[PATCH v2 hmm 9/9] mm/hmm: return error for non-vma snapshots

[Christoph Hellwig]

On Mon, Mar 23, 2020 at 10:14:57PM -0300, Jason Gunthorpe wrote:
> From: Jason Gunthorpe <jgg at mellanox.com>
> 
> The pagewalker does not call most ops with NULL vma, those are all routed
> to pte_hole instead.

Does ->pte_hole 

> 
> Thus hmm_vma_fault() is only called with a NULL vma from
> hmm_vma_walk_hole(), so hoist the check to there.
> 
> Now it is clear that snapshotting with no vma is a HMM_PFN_ERROR as
> without a vma we have no path to call hmm_vma_fault().
> 
> Signed-off-by: Jason Gunthorpe <jgg at mellanox.com>

Looks good,

Reviewed-by: Christoph Hellwig <hch at lst.de>