Taken largely from the commit of the patch that added this feature:

1c2fb7f9

I'm not sure about the ordering of the options in sysctl.txt,
so I took a wild guess about where it fits.
Signed-Off-By: NHorms <horms@verge.net.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>