Merge patch series "some pipe + wait stuff"

Mateusz Guzik <mjguzik@gmail.com> says:

As a side effect of looking at the pipe hang I came up with 3 changes to
consider for -next.

The first one is a trivial clean up which I wont mind if it merely gets
folded into someone else's change for pipes.

The second one reduces page alloc/free calls for the backing area (60%
less during a kernel build in my testing). I already posted this, but
the cc list was not proper.

The last one concerns the wait/wakeup mechanism and drops one lock trip
in the common case after waking up.

* patches from https://lore.kernel.org/r/20250303230409.452687-1-mjguzik@gmail.com:
  wait: avoid spurious calls to prepare_to_wait_event() in ___wait_event()
  pipe: cache 2 pages instead of 1
  pipe: drop an always true check in anon_pipe_write()

Link: https://lore.kernel.org/r/20250303230409.452687-1-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>