| Message ID | 20230827150551.1743497-1-yonghong.song@linux.dev (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 5439cfa7fe612e7d02d5a1234feda3fa6e483ba7 |
| Delegated to: | BPF |
| Headers | show |
| Series | [bpf] selftests/bpf: Fix flaky cgroup_iter_sleepable subtest | expand |
Hello: This patch was applied to bpf/bpf.git (master) by Daniel Borkmann <daniel@iogearbox.net>: On Sun, 27 Aug 2023 08:05:51 -0700 you wrote: > Occasionally, with './test_progs -j' on my vm, I will hit the > following failure: > test_cgrp_local_storage:PASS:join_cgroup /cgrp_local_storage 0 nsec > test_cgroup_iter_sleepable:PASS:skel_open 0 nsec > test_cgroup_iter_sleepable:PASS:skel_load 0 nsec > test_cgroup_iter_sleepable:PASS:attach_iter 0 nsec > test_cgroup_iter_sleepable:PASS:iter_create 0 nsec > test_cgroup_iter_sleepable:FAIL:cgroup_id unexpected cgroup_id: actual 1 != expected 2812 > #48/5 cgrp_local_storage/cgroup_iter_sleepable:FAIL > #48 cgrp_local_storage:FAIL > > [...] Here is the summary with links: - [bpf] selftests/bpf: Fix flaky cgroup_iter_sleepable subtest https://git.kernel.org/bpf/bpf/c/5439cfa7fe61 You are awesome, thank you!
diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_obj_pinning.c b/tools/testing/selftests/bpf/prog_tests/bpf_obj_pinning.c index 31f1e815f671..ee0458a5ce78 100644 --- a/tools/testing/selftests/bpf/prog_tests/bpf_obj_pinning.c +++ b/tools/testing/selftests/bpf/prog_tests/bpf_obj_pinning.c @@ -8,6 +8,7 @@ #include <linux/unistd.h> #include <linux/mount.h> #include <sys/syscall.h> +#include "bpf/libbpf_internal.h" static inline int sys_fsopen(const char *fsname, unsigned flags) { @@ -155,7 +156,7 @@ static void validate_pin(int map_fd, const char *map_name, int src_value, ASSERT_OK(err, "obj_pin"); /* cleanup */ - if (pin_opts.path_fd >= 0) + if (path_kind == PATH_FD_REL && pin_opts.path_fd >= 0) close(pin_opts.path_fd); if (old_cwd[0]) ASSERT_OK(chdir(old_cwd), "restore_cwd"); @@ -220,7 +221,7 @@ static void validate_get(int map_fd, const char *map_name, int src_value, goto cleanup; /* cleanup */ - if (get_opts.path_fd >= 0) + if (path_kind == PATH_FD_REL && get_opts.path_fd >= 0) close(get_opts.path_fd); if (old_cwd[0]) ASSERT_OK(chdir(old_cwd), "restore_cwd");
Occasionally, with './test_progs -j' on my vm, I will hit the following failure: test_cgrp_local_storage:PASS:join_cgroup /cgrp_local_storage 0 nsec test_cgroup_iter_sleepable:PASS:skel_open 0 nsec test_cgroup_iter_sleepable:PASS:skel_load 0 nsec test_cgroup_iter_sleepable:PASS:attach_iter 0 nsec test_cgroup_iter_sleepable:PASS:iter_create 0 nsec test_cgroup_iter_sleepable:FAIL:cgroup_id unexpected cgroup_id: actual 1 != expected 2812 #48/5 cgrp_local_storage/cgroup_iter_sleepable:FAIL #48 cgrp_local_storage:FAIL Finally, I decided to do some investigation since the test is introduced by myself. It turns out the reason is due to cgroup_fd with value 0. In cgroup_iter, a cgroup_fd of value 0 means the root cgroup. /* from cgroup_iter.c */ if (fd) cgrp = cgroup_v1v2_get_from_fd(fd); else if (id) cgrp = cgroup_get_from_id(id); else /* walk the entire hierarchy by default. */ cgrp = cgroup_get_from_path("/"); That is why we got cgroup_id 1 instead of expected 2812. Why we got a cgroup_fd 0? Nobody should really touch 'stdin' (fd 0) in test_progs. I traced 'close' syscall with stack trace and found the root cause, which is a bug in bpf_obj_pinning.c. Basically, the code closed fd 0 although it should not. Fixing the bug in bpf_obj_pinning.c also resolved the above cgroup_iter_sleepable subtest failure. Fixes: 3b22f98e5a05 ("selftests/bpf: Add path_fd-based BPF_OBJ_PIN and BPF_OBJ_GET tests") Signed-off-by: Yonghong Song <yonghong.song@linux.dev> --- tools/testing/selftests/bpf/prog_tests/bpf_obj_pinning.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)