[PATCH 1/2] mm/vmalloc: Introduce vmap_file()

[Vishal Moola]

On Thu, Jan 30, 2025 at 11:09 PM Christoph Hellwig <hch at infradead.org> wrote:
>
> On Thu, Jan 30, 2025 at 04:18:05PM -0800, Vishal Moola (Oracle) wrote:
> > +     rcu_read_lock();
> > +     xas_for_each(&xas, folio, last) {
>
> This only maps folios currently in the page cache, which makes it
> usefull for everything except ramfs-style purely in-memory file systems.
> I.e. for the shmem use case in the second patch it fails to swap in
> swapped out tmpfs folios.

Ah, I see. I can drop that patch then. Its primary purpose was to provide a
user for vmap_file(). As you've pointed out, that won't work with tmpfs or
anon pages. I'll hold off on a v2 until there are better usecases for
vmap_file().

> > +EXPORT_SYMBOL(vmap_file);
>
> EXPORT_SYMBOL_GPL for any advances vmalloc-layer functionality, please.

Ok, I'll keep that in mind in the future.