This calculation divides a fixed parameter by an environment-dependent parameter i.e. the number of CPUs.
The simple way to avoid machine-specific failures here is to just put a cap on the max value of the latter.
Suggested-by: Mateusz Guzik mjguzik@gmail.com Signed-off-by: Brendan Jackman jackmanb@google.com --- tools/testing/selftests/mm/uffd-stress.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/mm/uffd-stress.c b/tools/testing/selftests/mm/uffd-stress.c index 4ba5bf13a0108435ce8b53340b9e17ccd47e859e..40af7f67c4074d901be6608e5d64bd0490026dae 100644 --- a/tools/testing/selftests/mm/uffd-stress.c +++ b/tools/testing/selftests/mm/uffd-stress.c @@ -435,6 +435,7 @@ static void sigalrm(int sig)
int main(int argc, char **argv) { + unsigned long nr_cpus; size_t bytes;
if (argc < 4) @@ -453,7 +454,15 @@ int main(int argc, char **argv) return KSFT_SKIP; }
- nr_parallel = sysconf(_SC_NPROCESSORS_ONLN); + nr_cpus = sysconf(_SC_NPROCESSORS_ONLN); + if (nr_cpus > 32) { + /* Don't let calculation below go to zero. */ + ksft_print_msg("_SC_NPROCESSORS_ONLN (%lu) too large, capping nr_threads to 32\n", + nr_cpus); + nr_parallel = 32; + } else { + nr_parallel = nr_cpus; + }
nr_pages_per_cpu = bytes / page_size / nr_parallel; if (!nr_pages_per_cpu) {