linux-kernel - [PATCH] selftests/mm: Check for YAMA ptrace_scope configuraiton before modifying it

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Message-Id: <20250610-selftest-mm-enable-yama-v1-1-0097b6713116@kernel.org>
Date: Tue, 10 Jun 2025 15:07:44 +0100
From: Mark Brown <broonie@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>, 
 Shuah Khan <shuah@...nel.org>, Mike Rapoport <rppt@...nel.org>
Cc: linux-mm@...ck.org, linux-kselftest@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Mark Brown <broonie@...nel.org>
Subject: [PATCH] selftests/mm: Check for YAMA ptrace_scope configuraiton
 before modifying it

When running the memfd_secret test run_vmtests.sh unconditionally tries
to confgiure the YAMA LSM's ptrace_scope configuration, leading to an error
if YAMA is not in the running kernel:

# ./run_vmtests.sh: line 432: /proc/sys/kernel/yama/ptrace_scope: No such file or directory
# # ----------------------
# # running ./memfd_secret
# # ----------------------

Check that this file is present before trying to write to it.

The indentation here is a bit odd, and it doesn't seem great that we
configure but don't restore ptrace_scope.

Signed-off-by: Mark Brown <broonie@...nel.org>
---
 tools/testing/selftests/mm/run_vmtests.sh | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
index dddd1dd8af14..33fc7fafa8f9 100755
--- a/tools/testing/selftests/mm/run_vmtests.sh
+++ b/tools/testing/selftests/mm/run_vmtests.sh
@@ -429,7 +429,9 @@ CATEGORY="vma_merge" run_test ./merge
 
 if [ -x ./memfd_secret ]
 then
-(echo 0 > /proc/sys/kernel/yama/ptrace_scope 2>&1) | tap_prefix
+if [ -f /proc/sys/kernel/yama/ptrace_scope ]; then
+	(echo 0 > /proc/sys/kernel/yama/ptrace_scope 2>&1) | tap_prefix
+fi
 CATEGORY="memfd_secret" run_test ./memfd_secret
 fi
 

---
base-commit: 19272b37aa4f83ca52bdf9c16d5d81bdd1354494
change-id: 20250605-selftest-mm-enable-yama-1541c2d2ddcd

Best regards,
-- 
Mark Brown <broonie@...nel.org>