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

Kuehling, Felix Felix.Kuehling at amd.com
Wed Jun 19 00:53:55 UTC 2019

On 2019-06-18 1:37, Christoph Hellwig wrote:
> On Mon, Jun 17, 2019 at 09:45:09PM -0300, Jason Gunthorpe wrote:
>> Am I looking at the wrong thing? Looks like it calls it through a work
>> queue should should be OK..
> Yes, it calls it through a work queue.  I guess that is fine because
> it needs to take the lock again.
>> Though very strange that amdgpu only destroys the mirror via release,
>> that cannot be right.
> As said the whole things looks rather odd to me.

This code is derived from our old MMU notifier code. Before HMM we used 
to register a single MMU notifier per mm_struct and look up virtual 
address ranges that had been registered for mirroring via driver API 
calls. The idea was to reuse a single MMU notifier for the life time of 
the process. It would remain registered until we got a notifier_release.

hmm_mirror took the place of that when we converted the code to HMM.

I suppose we could destroy the mirror earlier, when we have no more 
registered virtual address ranges, and create a new one if needed later.


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