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 is a preparatory patch.
Patch 2 avoids unnecessary extra percpu memory allocation.
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 rejects percpu memory allocation with bpf_global_percpu_ma
when allocation size is greater than 512 bytes.
Patch 6 fixed one test due to Patch 5 and added one test to
show the verification failure log message.
Changelogs:
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.
Yonghong Song (6):
bpf: Refactor to have a memalloc cache destroying function
bpf: Avoid unnecessary extra percpu memory allocation
bpf: Allow per unit prefill for non-fix-size percpu memory allocator
bpf: Refill only one percpu element in memalloc
bpf: Limit up to 512 bytes for bpf_global_percpu_ma allocation
selftests/bpf: Cope with 512 bytes limit with bpf_global_percpu_ma
include/linux/bpf.h | 2 +-
include/linux/bpf_mem_alloc.h | 7 ++
kernel/bpf/core.c | 8 +-
kernel/bpf/memalloc.c | 100 +++++++++++++++---
kernel/bpf/verifier.c | 36 ++++---
.../selftests/bpf/progs/percpu_alloc_fail.c | 18 ++++
.../testing/selftests/bpf/progs/test_bpf_ma.c | 9 --
7 files changed, 138 insertions(+), 42 deletions(-)
--
2.34.1
