Merge branch 'bpf-reduce-memory-usage-for-bpf_global_percpu_ma'

Yonghong Song says:

====================
bpf: Reduce memory usage for bpf_global_percpu_ma

Currently when a bpf program intends to allocate memory for percpu kptr,
the verifier will call bpf_mem_alloc_init() to prefill all supported
unit sizes and this caused memory consumption very big for large number
of cpus. For example, for 128-cpu system, the total memory consumption
with initial prefill is ~175MB. Things will become worse for systems
with even more cpus.

Patch 1 avoids unnecessary extra percpu memory allocation.
Patch 2 adds objcg to bpf_mem_alloc at init stage so objcg can be
associated with root cgroup and objcg can be passed to later
bpf_mem_alloc_percpu_unit_init().
Patch 3 addresses memory consumption issue by avoiding to prefill
with all unit sizes, i.e. only prefilling with user specified size.
Patch 4 further reduces memory consumption by limiting the
number of prefill entries for percpu memory allocation.
Patch 5 has much smaller low/high watermarks for percpu allocation
to reduce memory consumption.
Patch 6 rejects percpu memory allocation with bpf_global_percpu_ma
when allocation size is greater than 512 bytes.
Patch 7 fixed test_bpf_ma test due to Patch 5.
Patch 8 added one test to show the verification failure log message.

Changelogs:
  v5 -> v6:
    . Change bpf_mem_alloc_percpu_init() to add objcg as one of parameters.
      For bpf_global_percpu_ma, the objcg is NULL, corresponding root memcg.
  v4 -> v5:
    . Do not do bpf_global_percpu_ma initialization at init stage, instead
      doing initialization when the verifier knows it is going to be used
      by bpf prog.
    . Using much smaller low/high watermarks for percpu allocation.
  v3 -> v4:
    . Add objcg to bpf_mem_alloc during init stage.
    . Initialize objcg at init stage but use it in bpf_mem_alloc_percpu_unit_init().
    . Remove check_obj_size() in bpf_mem_alloc_percpu_unit_init().
  v2 -> v3:
    . Clear the bpf_mem_cache if prefill fails.
    . Change test_bpf_ma percpu allocation tests to use bucket_size
      as allocation size instead of bucket_size - 8.
    . Remove __GFP_ZERO flag from __alloc_percpu_gfp() call.
  v1 -> v2:
    . Avoid unnecessary extra percpu memory allocation.
    . Add a separate function to do bpf_global_percpu_ma initialization
    . promote.
    . Promote function static 'sizes' array to file static.
    . Add comments to explain to refill only one item for percpu alloc.
====================

Link: https://lore.kernel.org/r/20231222031729.1287957-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>