[PATCH RFC 07/29] mm/migrate: rename isolate_movable_page() to isolate_movable_ops_page()
David Hildenbrand
david at redhat.com
Tue Jun 24 01:33:15 AEST 2025
On 18.06.25 20:48, Zi Yan wrote:
> 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.
Right, migration of folios will be handled by migration core.
>
> 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.
I assume they are proper folios, so yes. Just like they are handled
today (-> folios)
I was asking a related question at LSF/MM in Alistair's session: are we
sure these things will be folios even before they are assigned to a
filesystem? I recall the answer was "yes".
So we don't (and will not) support movable_ops for folios.
--
Cheers,
David / dhildenb
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