Date: Wed, 28 May 2003 03:59:39 -0700
From: Andrew Morton <akpm@digeo.com>
To: Jens Axboe <axboe@suse.de>
Cc: kernel@kolivas.org, matthias.mueller@rz.uni-karlsruhe.de,
       m.c.p@wolk-project.de, manish@storadinc.com, andrea@suse.de,
       marcelo@conectiva.com.br, linux-kernel@vger.kernel.org
Subject: Re: 2.4.20: Proccess stuck in __lock_page ...
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Jens Axboe <axboe@suse.de> wrote:
>
> > THIS IS IT! The last one. No pauses writing a 2Gb file now unless I do a read 
>  > midstream.
> 
>  Cool, especially since we can easily apply this to -rc5 without any
>  worries. Marcelo, if you please...?
> 
>  ===== drivers/block/ll_rw_blk.c 1.44 vs edited =====
>  --- 1.44/drivers/block/ll_rw_blk.c	Mon Apr 14 12:53:03 2003
>  +++ edited/drivers/block/ll_rw_blk.c	Wed May 28 12:49:30 2003
>  @@ -829,8 +829,7 @@
>   	 */
>   	if (q) {
>   		list_add(&req->queue, &q->rq[rw].free);
>  -		if (++q->rq[rw].count >= q->batch_requests &&
>  -				waitqueue_active(&q->wait_for_requests[rw]))
>  +		if (++q->rq[rw].count >= q->batch_requests)
>   			wake_up(&q->wait_for_requests[rw]);
>   	}
>   }

umm, I'd like confirmation of that.

The waitqueue_active() test is wrong because of a missing barrier, but only
on SMP.  And if it does make a mistake it will surely correct itself when the
next request is put back. (That's why I left it there...)

More testing, please.
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