Re: [PATCH v2 2/5] mm: migrate: add folio_isolate_movable()

[Kefeng Wang <wangkefeng.wang@huawei.com>]

On 2024/9/5 3:05, Matthew Wilcox wrote:
> On Thu, Aug 29, 2024 at 10:54:53PM +0800, Kefeng Wang wrote:
>> Like isolate_lru_page(), make isolate_movable_page() as a wrapper
>> around folio_isolate_movable(), since isolate_movable_page() always
> 
> But not everything that is movable is a folio.  Look at who sets movable
> ops to see counterexamples.

Confused, balloon, zsmalloc and z3fold(may deprecate) will set movable,
but for core migration, most functions are converted to folio, and all
callers of movable_operations are from folio to page too except
isolate_movable_page(),

   mops->migrate_page(&dst->page, &src->page, mode) // move_to_new_folio()
   mops->isolate_page(&folio->page, mode) // isolate_movable_page()
   mops->putback_page(&folio->page) // putback_movable_folio()

This try to unify them, so I move folio_get_nontail_page() out to 
compaction code, then isolate_movable_page-> folio_migrate_movable.
could you explain more about your comments?  thanks.