linux-kernel - [PATCH 6/6] selftests/mm: Don't fail uffd-stress if too many CPUs

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Message-ID: <20250220-mm-selftests-v1-6-9bbf57d64463@google.com>
Date: Thu, 20 Feb 2025 15:03:18 +0000
From: Brendan Jackman <jackmanb@...gle.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, Andrew Morton <akpm@...ux-foundation.org>, 
	Shuah Khan <shuah@...nel.org>
Cc: Mateusz Guzik <mjguzik@...il.com>, linux-mm@...ck.org, linux-kselftest@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Brendan Jackman <jackmanb@...gle.com>
Subject: [PATCH 6/6] 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.

Suggested-by: Mateusz Guzik <mjguzik@...il.com>
Signed-off-by: Brendan Jackman <jackmanb@...gle.com>
---
 tools/testing/selftests/mm/uffd-stress.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/testing/selftests/mm/uffd-stress.c b/tools/testing/selftests/mm/uffd-stress.c
index 1facfb79e09aa4113e344d7d90dec06a37264058..f306accbef255c79bc3eeba8b9e42161a88fc10e 100644
--- a/tools/testing/selftests/mm/uffd-stress.c
+++ b/tools/testing/selftests/mm/uffd-stress.c
@@ -453,6 +453,10 @@ int main(int argc, char **argv)
 	}
 
 	nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
+	if (nr_cpus > 32) {
+		/* Don't let calculation below go to zero. */
+		nr_cpus = 32;
+	}
 
 	nr_pages_per_cpu = bytes / page_size / nr_cpus;
 	if (!nr_pages_per_cpu) {

-- 
2.48.1.601.g30ceb7b040-goog