@@ -32,6 +32,8 @@
#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"
+/* Leave some available processes for the OS */
+#define PIDS_RESERVE 50
pid_t tst_get_unused_pid_(void (*cleanup_fn) (void))
{
@@ -124,6 +126,11 @@ int tst_get_free_pids_(void (*cleanup_fn) (void))
if ((max_session_pids > 0) && (max_session_pids < max_pids))
max_pids = max_session_pids;
+ if (max_pids > PIDS_RESERVE)
+ max_pids -= PIDS_RESERVE;
+ else
+ max_pids = 0;
+
/* max_pids contains the maximum PID + 1,
* used_pids contains used PIDs + 1,
* so this additional '1' is eliminated by the substraction */
Forking the exactly amount of processes as the limit (either from max_pids or from cgroups) is risky - OS might be doing some work and interfere with the test. Instead leave some reserve (hard-coded to 50) for the OS so the test won't fail on fork failure. Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com> --- Changes since v5: 1. Move the max-pid-reserve to cover non-systemd case. --- lib/tst_pid.c | 7 +++++++ 1 file changed, 7 insertions(+)