Re: [PATCH 3/6] drm/i915: use vmap in shmem_pin_map

From: Christoph Hellwig
Date: Tue Sep 22 2020 - 02:23:01 EST

On Mon, Sep 21, 2020 at 08:11:57PM +0100, Matthew Wilcox wrote:
> This is awkward. I'd like it if we had a vfree() variant which called
> put_page() instead of __free_pages(). I'd like it even more if we
> used release_pages() instead of our own loop that called put_page().

Note that we don't need a new vfree variant, we can do this manually if
we want, take a look at kernel/dma/remap.c. But I thought this code
intentionally doesn't want to do that to avoid locking in the memory
for the pages array. Maybe the i915 maintainers can clarify.