On Thu, Nov 15 2007, Rusty Russell wrote:
quoted text
> On Thursday 15 November 2007 19:47:05 Jens Axboe wrote:
> > On Thu, Nov 15 2007, Rusty Russell wrote:
> > > If blk_rq_map_sg returns more than was allocated, it's a bug, and
> > > something's already been overwritten.  BUG_ON() is probably the right
> > > thing here.
> >
> > It really just means that it mapped more segments than the block layer
> > said it would. Usually that wont overwrite memory here since scsi rounds
> > up on allocating the sg list, but it indeed can. Similar code has been
> > in scsi_lib.c for ages, I'd suggest covering that in the same patch.
> 
> Good point.  I assume that you've not seen these printks in recent memory?

I have not, they usually show up if we have bugs in the merge accounting
logic in the block layer (the merge functions and blk_rq_map_sg() not
agreeing). It's been ages since that was an issue, so I'm fine with the
bug.

quoted text
> This covers both cases:
> 
> Subject: [PATCH] scsi: BUG_ON() impossible condition.

You can add my

Acked-by: Jens Axboe <jens.axboe@oracle.com>

when you pass it through James, it should go in that way.

-- 
Jens Axboe

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