Hi, thanks for continuing with this. On Tue, Jul 28, 2026 at 04:37:42PM +0800, Tao Cui <[email protected]> wrote: > +/* Trigger smoke test: second on same fd -> EBUSY; IRQ rejects "some". */ > +static int test_proc_triggers(const char *root) > +{ > + static const char *const resources[] = { "io", "memory", "cpu" }; > + int ret = KSFT_FAIL; > + int fd = -1; > + int i; > + > + (void)root;
WTH?
> +
> + for (i = 0; i < (int)ARRAY_SIZE(resources); i++) {
This (int) cast is quite uncommon, look around.
> +/* Induce deterministic CPU pressure (more hogs than CPUs). */
> +static int test_cgroup_trigger_fire(const char *root)
> +{
> + char *cg = NULL, *cpupress = NULL;
> + int fd = -1, ret = KSFT_FAIL;
> + struct pollfd pfd;
> + long ncpus, i;
> + pid_t pid;
> +
> + cg = cg_name(root, "psi_trigger_test");
> + if (!cg)
> + goto cleanup;
> + if (cg_create(cg))
> + goto cleanup;
> +
> + cpupress = cg_control(cg, "cpu.pressure");
> + if (!cpupress)
> + goto cleanup;
> + fd = open(cpupress, O_RDWR);
> + if (fd < 0) {
> + ksft_print_msg("open cpu.pressure: %s\n", strerror(errno));
> + goto cleanup;
> + }
> +
> + /* 1us threshold in a 1s window: any cpu stall fires it. */
> + errno = 0;
> + if (write_trigger(fd, "some 1 1000000") <= 0) {
> + ksft_print_msg("arming trigger failed: %s\n", strerror(errno));
> + goto cleanup;
> + }
When I see this, could you increase the window size to 2000000 (so that
it has potential to run for unprivileged users)?
> +
> + ncpus = sysconf(_SC_NPROCESSORS_ONLN);
> + if (ncpus <= 0)
> + ncpus = 1;
> +
> + pid = fork();
> + if (pid < 0) {
> + ksft_print_msg("fork: %s\n", strerror(errno));
> + goto cleanup;
> + }
> + if (pid == 0) {
> + /* Enter the cgroup, then over-subscribe it with CPU hogs. */
> + if (cg_enter_current(cg))
> + _exit(KSFT_FAIL);
> + for (i = 0; i < ncpus; i++) {
> + if (fork() == 0) {
> + for (;;)
> + asm volatile("" ::: "memory");
> + _exit(0);
> + }
> + }
> + for (;;)
> + asm volatile("" ::: "memory"); /* child is also a hog
> */
> + _exit(0);
> + }
This part could be replaced with generalized hog_cpus_timed() from
test_cpu.c (after move to cgroup_util.c).
> +int main(int argc, char **argv)
> +{
> + char root[PATH_MAX];
> + int mempress_fd;
> + int i;
> +
> + (void)argc;
What's up with this?
> +
> + ksft_print_header();
> + ksft_set_plan(ARRAY_SIZE(tests));
> +
> + if (cg_find_unified_root(root, sizeof(root), NULL))
> + ksft_exit_skip("cgroup v2 isn't mounted\n");
> +
> + /* PSI must be enabled (CONFIG_PSI=y, not default-disabled). */
> + mempress_fd = open("/proc/pressure/memory", O_RDONLY);
> + if (mempress_fd < 0)
> + ksft_exit_skip("PSI unavailable (CONFIG_PSI=n or psi=0)\n");
> + close(mempress_fd);
> +
> + if (cg_read_strstr(root, "cgroup.controllers", "memory"))
> + ksft_exit_skip("memory controller isn't available\n");
> + if (cg_read_strstr(root, "cgroup.subtree_control", "memory"))
> + if (cg_write(root, "cgroup.subtree_control", "+memory"))
> + ksft_exit_skip("failed to enable memory controller\n");
The memory controller is unnecessary now, right?
Regards,
Michal
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