On Tue, Jul 28, 2020 at 11:00:40AM -0700, Jonathan Lemon wrote:

On Tue, Jul 28, 2020 at 06:28:25PM +0200, Greg KH wrote:

quoted

On Mon, Jul 27, 2020 at 03:44:34PM -0700, Jonathan Lemon wrote:

quoted

From: Jonathan Lemon <redacted>

netgpu pages will always have a refcount of at least one (held by
the netgpu module).  If the skb is marked as containing netgpu ZC
pages, recycle them back to netgpu.

What???

Yes, this is page refcount elevation.  ZONE_DEVICE pages do this also,
which is hidden in put_devmap_managed_page().  I would really like to
find a generic solution for this, as it has come up in other cases as
well (page recycling for page_pool, for example).  Some way to say "this
page is different", and a separate routine to release refcounts.

Can we have a discussion on this possibility?

Then propose a generic solution, not a "solution" like this.

greg k-h