Merge branch 'selftests-net-page_poll-allocation-error-injection'

Jakub Kicinski says:

====================
selftests: net: page_poll allocation error injection

Add a test for exercising driver memory allocation failure paths.
page pool is a bit tricky to inject errors into at the page allocator
level because of the bulk alloc and recycling, so add explicit error
injection support "in front" of the caches.

Add a test to exercise that using only the standard APIs.
This is the first useful test for the new tests with an endpoint.
There's no point testing netdevsim here, so this is also the first
HW-only test in Python.

I'm not super happy with the traffic generation using iperf3,
my initial approach was to use mausezahn. But it turned out to be
5x slower in terms of PPS. Hopefully this is good enough for now.

v1: https://lore.kernel.org/all/20240426232400.624864-1-kuba@kernel.org/
====================

Link: https://lore.kernel.org/r/20240429144426.743476-1-kuba@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>