zcrx for-6.18 updates

A bunch of assorted zcrx patches for 6.18, which includes
- Improve refill entry alignment for better caching (Patch 1)
- Various cleanups, especially around deduplicating normal memory vs dmabuf setup.
- Generalisation of the niov size (Patch 12). It's still hard coded to PAGE_SIZE on init, but will let the user to specify the rx buffer length on setup.
- Syscall / synchronous bufer return (Patch 19). It'll be used as a slow fallback path for returning buffers when the refill queue is full. Useful for tolerating slight queue size misconfiguration or with inconsistent load.
- Accounting more memory to cgroups (Patch 20)
- Additional independent cleanups that will also be useful for mutli-area support.

Pavel Begunkov (20):
io_uring/zcrx: improve rqe cache alignment io_uring/zcrx: replace memchar_inv with is_zero io_uring/zcrx: use page_pool_unref_and_test() io_uring/zcrx: remove extra io_zcrx_drop_netdev io_uring/zcrx: don't pass slot to io_zcrx_create_area io_uring/zcrx: move area reg checks into io_import_area io_uring/zcrx: check all niovs filled with dma addresses io_uring/zcrx: pass ifq to io_zcrx_alloc_fallback() io_uring/zcrx: deduplicate area mapping io_uring/zcrx: remove dmabuf_offset io_uring/zcrx: set sgt for umem area io_uring/zcrx: make niov size variable io_uring/zcrx: rename dma lock
io_uring/zcrx: protect netdev with pp_lock io_uring/zcrx: reduce netmem scope in refill io_uring/zcrx: use guards for the refill lock io_uring/zcrx: don't adjust free cache space io_uring/zcrx: introduce io_parse_rqe() io_uring/zcrx: allow synchronous buffer return io_uring/zcrx: account niov arrays to cgroup

 include/uapi/linux/io_uring.h |  12 ++
 io_uring/register.c           |   3 +
 io_uring/zcrx.c               | 285 +++++++++++++++++++++-------------
 io_uring/zcrx.h               |  19 ++-
 4 files changed, 211 insertions(+), 108 deletions(-)

2.49.0