Subject: Re: [PATCH v1 17/29] mm/page_isolation: drop __folio_test_movable() check for large folios

From: Harry Yoo <[email-masked]>
Date: Wed, 2 Jul 2025 18:54:15 +0900

On Tue, Jul 01, 2025 at 02:32:54PM +0200, David Hildenbrand wrote:
> On 01.07.25 13:03, Lorenzo Stoakes wrote:
> > On Mon, Jun 30, 2025 at 02:59:58PM +0200, David Hildenbrand wrote:
> > > Currently, we only support migration of individual movable_ops pages, so
> > > we can not run into that.
> > > 
> > > Reviewed-by: Zi Yan <[email-masked]>
> > > Signed-off-by: David Hildenbrand <[email-masked]>
> > 
> > Seems sensible, so:
> > 
> > Reviewed-by: Lorenzo Stoakes <[email-masked]>
> > 
> > Maybe worth adding a VM_WARN_ON_ONCE() just in case? Or do you think not worth it?
> 
> Not for now I think. Whoever wants to support compound pages has to fixup a
> bunch of other stuff first, before running into that one here.
> 
> So a full audit of all paths that handle page_has_movable_ops() is required
> either way.

IIRC there was an RFC series last year [1] that adds support for
order > 0 pages in zsmalloc.

Cc'ing Barry and Tangquan in case it's still on their TODO list... 

[1] https://lore.kernel.org/linux-mm/[email-masked]

-- 
Cheers,
Harry / Hyeonggon