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From: Roy Sigurd Karlsbakk <roy@karlsbakk.net>
Organization: ProntoTV AS
To: Zwane Mwaikambo <zwane@holomorphy.com>
Subject: Re: BUG in 2.5.50
Date: Mon, 9 Dec 2002 12:36:06 +0100
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Cc: Kernel mailing list <linux-kernel@vger.kernel.org>,
       Jens Axboe <axboe@suse.de>
References: <200212091056.08860.roy@karlsbakk.net> <Pine.LNX.4.50.0212090508390.2139-100000@montezuma.mastecende.com>
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> Perhaps this might help with debugging;
>
> He has CONFIG_BLK_DEV_IDE_TCQ enabled and his IBM supports it,
>
> when he gets to do_rw_disk();
>
> We know its a READ request
> 	if (rq_data_dir(rq) == READ) {
> 		if (blk_rq_tagged(rq))
> 			return hwif->ide_dma_queued_read(drive);
>
> ... the request isn't tagged so we drop down here...
>
> 		if (drive->using_dma && !hwif->ide_dma_read(drive))
> 			return ide_started;
>
> int __ide_dma_read (ide_drive_t *drive)
> ...
> 	if (HWGROUP(drive)->handler != NULL)
> 		BUG();
>
> and ->handler = ?
>
> Is this reproducible? If so without CONFIG_PREEMPT?

I found it easily reproducable - I just did the same old 'make 
modules_install' from the kernel dir, and BUG. Witout CONFIG_PREEMPT, 
however, I was not, and I tried to stress it quite a bit

roy
-- 
Roy Sigurd Karlsbakk, Datavaktmester
ProntoTV AS - http://www.pronto.tv/
Tel: +47 9801 3356

Computers are like air conditioners.
They stop working when you open Windows.

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