Re: [PATCH] Revert "mm, hugetlb: remove hugepages_treat_as_movable sysctl"

Gregory Price
2025-10-08T19:44:07Z

On Wed, Oct 08, 2025 at 09:01:09PM +0200, David Hildenbrand wrote:
> >
> > fwiw this works cleanly. Just dropping this here, but should continue
> > the zone conversation. I need to check, but does this actually allow
> > pinnable allocations? I thought pinning kicked off migration.
>
> Yes, it should because longterm pinning -> unmovable.
>

You know i just realized, my test here only works before I allocated 1GB
pages on both node0 and node1. If I only allocate 1gb hugetlb on node1,
then the migrate pages call fails - because there are no 1gb pages
available there.

I imagine this would cause hot-unplug/offline to fail since it uses the
same migration mechanisms.

Worse I would imagine this would fail for 2MB.

Seems like the 1GB limitation is arbitrary if 2MB causes the same issue.

~Gregory