host: Force memory overcommitment
host: Force memory overcommitment

This patch sets /proc/sys/vm/overcommit_memory to 1, which enables
virtual memory overcommit and disables heuristic based denial of
memory allocations (using these heuristics is the default setting of
0).

Due to the large virtual memory allocations that Go uses, and the
fact that flynn-host frequently forks, the default heuristics can
cause errors like this:

    fork/exec /sbin/zfs: cannot allocate memory

Since we rely on the OOM killer anyway, there's no need to
arbitrarily cause memory allocations to fail and we can turn off the
heuristics entirely.

Signed-off-by: Jonathan Rudenberg <3692bfa45759a67d83aedf0045f6cb635a966abf@titanous.com>

lmars/flynn,flynn/flynn,philiplb/flynn,flynn/flynn,flynn/flynn,philiplb/flynn,philiplb/flynn,flynn/flynn,flynn/flynn,philiplb/flynn,lmars/flynn,lmars/flynn,philiplb/flynn,lmars/flynn,lmars/flynn