[PATCH v3 hmm 11/12] mm/hmm: Remove confusing comment and logic from hmm_release

[Christoph Hellwig]

On Thu, Jun 13, 2019 at 09:44:49PM -0300, Jason Gunthorpe wrote:
> From: Jason Gunthorpe <jgg at mellanox.com>
> 
> hmm_release() is called exactly once per hmm. ops->release() cannot
> accidentally trigger any action that would recurse back onto
> hmm->mirrors_sem.

In linux-next amdgpu actually calls hmm_mirror_unregister from its
release function.  That whole release function looks rather sketchy,
but we probably need to sort that out first.