@@ -14,7 +14,9 @@ pid_t tst_get_unused_pid_(void (*cleanup_fn)(void));
/*
* Returns number of free pids by subtraction of the number of pids
- * currently used ('ps -eT') from max_pids
+ * currently used ('ps -eT') from maximum number of processes.
+ * The limit of processes come from kernel pid_max and cgroup session limits
+ * (e.g. configured by systemd user.slice).
*/
int tst_get_free_pids_(void (*cleanup_fn)(void));
@@ -18,14 +18,20 @@
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
+#include <errno.h>
#include <fcntl.h>
#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
#include <sys/types.h>
+#include <unistd.h>
#include "test.h"
#include "tst_pid.h"
#include "old_safe_file_ops.h"
#define PID_MAX_PATH "/proc/sys/kernel/pid_max"
+#define CGROUPS_V1_SLICE_FMT "/sys/fs/cgroup/pids/user.slice/user-%d.slice/pids.max"
+#define CGROUPS_V2_SLICE_FMT "/sys/fs/cgroup/user.slice/user-%d.slice/pids.max"
pid_t tst_get_unused_pid_(void (*cleanup_fn) (void))
{
@@ -36,10 +42,77 @@ pid_t tst_get_unused_pid_(void (*cleanup_fn) (void))
return pid;
}
+/*
+ * Get the effective session UID - either one invoking current test via sudo
+ * or the real UID.
+ */
+static int get_session_uid(void)
+{
+ const char *sudo_uid;
+
+ sudo_uid = getenv("SUDO_UID");
+ if (sudo_uid) {
+ int real_uid;
+
+ TEST(sscanf(sudo_uid, "%u", &real_uid));
+ if (TEST_RETURN != 1) {
+#ifdef DEBUG
+ tst_resm(TINFO, "No SUDO_UID from env");
+#endif
+ } else {
+ return real_uid;
+ }
+ }
+
+ return getuid();
+}
+
+static int read_session_pids_limit(const char *path_fmt, int uid,
+ void (*cleanup_fn) (void))
+{
+ int max_pids, ret;
+ char path[PATH_MAX];
+
+ ret = snprintf(path, sizeof(path), path_fmt, uid);
+ if (ret < 0 || (size_t)ret >= sizeof(path))
+ return -1;
+
+ if (access(path, R_OK) != 0) {
+ tst_resm(TINFO, "Cannot read session user limits from '%s'", path);
+ return -1;
+ }
+
+ SAFE_FILE_SCANF(cleanup_fn, path, "%d", &max_pids);
+ tst_resm(TINFO, "Found limit of processes %d (from %s)", max_pids, path);
+
+ return max_pids;
+}
+
+static int get_session_pids_limit(void (*cleanup_fn) (void))
+{
+ int max_pids, uid;
+
+ uid = get_session_uid();
+ if (TEST_RETURN != 1) {
+ tst_resm(TINFO, "Cannot get UID");
+ return -1;
+ }
+
+ max_pids = read_session_pids_limit(CGROUPS_V2_SLICE_FMT, uid, cleanup_fn);
+ if (max_pids < 0)
+ max_pids = read_session_pids_limit(CGROUPS_V1_SLICE_FMT, uid,
+ cleanup_fn);
+
+ if (max_pids < 0)
+ return -1;
+
+ return max_pids;
+}
+
int tst_get_free_pids_(void (*cleanup_fn) (void))
{
FILE *f;
- int rc, used_pids, max_pids;
+ int rc, used_pids, max_pids, max_session_pids;
f = popen("ps -eT | wc -l", "r");
if (!f) {
@@ -57,6 +130,10 @@ int tst_get_free_pids_(void (*cleanup_fn) (void))
SAFE_FILE_SCANF(cleanup_fn, PID_MAX_PATH, "%d", &max_pids);
+ max_session_pids = get_session_pids_limit(cleanup_fn);
+ if ((max_session_pids > 0) && (max_session_pids < max_pids))
+ max_pids = max_session_pids;
+
/* max_pids contains the maximum PID + 1,
* used_pids contains used PIDs + 1,
* so this additional '1' is eliminated by the substraction */
Running syscalls/msgstress04 on a system with less than ~4 GB of RAM fails: Fork failure in the first child of child group 4396 Fork failure in the second child of child group 4413 msgstress04 1 TFAIL : msgstress04.c:222: Child exit status = 1 The reason is cgroups pid limit set by systemd user.slice. The limit is set for login session, also for root user. For example on 2 GB RAM machine it is set as: /sys/fs/cgroup/pids/user.slice/user-0.slice/pids.max:5207 Read the maximum number of pids and adjust the test limit. Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com> --- include/tst_pid.h | 4 ++- lib/tst_pid.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 81 insertions(+), 2 deletions(-)