在 2026/8/14 18:00, Shaojie Sun 写道:
> test_cgcore_lesser_ns_open runs as root throughout and never changes its
> euid, so chowning the two cgroup.procs files to a non-root uid has no
> effect on the test.
>
> The ENOENT the test expects comes from the cgroup namespace delegation
> check in cgroup_procs_write_permission(): the source and destination
> cgroups must both be descendants of the namespace root captured at open
> time. That check does not depend on file ownership. In addition, the
> permission check only examines the common ancestor's cgroup.procs file
> (the test root here), which the chown calls do not touch.
>
> Remove the redundant chown calls and the now unused test_euid and
> cg_test_a_procs variables.
>
> Signed-off-by: Shaojie Sun <[email protected]>
> ---
> Changes in v2:
> - Remove the now unused cg_test_a_procs variable, as suggested by
> sashiko-bot.
>
> tools/testing/selftests/cgroup/test_core.c | 11 ++---------
> 1 file changed, 2 insertions(+), 9 deletions(-)
>
> diff --git a/tools/testing/selftests/cgroup/test_core.c
> b/tools/testing/selftests/cgroup/test_core.c
> index 88ca832d4fc1..5501be9912c0 100644
> --- a/tools/testing/selftests/cgroup/test_core.c
> +++ b/tools/testing/selftests/cgroup/test_core.c
> @@ -795,10 +795,9 @@ static int lesser_ns_open_thread_fn(void *arg)
> static int test_cgcore_lesser_ns_open(const char *root)
> {
> static char stack[65536];
> - const uid_t test_euid = 65534; /* usually nobody, any !root is fine */
> int ret = KSFT_FAIL;
> char *cg_test_a = NULL, *cg_test_b = NULL;
> - char *cg_test_a_procs = NULL, *cg_test_b_procs = NULL;
> + char *cg_test_b_procs = NULL;
> int cg_test_b_procs_fd = -1;
> struct lesser_ns_open_thread_arg targ = { .fd = -1 };
> pid_t pid;
> @@ -813,10 +812,9 @@ static int test_cgcore_lesser_ns_open(const char *root)
> if (!cg_test_a || !cg_test_b)
> goto cleanup;
>
> - cg_test_a_procs = cg_name(cg_test_a, "cgroup.procs");
> cg_test_b_procs = cg_name(cg_test_b, "cgroup.procs");
>
> - if (!cg_test_a_procs || !cg_test_b_procs)
> + if (!cg_test_b_procs)
> goto cleanup;
>
> if (cg_create(cg_test_a) || cg_create(cg_test_b))
> @@ -825,10 +823,6 @@ static int test_cgcore_lesser_ns_open(const char *root)
> if (cg_enter_current(cg_test_b))
> goto cleanup;
>
> - if (chown(cg_test_a_procs, test_euid, -1) ||
> - chown(cg_test_b_procs, test_euid, -1))
> - goto cleanup;
> -
> targ.path = cg_test_b_procs;
> pid = clone(lesser_ns_open_thread_fn, stack + sizeof(stack),
> CLONE_NEWCGROUP | CLONE_FILES | CLONE_VM | SIGCHLD,
> @@ -863,7 +857,6 @@ static int test_cgcore_lesser_ns_open(const char *root)
> if (cg_test_a)
> cg_destroy(cg_test_a);
> free(cg_test_b_procs);
> - free(cg_test_a_procs);
> free(cg_test_b);
> free(cg_test_a);
> return ret;
Reviewed-by: Tao Cui <[email protected]>
