Re: [PATCH bpf-next v2 3/4] selftests/bpf: Run arena tests serially

["Emil Tsalapatis" <emil@etsalapatis.com>]

On Fri Jul 17, 2026 at 7:37 AM EDT, Jiayuan Chen wrote:
> Every arena reserves a 4GB kernel vmalloc region at creation, and on a
> KASAN build that eagerly populates ~512MB of shadow memory per arena. When
> several arena tests run in parallel their shadow adds up, exhausts the
> memory of a small CI VM and trips the OOM killer during map creation.
>
> Make the dedicated arena tests (arena_* and libarena*) serial so they no
> longer pile up in the parallel phase. That alone brings the peak number of
> live arenas back within the CI memory budget.
>
> A few other tests such as verifier_arena*, stream and compute_live_registers
> create an arena too, but they run inside shared RUN_TESTS()/RUN() suites, so
> turning them serial would drag many unrelated subtests along with them.
> Leave those as-is.
>
> Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>

Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>

> ---
>  tools/testing/selftests/bpf/prog_tests/arena_atomics.c      | 2 +-
>  tools/testing/selftests/bpf/prog_tests/arena_direct_value.c | 2 +-
>  tools/testing/selftests/bpf/prog_tests/arena_htab.c         | 2 +-
>  tools/testing/selftests/bpf/prog_tests/arena_list.c         | 2 +-
>  tools/testing/selftests/bpf/prog_tests/arena_spin_lock.c    | 2 +-
>  tools/testing/selftests/bpf/prog_tests/arena_strsearch.c    | 2 +-
>  tools/testing/selftests/bpf/prog_tests/libarena.c           | 2 +-
>  tools/testing/selftests/bpf/prog_tests/libarena_asan.c      | 2 +-
>  8 files changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/arena_atomics.c b/tools/testing/selftests/bpf/prog_tests/arena_atomics.c
> index d98577a6babc..1ad5d03d07ad 100644
> --- a/tools/testing/selftests/bpf/prog_tests/arena_atomics.c
> +++ b/tools/testing/selftests/bpf/prog_tests/arena_atomics.c
> @@ -222,7 +222,7 @@ static void test_store_release(struct arena_atomics *skel)
>  		  "store_release64_result");
>  }
>  
> -void test_arena_atomics(void)
> +void serial_test_arena_atomics(void)
>  {
>  	struct arena_atomics *skel;
>  	int err;
> diff --git a/tools/testing/selftests/bpf/prog_tests/arena_direct_value.c b/tools/testing/selftests/bpf/prog_tests/arena_direct_value.c
> index 4b4adb3f4b71..01fcf4965ea4 100644
> --- a/tools/testing/selftests/bpf/prog_tests/arena_direct_value.c
> +++ b/tools/testing/selftests/bpf/prog_tests/arena_direct_value.c
> @@ -66,7 +66,7 @@ static void test_arena_direct_value_one_past_end(void)
>  	close(map_fd);
>  }
>  
> -void test_arena_direct_value(void)
> +void serial_test_arena_direct_value(void)
>  {
>  	if (test__start_subtest("one_past_end"))
>  		test_arena_direct_value_one_past_end();
> diff --git a/tools/testing/selftests/bpf/prog_tests/arena_htab.c b/tools/testing/selftests/bpf/prog_tests/arena_htab.c
> index d69fd2465f53..91ccf0402980 100644
> --- a/tools/testing/selftests/bpf/prog_tests/arena_htab.c
> +++ b/tools/testing/selftests/bpf/prog_tests/arena_htab.c
> @@ -81,7 +81,7 @@ static void test_arena_htab_asm(void)
>  	arena_htab_asm__destroy(skel);
>  }
>  
> -void test_arena_htab(void)
> +void serial_test_arena_htab(void)
>  {
>  	if (test__start_subtest("arena_htab_llvm"))
>  		test_arena_htab_llvm();
> diff --git a/tools/testing/selftests/bpf/prog_tests/arena_list.c b/tools/testing/selftests/bpf/prog_tests/arena_list.c
> index 4f2866a615ce..2648e06f53d0 100644
> --- a/tools/testing/selftests/bpf/prog_tests/arena_list.c
> +++ b/tools/testing/selftests/bpf/prog_tests/arena_list.c
> @@ -68,7 +68,7 @@ static void test_arena_list_add_del(int cnt, bool nonsleepable)
>  	arena_list__destroy(skel);
>  }
>  
> -void test_arena_list(void)
> +void serial_test_arena_list(void)
>  {
>  	if (test__start_subtest("arena_list_1"))
>  		test_arena_list_add_del(1, false);
> diff --git a/tools/testing/selftests/bpf/prog_tests/arena_spin_lock.c b/tools/testing/selftests/bpf/prog_tests/arena_spin_lock.c
> index acb9d53b5973..545b05d7a0aa 100644
> --- a/tools/testing/selftests/bpf/prog_tests/arena_spin_lock.c
> +++ b/tools/testing/selftests/bpf/prog_tests/arena_spin_lock.c
> @@ -101,7 +101,7 @@ static void test_arena_spin_lock_size(int size)
>  	return;
>  }
>  
> -void test_arena_spin_lock(void)
> +void serial_test_arena_spin_lock(void)
>  {
>  	repeat = 1000;
>  	if (test__start_subtest("arena_spin_lock_1"))
> diff --git a/tools/testing/selftests/bpf/prog_tests/arena_strsearch.c b/tools/testing/selftests/bpf/prog_tests/arena_strsearch.c
> index f81a0c066505..0c1c6cbfa0f1 100644
> --- a/tools/testing/selftests/bpf/prog_tests/arena_strsearch.c
> +++ b/tools/testing/selftests/bpf/prog_tests/arena_strsearch.c
> @@ -23,7 +23,7 @@ static void test_arena_str(void)
>  	arena_strsearch__destroy(skel);
>  }
>  
> -void test_arena_strsearch(void)
> +void serial_test_arena_strsearch(void)
>  {
>  	if (test__start_subtest("arena_strsearch"))
>  		test_arena_str();
> diff --git a/tools/testing/selftests/bpf/prog_tests/libarena.c b/tools/testing/selftests/bpf/prog_tests/libarena.c
> index ba5a5a50f7c0..df7e4b8dc394 100644
> --- a/tools/testing/selftests/bpf/prog_tests/libarena.c
> +++ b/tools/testing/selftests/bpf/prog_tests/libarena.c
> @@ -202,7 +202,7 @@ static void run_libarena_parallel_test(struct libarena *skel, struct bpf_program
>  	run_libarena_parallel_fini(skel, name, prefixlen);
>  }
>  
> -void test_libarena(void)
> +void serial_test_libarena(void)
>  {
>  	struct arena_alloc_reserve_args args;
>  	struct libarena *skel;
> diff --git a/tools/testing/selftests/bpf/prog_tests/libarena_asan.c b/tools/testing/selftests/bpf/prog_tests/libarena_asan.c
> index f897405f701d..9c31b17dbf39 100644
> --- a/tools/testing/selftests/bpf/prog_tests/libarena_asan.c
> +++ b/tools/testing/selftests/bpf/prog_tests/libarena_asan.c
> @@ -85,7 +85,7 @@ static void run_test(void)
>   * Run the test depending on whether LLVM can compile arena ASAN
>   * programs.
>   */
> -void test_libarena_asan(void)
> +void serial_test_libarena_asan(void)
>  {
>  #ifdef HAS_BPF_ARENA_ASAN
>  	run_test();