Re: [RFC PATCH 0/2] mm/migrate: wait for folio refcount during longterm pin migration

David Hildenbrand (Arm)
2026-04-21T16:00:38Z

On 4/21/26 11:19, Huang, Ying wrote:
> Hi, John,
>
> John Hubbard <jhubbard@nvidia.com> writes:
>
>> Hi,
>>
>> This adds a bounded sleep to migration so that FOLL_LONGTERM pinning can
>> wait for transient folio references to drain, instead of failing after a
>> fixed number of retries. The wait uses a one-second timeout. An
>
> Is the one-second timeout appropriate for all users? Do some users
> prefer fail-fast behavior instead? If so, should we add another FOLL
> flag to support a timed wait?

We should avoid a FOLL flag to affect that behavior. FOLL_LONGTERM
already implies that things could take a while.

So we have real examples were failing is even desirable? :)

--
Cheers,

David