[PATCH hmm 7/8] mm/hmm: return -EFAULT when setting HMM_PFN_ERROR on requested valid pages

[Christoph Hellwig]

On Wed, Mar 11, 2020 at 03:35:05PM -0300, Jason Gunthorpe wrote:
> From: Jason Gunthorpe <jgg at mellanox.com>
> 
> hmm_range_fault() should never return 0 if the caller requested a valid
> page, but the pfns output for that page would be HMM_PFN_ERROR.
> 
> hmm_pte_need_fault() must always be called before setting HMM_PFN_ERROR to
> detect if the page is in faulting mode or not.
> 
> Fix two cases in hmm_vma_walk_pmd() and reorganize some of the duplicated
> code.

Looks good,

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