Increase kernel.pid_max to a higher value

While running big boxes with 72 disks it's easy to get out of PID for
all the threads needed by Ceph. Increasing the default value removes
this limitation.

Signed-off-by: Sébastien Han <sebastien.han@enovance.com>

roles/ceph-common/tasks/main.yml

@@ -36,3 +36,6 @@
 - name: Disable OSD directory parsing by updatedb
   command: updatedb -e /var/lib/ceph
   ignore_errors: true
+
+- name: Increase PID max value to a very large value
+  sysctl: name="kernel.pid_max" value=4194303 state=present sysctl_file=/etc/sysctl.conf