John Lumby [off-list ref] :

Anyone have any further thoughts on the proposal to avoid
memcpy'ing?  (see earlier post)

The patch mixes different changes. Please avoid it.

Your MUA damaged the patch. Documentation/SubmittingPatches
could help if you have not read it yet.

The patch makes some gratuitous changes which needlessly
increase the differences (dirty_xy rename for instance).

A set_ringparam() method which does nothing until open()
is used does not exactly ring like "least surprize behavior"
to me.

The behavior under memory pressure is still unknown.

I am mildly convinced by the implementation.

-- 
Ueimor