Re: 2.6.17-rc1-mm2: badness in 3w_xxxx driver

[Nick Orlov]

On Sun, Apr 09, 2006 at 11:32:40AM -0700, Andrew Morton wrote:
> Nick Orlov <bugfixer@xxxxxxx> wrote:
> >
> > The following patch: x86-kmap_atomic-debugging.patch exposed a badness
> > in 3w_xxx driver.
> 
> Sweet, thanks.
> 
[[ skipped ]]
> 
> From: Andrew Morton <akpm@xxxxxxxx>
> 
> We must disable local IRQs while holding KM_IRQ0 or KM_IRQ1.  Otherwise, an
> IRQ handler could use those kmap slots while this code is using them,
> resulting in memory corruption.
> 
> Thanks to Nick Orlov <bugfixer@xxxxxxx> for reporting.
> 
> Cc: <linuxraid@xxxxxxxx>
> Cc: James Bottomley <James.Bottomley@xxxxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
> ---
> 
>  drivers/scsi/3w-xxxx.c |    3 +++
>  1 files changed, 3 insertions(+)
> 
> diff -puN drivers/scsi/3w-xxxx.c~3ware-kmap_atomic-fix drivers/scsi/3w-xxxx.c
> --- devel/drivers/scsi/3w-xxxx.c~3ware-kmap_atomic-fix	2006-04-09 11:28:08.000000000 -0700
> +++ devel-akpm/drivers/scsi/3w-xxxx.c	2006-04-09 11:29:21.000000000 -0700
> @@ -1508,10 +1508,12 @@ static void tw_transfer_internal(TW_Devi
>  	struct scsi_cmnd *cmd = tw_dev->srb[request_id];
>  	void *buf;
>  	unsigned int transfer_len;
> +	unsigned long flags = 0;
>  
>  	if (cmd->use_sg) {
>  		struct scatterlist *sg =
>  			(struct scatterlist *)cmd->request_buffer;
> +		local_irq_save(flags);
>  		buf = kmap_atomic(sg->page, KM_IRQ0) + sg->offset;
>  		transfer_len = min(sg->length, len);
>  	} else {
> @@ -1526,6 +1528,7 @@ static void tw_transfer_internal(TW_Devi
>  
>  		sg = (struct scatterlist *)cmd->request_buffer;
>  		kunmap_atomic(buf - sg->offset, KM_IRQ0);
> +		local_irq_restore(flags);
>  	}
>  }
>  
> _

Confirmed, this patch solves the "badness" problem for me.
I still experiencing a weird hangs though (the box just hangs, no
messages on console/syslog, nothing). I'll try to nail it down.

2.6.16-mm2 works like a charm with the same config.
Do you know which patches should I try to revert first?

-- 
With best wishes,
	Nick Orlov.

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