From ca5c89ba88a61a8c1eebe5cf3112315dbb832e10 Mon Sep 17 00:00:00 2001 From: Brendan Jackman Date: Fri, 21 Feb 2025 18:25:46 +0000 Subject: [PATCH] selftests/mm: don't fail uffd-stress if too many CPUs 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. Link: https://lkml.kernel.org/r/20250221-mm-selftests-v2-7-28c4d66383c5@google.com Signed-off-by: Brendan Jackman Suggested-by: Mateusz Guzik Cc: Dev Jain Cc: Lorenzo Stoakes Cc: Shuah Khan (Samsung OSG) Signed-off-by: Andrew Morton --- 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 91f33f80bbc7..329e070be7b1 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_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; + } nr_pages_per_cpu = bytes / page_size / nr_threads; if (!nr_pages_per_cpu) { -- 2.50.1