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 addresses memory consumption issue by avoiding to prefill with all unit sizes, i.e. only prefilling with user specified size. Patch 3 further reduces memory consumption by limiting the number of prefill entries for percpu memory allocation. Patch 4 rejects percpu memory allocation with bpf_global_percpu_ma when unit size is greater than 512 bytes. Patch 5 fixed one test due to Patch 4 and added one test to show the verification failure log message. Yonghong Song (5): bpf: Refactor to have a memalloc cache destroying function 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_mem_alloc.h | 5 ++ kernel/bpf/memalloc.c | 83 +++++++++++++++++-- kernel/bpf/verifier.c | 30 +++---- .../selftests/bpf/progs/percpu_alloc_fail.c | 18 ++++ .../testing/selftests/bpf/progs/test_bpf_ma.c | 9 -- 5 files changed, 114 insertions(+), 31 deletions(-) -- 2.34.1
