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Subject: Re: [PATCH v3 5/6] mm/gup: migrate pinned pages out of movable zone
To:     Pavel Tatashin <pasha.tatashin@soleen.com>,
        David Hildenbrand <david@redhat.com>
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From:   John Hubbard <jhubbard@nvidia.com>
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On 12/11/20 3:00 PM, Pavel Tatashin wrote:
>> I guess revert what we did (unpin) and return an error. The interesting question is what can make migration/isolation fail
> 
> OK. I will make the necessary changes. Let's handle errors properly.
> Whatever the cause for the error, we will know it when it happens, and
> when error is returned. I think I will add a 10-time retry instead of
> the infinite retry that we currently have. The 10-times retry we
> currently have during the hot-remove path.

It occurs to me that maybe the pre-existing infinite loop shouldn't be
there at all? Would it be better to let the callers retry? Obviously that
would be a separate patch and I'm not sure it's safe to make that change,
but the current loop seems buried maybe too far down.

Thoughts, anyone?

thanks,
-- 
John Hubbard
NVIDIA