is that grouped frees will be done as most often as possible without
dropping the cache lock in between. So, for the most part, they'll be
done without the lock being dropped. This is particularly true if you
have something that does a grouped m_getm() or m_getcl() (a cluster and
mbuf at the same time) - most likely getting the buffers from the
same per-CPU cache - and then frees them with m_free{,m}(). Unless
the buffers' underlying buckets were moved, the free will be done without
the lock getting dropped in between. So far, only m_free() has been
shown how to do this, and m_freem() will shortly follow.
Since I'm here, I also fixed a small (but mostly harmless) type-mismatch
introduced in the last commit.
93a279e095