Re: [bug] ata subsystem related crash with latest -git

[Jens Axboe <jens.axboe@oracle.com>]

On Wed, Oct 17 2007, Jens Axboe wrote:
> On Wed, Oct 17 2007, Linus Torvalds wrote:
> > 
> > 
> > On Wed, 17 Oct 2007, Jens Axboe wrote:
> > > 
> > > OK, I think you have a very good point here. Ingo, can you verify it
> > > goes away if apply the below? I have to tend to Other Life stuff but
> > > will take this up again tomorrow morning and fix the sg_next() usage.
> > 
> > This one will only fix the ones that use the SCSI-lib routines, so it will 
> > leave everything else broken, no?
> 
> Yes, it'll still crap out if you use debug page alloc for anything else
> :/

So until that is fixed up, how about this? Should cover all block
devices, and I don't think sg_next()/for_each_sg() has spread outside of
that yet.

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 3935469..8708ad0 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -631,7 +631,7 @@ void blk_queue_max_phys_segments(struct request_queue *q,
 		printk("%s: set to minimum %d\n", __FUNCTION__, max_segments);
 	}
 
-	q->max_phys_segments = max_segments;
+	q->max_phys_segments = max_segments - 1;
 }
 
 EXPORT_SYMBOL(blk_queue_max_phys_segments);

-- 
Jens Axboe

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