Bug#968338: WARNING: CPU: 0 PID: 0 at lib/percpu-refcount.c:155 percpu_ref_switch_to_atomic_rcu+0xf8/0x120

[tobias]

Hello,

wanted to add that the issue gets triggered when running the following 
script:

#!/bin/sh
if [ -x /usr/bin/certbot ]; then
  certbot -q    --authenticator standalone \
                --installer none renew  \
                --pre-hook "service apache2 stop" \
                --post-hook "service apache2 start"
  sleep 60
  /bin/systemctl restart apache2
fi

if i run this script using previous kernel ( linux-image-4.19.0-9-amd64 
) no kernel crash is happening.

tobias.