[PATCH v2] mm, hwpoison: Try to recover from copy-on write faults

[Luck, Tony]

> Given there is no use case for the residue value returned by
> copy_mc_to_kernel() perhaps just return EHWPOISON directly from
> copyuser_highpage_mc() in the short-copy case?

I don't think it hurts to keep the return value as residue count. It isn't
making that code any more complex and could be useful someday.

Other feedback looks good and I have applied ready for next version.

Thanks for the review.

-Tony