On Sun, Aug 23, 2026 at 10:02 PM Leon Hwang <[email protected]> wrote: > > On 22/8/26 01:58, Andrii Nakryiko wrote: > > On Tue, Aug 18, 2026 at 6:44 PM Leon Hwang <[email protected]> wrote: > >> > >> On 19/8/26 00:15, [email protected] wrote: > >>>> diff --git a/tools/testing/selftests/bpf/prog_tests/global_data_init.c > >>>> b/tools/testing/selftests/bpf/prog_tests/global_data_init.c > >>>> index 5671c31085cd..2b69290bcc3e 100644 > >>>> --- a/tools/testing/selftests/bpf/prog_tests/global_data_init.c > >>>> +++ b/tools/testing/selftests/bpf/prog_tests/global_data_init.c > >>> > >>> [ ... ] > >>> > >>>> @@ -236,6 +223,57 @@ static void test_global_percpu_data_lskel(void) > >>>> test_global_percpu_data_lskel__destroy(lskel); > >>>> } > >>>> > >>>> +#define PAGE_SIZE 4096 > >>>> + > >>>> +static void test_global_percpu_data_map_resize(void) > >>>> +{ > >>>> + const __u32 desired_sz = sysconf(_SC_PAGE_SIZE) * 2; > >>>> + struct test_global_percpu_data *skel; > >>>> + const int arr_value = -1; > >>>> + struct bpf_map *map; > >>>> + int err, prog_fd; > >>>> + size_t data_sz; > >>>> + > >>>> + if (sysconf(_SC_PAGE_SIZE) != PAGE_SIZE) { > >>>> + test__skip(); > >>>> + return; > >>>> + } > >>>> + > >>>> + skel = test_global_percpu_data__open(); > >>>> + if (!ASSERT_OK_PTR(skel, "test_global_percpu_data__open")) > >>>> + return; > >>>> + > >>>> + map = skel->maps.percpu_arr; > >>>> + skel->percpu_arr->arr[0] = arr_value; > >>>> + err = bpf_map__set_value_size(map, desired_sz); > >>> > >>> This isn't a bug, but since the guard above already pins the page size to > >>> 4096, would `const __u32 desired_sz = PAGE_SIZE * 2;` read more directly > >> > >> Will change to 'PAGE_SIZE * 2' if the next revision is needed. > >> > >>> here - and is the unguarded `#define PAGE_SIZE 4096` preferable to the > >>> `#ifndef PAGE_SIZE` form used in sockopt.c? > >> > >> No. PAGE_SIZE must be 4096 here. > >> > > > > can you please elaborate why do we care about specific PAGE_SIZE > > value? it's a bit weird to guard test based on page size... > > > It is to verify the mmap change in libbpf's bpf_map_mmap_resize() for > percpu data map, like those subtests in global_map_resize.c. >
this didn't explain much, but I think what you are trying to say is that this won't work for PERCPU arrays with PAGE_SIZE=64KB, because PERCPU value is limited to 32KB today, is that right? so maybe actually model that in the test itself, expect -E2BIG if PAGE_SIZE > 32KB or something, and otherwise check the resize? > Thanks, > Leon >
