Re: [2.6.24 REGRESSION] BUG: Soft lockup - with VFS

[FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>]

On Fri, 8 Feb 2008 23:46:19 -0800
Pete Zaitcev <zaitcev@redhat.com> wrote:

> On Tue, 5 Feb 2008 14:05:06 -0800, Andrew Morton <akpm@linux-foundation.org> wrote:
> 
> > > > http://students.zipernowsky.hu/~oliverp/kernel/regression_2624/
> 
> > I think ub.c is basically abandoned in favour of usb-storage.
> > If so, perhaps we should remove or disble ub.c?
> 
> Looks like it's just Tomo or Jens made a mistake when converting to
> the new s/g API. Nothing to be too concerned about. I know I should've
> reviewed their patch closer, but it seemed too simple...

I guess I can put the blame for this on Jens' commit (45711f1a) ;)

On a serious note, it seems that two scatter lists per request leaded
to this bug. Can the scatter list in struct ub_request be removed?

Thanks,

> -- Pete
> 
> Fix up the conversion to sg_init_table().
> 
> Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
> 
> --- a/drivers/block/ub.c
> +++ b/drivers/block/ub.c
> @@ -657,7 +657,6 @@ static int ub_request_fn_1(struct ub_lun *lun, struct request *rq)
>  	if ((cmd = ub_get_cmd(lun)) == NULL)
>  		return -1;
>  	memset(cmd, 0, sizeof(struct ub_scsi_cmd));
> -	sg_init_table(cmd->sgv, UB_MAX_REQ_SG);
>  
>  	blkdev_dequeue_request(rq);
>  
> @@ -668,6 +667,7 @@ static int ub_request_fn_1(struct ub_lun *lun, struct request *rq)
>  	/*
>  	 * get scatterlist from block layer
>  	 */
> +	sg_init_table(&urq->sgv[0], UB_MAX_REQ_SG);
>  	n_elem = blk_rq_map_sg(lun->disk->queue, rq, &urq->sgv[0]);
>  	if (n_elem < 0) {
>  		/* Impossible, because blk_rq_map_sg should not hit ENOMEM. */
> --
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