On Fri, 28 Feb 2025 at 17:55, Brendan Jackman jackmanb@google.com wrote:
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 efe2051c393096e237d942c04a264b6611a6e127..5656128590373ed376b3b5d9259e5ca3867a4099 100644 --- a/tools/testing/selftests/mm/uffd-stress.c +++ b/tools/testing/selftests/mm/uffd-stress.c @@ -434,6 +434,7 @@ static void sigalrm(int sig)
int main(int argc, char **argv) {
unsigned long nr_cpus; size_t bytes; if (argc < 4)@@ -452,7 +453,15 @@ int main(int argc, char **argv) return KSFT_SKIP; }
nr_threads = 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_threads = 32;} else {nr_cpus = nr_threads;
Won't have time to send v4 for a few days so I'll just note here: this shoudl be nr_thread = nr_cpus. This causes a division by zero on machines with less than 30 CPUs.