bpf,slab: Introduce bpf_arena_alloc() kfuncs

From: Alexei Starovoitov <ast@kernel.org>

Let BPF programs and kernel allocate objects in bpf arena via
kvmalloc-style API: bpf_arena_alloc() kfunc.

Currently sched-ext BPF programs implement various allocators
as BPF programs on top of bpf_arena_alloc_pages() kfunc. 
This is inefficient.

Recently sched-ext kernel core introduced scx_arena_alloc() backed
by gen_pool_alloc() to allocate arena memory too.
This is also inefficient and gen_pool_alloc() is not fast enough.

Hence adopt sheaves and slub as allocator.
See patch 3 for algorithm details.

Alexei Starovoitov (4):
  slab: Introduce kmem_cache_alloc_nolock()
  slub: Pass kmem_cache to alloc_slab_page()
  bpf,slab: Add slub-backed allocator for bpf_arena
  selftests/bpf: Add tests for arena slub-backed allocator

 include/linux/bpf_defs.h                      |  13 +
 include/linux/slab.h                          |  27 ++
 kernel/bpf/Kconfig                            |   3 +
 kernel/bpf/arena.c                            | 366 +++++++++++++++++-
 mm/slab.h                                     |   6 +-
 mm/slab_common.c                              |   2 +-
 mm/slub.c                                     | 201 +++++++++-
 .../selftests/bpf/prog_tests/arena_slab.c     |  59 +++
 .../prog_tests/arena_slab_freeptr_stale_pcs.c |  28 ++
 .../testing/selftests/bpf/progs/arena_slab.c  | 179 +++++++++
 .../bpf/progs/arena_slab_freeptr_stale_pcs.c  | 120 ++++++
 11 files changed, 977 insertions(+), 27 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/arena_slab.c
 create mode 100644 tools/testing/selftests/bpf/prog_tests/arena_slab_freeptr_stale_pcs.c
 create mode 100644 tools/testing/selftests/bpf/progs/arena_slab.c
 create mode 100644 tools/testing/selftests/bpf/progs/arena_slab_freeptr_stale_pcs.c

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2.53.0-Meta