Re: [PATCH 14/34] common: fix pkill by running test program in a separate session

[Dave Chinner <david@fromorbit.com>]

On Tue, Feb 04, 2025 at 01:25:57PM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
> 
> Run each test program with a separate session id so that we can tell
> pkill to kill all processes of a given name, but only within our own
> session id.  This /should/ suffice to run multiple fstests on the same
> machine without one instance shooting down processes of another
> instance.

I thought you were going to drop this because pidns stuff available.
Also, because it is only check parallel that needs the pidns
isolation, and I'm not doing that external to check. Hence we can
just get rid of the 'pkill --parent' requirement because the
concurrent tests are already being run in isolated PID namespaces...

Regardless, if ppl still want to both pid session and pidns directly
into check, the code is fine.

Just one little nit:

> diff --git a/tools/run_seq_setsid b/tools/run_seq_setsid
> new file mode 100755
> index 00000000000000..5938f80e689255
> --- /dev/null
> +++ b/tools/run_seq_setsid
> @@ -0,0 +1,22 @@
> +#!/bin/bash
> +
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2025 Oracle.  All Rights Reserved.
> +#
> +# Try starting things in a new process session so that test processes have
> +# something with which to filter only their own subprocesses.
> +
> +if [ -n "${FSTESTS_ISOL}" ]; then
> +	# Allow the test to become a target of the oom killer
> +	oom_knob="/proc/self/oom_score_adj"
> +	test -w "${oom_knob}" && echo 250 > "${oom_knob}"
> +
> +	exec "$@"
> +fi
> +
> +if [ -z "$1" ] || [ "$1" = "--help" ]; then
> +	echo "Usage: $0 command [args...]"
> +	exit 1
> +fi
> +
> +FSTESTS_ISOL=setsid exec setsid "$0" "$@"

The wrapper should be called 'run_setsid' because what check is
using it for has nothing to do with what the script actually does.

With that change:

Reviewed-by: Dave Chinner <dchinner@redhat.com>
-- 
Dave Chinner
david@fromorbit.com