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