On Wed, 2017-09-20 at 16:01 +0800, Herbert Xu wrote:
> Harsh Jain <Harsh@chelsio.com> wrote:
> > 
> > While debugging DMA mapping error in chelsio crypto driver we
> observed that when scatter/gather list received by driver has some
> entry with page->offset > 4096 (PAGE_SIZE). It starts giving DMA
> error.  Without IOMMU it works fine.
> 
> This is not a bug.  The network stack can and will feed us such
> SG lists.

Hm? Under what circumstances is the offset permitted to be >
PAGE_SIZE?