net: page_pool: Don't recycle into cache on PREEMPT_RT

[ Upstream commit 32471b2f ]

With preemptible softirq and no per-CPU locking in local_bh_disable() on
PREEMPT_RT the consumer can be preempted while a skb is returned.

Avoid the race by disabling the recycle into the cache on PREEMPT_RT.

Cc: Jesper Dangaard Brouer <hawk@kernel.org>
Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20250512092736.229935-2-bigeasy@linutronix.de


Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>