linux-kernel - Re: [PATCH] selftests/mm: Check for YAMA ptrace

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Message-ID: <aEhoWVH0Ka6jB8QR@kernel.org>
Date: Tue, 10 Jun 2025 20:16:09 +0300
From: Mike Rapoport <rppt@...nel.org>
To: Mark Brown <broonie@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	Shuah Khan <shuah@...nel.org>, linux-mm@...ck.org,
	linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] selftests/mm: Check for YAMA ptrace_scope configuraiton
 before modifying it

On Tue, Jun 10, 2025 at 03:07:44PM +0100, Mark Brown wrote:
> 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>

Acked-by: Mike Rapoport (Microsoft) <rppt@...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>
> 

-- 
Sincerely yours,
Mike.