Percpu map is often used, but the map value size limit often ignored, like issue: https://github.com/iovisor/bcc/issues/2519. Actually, percpu map value size is bound by PCPU_MIN_UNIT_SZIE, so we can check the value size whether it exceeds PCPU_MIN_UNIT_SZIE first, like percpu map of local_storage. Maybe the error message seems clearer compared with "cannot allocate memory". the test case we create a percpu map with large value like: struct test_t { int a[100000]; }; struct { __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); __uint(max_entries, 1); __type(key, u32); __type(value, struct test_t); } start SEC(".maps"); test on ubuntu24.04 vm: libbpf: Error in bpf_create_map_xattr(start):Argument list too long(-7). Retrying without BTF. Signed-off-by: Tao Chen <chen.dylane@xxxxxxxxx> --- kernel/bpf/arraymap.c | 3 +++ kernel/bpf/hashtab.c | 3 +++ 2 files changed, 6 insertions(+) diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index a43e62e2a8bb..7c3c32f156ff 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -73,6 +73,9 @@ int array_map_alloc_check(union bpf_attr *attr) /* avoid overflow on round_up(map->value_size) */ if (attr->value_size > INT_MAX) return -E2BIG; + /* percpu map value size is bound by PCPU_MIN_UNIT_SIZE */ + if (percpu && attr->value_size > PCPU_MIN_UNIT_SIZE) + return -E2BIG; return 0; } diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 45c7195b65ba..16d590fe1ffb 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -462,6 +462,9 @@ static int htab_map_alloc_check(union bpf_attr *attr) * kmalloc-able later in htab_map_update_elem() */ return -E2BIG; + /* percpu map value size is bound by PCPU_MIN_UNIT_SIZE */ + if (percpu && attr->value_size > PCPU_MIN_UNIT_SIZE) + return -E2BIG; return 0; } -- 2.25.1
