 -- Aaron


  reply	other threads:[~2008-04-24  0:38 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-04-23 19:08 [RFC][PATCH 0/3] Skip I/O merges when disabled Alan D. Brunelle
2008-04-23 19:12 ` [RFC][PATCH 1/3] Add flag and sysfs interfaces Alan D. Brunelle
2008-04-23 19:14 ` [RFC][PATCH 2/3] Have __make_request skip merges when disabled Alan D. Brunelle
2008-04-23 19:15 ` [RFC][PATCH 3/3] Do not use rqhash when merges disabled Alan D. Brunelle
2008-04-24  0:37   ` Aaron Carroll [this message]
2008-04-24  0:59     ` Alan D. Brunelle
2008-04-24  2:07       ` Aaron Carroll
2008-04-24  7:09 ` [RFC][PATCH 0/3] Skip I/O merges when disabled Jens Axboe
2008-04-24 12:09   ` Alan D. Brunelle
2008-04-25  8:38     ` Jens Axboe
2008-04-25 11:17       ` Alan D. Brunelle
2008-04-25 11:25         ` Jens Axboe
2008-04-25 12:06           ` Aaron Carroll
2008-04-25 12:14             ` Jens Axboe
2008-04-25 12:17         ` Alan D. Brunelle
2008-04-28 16:36           ` Alan D. Brunelle
2008-04-29  7:37             ` Jens Axboe
2008-04-24 20:38   ` Alan D. Brunelle
2008-04-24 13:29 ` Andi Kleen
2008-04-24 13:59   ` Jens Axboe
2008-04-24 14:13     ` Alan D. Brunelle
2008-04-24 15:05       ` Jens Axboe
2008-04-24 22:04       ` Carl Henrik Lunde
2008-04-25  7:13       ` Andi Kleen
2008-04-24 14:15     ` Andi Kleen
2008-04-24 15:04       ` Jens Axboe
2008-04-24 15:53         ` David Collier-Brown
2008-04-24 16:29           ` Alan D. Brunelle
2008-04-24 13:31 ` Alan D. Brunelle
2008-04-24 13:43   ` Alan D. Brunelle

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