Re: [RFC][PATCH 3/3] Do not use rqhash when merges disabled

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From: Aaron Carroll

Subject: Re: [RFC][PATCH 3/3] Do not use rqhash when merges disabled

Date: Wednesday, April 23, 2008 - 5:37 pm

Hi Alan,

Alan D. Brunelle wrote:
quoted text> --- 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

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Messages in current thread:

[RFC][PATCH 0/3] Skip I/O merges when disabled, Alan D. Brunelle, (Wed Apr 23, 12:08 pm)

Re: [RFC][PATCH 1/3] Add flag and sysfs interfaces, Alan D. Brunelle, (Wed Apr 23, 12:12 pm)

[RFC][PATCH 2/3] Have __make_request skip merges when disabled, Alan D. Brunelle, (Wed Apr 23, 12:14 pm)

[RFC][PATCH 3/3] Do not use rqhash when merges disabled, Alan D. Brunelle, (Wed Apr 23, 12:15 pm)

Re: [RFC][PATCH 3/3] Do not use rqhash when merges disabled, Aaron Carroll, (Wed Apr 23, 5:37 pm)

Re: [RFC][PATCH 3/3] Do not use rqhash when merges disabled, Alan D. Brunelle, (Wed Apr 23, 5:59 pm)

Re: [RFC][PATCH 3/3] Do not use rqhash when merges disabled, Aaron Carroll, (Wed Apr 23, 7:07 pm)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Jens Axboe, (Thu Apr 24, 12:09 am)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Alan D. Brunelle, (Thu Apr 24, 5:09 am)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Andi Kleen, (Thu Apr 24, 6:29 am)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Alan D. Brunelle, (Thu Apr 24, 6:31 am)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Alan D. Brunelle, (Thu Apr 24, 6:43 am)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Jens Axboe, (Thu Apr 24, 6:59 am)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Alan D. Brunelle, (Thu Apr 24, 7:13 am)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Andi Kleen, (Thu Apr 24, 7:15 am)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Jens Axboe, (Thu Apr 24, 8:04 am)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Jens Axboe, (Thu Apr 24, 8:05 am)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, David Collier-Brown, (Thu Apr 24, 8:53 am)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Alan D. Brunelle, (Thu Apr 24, 9:29 am)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Alan D. Brunelle, (Thu Apr 24, 1:38 pm)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Carl Henrik Lunde, (Thu Apr 24, 3:04 pm)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Andi Kleen, (Fri Apr 25, 12:13 am)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Jens Axboe, (Fri Apr 25, 1:38 am)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Alan D. Brunelle, (Fri Apr 25, 4:17 am)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Jens Axboe, (Fri Apr 25, 4:25 am)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Aaron Carroll, (Fri Apr 25, 5:06 am)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Jens Axboe, (Fri Apr 25, 5:14 am)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Alan D. Brunelle, (Fri Apr 25, 5:17 am)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Alan D. Brunelle, (Mon Apr 28, 9:36 am)

Re: [RFC][PATCH 0/3] Skip I/O merges when disabled, Jens Axboe, (Tue Apr 29, 12:37 am)