[PATCH v2 hmm 02/11] mm/hmm: Use hmm_mirror not mm as an argument for hmm_range_register

[Christoph Hellwig]

FYI, I very much disagree with the direction this is moving.

struct hmm_mirror literally is a trivial duplication of the
mmu_notifiers.  All these drivers should just use the mmu_notifiers
directly for the mirroring part instead of building a thing wrapper
that adds nothing but helping to manage the lifetime of struct hmm,
which shouldn't exist to start with.