On Wed, Jun 18, 2025 at 02:14:15PM -0400, Zi Yan wrote:

On 18 Jun 2025, at 13:39, David Hildenbrand wrote:

quoted

... and start moving back to per-page things that will absolutely not be
folio things in the future. Add documentation and a comment that the
remaining folio stuff (lock, refcount) will have to be reworked as well.

While at it, convert the VM_BUG_ON() into a WARN_ON_ONCE() and handle
it gracefully (relevant with further changes), and convert a
WARN_ON_ONCE() into a VM_WARN_ON_ONCE_PAGE().

The reason is that there is no upstream code, which use movable_ops for
folios? Is there any fundamental reason preventing movable_ops from
being used on folios?

folios either belong to a filesystem or they are anonymous memory, and
so either the filesystem knows how to migrate them (through its a_ops)
or the migration code knows how to handle anon folios directly.