From: Hou Tao <houtao1@xxxxxxxxxx> BPF CI failed due to map_percpu_stats_percpu_hash from time to time [1]. It seems that the failure reason is per-cpu bpf memory allocator may not be able to allocate per-cpu pointer successfully and it can not refill free llist timely, and bpf_map_update_elem() will return -ENOMEM. So mitigate the problem by retrying the update operation for non-preallocated per-cpu map. [1]: https://github.com/kernel-patches/bpf/actions/runs/6713177520/job/18244865326?pr=5909 Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx> --- .../bpf/map_tests/map_percpu_stats.c | 20 ++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/map_tests/map_percpu_stats.c b/tools/testing/selftests/bpf/map_tests/map_percpu_stats.c index 8ad17d051ef8f..e152535e9e3ec 100644 --- a/tools/testing/selftests/bpf/map_tests/map_percpu_stats.c +++ b/tools/testing/selftests/bpf/map_tests/map_percpu_stats.c @@ -141,6 +141,7 @@ struct upsert_opts { __u32 map_type; int map_fd; __u32 n; + bool retry_for_nomem; }; static int create_small_hash(void) @@ -154,6 +155,11 @@ static int create_small_hash(void) return map_fd; } +static bool retry_for_nomem_fn(int err) +{ + return err == ENOMEM; +} + static void *patch_map_thread(void *arg) { /* 8KB is enough for 1024 CPUs. And it is shared between N_THREADS. */ @@ -175,7 +181,12 @@ static void *patch_map_thread(void *arg) val_ptr = &val; } - ret = bpf_map_update_elem(opts->map_fd, &i, val_ptr, 0); + /* 2 seconds may be enough ? */ + if (opts->retry_for_nomem) + ret = map_update_retriable(opts->map_fd, &i, val_ptr, 0, + 40, retry_for_nomem_fn); + else + ret = bpf_map_update_elem(opts->map_fd, &i, val_ptr, 0); CHECK(ret < 0, "bpf_map_update_elem", "key=%d error: %s\n", i, strerror(errno)); if (opts->map_type == BPF_MAP_TYPE_HASH_OF_MAPS) @@ -296,6 +307,13 @@ static void __test(int map_fd) else opts.n /= 2; + /* per-cpu bpf memory allocator may not be able to allocate per-cpu + * pointer successfully and it can not refill free llist timely, and + * bpf_map_update_elem() will return -ENOMEM. so just retry to mitigate + * the problem temporarily. + */ + opts.retry_for_nomem = is_percpu(opts.map_type) && (info.map_flags & BPF_F_NO_PREALLOC); + /* * Upsert keys [0, n) under some competition: with random values from * N_THREADS threads. Check values, then delete all elements and check -- 2.29.2
