Re: [PATCH RFC 07/29] mm/migrate: rename isolate_movable_page() to isolate_movable_ops_page()

[Zi Yan <ziy@nvidia.com>]

On 18 Jun 2025, at 14:39, Matthew Wilcox wrote:

> On Wed, Jun 18, 2025 at 02:14:15PM -0400, Zi Yan wrote:
>> On 18 Jun 2025, at 13:39, David Hildenbrand wrote:
>>
>>> ... 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.

for device private pages, to support migrating >0 order anon or fs folios
to device, how should we represent them for devices? if you think folio is
only for anon and fs.

Best Regards,
Yan, Zi