Re: [RFC PATCH] block, fs: use FOLL_LONGTERM as gup_flags for direct IO

Christoph Hellwig
2025-03-12T15:17:15Z

On Thu, Mar 06, 2025 at 06:28:40PM -0800, Suren Baghdasaryan wrote:
> I think this will help you only when the pages are faulted in but if
> __get_user_pages() finds an already mapped page which happens to be
> allocated from CMA, it will not migrate it. So, you might still end up
> with unmovable pages inside CMA.

Direct I/O pages are not unmovable. They are temporarily pinned for
the duration of the direct I/O.

I really don't understand what problem you're trying to fix here.