[merged mm-stable] selftests-mm-dont-fail-uffd-stress-if-too-many-cpus.patch removed from -mm tree

[merged mm-stable] selftests-mm-dont-fail-uffd-stress-if-too-many-cpus.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: selftests/mm: don't fail uffd-stress if too many CPUs
has been removed from the -mm tree.  Its filename was
     selftests-mm-dont-fail-uffd-stress-if-too-many-cpus.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Brendan Jackman <jackmanb@google.com>
Subject: selftests/mm: don't fail uffd-stress if too many CPUs
Date: Tue, 11 Mar 2025 13:18:17 +0000

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/20250311-mm-selftests-v4-6-dec210a658f5@google.com
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Suggested-by: Mateusz Guzik <mjguzik@gmail.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 tools/testing/selftests/mm/uffd-stress.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

--- a/tools/testing/selftests/mm/uffd-stress.c~selftests-mm-dont-fail-uffd-stress-if-too-many-cpus
+++ a/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) {
_

Patches currently in -mm which might be from jackmanb@google.com are

scripts-gdb-add-lx_per_cpu_ptr.patch