[LTP] [PATCH] memcg/functional: check several times if the process is killed

[Cyril Hrubis]

Hi!
> On some systems it may take slightly more than one second
> to kill the memcg_process. So let's check several times if the
> process is alive.
> 
> Also removed sleep() before moving the process to the memory cgroup,
> since this looks reduntant.
> 
> Signed-off-by: Stanislav Kholmanskikh <stanislav.kholmanskikh@oracle.com>
> ---
>  .../controllers/memcg/functional/memcg_lib.sh      |   14 ++++++++++----
>  1 files changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/testcases/kernel/controllers/memcg/functional/memcg_lib.sh b/testcases/kernel/controllers/memcg/functional/memcg_lib.sh
> index 9b9b0fd..93c61a1 100755
> --- a/testcases/kernel/controllers/memcg/functional/memcg_lib.sh
> +++ b/testcases/kernel/controllers/memcg/functional/memcg_lib.sh
> @@ -220,14 +220,20 @@ test_proc_kill()
>  
>  	$TEST_PATH/memcg_process $2 -s $3 &
>  	pid=$!
> -	sleep 1

This sleep sure is useless.

>  	echo $pid > tasks
>  
>  	kill -s USR1 $pid 2> /dev/null
> -	sleep 1
> -
> -	ps -p $pid > /dev/null 2> /dev/null
> -	if [ $? -ne 0 ]; then
> +	pid_exists=1
> +	for tpk_iter in $(seq 5); do
> +	    if ! kill $pid 2> /dev/null; then
> +		pid_exists=0
> +		break
> +	    fi
> +	    sleep 1
> +	done

This does no seem right to me. The original code send a SIGUSR1 signal
to the memcg_process which caused it to allocate memory which supposedly
provokes OOM to kill it. Hence the sleep 1 after the kill -s USR $pid.

Now this code hammers the memcg_process with SIGKILL instead.

As far as I can tell the right thing to do here is to wait with
reasonable timeout for the memcg_process to become zombie and only kill
it if that hasn't happened. Or did I miss something?

> +	if [ $pid_exists -eq 0 ]; then
>  		wait $pid
>  		if [ $? -eq 1 ]; then
>  			result $FAIL "process $pid is killed by error"
> -- 
> 1.7.1
> 
> 
> -- 
> Mailing list info: https://lists.linux.it/listinfo/ltp

-- 
Cyril Hrubis
chrubis@suse.cz